apply: get rid of --index-info in favor of --build-fake-ancestor

git-am used "git apply -z --index-info" to find the original versions
of the files touched by the diff, to be able to do an inexpensive
three-way merge.

This operation makes only sense in a repository, since the index
information in the diff refers to blobs, which have to be present in
the current repository.

Therefore, teach "git apply" a mode to write out the result as an
index file to begin with, obviating the need for scripts to do it
themselves.

The sole user for --index-info is "git am" is converted to
use --build-fake-ancestor in this patch.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-apply.txt b/Documentation/git-apply.txt
index 4c7e3a2f7f5d542cd95059430f53143bba59fc7f..c1c54bfe0b7d2c1b133e245a3a963caa0b7afb8c 100644 (file)
--- a/Documentation/git-apply.txt
+++ b/Documentation/git-apply.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git-apply' [--stat] [--numstat] [--summary] [--check] [--index]
-         [--apply] [--no-add] [--index-info] [-R | --reverse]
+         [--apply] [--no-add] [--build-fake-ancestor <file>] [-R | --reverse]
          [--allow-binary-replacement | --binary] [--reject] [-z]
          [-pNUM] [-CNUM] [--inaccurate-eof] [--cached]
          [--whitespace=<nowarn|warn|error|error-all|strip>]
@@ -63,12 +63,15 @@ OPTIONS
        cached data, apply the patch, and store the result in the index,
        without using the working tree. This implies '--index'.
 
---index-info::
+--build-fake-ancestor <file>::
        Newer git-diff output has embedded 'index information'
        for each blob to help identify the original version that
        the patch applies to.  When this flag is given, and if
-       the original version of the blob is available locally,
-       outputs information about them to the standard output.
+       the original versions of the blobs is available locally,
+       builds a temporary index containing those blobs.
++
+When a pure mode change is encountered (which has no index information),
+the information is read from the current index instead.
 
 -R, --reverse::
        Apply the patch in reverse.

diff --git a/builtin-apply.c b/builtin-apply.c
index bd969778e063bab70eab14d6261d07edd926a115..5cc90e68f880180b072db946080c4168b98603cf 100644 (file)
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -41,7 +41,7 @@ static int apply_in_reverse;
 static int apply_with_reject;
 static int apply_verbosely;
 static int no_add;
-static int show_index_info;
+static const char *fake_ancestor;
 static int line_termination = '\n';
 static unsigned long p_context = ULONG_MAX;
 static const char apply_usage[] =
@@ -2248,9 +2248,12 @@ static int get_current_sha1(const char *path, unsigned char *sha1)
        return 0;
 }
 
-static void show_index_list(struct patch *list)
+/* Build an index that contains the just the files needed for a 3way merge */
+static void build_fake_ancestor(struct patch *list, const char *filename)
 {
        struct patch *patch;
+       struct index_state result = { 0 };
+       int fd;
 
        /* Once we start supporting the reverse patch, it may be
         * worth showing the new sha1 prefix, but until then...
@@ -2258,11 +2261,12 @@ static void show_index_list(struct patch *list)
        for (patch = list; patch; patch = patch->next) {
                const unsigned char *sha1_ptr;
                unsigned char sha1[20];
+               struct cache_entry *ce;
                const char *name;
 
                name = patch->old_name ? patch->old_name : patch->new_name;
                if (0 < patch->is_new)
-                       sha1_ptr = null_sha1;
+                       continue;
                else if (get_sha1(patch->old_sha1_prefix, sha1))
                        /* git diff has no index line for mode/type changes */
                        if (!patch->lines_added && !patch->lines_deleted) {
@@ -2277,13 +2281,16 @@ static void show_index_list(struct patch *list)
                else
                        sha1_ptr = sha1;
 
-               printf("%06o %s ",patch->old_mode, sha1_to_hex(sha1_ptr));
-               if (line_termination && quote_c_style(name, NULL, NULL, 0))
-                       quote_c_style(name, NULL, stdout, 0);
-               else
-                       fputs(name, stdout);
-               putchar(line_termination);
+               ce = make_cache_entry(patch->old_mode, sha1_ptr, name, 0, 0);
+               if (add_index_entry(&result, ce, ADD_CACHE_OK_TO_ADD))
+                       die ("Could not add %s to temporary index", name);
        }
+
+       fd = open(filename, O_WRONLY | O_CREAT, 0666);
+       if (fd < 0 || write_index(&result, fd) || close(fd))
+               die ("Could not write temporary index to %s", filename);
+
+       discard_index(&result);
 }
 
 static void stat_patch_list(struct patch *patch)
@@ -2805,8 +2812,8 @@ static int apply_patch(int fd, const char *filename, int inaccurate_eof)
        if (apply && write_out_results(list, skipped_patch))
                exit(1);
 
-       if (show_index_info)
-               show_index_list(list);
+       if (fake_ancestor)
+               build_fake_ancestor(list, fake_ancestor);
 
        if (diffstat)
                stat_patch_list(list);
@@ -2914,9 +2921,11 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
                        apply = 1;
                        continue;
                }
-               if (!strcmp(arg, "--index-info")) {
+               if (!strcmp(arg, "--build-fake-ancestor")) {
                        apply = 0;
-                       show_index_info = 1;
+                       if (++i >= argc)
+                               die ("need a filename");
+                       fake_ancestor = argv[i];
                        continue;
                }
                if (!strcmp(arg, "-z")) {

diff --git a/git-am.sh b/git-am.sh
index b66173c0cd8e7908c1ac9ffc9c9a6a91160849a0..32c46d7ed4b26220f4c9e7fc778bb240c85dae1c 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -62,10 +62,8 @@ fall_back_3way () {
     mkdir "$dotest/patch-merge-tmp-dir"
 
     # First see if the patch records the index info that we can use.
-    git apply -z --index-info "$dotest/patch" \
-       >"$dotest/patch-merge-index-info" &&
-    GIT_INDEX_FILE="$dotest/patch-merge-tmp-index" \
-    git update-index -z --index-info <"$dotest/patch-merge-index-info" &&
+    git apply --build-fake-ancestor "$dotest/patch-merge-tmp-index" \
+       "$dotest/patch" &&
     GIT_INDEX_FILE="$dotest/patch-merge-tmp-index" \
     git write-tree >"$dotest/patch-merge-base+" ||
     cannot_fallback "Repository lacks necessary blobs to fall back on 3-way merge."