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add-patch: handle splitting hunks with diff.suppressBlankEmpty

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When "add -p" parses diffs, it looks for context lines starting with a
single space. But when diff.suppressBlankEmpty is in effect, an empty
context line will omit the space, giving us a true empty line. This
confuses the parser, which is unable to split based on such a line.

It's tempting to say that we should just make sure that we generate a
diff without that option.  However, although we do not parse hunks that
the user has manually edited with parse_diff() we do allow the user
to split such hunks. As POSIX calls the decision of whether to print the
space here "implementation-defined" we need to handle edited hunks where
empty context lines omit the space.

So let's handle both cases: a context line either starts with a space or
consists of a totally empty line by normalizing the first character to a
space when we parse them. Normalizing the first character rather than
changing the code to check for a space or newline will hopefully future
proof against introducing similar bugs if the code is changed.

Reported-by: Ilya Tumaykin <itumaykin@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Phillip Wood
2024-07-20 16:01:59 +00:00
committed by Junio C Hamano
parent 337b4d4000
commit 39bdd84eaf
2 changed files with 32 additions and 6 deletions
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19
add-patch.c
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@ -400,6 +400,12 @@ static void complete_file(char marker, struct hunk *hunk)
hunk->splittable_into++;
}
/* Empty context lines may omit the leading ' ' */
static int normalize_marker(const char *p)
{
return p[0] == '\n' || (p[0] == '\r' && p[1] == '\n') ? ' ' : p[0];
}
static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
{
struct strvec args = STRVEC_INIT;
@ -485,6 +491,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
while (p != pend) {
char *eol = memchr(p, '\n', pend - p);
const char *deleted = NULL, *mode_change = NULL;
char ch = normalize_marker(p);
if (!eol)
eol = pend;
@ -532,7 +539,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
* Start counting into how many hunks this one can be
* split
*/
marker = *p;
marker = ch;
} else if (hunk == &file_diff->head &&
starts_with(p, "new file")) {
file_diff->added = 1;
@ -586,10 +593,10 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
(int)(eol - (plain->buf + file_diff->head.start)),
plain->buf + file_diff->head.start);
if ((marker == '-' || marker == '+') && *p == ' ')
if ((marker == '-' || marker == '+') && ch == ' ')
hunk->splittable_into++;
if (marker && *p != '\\')
marker = *p;
if (marker && ch != '\\')
marker = ch;
p = eol == pend ? pend : eol + 1;
hunk->end = p - plain->buf;
@ -813,7 +820,7 @@ static int merge_hunks(struct add_p_state *s, struct file_diff *file_diff,
(int)(hunk->end - hunk->start),
plain + hunk->start);
if (plain[overlap_end] != ' ')
if (normalize_marker(&plain[overlap_end]) != ' ')
return error(_("expected context line "
"#%d in\n%.*s"),
(int)(j + 1),
@ -953,7 +960,7 @@ static int split_hunk(struct add_p_state *s, struct file_diff *file_diff,
context_line_count = 0;
while (splittable_into > 1) {
ch = s->plain.buf[current];
ch = normalize_marker(&s->plain.buf[current]);
if (!ch)
BUG("buffer overrun while splitting hunks");