1 /*
2 * Copyright (C) the libgit2 contributors. All rights reserved.
3 *
4 * This file is part of libgit2, distributed under the GNU GPL v2 with
5 * a Linking Exception. For full terms see the included COPYING file.
6 */
7
8 #include "varint.h"
9
git_decode_varint(const unsigned char * bufp,size_t * varint_len)10 uintmax_t git_decode_varint(const unsigned char *bufp, size_t *varint_len)
11 {
12 const unsigned char *buf = bufp;
13 unsigned char c = *buf++;
14 uintmax_t val = c & 127;
15 while (c & 128) {
16 val += 1;
17 if (!val || MSB(val, 7)) {
18 /* This is not a valid varint_len, so it signals
19 the error */
20 *varint_len = 0;
21 return 0; /* overflow */
22 }
23 c = *buf++;
24 val = (val << 7) + (c & 127);
25 }
26 *varint_len = buf - bufp;
27 return val;
28 }
29
git_encode_varint(unsigned char * buf,size_t bufsize,uintmax_t value)30 int git_encode_varint(unsigned char *buf, size_t bufsize, uintmax_t value)
31 {
32 unsigned char varint[16];
33 unsigned pos = sizeof(varint) - 1;
34 varint[pos] = value & 127;
35 while (value >>= 7)
36 varint[--pos] = 128 | (--value & 127);
37 if (buf) {
38 if (bufsize < (sizeof(varint) - pos))
39 return -1;
40 memcpy(buf, varint + pos, sizeof(varint) - pos);
41 }
42 return sizeof(varint) - pos;
43 }
44