dedup

data deduplication program
git clone git://git.2f30.org/dedup.git
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commit 9817f61535da145c316a4bb5861ed913bc16b4cf
parent 022be48b38a5286cd9845f8397d8e491df80af31
Author: sin <sin@2f30.org>
Date:   Tue, 26 Feb 2019 11:10:48 +0000

Implement helpers for overflow detection

Diffstat:
Mdedup.c | 12+++++-------
Mdedup.h | 2++
Mutils.c | 13+++++++++++++
3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/dedup.c b/dedup.c @@ -4,7 +4,6 @@ #include <err.h> #include <fcntl.h> -#include <limits.h> #include <stdio.h> #include <stdint.h> #include <stdlib.h> @@ -136,16 +135,15 @@ free_snap(struct snapshot *snap) static struct snapshot * grow_snap(struct snapshot *snap, uint64_t nr_blk_descs) { - size_t size, mul; + size_t size; - if (nr_blk_descs > SIZE_MAX / sizeof(snap->blk_desc[0])) + if (mul_overflow(nr_blk_descs, sizeof(snap->blk_desc[0]))) errx(1, "grow_snap: overflow"); - mul = nr_blk_descs * sizeof(snap->blk_desc[0]); + size = nr_blk_descs * sizeof(snap->blk_desc[0]); - size = sizeof(*snap); - if (size > SIZE_MAX - mul) + if (add_overflow(size, sizeof(*snap))) errx(1, "grow_snap: overflow"); - size += mul; + size += sizeof(*snap); snap = realloc(snap, size); if (snap == NULL) diff --git a/dedup.h b/dedup.h @@ -96,3 +96,5 @@ void str2bin(char *s, uint8_t *d); off_t xlseek(int fd, off_t offset, int whence); ssize_t xread(int fd, void *buf, size_t nbytes); ssize_t xwrite(int fd, const void *buf, size_t nbytes); +int mul_overflow(size_t a, size_t b); +int add_overflow(size_t a, size_t b); diff --git a/utils.c b/utils.c @@ -1,6 +1,7 @@ #include <sys/types.h> #include <err.h> +#include <limits.h> #include <stdint.h> #include <stdio.h> #include <string.h> @@ -65,3 +66,15 @@ xwrite(int fd, const void *buf, size_t nbytes) } return total; } + +int +mul_overflow(size_t a, size_t b) +{ + return a > SIZE_MAX / b; +} + +int +add_overflow(size_t a, size_t b) +{ + return a > SIZE_MAX - b; +}