git/hex.c
Jeff King af49c6d091 add reentrant variants of sha1_to_hex and find_unique_abbrev
The sha1_to_hex and find_unique_abbrev functions always
write into reusable static buffers. There are a few problems
with this:

  - future calls overwrite our result. This is especially
    annoying with find_unique_abbrev, which does not have a
    ring of buffers, so you cannot even printf() a result
    that has two abbreviated sha1s.

  - if you want to put the result into another buffer, we
    often strcpy, which looks suspicious when auditing for
    overflows.

This patch introduces sha1_to_hex_r and find_unique_abbrev_r,
which write into a user-provided buffer. Of course this is
just punting on the overflow-auditing, as the buffer
obviously needs to be GIT_SHA1_HEXSZ + 1 bytes. But it is
much easier to audit, since that is a well-known size.

We retain the non-reentrant forms, which just become thin
wrappers around the reentrant ones. This patch also adds a
strbuf variant of find_unique_abbrev, which will be handy in
later patches.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-25 10:18:18 -07:00

91 lines
2.6 KiB
C

#include "cache.h"
const signed char hexval_table[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, /* 00-07 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 08-0f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 10-17 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 18-1f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 20-27 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 28-2f */
0, 1, 2, 3, 4, 5, 6, 7, /* 30-37 */
8, 9, -1, -1, -1, -1, -1, -1, /* 38-3f */
-1, 10, 11, 12, 13, 14, 15, -1, /* 40-47 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 48-4f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 50-57 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 58-5f */
-1, 10, 11, 12, 13, 14, 15, -1, /* 60-67 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 68-67 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 70-77 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 78-7f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 80-87 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 88-8f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 90-97 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 98-9f */
-1, -1, -1, -1, -1, -1, -1, -1, /* a0-a7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* a8-af */
-1, -1, -1, -1, -1, -1, -1, -1, /* b0-b7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* b8-bf */
-1, -1, -1, -1, -1, -1, -1, -1, /* c0-c7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* c8-cf */
-1, -1, -1, -1, -1, -1, -1, -1, /* d0-d7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* d8-df */
-1, -1, -1, -1, -1, -1, -1, -1, /* e0-e7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* e8-ef */
-1, -1, -1, -1, -1, -1, -1, -1, /* f0-f7 */
-1, -1, -1, -1, -1, -1, -1, -1, /* f8-ff */
};
int get_sha1_hex(const char *hex, unsigned char *sha1)
{
int i;
for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
unsigned int val;
/*
* hex[1]=='\0' is caught when val is checked below,
* but if hex[0] is NUL we have to avoid reading
* past the end of the string:
*/
if (!hex[0])
return -1;
val = (hexval(hex[0]) << 4) | hexval(hex[1]);
if (val & ~0xff)
return -1;
*sha1++ = val;
hex += 2;
}
return 0;
}
int get_oid_hex(const char *hex, struct object_id *oid)
{
return get_sha1_hex(hex, oid->hash);
}
char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
{
static const char hex[] = "0123456789abcdef";
char *buf = buffer;
int i;
for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
unsigned int val = *sha1++;
*buf++ = hex[val >> 4];
*buf++ = hex[val & 0xf];
}
*buf = '\0';
return buffer;
}
char *sha1_to_hex(const unsigned char *sha1)
{
static int bufno;
static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
return sha1_to_hex_r(hexbuffer[3 & ++bufno], sha1);
}
char *oid_to_hex(const struct object_id *oid)
{
return sha1_to_hex(oid->hash);
}