v4 adds 32-bit field to cache header after 32-bit number of entries.
If this field is zero, fall back to v3.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
Documentation/technical/index-format.txt | 4 ++-
cache.h | 6 +++++
read-cache.c | 31 ++++++++++++++++++++++-------
3 files changed, 32 insertions(+), 9 deletions(-)
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index 8930b3f..2b6a38e 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -12,10 +12,12 @@ GIT index format
The signature is { 'D', 'I', 'R', 'C' } (stands for "dircache")
4-byte version number:
- The current supported versions are 2 and 3.
+ The current supported versions are 2, 3 and 4.
32-bit number of index entries.
+ 32-bit flags (version 4 only).
+
- A number of sorted index entries (see below).
- Extensions
diff --git a/cache.h b/cache.h
index 9bd8c2d..c2e884a 100644
--- a/cache.h
+++ b/cache.h
@@ -105,6 +105,11 @@ struct cache_header {
unsigned int hdr_entries;
};
+struct ext_cache_header {
+ struct cache_header h;
+ unsigned int hdr_flags;
+};
+
/*
* The "cache_time" is just the low 32 bits of the
* time. It doesn't matter if it overflows - we only
@@ -314,6 +319,7 @@ static inline unsigned int canon_mode(unsigned int mode)
struct index_state {
struct cache_entry **cache;
unsigned int cache_nr, cache_alloc, cache_changed;
+ unsigned int hdr_flags;
struct string_list *resolve_undo;
struct cache_tree *cache_tree;
struct cache_time timestamp;
diff --git a/read-cache.c b/read-cache.c
index fe6b0e0..fd21af6 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1190,7 +1190,9 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
return error("bad signature");
- if (hdr->hdr_version != htonl(2) && hdr->hdr_version != htonl(3))
+ if (hdr->hdr_version != htonl(2) &&
+ hdr->hdr_version != htonl(3) &&
+ hdr->hdr_version != htonl(4))
return error("bad index version");
git_SHA1_Init(&c);
git_SHA1_Update(&c, hdr, size - 20);
@@ -1320,7 +1322,12 @@ int read_index_from(struct index_state *istate, const char *path)
istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
istate->initialized = 1;
- src_offset = sizeof(*hdr);
+ if (ntohl(hdr->hdr_version) >= 4) {
+ struct ext_cache_header *ehdr = mmap;
+ istate->hdr_flags = ntohl(ehdr->hdr_flags);
+ src_offset = sizeof(*ehdr);
+ } else
+ src_offset = sizeof(*hdr);
for (i = 0; i < istate->cache_nr; i++) {
struct ondisk_cache_entry *disk_ce;
struct cache_entry *ce;
@@ -1375,6 +1382,7 @@ int discard_index(struct index_state *istate)
resolve_undo_clear_index(istate);
istate->cache_nr = 0;
istate->cache_changed = 0;
+ istate->hdr_flags = 0;
istate->timestamp.sec = 0;
istate->timestamp.nsec = 0;
istate->name_hash_initialized = 0;
@@ -1531,8 +1539,8 @@ void update_index_if_able(struct index_state *istate, struct lock_file *lockfile
int write_index(struct index_state *istate, int newfd)
{
struct sha1file *f;
- struct cache_header hdr;
- int i, err, removed;
+ struct ext_cache_header hdr;
+ int i, err, removed, hdr_size;
struct cache_entry **cache = istate->cache;
int entries = istate->cache_nr;
struct stat st;
@@ -1548,12 +1556,19 @@ int write_index(struct index_state *istate, int newfd)
}
}
- hdr.hdr_signature = htonl(CACHE_SIGNATURE);
- hdr.hdr_version = htonl(3);
- hdr.hdr_entries = htonl(entries - removed);
+ hdr.h.hdr_signature = htonl(CACHE_SIGNATURE);
+ if (istate->hdr_flags) {
+ hdr.h.hdr_version = htonl(4);
+ hdr.hdr_flags = htonl(istate->hdr_flags);
+ hdr_size = sizeof(hdr);
+ } else {
+ hdr.h.hdr_version = htonl(3);
+ hdr_size = sizeof(hdr.h);
+ }
+ hdr.h.hdr_entries = htonl(entries - removed);
f = sha1fd(newfd, NULL);
- if (ce_write(f, &hdr, sizeof(hdr)) < 0)
+ if (ce_write(f, &hdr, hdr_size) < 0)
return -1;
for (i = 0; i < entries; i++) {
--
1.7.8.36.g69ee2
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