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/commit.c b/commit.c
index a33bc89..b781274 100644
--- a/commit.c
+++ b/commit.c
@@ -894,7 +894,72 @@
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)
