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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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15
pack-bitmap.c
View File

@ -292,9 +292,12 @@ static int load_bitmap_entries_v1(struct bitmap_index *index)
char *midx_bitmap_filename(struct multi_pack_index *midx)
{
return xstrfmt("%s-%s.bitmap",
get_midx_filename(midx->object_dir),
hash_to_hex(get_midx_checksum(midx)));
struct strbuf buf = STRBUF_INIT;
get_midx_filename(&buf, midx->object_dir);
strbuf_addf(&buf, "-%s.bitmap", hash_to_hex(get_midx_checksum(midx)));
return strbuf_detach(&buf, NULL);
}
char *pack_bitmap_filename(struct packed_git *p)
@ -324,10 +327,12 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git,
}
if (bitmap_git->pack || bitmap_git->midx) {
struct strbuf buf = STRBUF_INIT;
get_midx_filename(&buf, midx->object_dir);
/* ignore extra bitmap file; we can only handle one */
warning("ignoring extra bitmap file: %s",
get_midx_filename(midx->object_dir));
warning("ignoring extra bitmap file: %s", buf.buf);
close(fd);
strbuf_release(&buf);
return -1;
}