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In the de-duplication mode, when found matching md5 checksum also read

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back block and compare actual content. Just output original block
instead of back reference in the unlikely event of collision.
This commit is contained in:
sobomax 2016-03-13 21:09:08 +00:00
parent 94e9e924f7
commit bd7cbc7f20
2 changed files with 48 additions and 3 deletions
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49
usr.bin/mkuzip/mkuz_blockcache.c
View File

@ -29,7 +29,9 @@
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <err.h>
#include <md5.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
@ -49,6 +51,35 @@ struct mkuz_blkcache {
static struct mkuz_blkcache blkcache;
static int
verify_match(int fd, off_t data_offset, void *data, ssize_t len,
struct mkuz_blkcache *bcep)
{
void *vbuf;
ssize_t rlen;
int rval;
rval = -1;
vbuf = malloc(len);
if (vbuf == NULL) {
goto e0;
}
if (lseek(fd, bcep->data_offset, SEEK_SET) < 0) {
goto e1;
}
rlen = read(fd, vbuf, len);
if (rlen != len) {
goto e2;
}
rval = (memcmp(data, vbuf, len) == 0) ? 1 : 0;
e2:
lseek(fd, data_offset, SEEK_SET);
e1:
free(vbuf);
e0:
return (rval);
}
struct mkuz_blkcache_hit *
mkuz_blkcache_regblock(int fd, uint32_t blkno, off_t offset, ssize_t len,
void *data)
@ -57,6 +88,7 @@ mkuz_blkcache_regblock(int fd, uint32_t blkno, off_t offset, ssize_t len,
MD5_CTX mcontext;
off_t data_offset;
unsigned char mdigest[16];
int rval;
data_offset = lseek(fd, 0, SEEK_CUR);
if (data_offset < 0) {
@ -76,10 +108,23 @@ mkuz_blkcache_regblock(int fd, uint32_t blkno, off_t offset, ssize_t len,
}
}
if (bcep != NULL) {
rval = verify_match(fd, data_offset, data, len, bcep);
if (rval == 1) {
#if defined(MKUZ_DEBUG)
printf("cache hit %d, %d, %d\n", (int)bcep->hit.offset, (int)data_offset, (int)len);
fprintf(stderr, "cache hit %d, %d, %d\n",
(int)bcep->hit.offset, (int)data_offset, (int)len);
#endif
return (&bcep->hit);
return (&bcep->hit);
}
if (rval == 0) {
#if defined(MKUZ_DEBUG)
fprintf(stderr, "block MD5 collision, you should try lottery, "
"man!\n");
#endif
return (NULL);
}
warn("verify_match");
return (NULL);
}
bcep = malloc(sizeof(struct mkuz_blkcache));
if (bcep == NULL)

2
usr.bin/mkuzip/mkuzip.c
View File

@ -221,7 +221,7 @@ int main(int argc, char **argv)
}
toc = mkuz_safe_malloc((hdr.nblocks + 1) * sizeof(*toc));
fdw = open(oname, O_WRONLY | O_TRUNC | O_CREAT,
fdw = open(oname, (en_dedup ? O_RDWR : O_WRONLY) | O_TRUNC | O_CREAT,
S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
if (fdw < 0) {
err(1, "open(%s)", oname);