git-rerere: detect unparsable conflicts

diff --git a/builtin-commit.c b/builtin-commit.c
index b294c1f88c1eecde8d96d265c72376c789f24899..a33f43a209efc2abef209b10b55fa2fce1c7ce18 100644 (file)
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -502,7 +502,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 
        fp = fopen(git_path(commit_editmsg), "w");
        if (fp == NULL)
-               die("could not open %s", git_path(commit_editmsg));
+               die("could not open %s: %s",
+                   git_path(commit_editmsg), strerror(errno));
 
        if (cleanup_mode != CLEANUP_NONE)
                stripspace(&sb, 0);
@@ -883,10 +884,19 @@ static void add_parent(struct strbuf *sb, const unsigned char *sha1)
 {
        struct object *obj = parse_object(sha1);
        const char *parent = sha1_to_hex(sha1);
+       const char *cp;
+
        if (!obj)
                die("Unable to find commit parent %s", parent);
        if (obj->type != OBJ_COMMIT)
                die("Parent %s isn't a proper commit", parent);
+
+       for (cp = sb->buf; cp && (cp = strstr(cp, "\nparent ")); cp += 8) {
+               if (!memcmp(cp + 8, parent, 40) && cp[48] == '\n') {
+                       error("duplicate parent %s ignored", parent);
+                       return;
+               }
+       }
        strbuf_addf(sb, "parent %s\n", parent);
 }