libify git-ls-files directory traversal
[gitweb.git] / combine-diff.c
index 243f96775aaa058581491544f53f05a3bd038cc0..64b20cce2427fcf0cd9565f5e24efce78abb0088 100644 (file)
@@ -1,15 +1,16 @@
 #include "cache.h"
 #include "commit.h"
+#include "blob.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "quote.h"
+#include "xdiff-interface.h"
+#include "log-tree.h"
 
 static int uninteresting(struct diff_filepair *p)
 {
        if (diff_unmodified_pair(p))
                return 1;
-       if (!S_ISREG(p->one->mode) || !S_ISREG(p->two->mode))
-               return 1;
        return 0;
 }
 
@@ -28,15 +29,20 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
                                continue;
                        path = q->queue[i]->two->path;
                        len = strlen(path);
-
-                       p = xmalloc(sizeof(*p) + len + 1 + num_parent * 20);
-                       p->path = (char*) &(p->parent_sha1[num_parent][0]);
+                       p = xmalloc(combine_diff_path_size(num_parent, len));
+                       p->path = (char*) &(p->parent[num_parent]);
                        memcpy(p->path, path, len);
                        p->path[len] = 0;
                        p->len = len;
                        p->next = NULL;
+                       memset(p->parent, 0,
+                              sizeof(p->parent[0]) * num_parent);
+
                        memcpy(p->sha1, q->queue[i]->two->sha1, 20);
-                       memcpy(p->parent_sha1[n], q->queue[i]->one->sha1, 20);
+                       p->mode = q->queue[i]->two->mode;
+                       memcpy(p->parent[n].sha1, q->queue[i]->one->sha1, 20);
+                       p->parent[n].mode = q->queue[i]->one->mode;
+                       p->parent[n].status = q->queue[i]->status;
                        *tail = p;
                        tail = &p->next;
                }
@@ -57,8 +63,10 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
                        len = strlen(path);
                        if (len == p->len && !memcmp(path, p->path, len)) {
                                found = 1;
-                               memcpy(p->parent_sha1[n],
+                               memcpy(p->parent[n].sha1,
                                       q->queue[i]->one->sha1, 20);
+                               p->parent[n].mode = q->queue[i]->one->mode;
+                               p->parent[n].status = q->queue[i]->status;
                                break;
                        }
                }
@@ -68,6 +76,7 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
        return curr;
 }
 
+/* Lines lost from parent */
 struct lline {
        struct lline *next;
        int len;
@@ -75,11 +84,17 @@ struct lline {
        char line[FLEX_ARRAY];
 };
 
+/* Lines surviving in the merge result */
 struct sline {
        struct lline *lost_head, **lost_tail;
        char *bol;
        int len;
+       /* bit 0 up to (N-1) are on if the parent has this line (i.e.
+        * we did not change it).
+        * bit N is used for "interesting" lines, including context.
+        */
        unsigned long flag;
+       unsigned long *p_lno;
 };
 
 static char *grab_blob(const unsigned char *sha1, unsigned long *size)
@@ -92,83 +107,14 @@ static char *grab_blob(const unsigned char *sha1, unsigned long *size)
                return xcalloc(1, 1);
        }
        blob = read_sha1_file(sha1, type, size);
-       if (strcmp(type, "blob"))
+       if (strcmp(type, blob_type))
                die("object '%s' is not a blob!", sha1_to_hex(sha1));
        return blob;
 }
 
-#define TMPPATHLEN 50
-#define MAXLINELEN 10240
-
-static void write_to_temp_file(char *tmpfile, void *blob, unsigned long size)
-{
-       int fd = git_mkstemp(tmpfile, TMPPATHLEN, ".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);
-}
-
-static void write_temp_blob(char *tmpfile, const unsigned char *sha1)
-{
-       unsigned long size;
-       void *blob;
-       blob = grab_blob(sha1, &size);
-       write_to_temp_file(tmpfile, blob, size);
-       free(blob);
-}
-
-static int parse_num(char **cp_p, unsigned int *num_p)
-{
-       char *cp = *cp_p;
-       unsigned int num = 0;
-       int read_some;
-
-       while ('0' <= *cp && *cp <= '9')
-               num = num * 10 + *cp++ - '0';
-       if (!(read_some = cp - *cp_p))
-               return -1;
-       *cp_p = cp;
-       *num_p = num;
-       return 0;
-}
-
-static int parse_hunk_header(char *line, int len,
-                            unsigned int *ob, unsigned int *on,
-                            unsigned int *nb, unsigned int *nn)
-{
-       char *cp;
-       cp = line + 4;
-       if (parse_num(&cp, ob)) {
-       bad_line:
-               return error("malformed diff output: %s", line);
-       }
-       if (*cp == ',') {
-               cp++;
-               if (parse_num(&cp, on))
-                       goto bad_line;
-       }
-       else
-               *on = 1;
-       if (*cp++ != ' ' || *cp++ != '+')
-               goto bad_line;
-       if (parse_num(&cp, nb))
-               goto bad_line;
-       if (*cp == ',') {
-               cp++;
-               if (parse_num(&cp, nn))
-                       goto bad_line;
-       }
-       else
-               *nn = 1;
-       return -!!memcmp(cp, " @@", 3);
-}
-
-static void append_lost(struct sline *sline, int n, const char *line)
+static void append_lost(struct sline *sline, int n, const char *line, int len)
 {
        struct lline *lline;
-       int len = strlen(line);
        unsigned long this_mask = (1UL<<n);
        if (line[len-1] == '\n')
                len--;
@@ -203,115 +149,127 @@ static void append_lost(struct sline *sline, int n, const char *line)
        sline->lost_tail = &lline->next;
 }
 
-static void combine_diff(const unsigned char *parent, const char *ourtmp,
-                        struct sline *sline, int cnt, int n)
-{
-       FILE *in;
-       char parent_tmp[TMPPATHLEN];
-       char cmd[TMPPATHLEN * 2 + 1024];
-       char line[MAXLINELEN];
-       unsigned int lno, ob, on, nb, nn;
-       unsigned long pmask = ~(1UL << n);
-       struct sline *lost_bucket = NULL;
-
-       write_temp_blob(parent_tmp, parent);
-       sprintf(cmd, "diff --unified=0 -La/x -Lb/x '%s' '%s'",
-               parent_tmp, ourtmp);
-       in = popen(cmd, "r");
-       if (!in)
-               return;
-
-       lno = 1;
-       while (fgets(line, sizeof(line), in) != NULL) {
-               int len = strlen(line);
-               if (5 < len && !memcmp("@@ -", line, 4)) {
-                       if (parse_hunk_header(line, len,
-                                             &ob, &on, &nb, &nn))
-                               break;
-                       lno = nb;
-                       if (!nb) {
-                               /* @@ -1,2 +0,0 @@ to remove the
-                                * first two lines...
-                                */
-                               nb = 1;
-                       }
-                       lost_bucket = &sline[nb-1]; /* sline is 0 based */
-                       continue;
-               }
-               if (!lost_bucket)
-                       continue;
-               switch (line[0]) {
-               case '-':
-                       append_lost(lost_bucket, n, line+1);
-                       break;
-               case '+':
-                       sline[lno-1].flag &= pmask;
-                       lno++;
-                       break;
-               }
-       }
-       fclose(in);
-       unlink(parent_tmp);
-}
+struct combine_diff_state {
+       struct xdiff_emit_state xm;
 
-static unsigned long context = 3;
-static char combine_marker = '@';
+       unsigned int lno;
+       int ob, on, nb, nn;
+       unsigned long nmask;
+       int num_parent;
+       int n;
+       struct sline *sline;
+       struct sline *lost_bucket;
+};
 
-static int interesting(struct sline *sline, unsigned long all_mask)
+static void consume_line(void *state_, char *line, unsigned long len)
 {
-       return ((sline->flag & all_mask) != all_mask || sline->lost_head);
+       struct combine_diff_state *state = state_;
+       if (5 < len && !memcmp("@@ -", line, 4)) {
+               if (parse_hunk_header(line, len,
+                                     &state->ob, &state->on,
+                                     &state->nb, &state->nn))
+                       return;
+               state->lno = state->nb;
+               if (!state->nb)
+                       /* @@ -1,2 +0,0 @@ to remove the
+                        * first two lines...
+                        */
+                       state->nb = 1;
+               if (state->nn == 0)
+                       /* @@ -X,Y +N,0 @@ removed Y lines
+                        * that would have come *after* line N
+                        * in the result.  Our lost buckets hang
+                        * to the line after the removed lines,
+                        */
+                       state->lost_bucket = &state->sline[state->nb];
+               else
+                       state->lost_bucket = &state->sline[state->nb-1];
+               if (!state->sline[state->nb-1].p_lno)
+                       state->sline[state->nb-1].p_lno =
+                               xcalloc(state->num_parent,
+                                       sizeof(unsigned long));
+               state->sline[state->nb-1].p_lno[state->n] = state->ob;
+               return;
+       }
+       if (!state->lost_bucket)
+               return; /* not in any hunk yet */
+       switch (line[0]) {
+       case '-':
+               append_lost(state->lost_bucket, state->n, line+1, len-1);
+               break;
+       case '+':
+               state->sline[state->lno-1].flag |= state->nmask;
+               state->lno++;
+               break;
+       }
 }
 
-static unsigned long line_common_diff(struct sline *sline, unsigned long all_mask)
+static void combine_diff(const unsigned char *parent, mmfile_t *result_file,
+                        struct sline *sline, int cnt, int n, int num_parent)
 {
-       /*
-        * Look at the line and see from which parents we have the
-        * same difference.
-        */
-
-       /* Lower bits of sline->flag records if the parent had this
-        * line, so XOR with all_mask gives us on-bits for parents we
-        * have differences with.
+       unsigned int p_lno, lno;
+       unsigned long nmask = (1UL << n);
+       xpparam_t xpp;
+       xdemitconf_t xecfg;
+       mmfile_t parent_file;
+       xdemitcb_t ecb;
+       struct combine_diff_state state;
+       unsigned long sz;
+
+       if (!cnt)
+               return; /* result deleted */
+
+       parent_file.ptr = grab_blob(parent, &sz);
+       parent_file.size = sz;
+       xpp.flags = XDF_NEED_MINIMAL;
+       xecfg.ctxlen = 0;
+       xecfg.flags = 0;
+       ecb.outf = xdiff_outf;
+       ecb.priv = &state;
+       memset(&state, 0, sizeof(state));
+       state.xm.consume = consume_line;
+       state.nmask = nmask;
+       state.sline = sline;
+       state.lno = 1;
+       state.num_parent = num_parent;
+       state.n = n;
+
+       xdl_diff(&parent_file, result_file, &xpp, &xecfg, &ecb);
+       free(parent_file.ptr);
+
+       /* Assign line numbers for this parent.
+        *
+        * sline[lno].p_lno[n] records the first line number
+        * (counting from 1) for parent N if the final hunk display
+        * started by showing sline[lno] (possibly showing the lost
+        * lines attached to it first).
         */
-       unsigned long common_adds = (sline->flag ^ all_mask) & all_mask;
-       unsigned long common_removes = all_mask;
-
-       /* If all the parents have this line, that also counts as
-        * having the same difference.
-        */
-       if (!common_adds)
-               common_adds = all_mask;
-
-       if (sline->lost_head) {
-               /* Lost head list records the lines removed from
-                * the parents, and parent_map records from which
-                * parent the line was removed.
-                */
+       for (lno = 0,  p_lno = 1; lno <= cnt; lno++) {
                struct lline *ll;
-               for (ll = sline->lost_head; ll; ll = ll->next) {
-                       common_removes &= ll->parent_map;
+               sline[lno].p_lno[n] = p_lno;
+
+               /* How many lines would this sline advance the p_lno? */
+               ll = sline[lno].lost_head;
+               while (ll) {
+                       if (ll->parent_map & nmask)
+                               p_lno++; /* '-' means parent had it */
+                       ll = ll->next;
                }
+               if (lno < cnt && !(sline[lno].flag & nmask))
+                       p_lno++; /* no '+' means parent had it */
        }
-       return common_adds & common_removes;
+       sline[lno].p_lno[n] = p_lno; /* trailer */
 }
 
-static unsigned long line_all_diff(struct sline *sline, unsigned long all_mask)
+static unsigned long context = 3;
+static char combine_marker = '@';
+
+static int interesting(struct sline *sline, unsigned long all_mask)
 {
-       /*
-        * Look at the line and see from which parents we have some difference.
+       /* If some parents lost lines here, or if we have added to
+        * some parent, it is interesting.
         */
-       unsigned long different = (sline->flag ^ all_mask) & all_mask;
-       if (sline->lost_head) {
-               /* Lost head list records the lines removed from
-                * the parents, and parent_map records from which
-                * parent the line was removed.
-                */
-               struct lline *ll;
-               for (ll = sline->lost_head; ll; ll = ll->next) {
-                       different |= ll->parent_map;
-               }
-       }
-       return different;
+       return ((sline->flag & all_mask) || sline->lost_head);
 }
 
 static unsigned long adjust_hunk_tail(struct sline *sline,
@@ -319,32 +277,39 @@ static unsigned long adjust_hunk_tail(struct sline *sline,
                                      unsigned long hunk_begin,
                                      unsigned long i)
 {
-       /* i points at the first uninteresting line.
-        * If the last line of the hunk was interesting
-        * only because it has some deletion, then
-        * it is not all that interesting for the
-        * purpose of giving trailing context lines.
+       /* i points at the first uninteresting line.  If the last line
+        * of the hunk was interesting only because it has some
+        * deletion, then it is not all that interesting for the
+        * purpose of giving trailing context lines.  This is because
+        * we output '-' line and then unmodified sline[i-1] itself in
+        * that case which gives us one extra context line.
         */
-       if ((hunk_begin + 1 <= i) &&
-           ((sline[i-1].flag & all_mask) == all_mask))
+       if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
                i--;
        return i;
 }
 
-static unsigned long next_interesting(struct sline *sline,
-                                     unsigned long mark,
-                                     unsigned long i,
-                                     unsigned long cnt,
-                                     int uninteresting)
+static unsigned long find_next(struct sline *sline,
+                              unsigned long mark,
+                              unsigned long i,
+                              unsigned long cnt,
+                              int uninteresting)
 {
-       while (i < cnt)
-               if (uninteresting ?
-                   !(sline[i].flag & mark) :
-                   (sline[i].flag & mark))
+       /* We have examined up to i-1 and are about to look at i.
+        * Find next interesting or uninteresting line.  Here,
+        * "interesting" does not mean interesting(), but marked by
+        * the give_context() function below (i.e. it includes context
+        * lines that are not interesting to interesting() function
+        * that are surrounded by interesting() ones.
+        */
+       while (i <= cnt)
+               if (uninteresting
+                   ? !(sline[i].flag & mark)
+                   : (sline[i].flag & mark))
                        return i;
                else
                        i++;
-       return cnt;
+       return i;
 }
 
 static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
@@ -353,23 +318,37 @@ static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
        unsigned long mark = (1UL<<num_parent);
        unsigned long i;
 
-       i = next_interesting(sline, mark, 0, cnt, 0);
-       if (cnt <= i)
+       /* Two groups of interesting lines may have a short gap of
+        * unintersting lines.  Connect such groups to give them a
+        * bit of context.
+        *
+        * We first start from what the interesting() function says,
+        * and mark them with "mark", and paint context lines with the
+        * mark.  So interesting() would still say false for such context
+        * lines but they are treated as "interesting" in the end.
+        */
+       i = find_next(sline, mark, 0, cnt, 0);
+       if (cnt < i)
                return 0;
 
-       while (i < cnt) {
+       while (i <= cnt) {
                unsigned long j = (context < i) ? (i - context) : 0;
                unsigned long k;
+
+               /* Paint a few lines before the first interesting line. */
                while (j < i)
                        sline[j++].flag |= mark;
 
        again:
-               j = next_interesting(sline, mark, i, cnt, 1);
-               if (cnt <= j)
+               /* we know up to i is to be included.  where does the
+                * next uninteresting one start?
+                */
+               j = find_next(sline, mark, i, cnt, 1);
+               if (cnt < j)
                        break; /* the rest are all interesting */
 
                /* lookahead context lines */
-               k = next_interesting(sline, mark, j, cnt, 0);
+               k = find_next(sline, mark, j, cnt, 0);
                j = adjust_hunk_tail(sline, all_mask, i, j);
 
                if (k < j + context) {
@@ -383,10 +362,11 @@ static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
                }
 
                /* j is the first uninteresting line and there is
-                * no overlap beyond it within context lines.
+                * no overlap beyond it within context lines.  Paint
+                * the trailing edge a bit.
                 */
                i = k;
-               k = (j + context < cnt) ? j + context : cnt;
+               k = (j + context < cnt+1) ? j + context : cnt+1;
                while (j < k)
                        sline[j++].flag |= mark;
        }
@@ -401,7 +381,7 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
        unsigned long i;
        int has_interesting = 0;
 
-       for (i = 0; i < cnt; i++) {
+       for (i = 0; i <= cnt; i++) {
                if (interesting(&sline[i], all_mask))
                        sline[i].flag |= mark;
                else
@@ -415,16 +395,15 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
         * parent, mark that uninteresting.
         */
        i = 0;
-       while (i < cnt) {
+       while (i <= cnt) {
                unsigned long j, hunk_begin, hunk_end;
-               int same, diff;
-               unsigned long same_diff, all_diff;
-               while (i < cnt && !(sline[i].flag & mark))
+               unsigned long same_diff;
+               while (i <= cnt && !(sline[i].flag & mark))
                        i++;
-               if (cnt <= i)
+               if (cnt < i)
                        break; /* No more interesting hunks */
                hunk_begin = i;
-               for (j = i + 1; j < cnt; j++) {
+               for (j = i + 1; j <= cnt; j++) {
                        if (!(sline[j].flag & mark)) {
                                /* Look beyond the end to see if there
                                 * is an interesting line after this
@@ -434,8 +413,8 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
                                int contin = 0;
                                la = adjust_hunk_tail(sline, all_mask,
                                                     hunk_begin, j);
-                               la = (la + context < cnt) ?
-                                       (la + context) : cnt;
+                               la = (la + context < cnt + 1) ?
+                                       (la + context) : cnt + 1;
                                while (j <= --la) {
                                        if (sline[la].flag & mark) {
                                                contin = 1;
@@ -449,23 +428,56 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
                }
                hunk_end = j;
 
-               /* [i..hunk_end) are interesting.  Now does it have
-                * the same change with all but one parent?
+               /* [i..hunk_end) are interesting.  Now is it really
+                * interesting?  We check if there are only two versions
+                * and the result matches one of them.  That is, we look
+                * at:
+                *   (+) line, which records lines added to which parents;
+                *       this line appears in the result.
+                *   (-) line, which records from what parents the line
+                *       was removed; this line does not appear in the result.
+                * then check the set of parents the result has difference
+                * from, from all lines.  If there are lines that has
+                * different set of parents that the result has differences
+                * from, that means we have more than two versions.
+                *
+                * Even when we have only two versions, if the result does
+                * not match any of the parents, the it should be considered
+                * interesting.  In such a case, we would have all '+' line.
+                * After passing the above "two versions" test, that would
+                * appear as "the same set of parents" to be "all parents".
                 */
-               same_diff = all_mask;
-               all_diff = 0;
-               for (j = i; j < hunk_end; j++) {
-                       same_diff &= line_common_diff(sline + j, all_mask);
-                       all_diff |= line_all_diff(sline + j, all_mask);
-               }
-               diff = same = 0;
-               for (j = 0; j < num_parent; j++) {
-                       if (same_diff & (1UL<<j))
-                               same++;
-                       if (all_diff & (1UL<<j))
-                               diff++;
+               same_diff = 0;
+               has_interesting = 0;
+               for (j = i; j < hunk_end && !has_interesting; j++) {
+                       unsigned long this_diff = sline[j].flag & all_mask;
+                       struct lline *ll = sline[j].lost_head;
+                       if (this_diff) {
+                               /* This has some changes.  Is it the
+                                * same as others?
+                                */
+                               if (!same_diff)
+                                       same_diff = this_diff;
+                               else if (same_diff != this_diff) {
+                                       has_interesting = 1;
+                                       break;
+                               }
+                       }
+                       while (ll && !has_interesting) {
+                               /* Lost this line from these parents;
+                                * who are they?  Are they the same?
+                                */
+                               this_diff = ll->parent_map;
+                               if (!same_diff)
+                                       same_diff = this_diff;
+                               else if (same_diff != this_diff) {
+                                       has_interesting = 1;
+                               }
+                               ll = ll->next;
+                       }
                }
-               if ((num_parent - 1 <= same) || (diff == 1)) {
+
+               if (!has_interesting && same_diff != all_mask) {
                        /* This hunk is not that interesting after all */
                        for (j = hunk_begin; j < hunk_end; j++)
                                sline[j].flag &= ~mark;
@@ -477,29 +489,48 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
        return has_interesting;
 }
 
-static void dump_sline(struct sline *sline, int cnt, int num_parent)
+static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, unsigned long cnt, int n)
+{
+       l0 = sline[l0].p_lno[n];
+       l1 = sline[l1].p_lno[n];
+       printf(" -%lu,%lu", l0, l1-l0);
+}
+
+static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 {
        unsigned long mark = (1UL<<num_parent);
        int i;
-       int lno = 0;
+       unsigned long lno = 0;
+
+       if (!cnt)
+               return; /* result deleted */
 
        while (1) {
                struct sline *sl = &sline[lno];
-               int hunk_end;
-               while (lno < cnt && !(sline[lno].flag & mark))
+               unsigned long hunk_end;
+               unsigned long rlines;
+               while (lno <= cnt && !(sline[lno].flag & mark))
                        lno++;
-               if (cnt <= lno)
+               if (cnt < lno)
                        break;
-               for (hunk_end = lno + 1; hunk_end < cnt; hunk_end++)
-                       if (!(sline[hunk_end].flag & mark))
-                               break;
+               else {
+                       for (hunk_end = lno + 1; hunk_end <= cnt; hunk_end++)
+                               if (!(sline[hunk_end].flag & mark))
+                                       break;
+               }
+               rlines = hunk_end - lno;
+               if (cnt < hunk_end)
+                       rlines--; /* pointing at the last delete hunk */
                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
-               printf(" +%d,%d ", lno+1, hunk_end-lno);
+               for (i = 0; i < num_parent; i++)
+                       show_parent_lno(sline, lno, hunk_end, cnt, i);
+               printf(" +%lu,%lu ", lno+1, rlines);
                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
                putchar('\n');
                while (lno < hunk_end) {
                        struct lline *ll;
                        int j;
+                       unsigned long p_mask;
                        sl = &sline[lno++];
                        ll = sl->lost_head;
                        while (ll) {
@@ -512,110 +543,200 @@ static void dump_sline(struct sline *sline, int cnt, int num_parent)
                                puts(ll->line);
                                ll = ll->next;
                        }
+                       if (cnt < lno)
+                               break;
+                       p_mask = 1;
                        for (j = 0; j < num_parent; j++) {
-                               if ((1UL<<j) & sl->flag)
-                                       putchar(' ');
-                               else
+                               if (p_mask & sl->flag)
                                        putchar('+');
+                               else
+                                       putchar(' ');
+                               p_mask <<= 1;
                        }
                        printf("%.*s\n", sl->len, sl->bol);
                }
        }
 }
 
-int show_combined_diff(struct combine_diff_path *elem, int num_parent,
-                      int dense, const char *header, int show_empty)
+static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
+                              int i, int j)
+{
+       /* We have already examined parent j and we know parent i
+        * and parent j are the same, so reuse the combined result
+        * of parent j for parent i.
+        */
+       unsigned long lno, imask, jmask;
+       imask = (1UL<<i);
+       jmask = (1UL<<j);
+
+       for (lno = 0; lno <= cnt; lno++) {
+               struct lline *ll = sline->lost_head;
+               sline->p_lno[i] = sline->p_lno[j];
+               while (ll) {
+                       if (ll->parent_map & jmask)
+                               ll->parent_map |= imask;
+                       ll = ll->next;
+               }
+               if (sline->flag & jmask)
+                       sline->flag |= imask;
+               sline++;
+       }
+       /* the overall size of the file (sline[cnt]) */
+       sline->p_lno[i] = sline->p_lno[j];
+}
+
+static void dump_quoted_path(const char *prefix, const char *path)
+{
+       fputs(prefix, stdout);
+       if (quote_c_style(path, NULL, NULL, 0))
+               quote_c_style(path, NULL, stdout, 0);
+       else
+               printf("%s", path);
+       putchar('\n');
+}
+
+static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
+                          int dense, struct rev_info *rev)
 {
-       unsigned long size, cnt, lno;
-       char *result, *cp, *ep;
+       struct diff_options *opt = &rev->diffopt;
+       unsigned long result_size, cnt, lno;
+       char *result, *cp;
        struct sline *sline; /* survived lines */
+       int mode_differs = 0;
        int i, show_hunks, shown_header = 0;
-       char ourtmp_buf[TMPPATHLEN];
-       char *ourtmp = ourtmp_buf;
+       int working_tree_file = !memcmp(elem->sha1, null_sha1, 20);
+       int abbrev = opt->full_index ? 40 : DEFAULT_ABBREV;
+       mmfile_t result_file;
 
+       context = opt->context;
        /* Read the result of merge first */
-       if (memcmp(elem->sha1, null_sha1, 20)) {
-               result = grab_blob(elem->sha1, &size);
-               write_to_temp_file(ourtmp, result, size);
-       }
+       if (!working_tree_file)
+               result = grab_blob(elem->sha1, &result_size);
        else {
+               /* Used by diff-tree to read from the working tree */
                struct stat st;
                int fd;
-               ourtmp = elem->path;
-               if (0 <= (fd = open(ourtmp, O_RDONLY)) &&
+               if (0 <= (fd = open(elem->path, O_RDONLY)) &&
                    !fstat(fd, &st)) {
                        int len = st.st_size;
                        int cnt = 0;
 
-                       size = len;
+                       elem->mode = canon_mode(st.st_mode);
+                       result_size = len;
                        result = xmalloc(len + 1);
                        while (cnt < len) {
                                int done = xread(fd, result+cnt, len-cnt);
                                if (done == 0)
                                        break;
                                if (done < 0)
-                                       die("read error '%s'", ourtmp);
+                                       die("read error '%s'", elem->path);
                                cnt += done;
                        }
                        result[len] = 0;
                }
                else {
                        /* deleted file */
-                       size = 0;
+                       result_size = 0;
+                       elem->mode = 0;
                        result = xmalloc(1);
                        result[0] = 0;
-                       ourtmp = "/dev/null";
                }
                if (0 <= fd)
                        close(fd);
        }
 
-       for (cnt = 0, cp = result; cp - result < size; cp++) {
+       for (cnt = 0, cp = result; cp - result < result_size; cp++) {
                if (*cp == '\n')
                        cnt++;
        }
-       if (result[size-1] != '\n')
+       if (result_size && result[result_size-1] != '\n')
                cnt++; /* incomplete line */
 
-       sline = xcalloc(cnt, sizeof(*sline));
-       ep = result;
+       sline = xcalloc(cnt+2, sizeof(*sline));
        sline[0].bol = result;
-       for (lno = 0, cp = result; cp - result < size; cp++) {
+       for (lno = 0; lno <= cnt + 1; lno++) {
+               sline[lno].lost_tail = &sline[lno].lost_head;
+               sline[lno].flag = 0;
+       }
+       for (lno = 0, cp = result; cp - result < result_size; cp++) {
                if (*cp == '\n') {
-                       sline[lno].lost_tail = &sline[lno].lost_head;
                        sline[lno].len = cp - sline[lno].bol;
-                       sline[lno].flag = (1UL<<num_parent) - 1;
                        lno++;
                        if (lno < cnt)
                                sline[lno].bol = cp + 1;
                }
        }
-       if (result[size-1] != '\n') {
-               sline[cnt-1].lost_tail = &sline[cnt-1].lost_head;
-               sline[cnt-1].len = size - (sline[cnt-1].bol - result);
-               sline[cnt-1].flag = (1UL<<num_parent) - 1;
-       }
+       if (result_size && result[result_size-1] != '\n')
+               sline[cnt-1].len = result_size - (sline[cnt-1].bol - result);
 
-       for (i = 0; i < num_parent; i++)
-               combine_diff(elem->parent_sha1[i], ourtmp, sline, cnt, i);
+       result_file.ptr = result;
+       result_file.size = result_size;
+
+       /* Even p_lno[cnt+1] is valid -- that is for the end line number
+        * for deletion hunk at the end.
+        */
+       sline[0].p_lno = xcalloc((cnt+2) * num_parent, sizeof(unsigned long));
+       for (lno = 0; lno <= cnt; lno++)
+               sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
+
+       for (i = 0; i < num_parent; i++) {
+               int j;
+               for (j = 0; j < i; j++) {
+                       if (!memcmp(elem->parent[i].sha1,
+                                   elem->parent[j].sha1, 20)) {
+                               reuse_combine_diff(sline, cnt, i, j);
+                               break;
+                       }
+               }
+               if (i <= j)
+                       combine_diff(elem->parent[i].sha1, &result_file, sline,
+                                    cnt, i, num_parent);
+               if (elem->parent[i].mode != elem->mode)
+                       mode_differs = 1;
+       }
 
        show_hunks = make_hunks(sline, cnt, num_parent, dense);
 
-       if (header && (show_hunks || show_empty)) {
-               shown_header++;
-               puts(header);
-       }
-       if (show_hunks) {
-               printf("diff --%s ", dense ? "cc" : "combined");
-               if (quote_c_style(elem->path, NULL, NULL, 0))
-                       quote_c_style(elem->path, NULL, stdout, 0);
-               else
-                       printf("%s", elem->path);
-               putchar('\n');
+       if (show_hunks || mode_differs || working_tree_file) {
+               const char *abb;
+
+               if (rev->loginfo)
+                       show_log(rev, rev->loginfo, "\n");
+               dump_quoted_path(dense ? "diff --cc " : "diff --combined ", elem->path);
+               printf("index ");
+               for (i = 0; i < num_parent; i++) {
+                       abb = find_unique_abbrev(elem->parent[i].sha1,
+                                                abbrev);
+                       printf("%s%s", i ? "," : "", abb);
+               }
+               abb = find_unique_abbrev(elem->sha1, abbrev);
+               printf("..%s\n", abb);
+
+               if (mode_differs) {
+                       int added = !!elem->mode;
+                       for (i = 0; added && i < num_parent; i++)
+                               if (elem->parent[i].status !=
+                                   DIFF_STATUS_ADDED)
+                                       added = 0;
+                       if (added)
+                               printf("new file mode %06o", elem->mode);
+                       else {
+                               if (!elem->mode)
+                                       printf("deleted file ");
+                               printf("mode ");
+                               for (i = 0; i < num_parent; i++) {
+                                       printf("%s%06o", i ? "," : "",
+                                              elem->parent[i].mode);
+                               }
+                               if (elem->mode)
+                                       printf("..%06o", elem->mode);
+                       }
+                       putchar('\n');
+               }
+               dump_quoted_path("--- a/", elem->path);
+               dump_quoted_path("+++ b/", elem->path);
                dump_sline(sline, cnt, num_parent);
        }
-       if (ourtmp == ourtmp_buf)
-               unlink(ourtmp);
        free(result);
 
        for (i = 0; i < cnt; i++) {
@@ -628,39 +749,127 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
                        }
                }
        }
+       free(sline[0].p_lno);
        free(sline);
        return shown_header;
 }
 
-int diff_tree_combined_merge(const unsigned char *sha1,
-                            const char *header,
-                            int show_empty_merge, int dense)
+#define COLONS "::::::::::::::::::::::::::::::::"
+
+static void show_raw_diff(struct combine_diff_path *p, int num_parent, struct rev_info *rev)
 {
-       struct commit *commit = lookup_commit(sha1);
+       struct diff_options *opt = &rev->diffopt;
+       int i, offset;
+       const char *prefix;
+       int line_termination, inter_name_termination;
+
+       line_termination = opt->line_termination;
+       inter_name_termination = '\t';
+       if (!line_termination)
+               inter_name_termination = 0;
+
+       if (rev->loginfo)
+               show_log(rev, rev->loginfo, "\n");
+
+       if (opt->output_format == DIFF_FORMAT_RAW) {
+               offset = strlen(COLONS) - num_parent;
+               if (offset < 0)
+                       offset = 0;
+               prefix = COLONS + offset;
+
+               /* Show the modes */
+               for (i = 0; i < num_parent; i++) {
+                       printf("%s%06o", prefix, p->parent[i].mode);
+                       prefix = " ";
+               }
+               printf("%s%06o", prefix, p->mode);
+
+               /* Show sha1's */
+               for (i = 0; i < num_parent; i++)
+                       printf(" %s", diff_unique_abbrev(p->parent[i].sha1,
+                                                        opt->abbrev));
+               printf(" %s ", diff_unique_abbrev(p->sha1, opt->abbrev));
+       }
+
+       if (opt->output_format == DIFF_FORMAT_RAW ||
+           opt->output_format == DIFF_FORMAT_NAME_STATUS) {
+               for (i = 0; i < num_parent; i++)
+                       putchar(p->parent[i].status);
+               putchar(inter_name_termination);
+       }
+
+       if (line_termination) {
+               if (quote_c_style(p->path, NULL, NULL, 0))
+                       quote_c_style(p->path, NULL, stdout, 0);
+               else
+                       printf("%s", p->path);
+               putchar(line_termination);
+       }
+       else {
+               printf("%s%c", p->path, line_termination);
+       }
+}
+
+void show_combined_diff(struct combine_diff_path *p,
+                      int num_parent,
+                      int dense,
+                      struct rev_info *rev)
+{
+       struct diff_options *opt = &rev->diffopt;
+       if (!p->len)
+               return;
+       switch (opt->output_format) {
+       case DIFF_FORMAT_RAW:
+       case DIFF_FORMAT_NAME_STATUS:
+       case DIFF_FORMAT_NAME:
+               show_raw_diff(p, num_parent, rev);
+               return;
+       case DIFF_FORMAT_PATCH:
+               show_patch_diff(p, num_parent, dense, rev);
+               return;
+       default:
+               return;
+       }
+}
+
+void diff_tree_combined(const unsigned char *sha1,
+                       const unsigned char parent[][20],
+                       int num_parent,
+                       int dense,
+                       struct rev_info *rev)
+{
+       struct diff_options *opt = &rev->diffopt;
        struct diff_options diffopts;
-       struct commit_list *parents;
        struct combine_diff_path *p, *paths = NULL;
-       int num_parent, i, num_paths;
-
-       diff_setup(&diffopts);
-       diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
+       int i, num_paths;
+       int do_diffstat;
+
+       do_diffstat = (opt->output_format == DIFF_FORMAT_DIFFSTAT ||
+                      opt->with_stat);
+       diffopts = *opt;
+       diffopts.with_raw = 0;
+       diffopts.with_stat = 0;
        diffopts.recursive = 1;
 
-       /* count parents */
-       for (parents = commit->parents, num_parent = 0;
-            parents;
-            parents = parents->next, num_parent++)
-               ; /* nothing */
-
        /* find set of paths that everybody touches */
-       for (parents = commit->parents, i = 0;
-            parents;
-            parents = parents->next, i++) {
-               struct commit *parent = parents->item;
-               diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
-                              &diffopts);
+       for (i = 0; i < num_parent; i++) {
+               /* show stat against the first parent even
+                * when doing combined diff.
+                */
+               if (i == 0 && do_diffstat)
+                       diffopts.output_format = DIFF_FORMAT_DIFFSTAT;
+               else
+                       diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
+               diff_tree_sha1(parent[i], sha1, "", &diffopts);
+               diffcore_std(&diffopts);
                paths = intersect_paths(paths, i, num_parent);
+
+               if (do_diffstat && rev->loginfo)
+                       show_log(rev, rev->loginfo,
+                                opt->with_stat ? "---\n" : "\n");
                diff_flush(&diffopts);
+               if (opt->with_stat)
+                       putchar('\n');
        }
 
        /* find out surviving paths */
@@ -668,13 +877,18 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                if (p->len)
                        num_paths++;
        }
-       if (num_paths || show_empty_merge) {
+       if (num_paths) {
+               if (opt->with_raw) {
+                       int saved_format = opt->output_format;
+                       opt->output_format = DIFF_FORMAT_RAW;
+                       for (p = paths; p; p = p->next) {
+                               show_combined_diff(p, num_parent, dense, rev);
+                       }
+                       opt->output_format = saved_format;
+                       putchar(opt->line_termination);
+               }
                for (p = paths; p; p = p->next) {
-                       if (!p->len)
-                               continue;
-                       if (show_combined_diff(p, num_parent, dense, header,
-                                              show_empty_merge))
-                               header = NULL;
+                       show_combined_diff(p, num_parent, dense, rev);
                }
        }
 
@@ -684,5 +898,26 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                paths = paths->next;
                free(tmp);
        }
-       return 0;
+}
+
+void diff_tree_combined_merge(const unsigned char *sha1,
+                            int dense, struct rev_info *rev)
+{
+       int num_parent;
+       const unsigned char (*parent)[20];
+       struct commit *commit = lookup_commit(sha1);
+       struct commit_list *parents;
+
+       /* count parents */
+       for (parents = commit->parents, num_parent = 0;
+            parents;
+            parents = parents->next, num_parent++)
+               ; /* nothing */
+
+       parent = xmalloc(num_parent * sizeof(*parent));
+       for (parents = commit->parents, num_parent = 0;
+            parents;
+            parents = parents->next, num_parent++)
+               memcpy(parent + num_parent, parents->item->object.sha1, 20);
+       diff_tree_combined(sha1, parent, num_parent, dense, rev);
 }