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Make the sha1 of the index file go at the very end of the file. 

This allows us to both calculate it and verify it faster.
This commit is contained in:
Linus Torvalds 2005-04-20 12:36:41 -07:00
parent 4990aadc4c
commit ca9be05421
2 changed files with 21 additions and 24 deletions
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1
cache.h
View File

@ -28,7 +28,6 @@ struct cache_header {
unsigned int hdr_signature;
unsigned int hdr_version;
unsigned int hdr_entries;
unsigned char sha1[20];
};
/*

44
read-cache.c
View File

@ -161,14 +161,13 @@ 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(1))
return error("bad version");
if (hdr->hdr_version != htonl(2))
return error("bad index version");
SHA1_Init(&c);
SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
SHA1_Update(&c, hdr, size - 20);
SHA1_Final(sha1, &c);
if (memcmp(sha1, hdr->sha1, 20))
return error("bad header sha1");
if (memcmp(sha1, (void *)hdr + size - 20, 20))
return error("bad index file sha1 signature");
return 0;
}
@ -198,7 +197,7 @@ int read_cache(void)
if (!fstat(fd, &st)) {
size = st.st_size;
errno = EINVAL;
if (size >= sizeof(struct cache_header))
if (size >= sizeof(struct cache_header) + 20)
map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
}
close(fd);
@ -231,7 +230,7 @@ int read_cache(void)
static char write_buffer[WRITE_BUFFER_SIZE];
static unsigned long write_buffer_len;
static int ce_write(int fd, void *data, unsigned int len)
static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
{
while (len) {
unsigned int buffered = write_buffer_len;
@ -241,6 +240,7 @@ static int ce_write(int fd, void *data, unsigned int len)
memcpy(write_buffer + buffered, data, partial);
buffered += partial;
if (buffered == WRITE_BUFFER_SIZE) {
SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
return -1;
buffered = 0;
@ -252,14 +252,20 @@ static int ce_write(int fd, void *data, unsigned int len)
return 0;
}
static int ce_flush(int fd)
static int ce_flush(SHA_CTX *context, int fd)
{
unsigned int left = write_buffer_len;
if (left) {
write_buffer_len = 0;
if (write(fd, write_buffer, left) != left)
return -1;
SHA1_Update(context, write_buffer, left);
}
/* Append the SHA1 signature at the end */
SHA1_Final(write_buffer + left, context);
left += 20;
if (write(fd, write_buffer, left) != left)
return -1;
return 0;
}
@ -270,25 +276,17 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
int i;
hdr.hdr_signature = htonl(CACHE_SIGNATURE);
hdr.hdr_version = htonl(1);
hdr.hdr_version = htonl(2);
hdr.hdr_entries = htonl(entries);
SHA1_Init(&c);
SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
int size = ce_size(ce);
SHA1_Update(&c, ce, size);
}
SHA1_Final(hdr.sha1, &c);
if (ce_write(newfd, &hdr, sizeof(hdr)) < 0)
if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
return -1;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
if (ce_write(newfd, ce, ce_size(ce)) < 0)
if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
return -1;
}
return ce_flush(newfd);
return ce_flush(&c, newfd);
}