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lib: unify conversions to/from hex

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Curl_hexbyte - output a byte as a two-digit ASCII hex number

Curl_hexval - convert an ASCII hex digit to its binary value

... instead of duplicating similar code and hexdigit strings in numerous
places.

Closes #16888
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Daniel Stenberg 2025-03-31 23:12:09 +02:00
parent 1d84d683bb
commit 0c6e63a1be
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GPG key ID: 5CC908FDB71E12C2
8 changed files with 69 additions and 71 deletions
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30
lib/strparse.c
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@ -139,25 +139,23 @@ int Curl_str_singlespace(const char **linep)
/* given an ASCII character and max ascii, return TRUE if valid */
#define valid_digit(x,m) \
(((x) >= '0') && ((x) <= m) && hexasciitable[(x)-'0'])
(((x) >= '0') && ((x) <= m) && Curl_hexasciitable[(x)-'0'])
/* We use 16 for the zero index (and the necessary bitwise AND in the loop)
to be able to have a non-zero value there to make valid_digit() able to
use the info */
const unsigned char Curl_hexasciitable[] = {
16, 1, 2, 3, 4, 5, 6, 7, 8, 9, /* 0x30: 0 - 9 */
0, 0, 0, 0, 0, 0, 0,
10, 11, 12, 13, 14, 15, /* 0x41: A - F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
10, 11, 12, 13, 14, 15 /* 0x61: a - f */
};
/* no support for 0x prefix nor leading spaces */
static int str_num_base(const char **linep, curl_off_t *nump, curl_off_t max,
int base) /* 8, 10 or 16, nothing else */
{
/* We use 16 for the zero index (and the necessary bitwise AND in the loop)
to be able to have a non-zero value there to make valid_digit() able to
use the info */
static const unsigned char hexasciitable[] = {
16, 1, 2, 3, 4, 5, 6, 7, 8, 9, /* 0x30: 0 - 9 */
0, 0, 0, 0, 0, 0, 0,
10, 11, 12, 13, 14, 15, /* 0x41: A - F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0,
10, 11, 12, 13, 14, 15 /* 0x61: a - f */
};
curl_off_t num = 0;
const char *p;
int m = (base == 10) ? '9' : /* the largest digit possible */
@ -172,7 +170,7 @@ static int str_num_base(const char **linep, curl_off_t *nump, curl_off_t max,
if(max < base) {
/* special-case low max scenario because check needs to be different */
do {
int n = hexasciitable[*p++ - '0'] & 0x0f;
int n = Curl_hexval(*p++);
num = num * base + n;
if(num > max)
return STRE_OVERFLOW;
@ -180,7 +178,7 @@ static int str_num_base(const char **linep, curl_off_t *nump, curl_off_t max,
}
else {
do {
int n = hexasciitable[*p++ - '0'] & 0x0f;
int n = Curl_hexval(*p++);
if(num > ((max - n) / base))
return STRE_OVERFLOW;
num = num * base + n;