trailer: add interface for iterating over commit trailers

The trailer code knows how to parse out the trailers and re-format them,
but there's no easy way to iterate over the trailers (you can use
trailer_info, but you have to then do a bunch of extra parsing).

Let's add an iteration interface that makes this easy to do.

Signed-off-by: Jeff King <>
Signed-off-by: Junio C Hamano <>
Jeff King 2 years ago committed by Junio C Hamano
parent 92338c450b
commit f0939a0eb1
  1. 36
  2. 45

@ -1185,3 +1185,39 @@ void format_trailers_from_commit(struct strbuf *out, const char *msg,
format_trailer_info(out, &info, opts);
void trailer_iterator_init(struct trailer_iterator *iter, const char *msg)
struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
strbuf_init(&iter->key, 0);
strbuf_init(&iter->val, 0);
opts.no_divider = 1;
trailer_info_get(&iter->info, msg, &opts);
iter->cur = 0;
int trailer_iterator_advance(struct trailer_iterator *iter)
while (iter->cur < iter->info.trailer_nr) {
char *trailer = iter->info.trailers[iter->cur++];
int separator_pos = find_separator(trailer, separators);
if (separator_pos < 1)
continue; /* not a real trailer */
parse_trailer(&iter->key, &iter->val, NULL,
trailer, separator_pos);
return 1;
return 0;
void trailer_iterator_release(struct trailer_iterator *iter)

@ -2,8 +2,7 @@
#define TRAILER_H
#include "list.h"
struct strbuf;
#include "strbuf.h"
enum trailer_where {
@ -103,4 +102,46 @@ void trailer_info_release(struct trailer_info *info);
void format_trailers_from_commit(struct strbuf *out, const char *msg,
const struct process_trailer_options *opts);
* An interface for iterating over the trailers found in a particular commit
* message. Use like:
* struct trailer_iterator iter;
* trailer_iterator_init(&iter, msg);
* while (trailer_iterator_advance(&iter))
* ... do something with iter.key and iter.val ...
* trailer_iterator_release(&iter);
struct trailer_iterator {
struct strbuf key;
struct strbuf val;
/* private */
struct trailer_info info;
size_t cur;
* Initialize "iter" in preparation for walking over the trailers in the commit
* message "msg". The "msg" pointer must remain valid until the iterator is
* released.
* After initializing, note that key/val will not yet point to any trailer.
* Call advance() to parse the first one (if any).
void trailer_iterator_init(struct trailer_iterator *iter, const char *msg);
* Advance to the next trailer of the iterator. Returns 0 if there is no such
* trailer, and 1 otherwise. The key and value of the trailer can be
* fetched from the iter->key and iter->value fields (which are valid
* only until the next advance).
int trailer_iterator_advance(struct trailer_iterator *iter);
* Release all resources associated with the trailer iteration.
void trailer_iterator_release(struct trailer_iterator *iter);
#endif /* TRAILER_H */