commit: teach --amend to carry forward extra headers

After running "git pull $there for-linus" to merge a signed tag, the
integrator may need to amend the resulting merge commit to fix typoes
in it. Teach --amend option to read the existing extra headers, and
carry them forward.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/commit.c b/builtin/commit.c
index 4688a738f766ebc5166dce51da609332aa7303b0..fca7ea01f3369b6c7df0796ec4b6142472e46904 100644 (file)
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1382,6 +1382,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
        int allow_fast_forward = 1;
        struct wt_status s;
        struct commit *current_head = NULL;
+       struct commit_extra_header *extra = NULL;
 
        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(builtin_commit_usage, builtin_commit_options);
@@ -1483,12 +1484,16 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
                exit(1);
        }
 
-       if (commit_tree(sb.buf, active_cache_tree->sha1, parents, sha1,
-                       author_ident.buf)) {
+       if (amend)
+               extra = read_commit_extra_headers(current_head);
+
+       if (commit_tree_extended(sb.buf, active_cache_tree->sha1, parents, sha1,
+                                author_ident.buf, extra)) {
                rollback_index_files();
                die(_("failed to write commit object"));
        }
        strbuf_release(&author_ident);
+       free_commit_extra_headers(extra);
 
        ref_lock = lock_any_ref_for_update("HEAD",
                                           !current_head

diff --git a/commit.c b/commit.c
index a33bc89d8e37c5af37c6f1b65b4faa78927ee2fa..b78127403be65f5c26e35e53a59b91860396194a 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -894,7 +894,72 @@ static void add_extra_header(struct strbuf *buffer,
                             struct commit_extra_header *extra)
 {
        strbuf_addstr(buffer, extra->key);
-       strbuf_add_lines(buffer, " ", extra->value, extra->len);
+       if (extra->len)
+               strbuf_add_lines(buffer, " ", extra->value, extra->len);
+       else
+               strbuf_addch(buffer, '\n');
+}
+
+struct commit_extra_header *read_commit_extra_headers(struct commit *commit)
+{
+       struct commit_extra_header *extra = NULL;
+       unsigned long size;
+       enum object_type type;
+       char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
+       if (buffer && type == OBJ_COMMIT)
+               extra = read_commit_extra_header_lines(buffer, size);
+       free(buffer);
+       return extra;
+}
+
+static inline int standard_header_field(const char *field, size_t len)
+{
+       return ((len == 4 && !memcmp(field, "tree ", 5)) ||
+               (len == 6 && !memcmp(field, "parent ", 7)) ||
+               (len == 6 && !memcmp(field, "author ", 7)) ||
+               (len == 9 && !memcmp(field, "committer ", 10)) ||
+               (len == 8 && !memcmp(field, "encoding ", 9)));
+}
+
+struct commit_extra_header *read_commit_extra_header_lines(const char *buffer, size_t size)
+{
+       struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
+       const char *line, *next, *eof, *eob;
+       struct strbuf buf = STRBUF_INIT;
+
+       for (line = buffer, eob = line + size;
+            line < eob && *line != '\n';
+            line = next) {
+               next = memchr(line, '\n', eob - line);
+               next = next ? next + 1 : eob;
+               if (*line == ' ') {
+                       /* continuation */
+                       if (it)
+                               strbuf_add(&buf, line + 1, next - (line + 1));
+                       continue;
+               }
+               if (it)
+                       it->value = strbuf_detach(&buf, &it->len);
+               strbuf_reset(&buf);
+               it = NULL;
+
+               eof = strchr(line, ' ');
+               if (next <= eof)
+                       eof = next;
+
+               if (standard_header_field(line, eof - line))
+                       continue;
+
+               it = xcalloc(1, sizeof(*it));
+               it->key = xmemdupz(line, eof-line);
+               *tail = it;
+               tail = &it->next;
+               if (eof + 1 < next)
+                       strbuf_add(&buf, eof + 1, next - (eof + 1));
+       }
+       if (it)
+               it->value = strbuf_detach(&buf, &it->len);
+       return extra;
 }
 
 void free_commit_extra_headers(struct commit_extra_header *extra)

diff --git a/commit.h b/commit.h
index c1a723ecdb877bbbb75fe9fcaf98cef7b7edb59b..3745f120994cb6876e1ccc1bfc5e07c6cc3fc5c9 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -200,6 +200,9 @@ extern int commit_tree_extended(const char *msg, unsigned char *tree,
                                const char *author,
                                struct commit_extra_header *);
 
+extern struct commit_extra_header *read_commit_extra_headers(struct commit *);
+extern struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len);
+
 extern void free_commit_extra_headers(struct commit_extra_header *extra);
 
 struct merge_remote_desc {