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midx.c: write MIDX filenames to strbuf

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To ask for the name of a MIDX and its corresponding .rev file, callers
invoke get_midx_filename() and get_midx_rev_filename(), respectively.
These both invoke xstrfmt(), allocating a chunk of memory which must be
freed later on.

This makes callers in pack-bitmap.c somewhat awkward. Specifically,
midx_bitmap_filename(), which is implemented like:

    return xstrfmt("%s-%s.bitmap",
                   get_midx_filename(midx->object_dir),
                   hash_to_hex(get_midx_checksum(midx)));

this leaks the second argument to xstrfmt(), which itself was allocated
with xstrfmt(). This caller could assign both the result of
get_midx_filename() and the outer xstrfmt() to a temporary variable,
remembering to free() the former before returning. But that involves a
wasteful copy.

Instead, get_midx_filename() and get_midx_rev_filename() take a strbuf
as an output parameter. This way midx_bitmap_filename() can manipulate
and pass around a temporary buffer which it detaches back to its caller.

That allows us to implement the function without copying or open-coding
get_midx_filename() in a way that doesn't leak.

Update the other callers of get_midx_filename() and
get_midx_rev_filename() accordingly.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau
2021-10-26 17:01:21 -04:00
committed by Junio C Hamano
parent ee4a1d63d7
commit 60980aed78
4 changed files with 49 additions and 37 deletions
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59
midx.c
View File

@ -57,15 +57,15 @@ const unsigned char *get_midx_checksum(struct multi_pack_index *m)
return m->data + m->data_len - the_hash_algo->rawsz;
}
char *get_midx_filename(const char *object_dir)
void get_midx_filename(struct strbuf *out, const char *object_dir)
{
return xstrfmt("%s/pack/multi-pack-index", object_dir);
strbuf_addf(out, "%s/pack/multi-pack-index", object_dir);
}
char *get_midx_rev_filename(struct multi_pack_index *m)
void get_midx_rev_filename(struct strbuf *out, struct multi_pack_index *m)
{
return xstrfmt("%s/pack/multi-pack-index-%s.rev",
m->object_dir, hash_to_hex(get_midx_checksum(m)));
get_midx_filename(out, m->object_dir);
strbuf_addf(out, "-%s.rev", hash_to_hex(get_midx_checksum(m)));
}
static int midx_read_oid_fanout(const unsigned char *chunk_start,
@ -89,28 +89,30 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
size_t midx_size;
void *midx_map = NULL;
uint32_t hash_version;
char *midx_name = get_midx_filename(object_dir);
struct strbuf midx_name = STRBUF_INIT;
uint32_t i;
const char *cur_pack_name;
struct chunkfile *cf = NULL;
fd = git_open(midx_name);
get_midx_filename(&midx_name, object_dir);
fd = git_open(midx_name.buf);
if (fd < 0)
goto cleanup_fail;
if (fstat(fd, &st)) {
error_errno(_("failed to read %s"), midx_name);
error_errno(_("failed to read %s"), midx_name.buf);
goto cleanup_fail;
}
midx_size = xsize_t(st.st_size);
if (midx_size < MIDX_MIN_SIZE) {
error(_("multi-pack-index file %s is too small"), midx_name);
error(_("multi-pack-index file %s is too small"), midx_name.buf);
goto cleanup_fail;
}
FREE_AND_NULL(midx_name);
strbuf_release(&midx_name);
midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
@ -184,7 +186,7 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
cleanup_fail:
free(m);
free(midx_name);
strbuf_release(&midx_name);
free_chunkfile(cf);
if (midx_map)
munmap(midx_map, midx_size);
@ -1115,7 +1117,7 @@ static int write_midx_internal(const char *object_dir,
const char *refs_snapshot,
unsigned flags)
{
char *midx_name;
struct strbuf midx_name = STRBUF_INIT;
unsigned char midx_hash[GIT_MAX_RAWSZ];
uint32_t i;
struct hashfile *f = NULL;
@ -1130,10 +1132,10 @@ static int write_midx_internal(const char *object_dir,
/* Ensure the given object_dir is local, or a known alternate. */
find_odb(the_repository, object_dir);
midx_name = get_midx_filename(object_dir);
if (safe_create_leading_directories(midx_name))
get_midx_filename(&midx_name, object_dir);
if (safe_create_leading_directories(midx_name.buf))
die_errno(_("unable to create leading directories of %s"),
midx_name);
midx_name.buf);
if (!packs_to_include) {
/*
@ -1367,7 +1369,7 @@ static int write_midx_internal(const char *object_dir,
pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
(pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
hold_lock_file_for_update(&lk, midx_name.buf, LOCK_DIE_ON_ERROR);
f = hashfd(get_lock_file_fd(&lk), get_lock_file_path(&lk));
if (ctx.nr - dropped_packs == 0) {
@ -1404,9 +1406,9 @@ static int write_midx_internal(const char *object_dir,
ctx.pack_order = midx_pack_order(&ctx);
if (flags & MIDX_WRITE_REV_INDEX)
write_midx_reverse_index(midx_name, midx_hash, &ctx);
write_midx_reverse_index(midx_name.buf, midx_hash, &ctx);
if (flags & MIDX_WRITE_BITMAP) {
if (write_midx_bitmap(midx_name, midx_hash, &ctx,
if (write_midx_bitmap(midx_name.buf, midx_hash, &ctx,
refs_snapshot, flags) < 0) {
error(_("could not write multi-pack bitmap"));
result = 1;
@ -1435,7 +1437,7 @@ cleanup:
free(ctx.entries);
free(ctx.pack_perm);
free(ctx.pack_order);
free(midx_name);
strbuf_release(&midx_name);
return result;
}
@ -1499,20 +1501,22 @@ static void clear_midx_files_ext(const char *object_dir, const char *ext,
void clear_midx_file(struct repository *r)
{
char *midx = get_midx_filename(r->objects->odb->path);
struct strbuf midx = STRBUF_INIT;
get_midx_filename(&midx, r->objects->odb->path);
if (r->objects && r->objects->multi_pack_index) {
close_midx(r->objects->multi_pack_index);
r->objects->multi_pack_index = NULL;
}
if (remove_path(midx))
die(_("failed to clear multi-pack-index at %s"), midx);
if (remove_path(midx.buf))
die(_("failed to clear multi-pack-index at %s"), midx.buf);
clear_midx_files_ext(r->objects->odb->path, ".bitmap", NULL);
clear_midx_files_ext(r->objects->odb->path, ".rev", NULL);
free(midx);
strbuf_release(&midx);
}
static int verify_midx_error;
@ -1565,12 +1569,15 @@ int verify_midx_file(struct repository *r, const char *object_dir, unsigned flag
if (!m) {
int result = 0;
struct stat sb;
char *filename = get_midx_filename(object_dir);
if (!stat(filename, &sb)) {
struct strbuf filename = STRBUF_INIT;
get_midx_filename(&filename, object_dir);
if (!stat(filename.buf, &sb)) {
error(_("multi-pack-index file exists, but failed to parse"));
result = 1;
}
free(filename);
strbuf_release(&filename);
return result;
}