@matheusbsbs / matheus-bagliano / commits / abf94a283f

cat-file: fix mailmap application for different author and committer

The git cat-file command with --mailmap option fails to apply mailmap transformations to the committer field when the author and committer identities are different. This occurs due to a missing newline handling in apply_mailmap_to_header() after processing each identity line. When rewrite_ident_line() processes an identity, it stops at the end of the identity data (e.g., "Author Name <email> timestamp"), but doesn't account for the trailing newline. The current code adds the identity length to buf_offset but fails to advance past the newline character. This causes the next iteration to start parsing from the newline instead of the beginning of the next header line, making it impossible to match subsequent headers like "committer". Additionally, rewrite_ident_line() may reallocate the buffer during its operation. Any code using pointers into the old buffer would be using invalid memory after such a reallocation. This bug was introduced in e9c1b0e3 (revision: improve commit_rewrite_person(), 2022-07-19) when the much simpler version of commit_rewrite_person() that worked on one "person header" at a time was rewritten to use the current apply_mailmap_to_header() function. The original implementation processed author and committer separately, but the rewrite introduced this loop-based approach that failed to properly handle the transition between identity lines. Let's fix this by addressing both issues: 1. After processing an identity line, we now check if we're at a newline and advance past it, ensuring the next header line is parsed correctly. 2. We recompute the buffer position after rewrite_ident_line() to handle potential buffer reallocation. This ensures that all identity headers in commit and tag objects are consistently processed regardless of whether the author and committer are the same person. Reported-by: Vasilii Iakliushin <viakliushin@gitlab.com> Reviewed-by: Christian Couder <christian.couder@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Siddharth Asthana committed Jun 13, 2025 at 17:27 UTC abf94a283fd85e680f8d720241e6059dbb5f23f5

2 files changed +37

ident.c

@@ -412,6 +412,10 @@ void apply_mailmap_to_header(struct strbuf *buf, const char **header,

412 found_header = 1;

413 buf_offset += endp - line;

414 buf_offset += rewrite_ident_line(person, endp - person, buf, mailmap);

415 + /* Recompute endp after potential buffer reallocation */

416 + endp = buf->buf + buf_offset;

417 + if (*endp == '\n')

418 + buf_offset++;

419 break;

420 }

421

t/t4203-mailmap.sh

+33

@@ -1087,4 +1087,37 @@ test_expect_success 'git cat-file --batch-command returns correct size with --us

1087 test_cmp expect actual

1088 '

1089

1090 +test_expect_success 'git cat-file --mailmap works with different author and committer' '

1091 + test_when_finished "rm .mailmap" &&

1092 + cat >.mailmap <<-\EOF &&

1093 + Mailmapped User <mailmapped-user@gitlab.com> C O Mitter <committer@example.com>

1094 + EOF

1095 + git commit --allow-empty -m "different author/committer" \

1096 + --author="Different Author <different@example.com>" &&

1097 + cat >expect <<-\EOF &&

1098 + author Different Author <different@example.com>

1099 + committer Mailmapped User <mailmapped-user@gitlab.com>

1100 + EOF

1101 + git cat-file --mailmap commit HEAD >log &&

1102 + sed -n -e "/^author /s/>.*/>/p" -e "/^committer /s/>.*/>/p" log >actual &&

1103 + test_cmp expect actual

1104 +'

1105 +

1106 +test_expect_success 'git cat-file --mailmap maps both author and committer when both need mapping' '

1107 + test_when_finished "rm .mailmap" &&

1108 + cat >.mailmap <<-\EOF &&

1109 + Mapped Author <mapped-author@example.com> <different@example.com>

1110 + Mapped Committer <mapped-committer@example.com> C O Mitter <committer@example.com>

1111 + EOF

1112 + git commit --allow-empty -m "both author and committer mapped" \

1113 + --author="Different Author <different@example.com>" &&

1114 + cat >expect <<-\EOF &&

1115 + author Mapped Author <mapped-author@example.com>

1116 + committer Mapped Committer <mapped-committer@example.com>

1117 + EOF

1118 + git cat-file --mailmap commit HEAD >log &&

1119 + sed -n -e "/^author /s/>.*/>/p" -e "/^committer /s/>.*/>/p" log >actual &&

1120 + test_cmp expect actual

1121 +'

1122 +

1123 test_done