git-apply: parse index information

Add an new option --show-index-info to git-apply command to
summarize the index information new git-diff outputs.  The
command shows something similar to git-ls-files --stage output
for the pre-change image:

    100644 7be5041...	apply.c
    100644 ec2a161...	cache.h
    ...

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/apply.c b/apply.c
index 7be5041..155fbe8 100644 (file)
--- a/apply.c
+++ b/apply.c
@@ -14,6 +14,7 @@
 //    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
+//  --show-index-info shows the old and new index info for paths if available.
 //
 static int check_index = 0;
 static int write_index = 0;
@@ -22,8 +23,9 @@ static int summary = 0;
 static int check = 0;
 static int apply = 1;
 static int show_files = 0;
+static int show_index_info = 0;
 static const char apply_usage[] =
-"git-apply [--stat] [--summary] [--check] [--index] [--apply] [--show-files] <patch>...";
+"git-apply [--stat] [--summary] [--check] [--index] [--apply] [--show-files] [--show-index-info] <patch>...";
 
 /*
  * For "diff-stat" like behaviour, we keep track of the biggest change
@@ -56,6 +58,8 @@ struct patch {
        struct fragment *fragments;
        char *result;
        unsigned long resultsize;
+       char old_sha1_prefix[41];
+       char new_sha1_prefix[41];
        struct patch *next;
 };
 
@@ -334,6 +338,38 @@ static int gitdiff_dissimilarity(const char *line, struct patch *patch)
        return 0;
 }
 
+static int gitdiff_index(const char *line, struct patch *patch)
+{
+       /* index line is N hexadecimal, "..", N hexadecimal,
+        * and optional space with octal mode.
+        */
+       const char *ptr, *eol;
+       int len;
+
+       ptr = strchr(line, '.');
+       if (!ptr || ptr[1] != '.' || 40 <= ptr - line)
+               return 0;
+       len = ptr - line;
+       memcpy(patch->old_sha1_prefix, line, len);
+       patch->old_sha1_prefix[len] = 0;
+
+       line = ptr + 2;
+       ptr = strchr(line, ' ');
+       eol = strchr(line, '\n');
+
+       if (!ptr || eol < ptr)
+               ptr = eol;
+       len = ptr - line;
+
+       if (40 <= len)
+               return 0;
+       memcpy(patch->new_sha1_prefix, line, len);
+       patch->new_sha1_prefix[len] = 0;
+       if (*ptr == ' ')
+               patch->new_mode = patch->old_mode = strtoul(ptr+1, NULL, 8);
+       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.
@@ -438,6 +474,7 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
                        { "rename to ", gitdiff_renamedst },
                        { "similarity index ", gitdiff_similarity },
                        { "dissimilarity index ", gitdiff_dissimilarity },
+                       { "index ", gitdiff_index },
                        { "", gitdiff_unrecognized },
                };
                int i;
@@ -1136,6 +1173,36 @@ static void show_file_list(struct patch *patch)
        }
 }
 
+static inline int is_null_sha1(const unsigned char *sha1)
+{
+       return !memcmp(sha1, null_sha1, 20);
+}
+
+static void show_index_list(struct patch *list)
+{
+       struct patch *patch;
+
+       /* Once we start supporting the reverse patch, it may be
+        * worth showing the new sha1 prefix, but until then...
+        */
+       for (patch = list; patch; patch = patch->next) {
+               const unsigned char *sha1_ptr;
+               unsigned char sha1[20];
+               const char *name;
+
+               name = patch->old_name ? patch->old_name : patch->new_name;
+               if (patch->is_new)
+                       sha1_ptr = null_sha1;
+               else if (get_sha1(patch->old_sha1_prefix, sha1))
+                       die("sha1 information is lacking or useless (%s).",
+                           name);
+               else
+                       sha1_ptr = sha1;
+               printf("%06o %s %s\n",patch->old_mode,
+                      sha1_to_hex(sha1_ptr), name);
+       }
+}
+
 static void stat_patch_list(struct patch *patch)
 {
        int files, adds, dels;
@@ -1476,6 +1543,9 @@ static int apply_patch(int fd)
        if (show_files)
                show_file_list(list);
 
+       if (show_index_info)
+               show_index_list(list);
+
        if (diffstat)
                stat_patch_list(list);
 
@@ -1534,6 +1604,11 @@ int main(int argc, char **argv)
                        show_files = 1;
                        continue;
                }
+               if (!strcmp(arg, "--show-index-info")) {
+                       apply = 0;
+                       show_index_info = 1;
+                       continue;
+               }
                fd = open(arg, O_RDONLY);
                if (fd < 0)
                        usage(apply_usage);