Make git pack files use little-endian size encoding
[gitweb.git] / apply.c
diff --git a/apply.c b/apply.c
index 85d7965daa09d01f05a65f5bdde8d889fd21744b..c81b0a240a38b57a9bbd2586889304bef8f5cbbf 100644 (file)
--- a/apply.c
+++ b/apply.c
 #include "cache.h"
 
 // We default to the merge behaviour, since that's what most people would
-// expect
+// expect.
+//
+//  --check turns on checking that the working tree matches the
+//    files that are being modified, but doesn't apply the patch
+//  --stat does just a diffstat, and doesn't actually apply
+//  --show-files shows the directory changes
+//
 static int merge_patch = 1;
-static const char apply_usage[] = "git-apply <patch>";
+static int check_index = 0;
+static int write_index = 0;
+static int diffstat = 0;
+static int summary = 0;
+static int check = 0;
+static int apply = 1;
+static int show_files = 0;
+static const char apply_usage[] = "git-apply [--stat] [--summary] [--check] [--show-files] <patch>";
+
+/*
+ * For "diff-stat" like behaviour, we keep track of the biggest change
+ * we've seen, and the longest filename. That allows us to do simple
+ * scaling.
+ */
+static int max_change, max_len;
+
+/*
+ * Various "current state", notably line numbers and what
+ * file (and how) we're patching right now.. The "is_xxxx"
+ * things are flags, where -1 means "don't know yet".
+ */
+static int linenr = 1;
+
+struct fragment {
+       unsigned long oldpos, oldlines;
+       unsigned long newpos, newlines;
+       const char *patch;
+       int size;
+       struct fragment *next;
+};
+
+struct patch {
+       char *new_name, *old_name, *def_name;
+       unsigned int old_mode, new_mode;
+       int is_rename, is_copy, is_new, is_delete;
+       int lines_added, lines_deleted;
+       int score;
+       struct fragment *fragments;
+       char *result;
+       unsigned long resultsize;
+       struct patch *next;
+};
 
 #define CHUNKSIZE (8192)
+#define SLOP (16)
 
 static void *read_patch_file(int fd, unsigned long *sizep)
 {
@@ -46,10 +94,19 @@ static void *read_patch_file(int fd, unsigned long *sizep)
                size += nr;
        }
        *sizep = size;
+
+       /*
+        * Make sure that we have some slop in the buffer
+        * so that we can do speculative "memcmp" etc, and
+        * see to it that it is NUL-filled.
+        */
+       if (alloc < size + SLOP)
+               buffer = xrealloc(buffer, size + SLOP);
+       memset(buffer + size, 0, SLOP);
        return buffer;
 }
 
-static unsigned long linelen(char *buffer, unsigned long size)
+static unsigned long linelen(const char *buffer, unsigned long size)
 {
        unsigned long len = 0;
        while (size--) {
@@ -60,55 +117,432 @@ static unsigned long linelen(char *buffer, unsigned long size)
        return len;
 }
 
-static int match_word(const char *line, const char *match)
+static int is_dev_null(const char *str)
+{
+       return !memcmp("/dev/null", str, 9) && isspace(str[9]);
+}
+
+#define TERM_SPACE     1
+#define TERM_TAB       2
+
+static int name_terminate(const char *name, int namelen, int c, int terminate)
+{
+       if (c == ' ' && !(terminate & TERM_SPACE))
+               return 0;
+       if (c == '\t' && !(terminate & TERM_TAB))
+               return 0;
+
+       return 1;
+}
+
+static char * find_name(const char *line, char *def, int p_value, int terminate)
+{
+       int len;
+       const char *start = line;
+       char *name;
+
+       for (;;) {
+               char c = *line;
+
+               if (isspace(c)) {
+                       if (c == '\n')
+                               break;
+                       if (name_terminate(start, line-start, c, terminate))
+                               break;
+               }
+               line++;
+               if (c == '/' && !--p_value)
+                       start = line;
+       }
+       if (!start)
+               return def;
+       len = line - start;
+       if (!len)
+               return def;
+
+       /*
+        * Generally we prefer the shorter name, especially
+        * if the other one is just a variation of that with
+        * something else tacked on to the end (ie "file.orig"
+        * or "file~").
+        */
+       if (def) {
+               int deflen = strlen(def);
+               if (deflen < len && !strncmp(start, def, deflen))
+                       return def;
+       }
+
+       name = xmalloc(len + 1);
+       memcpy(name, start, len);
+       name[len] = 0;
+       free(def);
+       return name;
+}
+
+/*
+ * Get the name etc info from the --/+++ lines of a traditional patch header
+ *
+ * NOTE! This hardcodes "-p1" behaviour in filename detection.
+ *
+ * FIXME! The end-of-filename heuristics are kind of screwy. For existing
+ * files, we can happily check the index for a match, but for creating a
+ * new file we should try to match whatever "patch" does. I have no idea.
+ */
+static void parse_traditional_patch(const char *first, const char *second, struct patch *patch)
+{
+       int p_value = 1;
+       char *name;
+
+       first += 4;     // skip "--- "
+       second += 4;    // skip "+++ "
+       if (is_dev_null(first)) {
+               patch->is_new = 1;
+               patch->is_delete = 0;
+               name = find_name(second, NULL, p_value, TERM_SPACE | TERM_TAB);
+               patch->new_name = name;
+       } else if (is_dev_null(second)) {
+               patch->is_new = 0;
+               patch->is_delete = 1;
+               name = find_name(first, NULL, p_value, TERM_SPACE | TERM_TAB);
+               patch->old_name = name;
+       } else {
+               name = find_name(first, NULL, p_value, TERM_SPACE | TERM_TAB);
+               name = find_name(second, name, p_value, TERM_SPACE | TERM_TAB);
+               patch->old_name = patch->new_name = name;
+       }
+       if (!name)
+               die("unable to find filename in patch at line %d", linenr);
+}
+
+static int gitdiff_hdrend(const char *line, struct patch *patch)
+{
+       return -1;
+}
+
+/*
+ * We're anal about diff header consistency, to make
+ * sure that we don't end up having strange ambiguous
+ * patches floating around.
+ *
+ * As a result, gitdiff_{old|new}name() will check
+ * their names against any previous information, just
+ * to make sure..
+ */
+static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, const char *oldnew)
+{
+       int len;
+       const char *name;
+
+       if (!orig_name && !isnull)
+               return find_name(line, NULL, 1, 0);
+
+       name = "/dev/null";
+       len = 9;
+       if (orig_name) {
+               name = orig_name;
+               len = strlen(name);
+               if (isnull)
+                       die("git-apply: bad git-diff - expected /dev/null, got %s on line %d", name, linenr);
+       }
+
+       if (*name == '/')
+               goto absolute_path;
+
+       for (;;) {
+               char c = *line++;
+               if (c == '\n')
+                       break;
+               if (c != '/')
+                       continue;
+absolute_path:
+               if (memcmp(line, name, len) || line[len] != '\n')
+                       break;
+               return orig_name;
+       }
+       die("git-apply: bad git-diff - inconsistent %s filename on line %d", oldnew, linenr);
+       return NULL;
+}
+
+static int gitdiff_oldname(const char *line, struct patch *patch)
+{
+       patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name, "old");
+       return 0;
+}
+
+static int gitdiff_newname(const char *line, struct patch *patch)
+{
+       patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name, "new");
+       return 0;
+}
+
+static int gitdiff_oldmode(const char *line, struct patch *patch)
+{
+       patch->old_mode = strtoul(line, NULL, 8);
+       return 0;
+}
+
+static int gitdiff_newmode(const char *line, struct patch *patch)
+{
+       patch->new_mode = strtoul(line, NULL, 8);
+       return 0;
+}
+
+static int gitdiff_delete(const char *line, struct patch *patch)
+{
+       patch->is_delete = 1;
+       patch->old_name = patch->def_name;
+       return gitdiff_oldmode(line, patch);
+}
+
+static int gitdiff_newfile(const char *line, struct patch *patch)
+{
+       patch->is_new = 1;
+       patch->new_name = patch->def_name;
+       return gitdiff_newmode(line, patch);
+}
+
+static int gitdiff_copysrc(const char *line, struct patch *patch)
+{
+       patch->is_copy = 1;
+       patch->old_name = find_name(line, NULL, 0, 0);
+       return 0;
+}
+
+static int gitdiff_copydst(const char *line, struct patch *patch)
+{
+       patch->is_copy = 1;
+       patch->new_name = find_name(line, NULL, 0, 0);
+       return 0;
+}
+
+static int gitdiff_renamesrc(const char *line, struct patch *patch)
+{
+       patch->is_rename = 1;
+       patch->old_name = find_name(line, NULL, 0, 0);
+       return 0;
+}
+
+static int gitdiff_renamedst(const char *line, struct patch *patch)
+{
+       patch->is_rename = 1;
+       patch->new_name = find_name(line, NULL, 0, 0);
+       return 0;
+}
+
+static int gitdiff_similarity(const char *line, struct patch *patch)
+{
+       if ((patch->score = strtoul(line, NULL, 10)) == ULONG_MAX)
+               patch->score = 0;
+       return 0;
+}
+
+static int gitdiff_dissimilarity(const char *line, struct patch *patch)
+{
+       if ((patch->score = strtoul(line, NULL, 10)) == ULONG_MAX)
+               patch->score = 0;
+       return 0;
+}
+
+/*
+ * This is normal for a diff that doesn't change anything: we'll fall through
+ * into the next diff. Tell the parser to break out.
+ */
+static int gitdiff_unrecognized(const char *line, struct patch *patch)
+{
+       return -1;
+}
+
+static char *git_header_name(char *line)
 {
+       int len;
+       char *name, *second;
+
+       /*
+        * Find the first '/'
+        */
+       name = line;
        for (;;) {
-               char c = *match++;
-               if (!c)
+               char c = *name++;
+               if (c == '\n')
+                       return NULL;
+               if (c == '/')
+                       break;
+       }
+
+       /*
+        * We don't accept absolute paths (/dev/null) as possibly valid
+        */
+       if (name == line+1)
+               return NULL;
+
+       /*
+        * Accept a name only if it shows up twice, exactly the same
+        * form.
+        */
+       for (len = 0 ; ; len++) {
+               char c = name[len];
+
+               switch (c) {
+               default:
+                       continue;
+               case '\n':
                        break;
-               if (*line++ != c)
-                       return 0;
+               case '\t': case ' ':
+                       second = name+len;
+                       for (;;) {
+                               char c = *second++;
+                               if (c == '\n')
+                                       return NULL;
+                               if (c == '/')
+                                       break;
+                       }
+                       if (second[len] == '\n' && !memcmp(name, second, len)) {
+                               char *ret = xmalloc(len + 1);
+                               memcpy(ret, name, len);
+                               ret[len] = 0;
+                               return ret;
+                       }
+               }
        }
-       return *line == ' ';
+       return NULL;
 }
 
 /* Verify that we recognize the lines following a git header */
-static int parse_git_header(char *line, unsigned int size)
+static int parse_git_header(char *line, int len, unsigned int size, struct patch *patch)
 {
-       unsigned long offset, len;
+       unsigned long offset;
+
+       /* A git diff has explicit new/delete information, so we don't guess */
+       patch->is_new = 0;
+       patch->is_delete = 0;
+
+       /*
+        * Some things may not have the old name in the
+        * rest of the headers anywhere (pure mode changes,
+        * or removing or adding empty files), so we get
+        * the default name from the header.
+        */
+       patch->def_name = git_header_name(line + strlen("diff --git "));
+
+       line += len;
+       size -= len;
+       linenr++;
+       for (offset = len ; size > 0 ; offset += len, size -= len, line += len, linenr++) {
+               static const struct opentry {
+                       const char *str;
+                       int (*fn)(const char *, struct patch *);
+               } optable[] = {
+                       { "@@ -", gitdiff_hdrend },
+                       { "--- ", gitdiff_oldname },
+                       { "+++ ", gitdiff_newname },
+                       { "old mode ", gitdiff_oldmode },
+                       { "new mode ", gitdiff_newmode },
+                       { "deleted file mode ", gitdiff_delete },
+                       { "new file mode ", gitdiff_newfile },
+                       { "copy from ", gitdiff_copysrc },
+                       { "copy to ", gitdiff_copydst },
+                       { "rename old ", gitdiff_renamesrc },
+                       { "rename new ", gitdiff_renamedst },
+                       { "rename from ", gitdiff_renamesrc },
+                       { "rename to ", gitdiff_renamedst },
+                       { "similarity index ", gitdiff_similarity },
+                       { "dissimilarity index ", gitdiff_dissimilarity },
+                       { "", gitdiff_unrecognized },
+               };
+               int i;
 
-       for (offset = 0 ; size > 0 ; offset += len, size -= len, line += len) {
                len = linelen(line, size);
-               if (!len)
+               if (!len || line[len-1] != '\n')
                        break;
-               if (line[len-1] != '\n')
-                       return -1;
-               if (len < 4)
+               for (i = 0; i < sizeof(optable) / sizeof(optable[0]); i++) {
+                       const struct opentry *p = optable + i;
+                       int oplen = strlen(p->str);
+                       if (len < oplen || memcmp(p->str, line, oplen))
+                               continue;
+                       if (p->fn(line + oplen, patch) < 0)
+                               return offset;
                        break;
-               if (!memcmp(line, "@@ -", 4))
-                       return offset;
-               if (match_word(line, "new file mode"))
-                       continue;
-               if (match_word(line, "deleted file mode"))
-                       continue;
-               if (match_word(line, "copy"))
-                       continue;
-               if (match_word(line, "rename"))
-                       continue;
-               if (match_word(line, "similarity index"))
-                       continue;
-               break;
+               }
+       }
+
+       return offset;
+}
+
+static int parse_num(const char *line, unsigned long *p)
+{
+       char *ptr;
+
+       if (!isdigit(*line))
+               return 0;
+       *p = strtoul(line, &ptr, 10);
+       return ptr - line;
+}
+
+static int parse_range(const char *line, int len, int offset, const char *expect,
+                       unsigned long *p1, unsigned long *p2)
+{
+       int digits, ex;
+
+       if (offset < 0 || offset >= len)
+               return -1;
+       line += offset;
+       len -= offset;
+
+       digits = parse_num(line, p1);
+       if (!digits)
+               return -1;
+
+       offset += digits;
+       line += digits;
+       len -= digits;
+
+       *p2 = *p1;
+       if (*line == ',') {
+               digits = parse_num(line+1, p2);
+               if (!digits)
+                       return -1;
+
+               offset += digits+1;
+               line += digits+1;
+               len -= digits+1;
        }
 
-       /* We want either a patch _or_ something real */
-       return offset ? :-1;
+       ex = strlen(expect);
+       if (ex > len)
+               return -1;
+       if (memcmp(line, expect, ex))
+               return -1;
+
+       return offset + ex;
+}
+
+/*
+ * Parse a unified diff fragment header of the
+ * form "@@ -a,b +c,d @@"
+ */
+static int parse_fragment_header(char *line, int len, struct fragment *fragment)
+{
+       int offset;
+
+       if (!len || line[len-1] != '\n')
+               return -1;
+
+       /* Figure out the number of lines in a fragment */
+       offset = parse_range(line, len, 4, " +", &fragment->oldpos, &fragment->oldlines);
+       offset = parse_range(line, len, offset, " @@", &fragment->newpos, &fragment->newlines);
+
+       return offset;
 }
 
-static int find_header(char *line, unsigned long size, int *hdrsize)
+static int find_header(char *line, unsigned long size, int *hdrsize, struct patch *patch)
 {
        unsigned long offset, len;
 
-       for (offset = 0; size > 0; offset += len, size -= len, line += len) {
+       patch->is_rename = patch->is_copy = 0;
+       patch->is_new = patch->is_delete = -1;
+       patch->old_mode = patch->new_mode = 0;
+       patch->old_name = patch->new_name = NULL;
+       for (offset = 0; size > 0; offset += len, size -= len, line += len, linenr++) {
                unsigned long nextlen;
 
                len = linelen(line, size);
@@ -118,6 +552,19 @@ static int find_header(char *line, unsigned long size, int *hdrsize)
                /* Testing this early allows us to take a few shortcuts.. */
                if (len < 6)
                        continue;
+
+               /*
+                * Make sure we don't find any unconnected patch fragmants.
+                * That's a sign that we didn't find a header, and that a
+                * patch has become corrupted/broken up.
+                */
+               if (!memcmp("@@ -", line, 4)) {
+                       struct fragment dummy;
+                       if (parse_fragment_header(line, len, &dummy) < 0)
+                               continue;
+                       error("patch fragment without header at line %d: %.*s", linenr, len-1, line);
+               }
+
                if (size < len + 6)
                        break;
 
@@ -126,11 +573,15 @@ static int find_header(char *line, unsigned long size, int *hdrsize)
                 * or mode change, so we handle that specially
                 */
                if (!memcmp("diff --git ", line, 11)) {
-                       int git_hdr_len = parse_git_header(line + len, size - len);
-                       if (git_hdr_len < 0)
+                       int git_hdr_len = parse_git_header(line, len, size, patch);
+                       if (git_hdr_len <= len)
                                continue;
-
-                       *hdrsize = len + git_hdr_len;
+                       if (!patch->old_name && !patch->new_name) {
+                               if (!patch->def_name)
+                                       die("git diff header lacks filename information (line %d)", linenr);
+                               patch->old_name = patch->new_name = patch->def_name;
+                       }
+                       *hdrsize = git_hdr_len;
                        return offset;
                }
 
@@ -148,41 +599,14 @@ static int find_header(char *line, unsigned long size, int *hdrsize)
                        continue;
 
                /* Ok, we'll consider it a patch */
+               parse_traditional_patch(line, line+len, patch);
                *hdrsize = len + nextlen;
+               linenr += 2;
                return offset;
        }
        return -1;
 }
 
-static int parse_num(const char *line, int len, int offset, const char *expect, unsigned long *p)
-{
-       char *ptr;
-       int digits, ex;
-
-       if (offset < 0 || offset >= len)
-               return -1;
-       line += offset;
-       len -= offset;
-
-       if (!isdigit(*line))
-               return -1;
-       *p = strtoul(line, &ptr, 10);
-
-       digits = ptr - line;
-
-       offset += digits;
-       line += digits;
-       len -= digits;
-
-       ex = strlen(expect);
-       if (ex > len)
-               return -1;
-       if (memcmp(line, expect, ex))
-               return -1;
-
-       return offset + ex;
-}
-
 /*
  * Parse a unified diff. Note that this really needs
  * to parse each fragment separately, since the only
@@ -190,26 +614,43 @@ static int parse_num(const char *line, int len, int offset, const char *expect,
  * part of a patch, and a "---" that starts the next
  * patch is to look at the line counts..
  */
-static int apply_fragment(char *line, unsigned long size)
+static int parse_fragment(char *line, unsigned long size, struct patch *patch, struct fragment *fragment)
 {
+       int added, deleted;
        int len = linelen(line, size), offset;
-       unsigned long oldpos, oldlines, newpos, newlines;
-
-       if (!len || line[len-1] != '\n')
-               return -1;
+       unsigned long oldlines, newlines;
 
-       /* Figure out the number of lines in a fragment */
-       offset = parse_num(line, len, 4, ",", &oldpos);
-       offset = parse_num(line, len, offset, " +", &oldlines);
-       offset = parse_num(line, len, offset, ",", &newpos);
-       offset = parse_num(line, len, offset, " @@", &newlines);
+       offset = parse_fragment_header(line, len, fragment);
        if (offset < 0)
                return -1;
+       oldlines = fragment->oldlines;
+       newlines = fragment->newlines;
+
+       if (patch->is_new < 0) {
+               patch->is_new =  !oldlines;
+               if (!oldlines)
+                       patch->old_name = NULL;
+       }
+       if (patch->is_delete < 0) {
+               patch->is_delete = !newlines;
+               if (!newlines)
+                       patch->new_name = NULL;
+       }
+
+       if (patch->is_new != !oldlines)
+               return error("new file depends on old contents");
+       if (patch->is_delete != !newlines) {
+               if (newlines)
+                       return error("deleted file still has contents");
+               fprintf(stderr, "** warning: file %s becomes empty but is not deleted\n", patch->new_name);
+       }
 
        /* Parse the thing.. */
        line += len;
        size -= len;
-       for (offset = len; size > 0; offset += len, size -= len, line += len) {
+       linenr++;
+       added = deleted = 0;
+       for (offset = len; size > 0; offset += len, size -= len, line += len, linenr++) {
                if (!oldlines && !newlines)
                        break;
                len = linelen(line, size);
@@ -223,26 +664,45 @@ static int apply_fragment(char *line, unsigned long size)
                        newlines--;
                        break;
                case '-':
+                       deleted++;
                        oldlines--;
                        break;
                case '+':
+                       added++;
                        newlines--;
                        break;
+               /* We allow "\ No newline at end of file" */
+               case '\\':
+                       if (len < 12 || memcmp(line, "\\ No newline", 12))
+                               return -1;
+                       break;
                }
        }
+       patch->lines_added += added;
+       patch->lines_deleted += deleted;
        return offset;
 }
 
-static int apply_single_patch(char *line, unsigned long size)
+static int parse_single_patch(char *line, unsigned long size, struct patch *patch)
 {
        unsigned long offset = 0;
+       struct fragment **fragp = &patch->fragments;
 
        while (size > 4 && !memcmp(line, "@@ -", 4)) {
-               int len = apply_fragment(line, size);
+               struct fragment *fragment;
+               int len;
+
+               fragment = xmalloc(sizeof(*fragment));
+               memset(fragment, 0, sizeof(*fragment));
+               len = parse_fragment(line, size, patch, fragment);
                if (len <= 0)
-                       break;
+                       die("corrupt patch at line %d", linenr);
 
-printf("applying fragment:\n%.*s\n\n", len, line);
+               fragment->patch = line;
+               fragment->size = len;
+
+               *fragp = fragment;
+               fragp = &fragment->next;
 
                offset += len;
                line += len;
@@ -251,39 +711,687 @@ printf("applying fragment:\n%.*s\n\n", len, line);
        return offset;
 }
 
-static int apply_chunk(char *buffer, unsigned long size)
+static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
 {
        int hdrsize, patchsize;
-       int offset = find_header(buffer, size, &hdrsize);
-       char *header, *patch;
+       int offset = find_header(buffer, size, &hdrsize, patch);
 
        if (offset < 0)
                return offset;
-       header = buffer + offset;
-
-printf("Found header:\n%.*s\n\n", hdrsize, header);
 
-       patch = header + hdrsize;
-       patchsize = apply_single_patch(patch, size - offset - hdrsize);
+       patchsize = parse_single_patch(buffer + offset + hdrsize, size - offset - hdrsize, patch);
 
        return offset + hdrsize + patchsize;
 }
 
+const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
+const char minuses[]= "----------------------------------------------------------------------";
+
+static void show_stats(struct patch *patch)
+{
+       char *name = patch->new_name;
+       int len, max, add, del, total;
+
+       if (!name)
+               name = patch->old_name;
+
+       /*
+        * "scale" the filename
+        */
+       len = strlen(name);
+       max = max_len;
+       if (max > 50)
+               max = 50;
+       if (len > max)
+               name += len - max;
+       len = max;
+
+       /*
+        * scale the add/delete
+        */
+       max = max_change;
+       if (max + len > 70)
+               max = 70 - len;
+
+       add = patch->lines_added;
+       del = patch->lines_deleted;
+       total = add + del;
+
+       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 |%5d %.*s%.*s\n",
+               len, name, patch->lines_added + patch->lines_deleted,
+               add, pluses, del, minuses);
+}
+
+static int read_old_data(struct stat *st, const char *path, void *buf, unsigned long size)
+{
+       int fd;
+       unsigned long got;
+
+       switch (st->st_mode & S_IFMT) {
+       case S_IFLNK:
+               return readlink(path, buf, size);
+       case S_IFREG:
+               fd = open(path, O_RDONLY);
+               if (fd < 0)
+                       return error("unable to open %s", path);
+               got = 0;
+               for (;;) {
+                       int ret = read(fd, buf + got, size - got);
+                       if (ret < 0) {
+                               if (errno == EAGAIN)
+                                       continue;
+                               break;
+                       }
+                       if (!ret)
+                               break;
+                       got += ret;
+               }
+               close(fd);
+               return got;
+
+       default:
+               return -1;
+       }
+}
+
+static int find_offset(const char *buf, unsigned long size, const char *fragment, unsigned long fragsize, int line)
+{
+       int i;
+       unsigned long start, backwards, forwards;
+
+       if (fragsize > size)
+               return -1;
+
+       start = 0;
+       if (line > 1) {
+               unsigned long offset = 0;
+               i = line-1;
+               while (offset + fragsize <= size) {
+                       if (buf[offset++] == '\n') {
+                               start = offset;
+                               if (!--i)
+                                       break;
+                       }
+               }
+       }
+
+       /* Exact line number? */
+       if (!memcmp(buf + start, fragment, fragsize))
+               return start;
+
+       /*
+        * There's probably some smart way to do this, but I'll leave
+        * that to the smart and beautiful people. I'm simple and stupid.
+        */
+       backwards = start;
+       forwards = start;
+       for (i = 0; ; i++) {
+               unsigned long try;
+               int n;
+
+               /* "backward" */
+               if (i & 1) {
+                       if (!backwards) {
+                               if (forwards + fragsize > size)
+                                       break;
+                               continue;
+                       }
+                       do {
+                               --backwards;
+                       } while (backwards && buf[backwards-1] != '\n');
+                       try = backwards;
+               } else {
+                       while (forwards + fragsize <= size) {
+                               if (buf[forwards++] == '\n')
+                                       break;
+                       }
+                       try = forwards;
+               }
+
+               if (try + fragsize > size)
+                       continue;
+               if (memcmp(buf + try, fragment, fragsize))
+                       continue;
+               n = (i >> 1)+1;
+               if (i & 1)
+                       n = -n;
+               return try;
+       }
+
+       /*
+        * We should start searching forward and backward.
+        */
+       return -1;
+}
+
+struct buffer_desc {
+       char *buffer;
+       unsigned long size;
+       unsigned long alloc;
+};
+
+static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag)
+{
+       char *buf = desc->buffer;
+       const char *patch = frag->patch;
+       int offset, size = frag->size;
+       char *old = xmalloc(size);
+       char *new = xmalloc(size);
+       int oldsize = 0, newsize = 0;
+
+       while (size > 0) {
+               int len = linelen(patch, size);
+               int plen;
+
+               if (!len)
+                       break;
+
+               /*
+                * "plen" is how much of the line we should use for
+                * the actual patch data. Normally we just remove the
+                * first character on the line, but if the line is
+                * followed by "\ No newline", then we also remove the
+                * last one (which is the newline, of course).
+                */
+               plen = len-1;
+               if (len > size && patch[len] == '\\')
+                       plen--;
+               switch (*patch) {
+               case ' ':
+               case '-':
+                       memcpy(old + oldsize, patch + 1, plen);
+                       oldsize += plen;
+                       if (*patch == '-')
+                               break;
+               /* Fall-through for ' ' */
+               case '+':
+                       memcpy(new + newsize, patch + 1, plen);
+                       newsize += plen;
+                       break;
+               case '@': case '\\':
+                       /* Ignore it, we already handled it */
+                       break;
+               default:
+                       return -1;
+               }
+               patch += len;
+               size -= len;
+       }
+
+       offset = find_offset(buf, desc->size, old, oldsize, frag->newpos);
+       if (offset >= 0) {
+               int diff = newsize - oldsize;
+               unsigned long size = desc->size + diff;
+               unsigned long alloc = desc->alloc;
+
+               if (size > alloc) {
+                       alloc = size + 8192;
+                       desc->alloc = alloc;
+                       buf = xrealloc(buf, alloc);
+                       desc->buffer = buf;
+               }
+               desc->size = size;
+               memmove(buf + offset + newsize, buf + offset + oldsize, size - offset - newsize);
+               memcpy(buf + offset, new, newsize);
+               offset = 0;
+       }
+
+       free(old);
+       free(new);
+       return offset;
+}
+
+static int apply_fragments(struct buffer_desc *desc, struct patch *patch)
+{
+       struct fragment *frag = patch->fragments;
+
+       while (frag) {
+               if (apply_one_fragment(desc, frag) < 0)
+                       return error("patch failed: %s:%d", patch->old_name, frag->oldpos);
+               frag = frag->next;
+       }
+       return 0;
+}
+
+static int apply_data(struct patch *patch, struct stat *st)
+{
+       char *buf;
+       unsigned long size, alloc;
+       struct buffer_desc desc;
+
+       size = 0;
+       alloc = 0;
+       buf = NULL;
+       if (patch->old_name) {
+               size = st->st_size;
+               alloc = size + 8192;
+               buf = xmalloc(alloc);
+               if (read_old_data(st, patch->old_name, buf, alloc) != size)
+                       return error("read of %s failed", patch->old_name);
+       }
+
+       desc.size = size;
+       desc.alloc = alloc;
+       desc.buffer = buf;
+       if (apply_fragments(&desc, patch) < 0)
+               return -1;
+       patch->result = desc.buffer;
+       patch->resultsize = desc.size;
+
+       if (patch->is_delete && patch->resultsize)
+               return error("removal patch leaves file contents");
+
+       return 0;
+}
+
+static int check_patch(struct patch *patch)
+{
+       struct stat st;
+       const char *old_name = patch->old_name;
+       const char *new_name = patch->new_name;
+
+       if (old_name) {
+               int changed;
+
+               if (lstat(old_name, &st) < 0)
+                       return error("%s: %s", old_name, strerror(errno));
+               if (check_index) {
+                       int pos = cache_name_pos(old_name, strlen(old_name));
+                       if (pos < 0)
+                               return error("%s: does not exist in index", old_name);
+                       changed = ce_match_stat(active_cache[pos], &st);
+                       if (changed)
+                               return error("%s: does not match index", old_name);
+               }
+               if (patch->is_new < 0)
+                       patch->is_new = 0;
+               st.st_mode = ntohl(create_ce_mode(st.st_mode));
+               if (!patch->old_mode)
+                       patch->old_mode = st.st_mode;
+               if ((st.st_mode ^ patch->old_mode) & S_IFMT)
+                       return error("%s: wrong type", old_name);
+               if (st.st_mode != patch->old_mode)
+                       fprintf(stderr, "warning: %s has type %o, expected %o\n",
+                               old_name, st.st_mode, patch->old_mode);
+       }
+
+       if (new_name && (patch->is_new | patch->is_rename | patch->is_copy)) {
+               if (check_index && cache_name_pos(new_name, strlen(new_name)) >= 0)
+                       return error("%s: already exists in index", new_name);
+               if (!lstat(new_name, &st))
+                       return error("%s: already exists in working directory", new_name);
+               if (errno != ENOENT)
+                       return error("%s: %s", new_name, strerror(errno));
+               if (!patch->new_mode)
+                       patch->new_mode = S_IFREG | 0644;
+       }
+
+       if (new_name && old_name) {
+               int same = !strcmp(old_name, new_name);
+               if (!patch->new_mode)
+                       patch->new_mode = patch->old_mode;
+               if ((patch->old_mode ^ patch->new_mode) & S_IFMT)
+                       return error("new mode (%o) of %s does not match old mode (%o)%s%s",
+                               patch->new_mode, new_name, patch->old_mode,
+                               same ? "" : " of ", same ? "" : old_name);
+       }       
+
+       if (apply_data(patch, &st) < 0)
+               return error("%s: patch does not apply", old_name);
+       return 0;
+}
+
+static int check_patch_list(struct patch *patch)
+{
+       int error = 0;
+
+       for (;patch ; patch = patch->next)
+               error |= check_patch(patch);
+       return error;
+}
+
+static void show_file(int c, unsigned int mode, const char *name)
+{
+       printf("%c %o %s\n", c, mode, name);
+}
+
+static void show_file_list(struct patch *patch)
+{
+       for (;patch ; patch = patch->next) {
+               if (patch->is_rename) {
+                       show_file('-', patch->old_mode, patch->old_name);
+                       show_file('+', patch->new_mode, patch->new_name);
+                       continue;
+               }
+               if (patch->is_copy || patch->is_new) {
+                       show_file('+', patch->new_mode, patch->new_name);
+                       continue;
+               }
+               if (patch->is_delete) {
+                       show_file('-', patch->old_mode, patch->old_name);
+                       continue;
+               }
+               if (patch->old_mode && patch->new_mode && patch->old_mode != patch->new_mode) {
+                       printf("M %o:%o %s\n", patch->old_mode, patch->new_mode, patch->old_name);
+                       continue;
+               }
+               printf("M %o %s\n", patch->old_mode, patch->old_name);
+       }
+}
+
+static void stat_patch_list(struct patch *patch)
+{
+       int files, adds, dels;
+
+       for (files = adds = dels = 0 ; patch ; patch = patch->next) {
+               files++;
+               adds += patch->lines_added;
+               dels += patch->lines_deleted;
+               show_stats(patch);
+       }
+
+       printf(" %d files changed, %d insertions(+), %d deletions(-)\n", files, adds, dels);
+}
+
+static void show_file_mode_name(const char *newdelete, unsigned int mode, const char *name)
+{
+       if (mode)
+               printf(" %s mode %06o %s\n", newdelete, mode, name);
+       else
+               printf(" %s %s\n", newdelete, name);
+}
+
+static void show_mode_change(struct patch *p, int show_name)
+{
+       if (p->old_mode && p->new_mode && p->old_mode != p->new_mode) {
+               if (show_name)
+                       printf(" mode change %06o => %06o %s\n",
+                              p->old_mode, p->new_mode, p->new_name);
+               else
+                       printf(" mode change %06o => %06o\n",
+                              p->old_mode, p->new_mode);
+       }
+}
+
+static void show_rename_copy(struct patch *p)
+{
+       const char *renamecopy = p->is_rename ? "rename" : "copy";
+       const char *old, *new;
+
+       /* Find common prefix */
+       old = p->old_name;
+       new = p->new_name;
+       while (1) {
+               const char *slash_old, *slash_new;
+               slash_old = strchr(old, '/');
+               slash_new = strchr(new, '/');
+               if (!slash_old ||
+                   !slash_new ||
+                   slash_old - old != slash_new - new ||
+                   memcmp(old, new, slash_new - new))
+                       break;
+               old = slash_old + 1;
+               new = slash_new + 1;
+       }
+       /* p->old_name thru old is the common prefix, and old and new
+        * through the end of names are renames
+        */
+       if (old != p->old_name)
+               printf(" %s %.*s{%s => %s} (%d%%)\n", renamecopy,
+                      old - p->old_name, p->old_name,
+                      old, new, p->score);
+       else
+               printf(" %s %s => %s (%d%%)\n", renamecopy,
+                      p->old_name, p->new_name, p->score);
+       show_mode_change(p, 0);
+}
+
+static void summary_patch_list(struct patch *patch)
+{
+       struct patch *p;
+
+       for (p = patch; p; p = p->next) {
+               if (p->is_new)
+                       show_file_mode_name("create", p->new_mode, p->new_name);
+               else if (p->is_delete)
+                       show_file_mode_name("delete", p->old_mode, p->old_name);
+               else {
+                       if (p->is_rename || p->is_copy)
+                               show_rename_copy(p);
+                       else {
+                               if (p->score) {
+                                       printf(" rewrite %s (%d%%)\n",
+                                              p->new_name, p->score);
+                                       show_mode_change(p, 0);
+                               }
+                               else
+                                       show_mode_change(p, 1);
+                       }
+               }
+       }
+}
+
+static void patch_stats(struct patch *patch)
+{
+       int lines = patch->lines_added + patch->lines_deleted;
+
+       if (lines > max_change)
+               max_change = lines;
+       if (patch->old_name) {
+               int len = strlen(patch->old_name);
+               if (len > max_len)
+                       max_len = len;
+       }
+       if (patch->new_name) {
+               int len = strlen(patch->new_name);
+               if (len > max_len)
+                       max_len = len;
+       }
+}
+
+static void remove_file(struct patch *patch)
+{
+       if (write_index) {
+               if (remove_file_from_cache(patch->old_name) < 0)
+                       die("unable to remove %s from index", patch->old_name);
+       }
+       unlink(patch->old_name);
+}
+
+static void add_index_file(const char *path, unsigned mode, void *buf, unsigned long size)
+{
+       struct stat st;
+       struct cache_entry *ce;
+       int namelen = strlen(path);
+       unsigned ce_size = cache_entry_size(namelen);
+
+       if (!write_index)
+               return;
+
+       ce = xmalloc(ce_size);
+       memset(ce, 0, ce_size);
+       memcpy(ce->name, path, namelen);
+       ce->ce_mode = create_ce_mode(mode);
+       ce->ce_flags = htons(namelen);
+       if (lstat(path, &st) < 0)
+               die("unable to stat newly created file %s", path);
+       fill_stat_cache_info(ce, &st);
+       if (write_sha1_file(buf, size, "blob", ce->sha1) < 0)
+               die("unable to create backing store for newly created file %s", path);
+       if (add_cache_entry(ce, ADD_CACHE_OK_TO_ADD) < 0)
+               die("unable to add cache entry for %s", path);
+}
+
+static void create_subdirectories(const char *path)
+{
+       int len = strlen(path);
+       char *buf = xmalloc(len + 1);
+       const char *slash = path;
+
+       while ((slash = strchr(slash+1, '/')) != NULL) {
+               len = slash - path;
+               memcpy(buf, path, len);
+               buf[len] = 0;
+               if (mkdir(buf, 0755) < 0) {
+                       if (errno != EEXIST)
+                               break;
+               }
+       }
+       free(buf);
+}
+
+/*
+ * We optimistically assume that the directories exist,
+ * which is true 99% of the time anyway. If they don't,
+ * we create them and try again.
+ */
+static int create_regular_file(const char *path, unsigned int mode)
+{
+       int ret = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+
+       if (ret < 0 && errno == ENOENT) {
+               create_subdirectories(path);
+               ret = open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
+       }
+       return ret;
+}
+
+static int create_symlink(const char *buf, const char *path)
+{
+       int ret = symlink(buf, path);
+
+       if (ret < 0 && errno == ENOENT) {
+               create_subdirectories(path);
+               ret = symlink(buf, path);
+       }
+       return ret;
+}
+
+static void create_file(struct patch *patch)
+{
+       const char *path = patch->new_name;
+       unsigned mode = patch->new_mode;
+       unsigned long size = patch->resultsize;
+       char *buf = patch->result;
+
+       if (!mode)
+               mode = S_IFREG | 0644;
+       if (S_ISREG(mode)) {
+               int fd;
+               mode = (mode & 0100) ? 0777 : 0666;
+               fd = create_regular_file(path, mode);
+               if (fd < 0)
+                       die("unable to create file %s (%s)", path, strerror(errno));
+               if (write(fd, buf, size) != size)
+                       die("unable to write file %s", path);
+               close(fd);
+               add_index_file(path, mode, buf, size);
+               return;
+       }
+       if (S_ISLNK(mode)) {
+               if (size && buf[size-1] == '\n')
+                       size--;
+               buf[size] = 0;
+               if (create_symlink(buf, path) < 0)
+                       die("unable to write symlink %s", path);
+               add_index_file(path, mode, buf, size);
+               return;
+       }
+       die("unable to write file mode %o", mode);
+}
+
+static void write_out_one_result(struct patch *patch)
+{
+       if (patch->is_delete > 0) {
+               remove_file(patch);
+               return;
+       }
+       if (patch->is_new > 0 || patch->is_copy) {
+               create_file(patch);
+               return;
+       }
+       /*
+        * Rename or modification boils down to the same
+        * thing: remove the old, write the new
+        */
+       remove_file(patch);
+       create_file(patch);
+}
+
+static void write_out_results(struct patch *list)
+{
+       if (!list)
+               die("No changes");
+
+       while (list) {
+               write_out_one_result(list);
+               list = list->next;
+       }
+}
+
+static struct cache_file cache_file;
+
 static int apply_patch(int fd)
 {
+       int newfd;
        unsigned long offset, size;
        char *buffer = read_patch_file(fd, &size);
+       struct patch *list = NULL, **listp = &list;
 
        if (!buffer)
                return -1;
        offset = 0;
        while (size > 0) {
-               int nr = apply_chunk(buffer + offset, size);
+               struct patch *patch;
+               int nr;
+
+               patch = xmalloc(sizeof(*patch));
+               memset(patch, 0, sizeof(*patch));
+               nr = parse_chunk(buffer + offset, size, patch);
                if (nr < 0)
                        break;
+               patch_stats(patch);
+               *listp = patch;
+               listp = &patch->next;
                offset += nr;
                size -= nr;
        }
+
+       newfd = -1;
+       write_index = check_index && apply;
+       if (write_index)
+               newfd = hold_index_file_for_update(&cache_file, get_index_file());
+       if (check_index) {
+               if (read_cache() < 0)
+                       die("unable to read index file");
+       }
+
+       if ((check || apply) && check_patch_list(list) < 0)
+               exit(1);
+
+       if (apply)
+               write_out_results(list);
+
+       if (write_index) {
+               if (write_cache(newfd, active_cache, active_nr) ||
+                   commit_index_file(&cache_file))
+                       die("Unable to write new cachefile");
+       }
+
+       if (show_files)
+               show_file_list(list);
+
+       if (diffstat)
+               stat_patch_list(list);
+
+       if (summary)
+               summary_patch_list(list);
+
        free(buffer);
        return 0;
 }
@@ -291,9 +1399,7 @@ static int apply_patch(int fd)
 int main(int argc, char **argv)
 {
        int i;
-
-       if (read_cache() < 0)
-               die("unable to read index file");
+       int read_stdin = 1;
 
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
@@ -301,17 +1407,48 @@ int main(int argc, char **argv)
 
                if (!strcmp(arg, "-")) {
                        apply_patch(0);
+                       read_stdin = 0;
                        continue;
                }
                if (!strcmp(arg, "--no-merge")) {
                        merge_patch = 0;
                        continue;
                }
+               if (!strcmp(arg, "--stat")) {
+                       apply = 0;
+                       diffstat = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--summary")) {
+                       apply = 0;
+                       summary = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--check")) {
+                       apply = 0;
+                       check = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--index")) {
+                       check_index = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--apply")) {
+                       apply = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--show-files")) {
+                       show_files = 1;
+                       continue;
+               }
                fd = open(arg, O_RDONLY);
                if (fd < 0)
                        usage(apply_usage);
+               read_stdin = 0;
                apply_patch(fd);
                close(fd);
        }
+       if (read_stdin)
+               apply_patch(0);
        return 0;
 }