Reduce the number of connects when fetching
[gitweb.git] / diff-lib.c
index 13b216f2733763b4e6cc6a3c37ff2624d7f55266..d85d8f34ba055ad7e02bf5d61ae4a675ce0be1d3 100644 (file)
 /*
  * Copyright (C) 2005 Junio C Hamano
  */
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <signal.h>
 #include "cache.h"
 #include "quote.h"
+#include "commit.h"
 #include "diff.h"
 #include "diffcore.h"
-#include "xdiff-interface.h"
+#include "revision.h"
+#include "cache-tree.h"
+#include "path-list.h"
 
-static int use_size_cache;
-
-int diff_rename_limit_default = -1;
-
-int git_diff_config(const char *var, const char *value)
-{
-       if (!strcmp(var, "diff.renamelimit")) {
-               diff_rename_limit_default = git_config_int(var, value);
-               return 0;
-       }
-
-       return git_default_config(var, value);
-}
-
-static char *quote_one(const char *str)
-{
-       int needlen;
-       char *xp;
-
-       if (!str)
-               return NULL;
-       needlen = quote_c_style(str, NULL, NULL, 0);
-       if (!needlen)
-               return strdup(str);
-       xp = xmalloc(needlen + 1);
-       quote_c_style(str, xp, NULL, 0);
-       return xp;
-}
-
-static char *quote_two(const char *one, const char *two)
-{
-       int need_one = quote_c_style(one, NULL, NULL, 1);
-       int need_two = quote_c_style(two, NULL, NULL, 1);
-       char *xp;
-
-       if (need_one + need_two) {
-               if (!need_one) need_one = strlen(one);
-               if (!need_two) need_one = strlen(two);
-
-               xp = xmalloc(need_one + need_two + 3);
-               xp[0] = '"';
-               quote_c_style(one, xp + 1, NULL, 1);
-               quote_c_style(two, xp + need_one + 1, NULL, 1);
-               strcpy(xp + need_one + need_two + 1, "\"");
-               return xp;
-       }
-       need_one = strlen(one);
-       need_two = strlen(two);
-       xp = xmalloc(need_one + need_two + 1);
-       strcpy(xp, one);
-       strcpy(xp + need_one, two);
-       return xp;
-}
-
-static const char *external_diff(void)
-{
-       static const char *external_diff_cmd = NULL;
-       static int done_preparing = 0;
-
-       if (done_preparing)
-               return external_diff_cmd;
-       external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
-       done_preparing = 1;
-       return external_diff_cmd;
-}
-
-#define TEMPFILE_PATH_LEN              50
-
-static struct diff_tempfile {
-       const char *name; /* filename external diff should read from */
-       char hex[41];
-       char mode[10];
-       char tmp_path[TEMPFILE_PATH_LEN];
-} diff_temp[2];
-
-static int count_lines(const char *data, int size)
-{
-       int count, ch, completely_empty = 1, nl_just_seen = 0;
-       count = 0;
-       while (0 < size--) {
-               ch = *data++;
-               if (ch == '\n') {
-                       count++;
-                       nl_just_seen = 1;
-                       completely_empty = 0;
-               }
-               else {
-                       nl_just_seen = 0;
-                       completely_empty = 0;
-               }
-       }
-       if (completely_empty)
-               return 0;
-       if (!nl_just_seen)
-               count++; /* no trailing newline */
-       return count;
-}
-
-static void print_line_count(int count)
-{
-       switch (count) {
-       case 0:
-               printf("0,0");
-               break;
-       case 1:
-               printf("1");
-               break;
-       default:
-               printf("1,%d", count);
-               break;
-       }
-}
-
-static void copy_file(int prefix, const char *data, int size)
-{
-       int ch, nl_just_seen = 1;
-       while (0 < size--) {
-               ch = *data++;
-               if (nl_just_seen)
-                       putchar(prefix);
-               putchar(ch);
-               if (ch == '\n')
-                       nl_just_seen = 1;
-               else
-                       nl_just_seen = 0;
-       }
-       if (!nl_just_seen)
-               printf("\n\\ No newline at end of file\n");
-}
-
-static void emit_rewrite_diff(const char *name_a,
-                             const char *name_b,
-                             struct diff_filespec *one,
-                             struct diff_filespec *two)
-{
-       int lc_a, lc_b;
-       diff_populate_filespec(one, 0);
-       diff_populate_filespec(two, 0);
-       lc_a = count_lines(one->data, one->size);
-       lc_b = count_lines(two->data, two->size);
-       printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
-       print_line_count(lc_a);
-       printf(" +");
-       print_line_count(lc_b);
-       printf(" @@\n");
-       if (lc_a)
-               copy_file('-', one->data, one->size);
-       if (lc_b)
-               copy_file('+', two->data, two->size);
-}
+/*
+ * diff-files
+ */
 
-static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
+static int read_directory(const char *path, struct path_list *list)
 {
-       if (!DIFF_FILE_VALID(one)) {
-               mf->ptr = ""; /* does not matter */
-               mf->size = 0;
-               return 0;
-       }
-       else if (diff_populate_filespec(one, 0))
-               return -1;
-       mf->ptr = one->data;
-       mf->size = one->size;
-       return 0;
-}
+       DIR *dir;
+       struct dirent *e;
 
-struct emit_callback {
-       const char **label_path;
-};
+       if (!(dir = opendir(path)))
+               return error("Could not open directory %s", path);
 
-static int fn_out(void *priv, mmbuffer_t *mb, int nbuf)
-{
-       int i;
-       struct emit_callback *ecbdata = priv;
+       while ((e = readdir(dir)))
+               if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
+                       path_list_insert(e->d_name, list);
 
-       if (ecbdata->label_path[0]) {
-               printf("--- %s\n", ecbdata->label_path[0]);
-               printf("+++ %s\n", ecbdata->label_path[1]);
-               ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
-       }
-       for (i = 0; i < nbuf; i++)
-               if (!fwrite(mb[i].ptr, mb[i].size, 1, stdout))
-                       return -1;
+       closedir(dir);
        return 0;
 }
 
-static char *pprint_rename(const char *a, const char *b)
+static int get_mode(const char *path, int *mode)
 {
-       const char *old = a;
-       const char *new = b;
-       char *name = NULL;
-       int pfx_length, sfx_length;
-       int len_a = strlen(a);
-       int len_b = strlen(b);
-
-       /* Find common prefix */
-       pfx_length = 0;
-       while (*old && *new && *old == *new) {
-               if (*old == '/')
-                       pfx_length = old - a + 1;
-               old++;
-               new++;
-       }
-
-       /* Find common suffix */
-       old = a + len_a;
-       new = b + len_b;
-       sfx_length = 0;
-       while (a <= old && b <= new && *old == *new) {
-               if (*old == '/')
-                       sfx_length = len_a - (old - a);
-               old--;
-               new--;
-       }
-
-       /*
-        * pfx{mid-a => mid-b}sfx
-        * {pfx-a => pfx-b}sfx
-        * pfx{sfx-a => sfx-b}
-        * name-a => name-b
-        */
-       if (pfx_length + sfx_length) {
-               name = xmalloc(len_a + len_b - pfx_length - sfx_length + 7);
-               sprintf(name, "%.*s{%.*s => %.*s}%s",
-                       pfx_length, a,
-                       len_a - pfx_length - sfx_length, a + pfx_length,
-                       len_b - pfx_length - sfx_length, b + pfx_length,
-                       a + len_a - sfx_length);
-       }
-       else {
-               name = xmalloc(len_a + len_b + 5);
-               sprintf(name, "%s => %s", a, b);
-       }
-       return name;
-}
+       struct stat st;
 
-struct diffstat_t {
-       struct xdiff_emit_state xm;
-
-       int nr;
-       int alloc;
-       struct diffstat_file {
-               char *name;
-               unsigned is_unmerged:1;
-               unsigned is_binary:1;
-               unsigned is_renamed:1;
-               unsigned int added, deleted;
-       } **files;
-};
-
-static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
-                                         const char *name_a,
-                                         const char *name_b)
-{
-       struct diffstat_file *x;
-       x = xcalloc(sizeof (*x), 1);
-       if (diffstat->nr == diffstat->alloc) {
-               diffstat->alloc = alloc_nr(diffstat->alloc);
-               diffstat->files = xrealloc(diffstat->files,
-                               diffstat->alloc * sizeof(x));
-       }
-       diffstat->files[diffstat->nr++] = x;
-       if (name_b) {
-               x->name = pprint_rename(name_a, name_b);
-               x->is_renamed = 1;
-       }
+       if (!path || !strcmp(path, "/dev/null"))
+               *mode = 0;
+       else if (!strcmp(path, "-"))
+               *mode = ntohl(create_ce_mode(0666));
+       else if (stat(path, &st))
+               return error("Could not access '%s'", path);
        else
-               x->name = strdup(name_a);
-       return x;
+               *mode = st.st_mode;
+       return 0;
 }
 
-static void diffstat_consume(void *priv, char *line, unsigned long len)
+static int queue_diff(struct diff_options *o,
+               const char *name1, const char *name2)
 {
-       struct diffstat_t *diffstat = priv;
-       struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
+       int mode1 = 0, mode2 = 0;
 
-       if (line[0] == '+')
-               x->added++;
-       else if (line[0] == '-')
-               x->deleted++;
-}
+       if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
+               return -1;
 
-static const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
-static const char minuses[]= "----------------------------------------------------------------------";
+       if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
+               return error("file/directory conflict: %s, %s", name1, name2);
 
-static void show_stats(struct diffstat_t* data)
-{
-       char *prefix = "";
-       int i, len, add, del, total, adds = 0, dels = 0;
-       int max, max_change = 0, max_len = 0;
-       int total_files = data->nr;
+       if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
+               char buffer1[PATH_MAX], buffer2[PATH_MAX];
+               struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
+               int len1 = 0, len2 = 0, i1, i2, ret = 0;
 
-       if (data->nr == 0)
-               return;
+               if (name1 && read_directory(name1, &p1))
+                       return -1;
+               if (name2 && read_directory(name2, &p2)) {
+                       path_list_clear(&p1, 0);
+                       return -1;
+               }
 
-       for (i = 0; i < data->nr; i++) {
-               struct diffstat_file *file = data->files[i];
+               if (name1) {
+                       len1 = strlen(name1);
+                       if (len1 > 0 && name1[len1 - 1] == '/')
+                               len1--;
+                       memcpy(buffer1, name1, len1);
+                       buffer1[len1++] = '/';
+               }
 
-               len = strlen(file->name);
-               if (max_len < len)
-                       max_len = len;
+               if (name2) {
+                       len2 = strlen(name2);
+                       if (len2 > 0 && name2[len2 - 1] == '/')
+                               len2--;
+                       memcpy(buffer2, name2, len2);
+                       buffer2[len2++] = '/';
+               }
 
-               if (file->is_binary || file->is_unmerged)
-                       continue;
-               if (max_change < file->added + file->deleted)
-                       max_change = file->added + file->deleted;
-       }
+               for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
+                       const char *n1, *n2;
+                       int comp;
 
-       for (i = 0; i < data->nr; i++) {
-               char *name = data->files[i]->name;
-               int added = data->files[i]->added;
-               int deleted = data->files[i]->deleted;
+                       if (i1 == p1.nr)
+                               comp = 1;
+                       else if (i2 == p2.nr)
+                               comp = -1;
+                       else
+                               comp = strcmp(p1.items[i1].path,
+                                       p2.items[i2].path);
+
+                       if (comp > 0)
+                               n1 = NULL;
+                       else {
+                               n1 = buffer1;
+                               strncpy(buffer1 + len1, p1.items[i1++].path,
+                                               PATH_MAX - len1);
+                       }
 
-               if (0 < (len = quote_c_style(name, NULL, NULL, 0))) {
-                       char *qname = xmalloc(len + 1);
-                       quote_c_style(name, qname, NULL, 0);
-                       free(name);
-                       data->files[i]->name = name = qname;
-               }
+                       if (comp < 0)
+                               n2 = NULL;
+                       else {
+                               n2 = buffer2;
+                               strncpy(buffer2 + len2, p2.items[i2++].path,
+                                               PATH_MAX - len2);
+                       }
 
-               /*
-                * "scale" the filename
-                */
-               len = strlen(name);
-               max = max_len;
-               if (max > 50)
-                       max = 50;
-               if (len > max) {
-                       char *slash;
-                       prefix = "...";
-                       max -= 3;
-                       name += len - max;
-                       slash = strchr(name, '/');
-                       if (slash)
-                               name = slash;
+                       ret = queue_diff(o, n1, n2);
                }
-               len = max;
+               path_list_clear(&p1, 0);
+               path_list_clear(&p2, 0);
 
-               /*
-                * scale the add/delete
-                */
-               max = max_change;
-               if (max + len > 70)
-                       max = 70 - len;
+               return ret;
+       } else {
+               struct diff_filespec *d1, *d2;
 
-               if (data->files[i]->is_binary) {
-                       printf(" %s%-*s |  Bin\n", prefix, len, name);
-                       goto free_diffstat_file;
-               }
-               else if (data->files[i]->is_unmerged) {
-                       printf(" %s%-*s |  Unmerged\n", prefix, len, name);
-                       goto free_diffstat_file;
-               }
-               else if (!data->files[i]->is_renamed &&
-                        (added + deleted == 0)) {
-                       total_files--;
-                       goto free_diffstat_file;
+               if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
+                       unsigned tmp;
+                       const char *tmp_c;
+                       tmp = mode1; mode1 = mode2; mode2 = tmp;
+                       tmp_c = name1; name1 = name2; name2 = tmp_c;
                }
 
-               add = added;
-               del = deleted;
-               total = add + del;
-               adds += add;
-               dels += del;
+               if (!name1)
+                       name1 = "/dev/null";
+               if (!name2)
+                       name2 = "/dev/null";
+               d1 = alloc_filespec(name1);
+               d2 = alloc_filespec(name2);
+               fill_filespec(d1, null_sha1, mode1);
+               fill_filespec(d2, null_sha1, mode2);
 
-               if (max_change > 0) {
-                       total = (total * max + max_change / 2) / max_change;
-                       add = (add * max + max_change / 2) / max_change;
-                       del = total - add;
-               }
-               printf(" %s%-*s |%5d %.*s%.*s\n", prefix,
-                               len, name, added + deleted,
-                               add, pluses, del, minuses);
-       free_diffstat_file:
-               free(data->files[i]->name);
-               free(data->files[i]);
+               diff_queue(&diff_queued_diff, d1, d2);
+               return 0;
        }
-       free(data->files);
-       printf(" %d files changed, %d insertions(+), %d deletions(-)\n",
-                       total_files, adds, dels);
 }
 
-#define FIRST_FEW_BYTES 8000
-static int mmfile_is_binary(mmfile_t *mf)
+/*
+ * Does the path name a blob in the working tree, or a directory
+ * in the working tree?
+ */
+static int is_in_index(const char *path)
 {
-       long sz = mf->size;
-       if (FIRST_FEW_BYTES < sz)
-               sz = FIRST_FEW_BYTES;
-       if (memchr(mf->ptr, 0, sz))
+       int len, pos;
+       struct cache_entry *ce;
+
+       len = strlen(path);
+       while (path[len-1] == '/')
+               len--;
+       if (!len)
+               return 1; /* "." */
+       pos = cache_name_pos(path, len);
+       if (0 <= pos)
                return 1;
+       pos = -1 - pos;
+       while (pos < active_nr) {
+               ce = active_cache[pos++];
+               if (ce_namelen(ce) <= len ||
+                   strncmp(ce->name, path, len) ||
+                   (ce->name[len] > '/'))
+                       break; /* path cannot be a prefix */
+               if (ce->name[len] == '/')
+                       return 1;
+       }
        return 0;
 }
 
-static void builtin_diff(const char *name_a,
-                        const char *name_b,
-                        struct diff_filespec *one,
-                        struct diff_filespec *two,
-                        const char *xfrm_msg,
-                        int complete_rewrite)
-{
-       mmfile_t mf1, mf2;
-       const char *lbl[2];
-       char *a_one, *b_two;
-
-       a_one = quote_two("a/", name_a);
-       b_two = quote_two("b/", name_b);
-       lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
-       lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-       printf("diff --git %s %s\n", a_one, b_two);
-       if (lbl[0][0] == '/') {
-               /* /dev/null */
-               printf("new file mode %06o\n", two->mode);
-               if (xfrm_msg && xfrm_msg[0])
-                       puts(xfrm_msg);
-       }
-       else if (lbl[1][0] == '/') {
-               printf("deleted file mode %06o\n", one->mode);
-               if (xfrm_msg && xfrm_msg[0])
-                       puts(xfrm_msg);
+static int handle_diff_files_args(struct rev_info *revs,
+                                 int argc, const char **argv,
+                                 unsigned int *options)
+{
+       *options = 0;
+
+       /* revs->max_count == -2 means --no-index */
+       while (1 < argc && argv[1][0] == '-') {
+               if (!strcmp(argv[1], "--base"))
+                       revs->max_count = 1;
+               else if (!strcmp(argv[1], "--ours"))
+                       revs->max_count = 2;
+               else if (!strcmp(argv[1], "--theirs"))
+                       revs->max_count = 3;
+               else if (!strcmp(argv[1], "-n") ||
+                               !strcmp(argv[1], "--no-index")) {
+                       revs->max_count = -2;
+                       DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
+                       DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
+               }
+               else if (!strcmp(argv[1], "-q"))
+                       *options |= DIFF_SILENT_ON_REMOVED;
+               else
+                       return error("invalid option: %s", argv[1]);
+               argv++; argc--;
        }
-       else {
-               if (one->mode != two->mode) {
-                       printf("old mode %06o\n", one->mode);
-                       printf("new mode %06o\n", two->mode);
-               }
-               if (xfrm_msg && xfrm_msg[0])
-                       puts(xfrm_msg);
+
+       if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
                /*
-                * we do not run diff between different kind
-                * of objects.
+                * If two files are specified, and at least one is untracked,
+                * default to no-index.
                 */
-               if ((one->mode ^ two->mode) & S_IFMT)
-                       goto free_ab_and_return;
-               if (complete_rewrite) {
-                       emit_rewrite_diff(name_a, name_b, one, two);
-                       goto free_ab_and_return;
+               read_cache();
+               if (!is_in_index(revs->diffopt.paths[0]) ||
+                                       !is_in_index(revs->diffopt.paths[1])) {
+                       revs->max_count = -2;
+                       DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
                }
        }
 
-       if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-               die("unable to read files to diff");
-
-       if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
-               printf("Binary files %s and %s differ\n", lbl[0], lbl[1]);
-       else {
-               /* Crazy xdl interfaces.. */
-               const char *diffopts = getenv("GIT_DIFF_OPTS");
-               xpparam_t xpp;
-               xdemitconf_t xecfg;
-               xdemitcb_t ecb;
-               struct emit_callback ecbdata;
-
-               ecbdata.label_path = lbl;
-               xpp.flags = XDF_NEED_MINIMAL;
-               xecfg.ctxlen = 3;
-               xecfg.flags = XDL_EMIT_FUNCNAMES;
-               if (!diffopts)
-                       ;
-               else if (!strncmp(diffopts, "--unified=", 10))
-                       xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
-               else if (!strncmp(diffopts, "-u", 2))
-                       xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-               ecb.outf = fn_out;
-               ecb.priv = &ecbdata;
-               xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
-       }
-
- free_ab_and_return:
-       free(a_one);
-       free(b_two);
-       return;
-}
-
-static void builtin_diffstat(const char *name_a, const char *name_b,
-                            struct diff_filespec *one,
-                            struct diff_filespec *two,
-                            struct diffstat_t *diffstat)
-{
-       mmfile_t mf1, mf2;
-       struct diffstat_file *data;
-
-       data = diffstat_add(diffstat, name_a, name_b);
-
-       if (!one || !two) {
-               data->is_unmerged = 1;
-               return;
-       }
-
-       if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-               die("unable to read files to diff");
-
-       if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
-               data->is_binary = 1;
-       else {
-               /* Crazy xdl interfaces.. */
-               xpparam_t xpp;
-               xdemitconf_t xecfg;
-               xdemitcb_t ecb;
-
-               xpp.flags = XDF_NEED_MINIMAL;
-               xecfg.ctxlen = 0;
-               xecfg.flags = 0;
-               ecb.outf = xdiff_outf;
-               ecb.priv = diffstat;
-               xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
-       }
-}
+       /*
+        * Make sure there are NO revision (i.e. pending object) parameter,
+        * rev.max_count is reasonable (0 <= n <= 3),
+        * there is no other revision filtering parameters.
+        */
+       if (revs->pending.nr || revs->max_count > 3 ||
+           revs->min_age != -1 || revs->max_age != -1)
+               return error("no revision allowed with diff-files");
 
-struct diff_filespec *alloc_filespec(const char *path)
-{
-       int namelen = strlen(path);
-       struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
+       if (revs->max_count == -1 &&
+           (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
+               revs->combine_merges = revs->dense_combined_merges = 1;
 
-       memset(spec, 0, sizeof(*spec));
-       spec->path = (char *)(spec + 1);
-       memcpy(spec->path, path, namelen+1);
-       return spec;
-}
-
-void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
-                  unsigned short mode)
-{
-       if (mode) {
-               spec->mode = canon_mode(mode);
-               memcpy(spec->sha1, sha1, 20);
-               spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
-       }
+       return 0;
 }
 
-/*
- * Given a name and sha1 pair, if the dircache tells us the file in
- * the work tree has that object contents, return true, so that
- * prepare_temp_file() does not have to inflate and extract.
- */
-static int work_tree_matches(const char *name, const unsigned char *sha1)
+static int is_outside_repo(const char *path, int nongit, const char *prefix)
 {
-       struct cache_entry *ce;
-       struct stat st;
-       int pos, len;
-
-       /* We do not read the cache ourselves here, because the
-        * benchmark with my previous version that always reads cache
-        * shows that it makes things worse for diff-tree comparing
-        * two linux-2.6 kernel trees in an already checked out work
-        * tree.  This is because most diff-tree comparisons deal with
-        * only a small number of files, while reading the cache is
-        * expensive for a large project, and its cost outweighs the
-        * savings we get by not inflating the object to a temporary
-        * file.  Practically, this code only helps when we are used
-        * by diff-cache --cached, which does read the cache before
-        * calling us.
-        */
-       if (!active_cache)
-               return 0;
-
-       len = strlen(name);
-       pos = cache_name_pos(name, len);
-       if (pos < 0)
-               return 0;
-       ce = active_cache[pos];
-       if ((lstat(name, &st) < 0) ||
-           !S_ISREG(st.st_mode) || /* careful! */
-           ce_match_stat(ce, &st, 0) ||
-           memcmp(sha1, ce->sha1, 20))
+       int i;
+       if (nongit || !strcmp(path, "-") || is_absolute_path(path))
+               return 1;
+       if (prefixcmp(path, "../"))
                return 0;
-       /* we return 1 only when we can stat, it is a regular file,
-        * stat information matches, and sha1 recorded in the cache
-        * matches.  I.e. we know the file in the work tree really is
-        * the same as the <name, sha1> pair.
-        */
-       return 1;
-}
-
-static struct sha1_size_cache {
-       unsigned char sha1[20];
-       unsigned long size;
-} **sha1_size_cache;
-static int sha1_size_cache_nr, sha1_size_cache_alloc;
-
-static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
-                                                int find_only,
-                                                unsigned long size)
-{
-       int first, last;
-       struct sha1_size_cache *e;
-
-       first = 0;
-       last = sha1_size_cache_nr;
-       while (last > first) {
-               int cmp, next = (last + first) >> 1;
-               e = sha1_size_cache[next];
-               cmp = memcmp(e->sha1, sha1, 20);
-               if (!cmp)
-                       return e;
-               if (cmp < 0) {
-                       last = next;
-                       continue;
-               }
-               first = next+1;
-       }
-       /* not found */
-       if (find_only)
-               return NULL;
-       /* insert to make it at "first" */
-       if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
-               sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
-               sha1_size_cache = xrealloc(sha1_size_cache,
-                                          sha1_size_cache_alloc *
-                                          sizeof(*sha1_size_cache));
+       if (!prefix)
+               return 1;
+       for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
+               while (i > 0 && prefix[i - 1] != '/')
+                       i--;
+               if (--i < 0)
+                       return 1;
+               path += 3;
        }
-       sha1_size_cache_nr++;
-       if (first < sha1_size_cache_nr)
-               memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
-                       (sha1_size_cache_nr - first - 1) *
-                       sizeof(*sha1_size_cache));
-       e = xmalloc(sizeof(struct sha1_size_cache));
-       sha1_size_cache[first] = e;
-       memcpy(e->sha1, sha1, 20);
-       e->size = size;
-       return e;
+       return 0;
 }
 
-/*
- * While doing rename detection and pickaxe operation, we may need to
- * grab the data for the blob (or file) for our own in-core comparison.
- * diff_filespec has data and size fields for this purpose.
- */
-int diff_populate_filespec(struct diff_filespec *s, int size_only)
+int setup_diff_no_index(struct rev_info *revs,
+               int argc, const char ** argv, int nongit, const char *prefix)
 {
-       int err = 0;
-       if (!DIFF_FILE_VALID(s))
-               die("internal error: asking to populate invalid file.");
-       if (S_ISDIR(s->mode))
+       int i;
+       for (i = 1; i < argc; i++)
+               if (argv[i][0] != '-' || argv[i][1] == '\0')
+                       break;
+               else if (!strcmp(argv[i], "--")) {
+                       i++;
+                       break;
+               } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
+                       i = argc - 3;
+                       DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
+                       break;
+               }
+       if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
+                               !is_outside_repo(argv[i], nongit, prefix)))
                return -1;
 
-       if (!use_size_cache)
-               size_only = 0;
-
-       if (s->data)
-               return err;
-       if (!s->sha1_valid ||
-           work_tree_matches(s->path, s->sha1)) {
-               struct stat st;
-               int fd;
-               if (lstat(s->path, &st) < 0) {
-                       if (errno == ENOENT) {
-                       err_empty:
-                               err = -1;
-                       empty:
-                               s->data = "";
-                               s->size = 0;
-                               return err;
-                       }
-               }
-               s->size = st.st_size;
-               if (!s->size)
-                       goto empty;
-               if (size_only)
-                       return 0;
-               if (S_ISLNK(st.st_mode)) {
-                       int ret;
-                       s->data = xmalloc(s->size);
-                       s->should_free = 1;
-                       ret = readlink(s->path, s->data, s->size);
-                       if (ret < 0) {
-                               free(s->data);
-                               goto err_empty;
-                       }
-                       return 0;
-               }
-               fd = open(s->path, O_RDONLY);
-               if (fd < 0)
-                       goto err_empty;
-               s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
-               close(fd);
-               if (s->data == MAP_FAILED)
-                       goto err_empty;
-               s->should_munmap = 1;
-       }
-       else {
-               char type[20];
-               struct sha1_size_cache *e;
-
-               if (size_only) {
-                       e = locate_size_cache(s->sha1, 1, 0);
-                       if (e) {
-                               s->size = e->size;
-                               return 0;
-                       }
-                       if (!sha1_object_info(s->sha1, type, &s->size))
-                               locate_size_cache(s->sha1, 0, s->size);
-               }
+       diff_setup(&revs->diffopt);
+       for (i = 1; i < argc - 2; )
+               if (!strcmp(argv[i], "--no-index"))
+                       i++;
                else {
-                       s->data = read_sha1_file(s->sha1, type, &s->size);
-                       s->should_free = 1;
+                       int j = diff_opt_parse(&revs->diffopt,
+                                       argv + i, argc - i);
+                       if (!j)
+                               die("invalid diff option/value: %s", argv[i]);
+                       i += j;
+               }
+
+       if (prefix) {
+               int len = strlen(prefix);
+
+               revs->diffopt.paths = xcalloc(2, sizeof(char*));
+               for (i = 0; i < 2; i++) {
+                       const char *p = argv[argc - 2 + i];
+                       /*
+                        * stdin should be spelled as '-'; if you have
+                        * path that is '-', spell it as ./-.
+                        */
+                       p = (strcmp(p, "-")
+                            ? xstrdup(prefix_filename(prefix, len, p))
+                            : p);
+                       revs->diffopt.paths[i] = p;
                }
        }
+       else
+               revs->diffopt.paths = argv + argc - 2;
+       revs->diffopt.nr_paths = 2;
+       DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
+       revs->max_count = -2;
+       if (diff_setup_done(&revs->diffopt) < 0)
+               die("diff_setup_done failed");
        return 0;
 }
 
-void diff_free_filespec_data(struct diff_filespec *s)
+int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
 {
-       if (s->should_free)
-               free(s->data);
-       else if (s->should_munmap)
-               munmap(s->data, s->size);
-       s->should_free = s->should_munmap = 0;
-       s->data = NULL;
-       free(s->cnt_data);
-       s->cnt_data = NULL;
-}
+       unsigned int options;
 
-static void prep_temp_blob(struct diff_tempfile *temp,
-                          void *blob,
-                          unsigned long size,
-                          const unsigned char *sha1,
-                          int mode)
-{
-       int fd;
-
-       fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
-       if (fd < 0)
-               die("unable to create temp-file");
-       if (write(fd, blob, size) != size)
-               die("unable to write temp-file");
-       close(fd);
-       temp->name = temp->tmp_path;
-       strcpy(temp->hex, sha1_to_hex(sha1));
-       temp->hex[40] = 0;
-       sprintf(temp->mode, "%06o", mode);
-}
+       if (handle_diff_files_args(revs, argc, argv, &options))
+               return -1;
 
-static void prepare_temp_file(const char *name,
-                             struct diff_tempfile *temp,
-                             struct diff_filespec *one)
-{
-       if (!DIFF_FILE_VALID(one)) {
-       not_a_valid_file:
-               /* A '-' entry produces this for file-2, and
-                * a '+' entry produces this for file-1.
+       if (DIFF_OPT_TST(&revs->diffopt, NO_INDEX)) {
+               if (revs->diffopt.nr_paths != 2)
+                       return error("need two files/directories with --no-index");
+               if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
+                               revs->diffopt.paths[1]))
+                       return -1;
+               diffcore_std(&revs->diffopt);
+               diff_flush(&revs->diffopt);
+               /*
+                * The return code for --no-index imitates diff(1):
+                * 0 = no changes, 1 = changes, else error
                 */
-               temp->name = "/dev/null";
-               strcpy(temp->hex, ".");
-               strcpy(temp->mode, ".");
-               return;
+               return revs->diffopt.found_changes;
        }
 
-       if (!one->sha1_valid ||
-           work_tree_matches(name, one->sha1)) {
-               struct stat st;
-               if (lstat(name, &st) < 0) {
-                       if (errno == ENOENT)
-                               goto not_a_valid_file;
-                       die("stat(%s): %s", name, strerror(errno));
-               }
-               if (S_ISLNK(st.st_mode)) {
-                       int ret;
-                       char buf[PATH_MAX + 1]; /* ought to be SYMLINK_MAX */
-                       if (sizeof(buf) <= st.st_size)
-                               die("symlink too long: %s", name);
-                       ret = readlink(name, buf, st.st_size);
-                       if (ret < 0)
-                               die("readlink(%s)", name);
-                       prep_temp_blob(temp, buf, st.st_size,
-                                      (one->sha1_valid ?
-                                       one->sha1 : null_sha1),
-                                      (one->sha1_valid ?
-                                       one->mode : S_IFLNK));
-               }
-               else {
-                       /* we can borrow from the file in the work tree */
-                       temp->name = name;
-                       if (!one->sha1_valid)
-                               strcpy(temp->hex, sha1_to_hex(null_sha1));
-                       else
-                               strcpy(temp->hex, sha1_to_hex(one->sha1));
-                       /* Even though we may sometimes borrow the
-                        * contents from the work tree, we always want
-                        * one->mode.  mode is trustworthy even when
-                        * !(one->sha1_valid), as long as
-                        * DIFF_FILE_VALID(one).
-                        */
-                       sprintf(temp->mode, "%06o", one->mode);
-               }
-               return;
-       }
-       else {
-               if (diff_populate_filespec(one, 0))
-                       die("cannot read data blob for %s", one->path);
-               prep_temp_blob(temp, one->data, one->size,
-                              one->sha1, one->mode);
+       if (read_cache() < 0) {
+               perror("read_cache");
+               return -1;
        }
+       return run_diff_files(revs, options);
 }
 
-static void remove_tempfile(void)
+int run_diff_files(struct rev_info *revs, unsigned int option)
 {
-       int i;
+       int entries, i;
+       int diff_unmerged_stage = revs->max_count;
+       int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
+       unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
+                             ? CE_MATCH_RACY_IS_DIRTY : 0);
 
-       for (i = 0; i < 2; i++)
-               if (diff_temp[i].name == diff_temp[i].tmp_path) {
-                       unlink(diff_temp[i].name);
-                       diff_temp[i].name = NULL;
-               }
-}
-
-static void remove_tempfile_on_signal(int signo)
-{
-       remove_tempfile();
-       signal(SIGINT, SIG_DFL);
-       raise(signo);
-}
+       if (diff_unmerged_stage < 0)
+               diff_unmerged_stage = 2;
+       entries = active_nr;
+       for (i = 0; i < entries; i++) {
+               struct stat st;
+               unsigned int oldmode, newmode;
+               struct cache_entry *ce = active_cache[i];
+               int changed;
 
-static int spawn_prog(const char *pgm, const char **arg)
-{
-       pid_t pid;
-       int status;
-
-       fflush(NULL);
-       pid = fork();
-       if (pid < 0)
-               die("unable to fork");
-       if (!pid) {
-               execvp(pgm, (char *const*) arg);
-               exit(255);
-       }
+               if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
+                       DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
+                       break;
 
-       while (waitpid(pid, &status, 0) < 0) {
-               if (errno == EINTR)
+               if (!ce_path_match(ce, revs->prune_data))
                        continue;
-               return -1;
-       }
 
-       /* Earlier we did not check the exit status because
-        * diff exits non-zero if files are different, and
-        * we are not interested in knowing that.  It was a
-        * mistake which made it harder to quit a diff-*
-        * session that uses the git-apply-patch-script as
-        * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
-        * should also exit non-zero only when it wants to
-        * abort the entire diff-* session.
-        */
-       if (WIFEXITED(status) && !WEXITSTATUS(status))
-               return 0;
-       return -1;
-}
-
-/* An external diff command takes:
- *
- * diff-cmd name infile1 infile1-sha1 infile1-mode \
- *               infile2 infile2-sha1 infile2-mode [ rename-to ]
- *
- */
-static void run_external_diff(const char *pgm,
-                             const char *name,
-                             const char *other,
-                             struct diff_filespec *one,
-                             struct diff_filespec *two,
-                             const char *xfrm_msg,
-                             int complete_rewrite)
-{
-       const char *spawn_arg[10];
-       struct diff_tempfile *temp = diff_temp;
-       int retval;
-       static int atexit_asked = 0;
-       const char *othername;
-       const char **arg = &spawn_arg[0];
-
-       othername = (other? other : name);
-       if (one && two) {
-               prepare_temp_file(name, &temp[0], one);
-               prepare_temp_file(othername, &temp[1], two);
-               if (! atexit_asked &&
-                   (temp[0].name == temp[0].tmp_path ||
-                    temp[1].name == temp[1].tmp_path)) {
-                       atexit_asked = 1;
-                       atexit(remove_tempfile);
-               }
-               signal(SIGINT, remove_tempfile_on_signal);
-       }
-
-       if (one && two) {
-               *arg++ = pgm;
-               *arg++ = name;
-               *arg++ = temp[0].name;
-               *arg++ = temp[0].hex;
-               *arg++ = temp[0].mode;
-               *arg++ = temp[1].name;
-               *arg++ = temp[1].hex;
-               *arg++ = temp[1].mode;
-               if (other) {
-                       *arg++ = other;
-                       *arg++ = xfrm_msg;
-               }
-       } else {
-               *arg++ = pgm;
-               *arg++ = name;
-       }
-       *arg = NULL;
-       retval = spawn_prog(pgm, spawn_arg);
-       remove_tempfile();
-       if (retval) {
-               fprintf(stderr, "external diff died, stopping at %s.\n", name);
-               exit(1);
-       }
-}
+               if (ce_stage(ce)) {
+                       struct combine_diff_path *dpath;
+                       int num_compare_stages = 0;
+                       size_t path_len;
+
+                       path_len = ce_namelen(ce);
+
+                       dpath = xmalloc(combine_diff_path_size(5, path_len));
+                       dpath->path = (char *) &(dpath->parent[5]);
+
+                       dpath->next = NULL;
+                       dpath->len = path_len;
+                       memcpy(dpath->path, ce->name, path_len);
+                       dpath->path[path_len] = '\0';
+                       hashclr(dpath->sha1);
+                       memset(&(dpath->parent[0]), 0,
+                              sizeof(struct combine_diff_parent)*5);
+
+                       if (lstat(ce->name, &st) < 0) {
+                               if (errno != ENOENT && errno != ENOTDIR) {
+                                       perror(ce->name);
+                                       continue;
+                               }
+                               if (silent_on_removed)
+                                       continue;
+                       }
+                       else
+                               dpath->mode = ntohl(ce_mode_from_stat(ce, st.st_mode));
+
+                       while (i < entries) {
+                               struct cache_entry *nce = active_cache[i];
+                               int stage;
+
+                               if (strcmp(ce->name, nce->name))
+                                       break;
+
+                               /* Stage #2 (ours) is the first parent,
+                                * stage #3 (theirs) is the second.
+                                */
+                               stage = ce_stage(nce);
+                               if (2 <= stage) {
+                                       int mode = ntohl(nce->ce_mode);
+                                       num_compare_stages++;
+                                       hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
+                                       dpath->parent[stage-2].mode = ntohl(ce_mode_from_stat(nce, mode));
+                                       dpath->parent[stage-2].status =
+                                               DIFF_STATUS_MODIFIED;
+                               }
+
+                               /* diff against the proper unmerged stage */
+                               if (stage == diff_unmerged_stage)
+                                       ce = nce;
+                               i++;
+                       }
+                       /*
+                        * Compensate for loop update
+                        */
+                       i--;
 
-static void run_diff_cmd(const char *pgm,
-                        const char *name,
-                        const char *other,
-                        struct diff_filespec *one,
-                        struct diff_filespec *two,
-                        const char *xfrm_msg,
-                        int complete_rewrite)
-{
-       if (pgm) {
-               run_external_diff(pgm, name, other, one, two, xfrm_msg,
-                                 complete_rewrite);
-               return;
-       }
-       if (one && two)
-               builtin_diff(name, other ? other : name,
-                            one, two, xfrm_msg, complete_rewrite);
-       else
-               printf("* Unmerged path %s\n", name);
-}
+                       if (revs->combine_merges && num_compare_stages == 2) {
+                               show_combined_diff(dpath, 2,
+                                                  revs->dense_combined_merges,
+                                                  revs);
+                               free(dpath);
+                               continue;
+                       }
+                       free(dpath);
+                       dpath = NULL;
 
-static void diff_fill_sha1_info(struct diff_filespec *one)
-{
-       if (DIFF_FILE_VALID(one)) {
-               if (!one->sha1_valid) {
-                       struct stat st;
-                       if (lstat(one->path, &st) < 0)
-                               die("stat %s", one->path);
-                       if (index_path(one->sha1, one->path, &st, 0))
-                               die("cannot hash %s\n", one->path);
+                       /*
+                        * Show the diff for the 'ce' if we found the one
+                        * from the desired stage.
+                        */
+                       diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
+                       if (ce_stage(ce) != diff_unmerged_stage)
+                               continue;
                }
-       }
-       else
-               memset(one->sha1, 0, 20);
-}
-
-static void run_diff(struct diff_filepair *p, struct diff_options *o)
-{
-       const char *pgm = external_diff();
-       char msg[PATH_MAX*2+300], *xfrm_msg;
-       struct diff_filespec *one;
-       struct diff_filespec *two;
-       const char *name;
-       const char *other;
-       char *name_munged, *other_munged;
-       int complete_rewrite = 0;
-       int len;
-
-       if (DIFF_PAIR_UNMERGED(p)) {
-               /* unmerged */
-               run_diff_cmd(pgm, p->one->path, NULL, NULL, NULL, NULL, 0);
-               return;
-       }
 
-       name = p->one->path;
-       other = (strcmp(name, p->two->path) ? p->two->path : NULL);
-       name_munged = quote_one(name);
-       other_munged = quote_one(other);
-       one = p->one; two = p->two;
-
-       diff_fill_sha1_info(one);
-       diff_fill_sha1_info(two);
-
-       len = 0;
-       switch (p->status) {
-       case DIFF_STATUS_COPIED:
-               len += snprintf(msg + len, sizeof(msg) - len,
-                               "similarity index %d%%\n"
-                               "copy from %s\n"
-                               "copy to %s\n",
-                               (int)(0.5 + p->score * 100.0/MAX_SCORE),
-                               name_munged, other_munged);
-               break;
-       case DIFF_STATUS_RENAMED:
-               len += snprintf(msg + len, sizeof(msg) - len,
-                               "similarity index %d%%\n"
-                               "rename from %s\n"
-                               "rename to %s\n",
-                               (int)(0.5 + p->score * 100.0/MAX_SCORE),
-                               name_munged, other_munged);
-               break;
-       case DIFF_STATUS_MODIFIED:
-               if (p->score) {
-                       len += snprintf(msg + len, sizeof(msg) - len,
-                                       "dissimilarity index %d%%\n",
-                                       (int)(0.5 + p->score *
-                                             100.0/MAX_SCORE));
-                       complete_rewrite = 1;
-                       break;
+               if (lstat(ce->name, &st) < 0) {
+                       if (errno != ENOENT && errno != ENOTDIR) {
+                               perror(ce->name);
+                               continue;
+                       }
+                       if (silent_on_removed)
+                               continue;
+                       diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
+                                      ce->sha1, ce->name, NULL);
+                       continue;
                }
-               /* fallthru */
-       default:
-               /* nothing */
-               ;
-       }
-
-       if (memcmp(one->sha1, two->sha1, 20)) {
-               char one_sha1[41];
-               int abbrev = o->full_index ? 40 : DEFAULT_ABBREV;
-               memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
-
-               len += snprintf(msg + len, sizeof(msg) - len,
-                               "index %.*s..%.*s",
-                               abbrev, one_sha1, abbrev,
-                               sha1_to_hex(two->sha1));
-               if (one->mode == two->mode)
-                       len += snprintf(msg + len, sizeof(msg) - len,
-                                       " %06o", one->mode);
-               len += snprintf(msg + len, sizeof(msg) - len, "\n");
-       }
-
-       if (len)
-               msg[--len] = 0;
-       xfrm_msg = len ? msg : NULL;
-
-       if (!pgm &&
-           DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
-           (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
-               /* a filepair that changes between file and symlink
-                * needs to be split into deletion and creation.
-                */
-               struct diff_filespec *null = alloc_filespec(two->path);
-               run_diff_cmd(NULL, name, other, one, null, xfrm_msg, 0);
-               free(null);
-               null = alloc_filespec(one->path);
-               run_diff_cmd(NULL, name, other, null, two, xfrm_msg, 0);
-               free(null);
-       }
-       else
-               run_diff_cmd(pgm, name, other, one, two, xfrm_msg,
-                            complete_rewrite);
-
-       free(name_munged);
-       free(other_munged);
-}
-
-static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
-                        struct diffstat_t *diffstat)
-{
-       const char *name;
-       const char *other;
+               changed = ce_match_stat(ce, &st, ce_option);
+               if (!changed && !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
+                       continue;
+               oldmode = ntohl(ce->ce_mode);
+               newmode = ntohl(ce_mode_from_stat(ce, st.st_mode));
+               diff_change(&revs->diffopt, oldmode, newmode,
+                           ce->sha1, (changed ? null_sha1 : ce->sha1),
+                           ce->name, NULL);
 
-       if (DIFF_PAIR_UNMERGED(p)) {
-               /* unmerged */
-               builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat);
-               return;
        }
-
-       name = p->one->path;
-       other = (strcmp(name, p->two->path) ? p->two->path : NULL);
-
-       diff_fill_sha1_info(p->one);
-       diff_fill_sha1_info(p->two);
-
-       builtin_diffstat(name, other, p->one, p->two, diffstat);
+       diffcore_std(&revs->diffopt);
+       diff_flush(&revs->diffopt);
+       return 0;
 }
 
-void diff_setup(struct diff_options *options)
-{
-       memset(options, 0, sizeof(*options));
-       options->output_format = DIFF_FORMAT_RAW;
-       options->line_termination = '\n';
-       options->break_opt = -1;
-       options->rename_limit = -1;
-
-       options->change = diff_change;
-       options->add_remove = diff_addremove;
-}
+/*
+ * diff-index
+ */
 
-int diff_setup_done(struct diff_options *options)
+/* A file entry went away or appeared */
+static void diff_index_show_file(struct rev_info *revs,
+                                const char *prefix,
+                                struct cache_entry *ce,
+                                unsigned char *sha1, unsigned int mode)
 {
-       if ((options->find_copies_harder &&
-            options->detect_rename != DIFF_DETECT_COPY) ||
-           (0 <= options->rename_limit && !options->detect_rename))
-               return -1;
-
-       /*
-        * These cases always need recursive; we do not drop caller-supplied
-        * recursive bits for other formats here.
-        */
-       if ((options->output_format == DIFF_FORMAT_PATCH) ||
-           (options->output_format == DIFF_FORMAT_DIFFSTAT))
-               options->recursive = 1;
-
-       if (options->detect_rename && options->rename_limit < 0)
-               options->rename_limit = diff_rename_limit_default;
-       if (options->setup & DIFF_SETUP_USE_CACHE) {
-               if (!active_cache)
-                       /* read-cache does not die even when it fails
-                        * so it is safe for us to do this here.  Also
-                        * it does not smudge active_cache or active_nr
-                        * when it fails, so we do not have to worry about
-                        * cleaning it up ourselves either.
-                        */
-                       read_cache();
-       }
-       if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
-               use_size_cache = 1;
-       if (options->abbrev <= 0 || 40 < options->abbrev)
-               options->abbrev = 40; /* full */
-
-       return 0;
+       diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
+                      sha1, ce->name, NULL);
 }
 
-int diff_opt_parse(struct diff_options *options, const char **av, int ac)
+static int get_stat_data(struct cache_entry *ce,
+                        unsigned char **sha1p,
+                        unsigned int *modep,
+                        int cached, int match_missing)
 {
-       const char *arg = av[0];
-       if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
-               options->output_format = DIFF_FORMAT_PATCH;
-       else if (!strcmp(arg, "--patch-with-raw")) {
-               options->output_format = DIFF_FORMAT_PATCH;
-               options->with_raw = 1;
-       }
-       else if (!strcmp(arg, "--stat"))
-               options->output_format = DIFF_FORMAT_DIFFSTAT;
-       else if (!strcmp(arg, "--patch-with-stat")) {
-               options->output_format = DIFF_FORMAT_PATCH;
-               options->with_stat = 1;
-       }
-       else if (!strcmp(arg, "-z"))
-               options->line_termination = 0;
-       else if (!strncmp(arg, "-l", 2))
-               options->rename_limit = strtoul(arg+2, NULL, 10);
-       else if (!strcmp(arg, "--full-index"))
-               options->full_index = 1;
-       else if (!strcmp(arg, "--name-only"))
-               options->output_format = DIFF_FORMAT_NAME;
-       else if (!strcmp(arg, "--name-status"))
-               options->output_format = DIFF_FORMAT_NAME_STATUS;
-       else if (!strcmp(arg, "-R"))
-               options->reverse_diff = 1;
-       else if (!strncmp(arg, "-S", 2))
-               options->pickaxe = arg + 2;
-       else if (!strcmp(arg, "-s"))
-               options->output_format = DIFF_FORMAT_NO_OUTPUT;
-       else if (!strncmp(arg, "-O", 2))
-               options->orderfile = arg + 2;
-       else if (!strncmp(arg, "--diff-filter=", 14))
-               options->filter = arg + 14;
-       else if (!strcmp(arg, "--pickaxe-all"))
-               options->pickaxe_opts = DIFF_PICKAXE_ALL;
-       else if (!strcmp(arg, "--pickaxe-regex"))
-               options->pickaxe_opts = DIFF_PICKAXE_REGEX;
-       else if (!strncmp(arg, "-B", 2)) {
-               if ((options->break_opt =
-                    diff_scoreopt_parse(arg)) == -1)
-                       return -1;
-       }
-       else if (!strncmp(arg, "-M", 2)) {
-               if ((options->rename_score =
-                    diff_scoreopt_parse(arg)) == -1)
-                       return -1;
-               options->detect_rename = DIFF_DETECT_RENAME;
-       }
-       else if (!strncmp(arg, "-C", 2)) {
-               if ((options->rename_score =
-                    diff_scoreopt_parse(arg)) == -1)
-                       return -1;
-               options->detect_rename = DIFF_DETECT_COPY;
-       }
-       else if (!strcmp(arg, "--find-copies-harder"))
-               options->find_copies_harder = 1;
-       else if (!strcmp(arg, "--abbrev"))
-               options->abbrev = DEFAULT_ABBREV;
-       else if (!strncmp(arg, "--abbrev=", 9)) {
-               options->abbrev = strtoul(arg + 9, NULL, 10);
-               if (options->abbrev < MINIMUM_ABBREV)
-                       options->abbrev = MINIMUM_ABBREV;
-               else if (40 < options->abbrev)
-                       options->abbrev = 40;
-       }
-       else
-               return 0;
-       return 1;
-}
+       unsigned char *sha1 = ce->sha1;
+       unsigned int mode = ce->ce_mode;
 
-static int parse_num(const char **cp_p)
-{
-       unsigned long num, scale;
-       int ch, dot;
-       const char *cp = *cp_p;
-
-       num = 0;
-       scale = 1;
-       dot = 0;
-       for(;;) {
-               ch = *cp;
-               if ( !dot && ch == '.' ) {
-                       scale = 1;
-                       dot = 1;
-               } else if ( ch == '%' ) {
-                       scale = dot ? scale*100 : 100;
-                       cp++;   /* % is always at the end */
-                       break;
-               } else if ( ch >= '0' && ch <= '9' ) {
-                       if ( scale < 100000 ) {
-                               scale *= 10;
-                               num = (num*10) + (ch-'0');
+       if (!cached) {
+               static unsigned char no_sha1[20];
+               int changed;
+               struct stat st;
+               if (lstat(ce->name, &st) < 0) {
+                       if (errno == ENOENT && match_missing) {
+                               *sha1p = sha1;
+                               *modep = mode;
+                               return 0;
                        }
-               } else {
-                       break;
+                       return -1;
                }
-               cp++;
-       }
-       *cp_p = cp;
-
-       /* user says num divided by scale and we say internally that
-        * is MAX_SCORE * num / scale.
-        */
-       return (num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale);
-}
-
-int diff_scoreopt_parse(const char *opt)
-{
-       int opt1, opt2, cmd;
-
-       if (*opt++ != '-')
-               return -1;
-       cmd = *opt++;
-       if (cmd != 'M' && cmd != 'C' && cmd != 'B')
-               return -1; /* that is not a -M, -C nor -B option */
-
-       opt1 = parse_num(&opt);
-       if (cmd != 'B')
-               opt2 = 0;
-       else {
-               if (*opt == 0)
-                       opt2 = 0;
-               else if (*opt != '/')
-                       return -1; /* we expect -B80/99 or -B80 */
-               else {
-                       opt++;
-                       opt2 = parse_num(&opt);
+               changed = ce_match_stat(ce, &st, 0);
+               if (changed) {
+                       mode = ce_mode_from_stat(ce, st.st_mode);
+                       sha1 = no_sha1;
                }
        }
-       if (*opt != 0)
-               return -1;
-       return opt1 | (opt2 << 16);
-}
 
-struct diff_queue_struct diff_queued_diff;
-
-void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
-{
-       if (queue->alloc <= queue->nr) {
-               queue->alloc = alloc_nr(queue->alloc);
-               queue->queue = xrealloc(queue->queue,
-                                       sizeof(dp) * queue->alloc);
-       }
-       queue->queue[queue->nr++] = dp;
+       *sha1p = sha1;
+       *modep = mode;
+       return 0;
 }
 
-struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
-                                struct diff_filespec *one,
-                                struct diff_filespec *two)
+static void show_new_file(struct rev_info *revs,
+                         struct cache_entry *new,
+                         int cached, int match_missing)
 {
-       struct diff_filepair *dp = xmalloc(sizeof(*dp));
-       dp->one = one;
-       dp->two = two;
-       dp->score = 0;
-       dp->status = 0;
-       dp->source_stays = 0;
-       dp->broken_pair = 0;
-       if (queue)
-               diff_q(queue, dp);
-       return dp;
-}
+       unsigned char *sha1;
+       unsigned int mode;
 
-void diff_free_filepair(struct diff_filepair *p)
-{
-       diff_free_filespec_data(p->one);
-       diff_free_filespec_data(p->two);
-       free(p->one);
-       free(p->two);
-       free(p);
-}
+       /* New file in the index: it might actually be different in
+        * the working copy.
+        */
+       if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
+               return;
 
-/* This is different from find_unique_abbrev() in that
- * it stuffs the result with dots for alignment.
- */
-const char *diff_unique_abbrev(const unsigned char *sha1, int len)
-{
-       int abblen;
-       const char *abbrev;
-       if (len == 40)
-               return sha1_to_hex(sha1);
-
-       abbrev = find_unique_abbrev(sha1, len);
-       if (!abbrev)
-               return sha1_to_hex(sha1);
-       abblen = strlen(abbrev);
-       if (abblen < 37) {
-               static char hex[41];
-               if (len < abblen && abblen <= len + 2)
-                       sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
-               else
-                       sprintf(hex, "%s...", abbrev);
-               return hex;
-       }
-       return sha1_to_hex(sha1);
+       diff_index_show_file(revs, "+", new, sha1, mode);
 }
 
-static void diff_flush_raw(struct diff_filepair *p,
-                          int line_termination,
-                          int inter_name_termination,
-                          struct diff_options *options,
-                          int output_format)
+static int show_modified(struct rev_info *revs,
+                        struct cache_entry *old,
+                        struct cache_entry *new,
+                        int report_missing,
+                        int cached, int match_missing)
 {
-       int two_paths;
-       char status[10];
-       int abbrev = options->abbrev;
-       const char *path_one, *path_two;
-
-       path_one = p->one->path;
-       path_two = p->two->path;
-       if (line_termination) {
-               path_one = quote_one(path_one);
-               path_two = quote_one(path_two);
-       }
+       unsigned int mode, oldmode;
+       unsigned char *sha1;
 
-       if (p->score)
-               sprintf(status, "%c%03d", p->status,
-                       (int)(0.5 + p->score * 100.0/MAX_SCORE));
-       else {
-               status[0] = p->status;
-               status[1] = 0;
-       }
-       switch (p->status) {
-       case DIFF_STATUS_COPIED:
-       case DIFF_STATUS_RENAMED:
-               two_paths = 1;
-               break;
-       case DIFF_STATUS_ADDED:
-       case DIFF_STATUS_DELETED:
-               two_paths = 0;
-               break;
-       default:
-               two_paths = 0;
-               break;
-       }
-       if (output_format != DIFF_FORMAT_NAME_STATUS) {
-               printf(":%06o %06o %s ",
-                      p->one->mode, p->two->mode,
-                      diff_unique_abbrev(p->one->sha1, abbrev));
-               printf("%s ",
-                      diff_unique_abbrev(p->two->sha1, abbrev));
+       if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
+               if (report_missing)
+                       diff_index_show_file(revs, "-", old,
+                                            old->sha1, old->ce_mode);
+               return -1;
        }
-       printf("%s%c%s", status, inter_name_termination, path_one);
-       if (two_paths)
-               printf("%c%s", inter_name_termination, path_two);
-       putchar(line_termination);
-       if (path_one != p->one->path)
-               free((void*)path_one);
-       if (path_two != p->two->path)
-               free((void*)path_two);
-}
-
-static void diff_flush_name(struct diff_filepair *p,
-                           int inter_name_termination,
-                           int line_termination)
-{
-       char *path = p->two->path;
-
-       if (line_termination)
-               path = quote_one(p->two->path);
-       else
-               path = p->two->path;
-       printf("%s%c", path, line_termination);
-       if (p->two->path != path)
-               free(path);
-}
-
-int diff_unmodified_pair(struct diff_filepair *p)
-{
-       /* This function is written stricter than necessary to support
-        * the currently implemented transformers, but the idea is to
-        * let transformers to produce diff_filepairs any way they want,
-        * and filter and clean them up here before producing the output.
-        */
-       struct diff_filespec *one, *two;
-
-       if (DIFF_PAIR_UNMERGED(p))
-               return 0; /* unmerged is interesting */
-
-       one = p->one;
-       two = p->two;
 
-       /* deletion, addition, mode or type change
-        * and rename are all interesting.
-        */
-       if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
-           DIFF_PAIR_MODE_CHANGED(p) ||
-           strcmp(one->path, two->path))
+       if (revs->combine_merges && !cached &&
+           (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
+               struct combine_diff_path *p;
+               int pathlen = ce_namelen(new);
+
+               p = xmalloc(combine_diff_path_size(2, pathlen));
+               p->path = (char *) &p->parent[2];
+               p->next = NULL;
+               p->len = pathlen;
+               memcpy(p->path, new->name, pathlen);
+               p->path[pathlen] = 0;
+               p->mode = ntohl(mode);
+               hashclr(p->sha1);
+               memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
+               p->parent[0].status = DIFF_STATUS_MODIFIED;
+               p->parent[0].mode = ntohl(new->ce_mode);
+               hashcpy(p->parent[0].sha1, new->sha1);
+               p->parent[1].status = DIFF_STATUS_MODIFIED;
+               p->parent[1].mode = ntohl(old->ce_mode);
+               hashcpy(p->parent[1].sha1, old->sha1);
+               show_combined_diff(p, 2, revs->dense_combined_merges, revs);
+               free(p);
                return 0;
+       }
 
-       /* both are valid and point at the same path.  that is, we are
-        * dealing with a change.
-        */
-       if (one->sha1_valid && two->sha1_valid &&
-           !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
-               return 1; /* no change */
-       if (!one->sha1_valid && !two->sha1_valid)
-               return 1; /* both look at the same file on the filesystem. */
-       return 0;
-}
-
-static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
-{
-       if (diff_unmodified_pair(p))
-               return;
-
-       if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
-           (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
-               return; /* no tree diffs in patch format */
-
-       run_diff(p, o);
-}
-
-static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
-                           struct diffstat_t *diffstat)
-{
-       if (diff_unmodified_pair(p))
-               return;
-
-       if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
-           (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
-               return; /* no tree diffs in patch format */
+       oldmode = old->ce_mode;
+       if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
+           !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
+               return 0;
 
-       run_diffstat(p, o, diffstat);
-}
+       mode = ntohl(mode);
+       oldmode = ntohl(oldmode);
 
-int diff_queue_is_empty(void)
-{
-       struct diff_queue_struct *q = &diff_queued_diff;
-       int i;
-       for (i = 0; i < q->nr; i++)
-               if (!diff_unmodified_pair(q->queue[i]))
-                       return 0;
-       return 1;
+       diff_change(&revs->diffopt, oldmode, mode,
+                   old->sha1, sha1, old->name, NULL);
+       return 0;
 }
 
-#if DIFF_DEBUG
-void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
+static int diff_cache(struct rev_info *revs,
+                     struct cache_entry **ac, int entries,
+                     const char **pathspec,
+                     int cached, int match_missing)
 {
-       fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
-               x, one ? one : "",
-               s->path,
-               DIFF_FILE_VALID(s) ? "valid" : "invalid",
-               s->mode,
-               s->sha1_valid ? sha1_to_hex(s->sha1) : "");
-       fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
-               x, one ? one : "",
-               s->size, s->xfrm_flags);
-}
+       while (entries) {
+               struct cache_entry *ce = *ac;
+               int same = (entries > 1) && ce_same_name(ce, ac[1]);
 
-void diff_debug_filepair(const struct diff_filepair *p, int i)
-{
-       diff_debug_filespec(p->one, i, "one");
-       diff_debug_filespec(p->two, i, "two");
-       fprintf(stderr, "score %d, status %c stays %d broken %d\n",
-               p->score, p->status ? p->status : '?',
-               p->source_stays, p->broken_pair);
-}
+               if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
+                       DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
+                       break;
 
-void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
-{
-       int i;
-       if (msg)
-               fprintf(stderr, "%s\n", msg);
-       fprintf(stderr, "q->nr = %d\n", q->nr);
-       for (i = 0; i < q->nr; i++) {
-               struct diff_filepair *p = q->queue[i];
-               diff_debug_filepair(p, i);
-       }
-}
-#endif
+               if (!ce_path_match(ce, pathspec))
+                       goto skip_entry;
 
-static void diff_resolve_rename_copy(void)
-{
-       int i, j;
-       struct diff_filepair *p, *pp;
-       struct diff_queue_struct *q = &diff_queued_diff;
-
-       diff_debug_queue("resolve-rename-copy", q);
-
-       for (i = 0; i < q->nr; i++) {
-               p = q->queue[i];
-               p->status = 0; /* undecided */
-               if (DIFF_PAIR_UNMERGED(p))
-                       p->status = DIFF_STATUS_UNMERGED;
-               else if (!DIFF_FILE_VALID(p->one))
-                       p->status = DIFF_STATUS_ADDED;
-               else if (!DIFF_FILE_VALID(p->two))
-                       p->status = DIFF_STATUS_DELETED;
-               else if (DIFF_PAIR_TYPE_CHANGED(p))
-                       p->status = DIFF_STATUS_TYPE_CHANGED;
-
-               /* from this point on, we are dealing with a pair
-                * whose both sides are valid and of the same type, i.e.
-                * either in-place edit or rename/copy edit.
-                */
-               else if (DIFF_PAIR_RENAME(p)) {
-                       if (p->source_stays) {
-                               p->status = DIFF_STATUS_COPIED;
-                               continue;
+               switch (ce_stage(ce)) {
+               case 0:
+                       /* No stage 1 entry? That means it's a new file */
+                       if (!same) {
+                               show_new_file(revs, ce, cached, match_missing);
+                               break;
                        }
-                       /* See if there is some other filepair that
-                        * copies from the same source as us.  If so
-                        * we are a copy.  Otherwise we are either a
-                        * copy if the path stays, or a rename if it
-                        * does not, but we already handled "stays" case.
+                       /* Show difference between old and new */
+                       show_modified(revs, ac[1], ce, 1,
+                                     cached, match_missing);
+                       break;
+               case 1:
+                       /* No stage 3 (merge) entry?
+                        * That means it's been deleted.
                         */
-                       for (j = i + 1; j < q->nr; j++) {
-                               pp = q->queue[j];
-                               if (strcmp(pp->one->path, p->one->path))
-                                       continue; /* not us */
-                               if (!DIFF_PAIR_RENAME(pp))
-                                       continue; /* not a rename/copy */
-                               /* pp is a rename/copy from the same source */
-                               p->status = DIFF_STATUS_COPIED;
+                       if (!same) {
+                               diff_index_show_file(revs, "-", ce,
+                                                    ce->sha1, ce->ce_mode);
                                break;
                        }
-                       if (!p->status)
-                               p->status = DIFF_STATUS_RENAMED;
-               }
-               else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
-                        p->one->mode != p->two->mode)
-                       p->status = DIFF_STATUS_MODIFIED;
-               else {
-                       /* This is a "no-change" entry and should not
-                        * happen anymore, but prepare for broken callers.
+                       /* We come here with ce pointing at stage 1
+                        * (original tree) and ac[1] pointing at stage
+                        * 3 (unmerged).  show-modified with
+                        * report-missing set to false does not say the
+                        * file is deleted but reports true if work
+                        * tree does not have it, in which case we
+                        * fall through to report the unmerged state.
+                        * Otherwise, we show the differences between
+                        * the original tree and the work tree.
                         */
-                       error("feeding unmodified %s to diffcore",
-                             p->one->path);
-                       p->status = DIFF_STATUS_UNKNOWN;
-               }
-       }
-       diff_debug_queue("resolve-rename-copy done", q);
-}
-
-static void flush_one_pair(struct diff_filepair *p,
-                          int diff_output_format,
-                          struct diff_options *options,
-                          struct diffstat_t *diffstat)
-{
-       int inter_name_termination = '\t';
-       int line_termination = options->line_termination;
-       if (!line_termination)
-               inter_name_termination = 0;
-
-       switch (p->status) {
-       case DIFF_STATUS_UNKNOWN:
-               break;
-       case 0:
-               die("internal error in diff-resolve-rename-copy");
-               break;
-       default:
-               switch (diff_output_format) {
-               case DIFF_FORMAT_DIFFSTAT:
-                       diff_flush_stat(p, options, diffstat);
-                       break;
-               case DIFF_FORMAT_PATCH:
-                       diff_flush_patch(p, options);
-                       break;
-               case DIFF_FORMAT_RAW:
-               case DIFF_FORMAT_NAME_STATUS:
-                       diff_flush_raw(p, line_termination,
-                                      inter_name_termination,
-                                      options, diff_output_format);
-                       break;
-               case DIFF_FORMAT_NAME:
-                       diff_flush_name(p,
-                                       inter_name_termination,
-                                       line_termination);
+                       if (!cached &&
+                           !show_modified(revs, ce, ac[1], 0,
+                                          cached, match_missing))
+                               break;
+                       diff_unmerge(&revs->diffopt, ce->name,
+                                    ntohl(ce->ce_mode), ce->sha1);
                        break;
-               case DIFF_FORMAT_NO_OUTPUT:
+               case 3:
+                       diff_unmerge(&revs->diffopt, ce->name,
+                                    0, null_sha1);
                        break;
-               }
-       }
-}
-
-void diff_flush(struct diff_options *options)
-{
-       struct diff_queue_struct *q = &diff_queued_diff;
-       int i;
-       int diff_output_format = options->output_format;
-       struct diffstat_t *diffstat = NULL;
 
-       if (diff_output_format == DIFF_FORMAT_DIFFSTAT || options->with_stat) {
-               diffstat = xcalloc(sizeof (struct diffstat_t), 1);
-               diffstat->xm.consume = diffstat_consume;
-       }
-
-       if (options->with_raw) {
-               for (i = 0; i < q->nr; i++) {
-                       struct diff_filepair *p = q->queue[i];
-                       flush_one_pair(p, DIFF_FORMAT_RAW, options, NULL);
-               }
-               putchar(options->line_termination);
-       }
-       if (options->with_stat) {
-               for (i = 0; i < q->nr; i++) {
-                       struct diff_filepair *p = q->queue[i];
-                       flush_one_pair(p, DIFF_FORMAT_DIFFSTAT, options,
-                                      diffstat);
+               default:
+                       die("impossible cache entry stage");
                }
-               show_stats(diffstat);
-               free(diffstat);
-               diffstat = NULL;
-               putchar(options->line_termination);
-       }
-       for (i = 0; i < q->nr; i++) {
-               struct diff_filepair *p = q->queue[i];
-               flush_one_pair(p, diff_output_format, options, diffstat);
-               diff_free_filepair(p);
-       }
 
-       if (diffstat) {
-               show_stats(diffstat);
-               free(diffstat);
+skip_entry:
+               /*
+                * Ignore all the different stages for this file,
+                * we've handled the relevant cases now.
+                */
+               do {
+                       ac++;
+                       entries--;
+               } while (entries && ce_same_name(ce, ac[0]));
        }
-
-       free(q->queue);
-       q->queue = NULL;
-       q->nr = q->alloc = 0;
+       return 0;
 }
 
-static void diffcore_apply_filter(const char *filter)
+/*
+ * This turns all merge entries into "stage 3". That guarantees that
+ * when we read in the new tree (into "stage 1"), we won't lose sight
+ * of the fact that we had unmerged entries.
+ */
+static void mark_merge_entries(void)
 {
        int i;
-       struct diff_queue_struct *q = &diff_queued_diff;
-       struct diff_queue_struct outq;
-       outq.queue = NULL;
-       outq.nr = outq.alloc = 0;
-
-       if (!filter)
-               return;
-
-       if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
-               int found;
-               for (i = found = 0; !found && i < q->nr; i++) {
-                       struct diff_filepair *p = q->queue[i];
-                       if (((p->status == DIFF_STATUS_MODIFIED) &&
-                            ((p->score &&
-                              strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-                             (!p->score &&
-                              strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-                           ((p->status != DIFF_STATUS_MODIFIED) &&
-                            strchr(filter, p->status)))
-                               found++;
-               }
-               if (found)
-                       return;
-
-               /* otherwise we will clear the whole queue
-                * by copying the empty outq at the end of this
-                * function, but first clear the current entries
-                * in the queue.
-                */
-               for (i = 0; i < q->nr; i++)
-                       diff_free_filepair(q->queue[i]);
-       }
-       else {
-               /* Only the matching ones */
-               for (i = 0; i < q->nr; i++) {
-                       struct diff_filepair *p = q->queue[i];
-
-                       if (((p->status == DIFF_STATUS_MODIFIED) &&
-                            ((p->score &&
-                              strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-                             (!p->score &&
-                              strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-                           ((p->status != DIFF_STATUS_MODIFIED) &&
-                            strchr(filter, p->status)))
-                               diff_q(&outq, p);
-                       else
-                               diff_free_filepair(p);
-               }
+       for (i = 0; i < active_nr; i++) {
+               struct cache_entry *ce = active_cache[i];
+               if (!ce_stage(ce))
+                       continue;
+               ce->ce_flags |= htons(CE_STAGEMASK);
        }
-       free(q->queue);
-       *q = outq;
 }
 
-void diffcore_std(struct diff_options *options)
+int run_diff_index(struct rev_info *revs, int cached)
 {
-       if (options->break_opt != -1)
-               diffcore_break(options->break_opt);
-       if (options->detect_rename)
-               diffcore_rename(options);
-       if (options->break_opt != -1)
-               diffcore_merge_broken();
-       if (options->pickaxe)
-               diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
-       if (options->orderfile)
-               diffcore_order(options->orderfile);
-       diff_resolve_rename_copy();
-       diffcore_apply_filter(options->filter);
-}
-
+       int ret;
+       struct object *ent;
+       struct tree *tree;
+       const char *tree_name;
+       int match_missing = 0;
 
-void diffcore_std_no_resolve(struct diff_options *options)
-{
-       if (options->pickaxe)
-               diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
-       if (options->orderfile)
-               diffcore_order(options->orderfile);
-       diffcore_apply_filter(options->filter);
-}
-
-void diff_addremove(struct diff_options *options,
-                   int addremove, unsigned mode,
-                   const unsigned char *sha1,
-                   const char *base, const char *path)
-{
-       char concatpath[PATH_MAX];
-       struct diff_filespec *one, *two;
-
-       /* This may look odd, but it is a preparation for
-        * feeding "there are unchanged files which should
-        * not produce diffs, but when you are doing copy
-        * detection you would need them, so here they are"
-        * entries to the diff-core.  They will be prefixed
-        * with something like '=' or '*' (I haven't decided
-        * which but should not make any difference).
-        * Feeding the same new and old to diff_change() 
-        * also has the same effect.
-        * Before the final output happens, they are pruned after
-        * merged into rename/copy pairs as appropriate.
+       /*
+        * Backward compatibility wart - "diff-index -m" does
+        * not mean "do not ignore merges", but totally different.
         */
-       if (options->reverse_diff)
-               addremove = (addremove == '+' ? '-' :
-                            addremove == '-' ? '+' : addremove);
-
-       if (!path) path = "";
-       sprintf(concatpath, "%s%s", base, path);
-       one = alloc_filespec(concatpath);
-       two = alloc_filespec(concatpath);
+       if (!revs->ignore_merges)
+               match_missing = 1;
 
-       if (addremove != '+')
-               fill_filespec(one, sha1, mode);
-       if (addremove != '-')
-               fill_filespec(two, sha1, mode);
+       mark_merge_entries();
 
-       diff_queue(&diff_queued_diff, one, two);
+       ent = revs->pending.objects[0].item;
+       tree_name = revs->pending.objects[0].name;
+       tree = parse_tree_indirect(ent->sha1);
+       if (!tree)
+               return error("bad tree object %s", tree_name);
+       if (read_tree(tree, 1, revs->prune_data))
+               return error("unable to read tree object %s", tree_name);
+       ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
+                        cached, match_missing);
+       diffcore_std(&revs->diffopt);
+       diff_flush(&revs->diffopt);
+       return ret;
 }
 
-void diff_change(struct diff_options *options,
-                unsigned old_mode, unsigned new_mode,
-                const unsigned char *old_sha1,
-                const unsigned char *new_sha1,
-                const char *base, const char *path) 
+int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 {
-       char concatpath[PATH_MAX];
-       struct diff_filespec *one, *two;
-
-       if (options->reverse_diff) {
-               unsigned tmp;
-               const unsigned char *tmp_c;
-               tmp = old_mode; old_mode = new_mode; new_mode = tmp;
-               tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
-       }
-       if (!path) path = "";
-       sprintf(concatpath, "%s%s", base, path);
-       one = alloc_filespec(concatpath);
-       two = alloc_filespec(concatpath);
-       fill_filespec(one, old_sha1, old_mode);
-       fill_filespec(two, new_sha1, new_mode);
-
-       diff_queue(&diff_queued_diff, one, two);
-}
+       struct tree *tree;
+       struct rev_info revs;
+       int i;
+       struct cache_entry **dst;
+       struct cache_entry *last = NULL;
 
-void diff_unmerge(struct diff_options *options,
-                 const char *path)
-{
-       struct diff_filespec *one, *two;
-       one = alloc_filespec(path);
-       two = alloc_filespec(path);
-       diff_queue(&diff_queued_diff, one, two);
+       /*
+        * This is used by git-blame to run diff-cache internally;
+        * it potentially needs to repeatedly run this, so we will
+        * start by removing the higher order entries the last round
+        * left behind.
+        */
+       dst = active_cache;
+       for (i = 0; i < active_nr; i++) {
+               struct cache_entry *ce = active_cache[i];
+               if (ce_stage(ce)) {
+                       if (last && !strcmp(ce->name, last->name))
+                               continue;
+                       cache_tree_invalidate_path(active_cache_tree,
+                                                  ce->name);
+                       last = ce;
+                       ce->ce_mode = 0;
+                       ce->ce_flags &= ~htons(CE_STAGEMASK);
+               }
+               *dst++ = ce;
+       }
+       active_nr = dst - active_cache;
+
+       init_revisions(&revs, NULL);
+       revs.prune_data = opt->paths;
+       tree = parse_tree_indirect(tree_sha1);
+       if (!tree)
+               die("bad tree object %s", sha1_to_hex(tree_sha1));
+       if (read_tree(tree, 1, opt->paths))
+               return error("unable to read tree %s", sha1_to_hex(tree_sha1));
+       return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
+                         1, 0);
 }