Junio,
On Fri, May 20, 2022 at 07:17:35PM -0400, Taylor Blau wrote:
> To store the individual mtimes of objects in a cruft pack, introduce a
> new `.mtimes` format that can optionally accompany a single pack in the
> repository.
Like I mentioned in this sub-thread, here is a small fixup! to apply on
top of this patch when queueing. I'm hoping this will be easier than
reapplying the dozen+ or so patches in this series (the rest of which
are unchanged). But if it isn't, please let me know and I can send you a
reroll of the whole thing.
In the meantime, here's the fixup...
--- 8< ---
Subject: [PATCH] fixup! pack-mtimes: support reading .mtimes files
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
object-store.h | 5 +++++
pack-mtimes.c | 35 +++++++++++++++++++----------------
pack-mtimes.h | 11 +++++++++++
3 files changed, 35 insertions(+), 16 deletions(-)
diff --git a/object-store.h b/object-store.h
index 2c4671ed7a..05cc9a33ed 100644
--- a/object-store.h
+++ b/object-store.h
@@ -122,6 +122,11 @@ struct packed_git {
const uint32_t *revindex_data;
const uint32_t *revindex_map;
size_t revindex_size;
+ /*
+ * mtimes_map points at the beginning of the memory mapped region of
+ * this pack's corresponding .mtimes file, and mtimes_size is the size
+ * of that .mtimes file
+ */
const uint32_t *mtimes_map;
size_t mtimes_size;
/* something like ".git/objects/pack/xxxxx.pack" */
diff --git a/pack-mtimes.c b/pack-mtimes.c
index 46ad584af1..0e0aafdcb0 100644
--- a/pack-mtimes.c
+++ b/pack-mtimes.c
@@ -1,3 +1,4 @@
+#include "git-compat-util.h"
#include "pack-mtimes.h"
#include "object-store.h"
#include "packfile.h"
@@ -7,12 +8,10 @@ static char *pack_mtimes_filename(struct packed_git *p)
size_t len;
if (!strip_suffix(p->pack_name, ".pack", &len))
BUG("pack_name does not end in .pack");
- /* NEEDSWORK: this could reuse code from pack-revindex.c. */
return xstrfmt("%.*s.mtimes", (int)len, p->pack_name);
}
#define MTIMES_HEADER_SIZE (12)
-#define MTIMES_MIN_SIZE (MTIMES_HEADER_SIZE + (2 * the_hash_algo->rawsz))
struct mtimes_header {
uint32_t signature;
@@ -26,10 +25,9 @@ static int load_pack_mtimes_file(char *mtimes_file,
{
int fd, ret = 0;
struct stat st;
- void *data = NULL;
- size_t mtimes_size;
+ uint32_t *data = NULL;
+ size_t mtimes_size, expected_size;
struct mtimes_header header;
- uint32_t *hdr;
fd = git_open(mtimes_file);
@@ -44,21 +42,16 @@ static int load_pack_mtimes_file(char *mtimes_file,
mtimes_size = xsize_t(st.st_size);
- if (mtimes_size < MTIMES_MIN_SIZE) {
+ if (mtimes_size < MTIMES_HEADER_SIZE) {
ret = error(_("mtimes file %s is too small"), mtimes_file);
goto cleanup;
}
- if (mtimes_size - MTIMES_MIN_SIZE != st_mult(sizeof(uint32_t), num_objects)) {
- ret = error(_("mtimes file %s is corrupt"), mtimes_file);
- goto cleanup;
- }
+ data = xmmap(NULL, mtimes_size, PROT_READ, MAP_PRIVATE, fd, 0);
- data = hdr = xmmap(NULL, mtimes_size, PROT_READ, MAP_PRIVATE, fd, 0);
-
- header.signature = ntohl(hdr[0]);
- header.version = ntohl(hdr[1]);
- header.hash_id = ntohl(hdr[2]);
+ header.signature = ntohl(data[0]);
+ header.version = ntohl(data[1]);
+ header.hash_id = ntohl(data[2]);
if (header.signature != MTIMES_SIGNATURE) {
ret = error(_("mtimes file %s has unknown signature"), mtimes_file);
@@ -77,13 +70,23 @@ static int load_pack_mtimes_file(char *mtimes_file,
goto cleanup;
}
+
+ expected_size = MTIMES_HEADER_SIZE;
+ expected_size = st_add(expected_size, st_mult(sizeof(uint32_t), num_objects));
+ expected_size = st_add(expected_size, 2 * (header.hash_id == 1 ? GIT_SHA1_RAWSZ : GIT_SHA256_RAWSZ));
+
+ if (mtimes_size != expected_size) {
+ ret = error(_("mtimes file %s is corrupt"), mtimes_file);
+ goto cleanup;
+ }
+
cleanup:
if (ret) {
if (data)
munmap(data, mtimes_size);
} else {
*len_p = mtimes_size;
- *data_p = (const uint32_t *)data;
+ *data_p = data;
}
close(fd);
diff --git a/pack-mtimes.h b/pack-mtimes.h
index 38ddb9f893..cc957b3e85 100644
--- a/pack-mtimes.h
+++ b/pack-mtimes.h
@@ -8,8 +8,19 @@
struct packed_git;
+/*
+ * Loads the .mtimes file corresponding to "p", if any, returning zero
+ * on success.
+ */
int load_pack_mtimes(struct packed_git *p);
+/* Returns the mtime associated with the object at position "pos" (in
+ * lexicographic/index order) in pack "p".
+ *
+ * Note that it is a BUG() to call this function if either (a) "p" does
+ * not have a corresponding .mtimes file, or (b) it does, but it hasn't
+ * been loaded
+ */
uint32_t nth_packed_mtime(struct packed_git *p, uint32_t pos);
#endif
--
2.36.1.94.gb0d54bedca
--- >8 ---
