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fast-export: do not modify memory from get_commit_buffer

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fast-export's helper function find_encoding() takes a `const char *`, but
modifies that memory despite the `const`.  Ultimately, this memory came
from get_commit_buffer(), and you're not supposed to modify the memory
that you get from get_commit_buffer().

So, get rid of find_encoding() in favor of commit.h:find_commit_header(),
which gives back a string length, rather than mutating the memory to
insert a '\0' terminator.

Because find_commit_header() detects the "\n\n" string that separates the
headers and the commit message, move the call to be above the
`message = strstr(..., "\n\n")` call.  This helps readability, and allows
for the value of `encoding` to be used for a better value of "..." so that
the same memory doesn't need to be checked twice.  Introduce a
`commit_buffer_cursor` variable to avoid writing an awkward
`encoding ? encoding + encoding_len : committer_end` expression.

Signed-off-by: Luke Shumaker <lukeshu@datawire.io>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Luke Shumaker
2025-03-10 16:57:45 +01:00
committed by Junio C Hamano
parent 87f2a9195e
commit dda9bff3c5
1 changed files with 33 additions and 28 deletions
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61
builtin/fast-export.c
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@@ -510,21 +510,6 @@ static void show_filemodify(struct diff_queue_struct *q,
}
}
static const char *find_encoding(const char *begin, const char *end)
{
const char *needle = "\nencoding ";
char *bol, *eol;
bol = memmem(begin, end ? end - begin : strlen(begin),
needle, strlen(needle));
if (!bol)
return NULL;
bol += strlen(needle);
eol = strchrnul(bol, '\n');
*eol = '\0';
return bol;
}
static char *anonymize_ref_component(void)
{
static int counter;
@@ -630,9 +615,11 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
struct string_list *paths_of_changed_objects)
{
int saved_output_format = rev->diffopt.output_format;
const char *commit_buffer;
const char *commit_buffer, *commit_buffer_cursor;
const char *author, *author_end, *committer, *committer_end;
const char *encoding, *message;
const char *encoding = NULL;
size_t encoding_len;
const char *message;
char *reencoded = NULL;
struct commit_list *p;
const char *refname;
@@ -641,21 +628,35 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
rev->diffopt.output_format = DIFF_FORMAT_CALLBACK;
parse_commit_or_die(commit);
commit_buffer = repo_get_commit_buffer(the_repository, commit, NULL);
author = strstr(commit_buffer, "\nauthor ");
commit_buffer_cursor = commit_buffer = repo_get_commit_buffer(the_repository, commit, NULL);
author = strstr(commit_buffer_cursor, "\nauthor ");
if (!author)
die("could not find author in commit %s",
oid_to_hex(&commit->object.oid));
author++;
author_end = strchrnul(author, '\n');
committer = strstr(author_end, "\ncommitter ");
commit_buffer_cursor = author_end = strchrnul(author, '\n');
committer = strstr(commit_buffer_cursor, "\ncommitter ");
if (!committer)
die("could not find committer in commit %s",
oid_to_hex(&commit->object.oid));
committer++;
committer_end = strchrnul(committer, '\n');
message = strstr(committer_end, "\n\n");
encoding = find_encoding(committer_end, message);
commit_buffer_cursor = committer_end = strchrnul(committer, '\n');
/*
* find_commit_header() gets a `+ 1` because
* commit_buffer_cursor points at the trailing "\n" at the end
* of the previous line, but find_commit_header() wants a
* pointer to the beginning of the next line.
*/
if (*commit_buffer_cursor == '\n') {
encoding = find_commit_header(commit_buffer_cursor + 1, "encoding", &encoding_len);
if (encoding)
commit_buffer_cursor = encoding + encoding_len;
}
message = strstr(commit_buffer_cursor, "\n\n");
if (message)
message += 2;
@@ -694,16 +695,20 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
if (anonymize) {
reencoded = anonymize_commit_message();
} else if (encoding) {
char *buf;
switch (reencode_mode) {
case REENCODE_YES:
reencoded = reencode_string(message, "UTF-8", encoding);
buf = xstrfmt("%.*s", (int)encoding_len, encoding);
reencoded = reencode_string(message, "UTF-8", buf);
free(buf);
break;
case REENCODE_NO:
break;
case REENCODE_ABORT:
die("Encountered commit-specific encoding %s in commit "
die("Encountered commit-specific encoding %.*s in commit "
"%s; use --reencode=[yes|no] to handle it",
encoding, oid_to_hex(&commit->object.oid));
(int)encoding_len, encoding,
oid_to_hex(&commit->object.oid));
}
}
if (!commit->parents)
@@ -715,7 +720,7 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,
(int)(author_end - author), author,
(int)(committer_end - committer), committer);
if (!reencoded && encoding)
printf("encoding %s\n", encoding);
printf("encoding %.*s\n", (int)encoding_len, encoding);
printf("data %u\n%s",
(unsigned)(reencoded
? strlen(reencoded) : message