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stdlib: Rewrite SDL_strtoull impl

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This commit is contained in:
Carl Åstholm
2024-09-11 22:32:45 +02:00
committed by Sam Lantinga
parent 5331f36789
commit fb82772fb3
2 changed files with 99 additions and 49 deletions
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134
src/stdlib/SDL_string.c
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@@ -326,6 +326,91 @@ static size_t UTF8_GetTrailingBytes(unsigned char c)
return 0;
}
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOL) || !defined(HAVE_STRTOUL) || !defined(HAVE_STRTOLL) || !defined(HAVE_STRTOULL) || !defined(HAVE_STRTOD)
/**
* Parses an unsigned long long and returns the unsigned value and sign bit.
*
* Positive values are clamped to ULLONG_MAX.
* The result `value == 0 && negative` indicates negative overflow
* and might need to be handled differently depending on whether a
* signed or unsigned integer is being parsed.
*/
static size_t SDL_ScanUnsignedLongLongInternal(const char *text, int count, int radix, unsigned long long *valuep, bool *negativep)
{
const unsigned long long ullong_max = ~0ULL;
const char *text_start = text;
const char *number_start = text_start;
unsigned long long value = 0;
bool negative = false;
bool overflow = false;
if (radix == 0 || (radix >= 2 && radix <= 36)) {
while (SDL_isspace(*text)) {
++text;
}
if (*text == '-' || *text == '+') {
negative = *text == '-';
++text;
}
if ((radix == 0 || radix == 16) && *text == '0') {
++text;
if (*text == 'x' || *text == 'X') {
radix = 16;
++text;
} else if (radix == 0) {
radix = 8;
}
} else if (radix == 0) {
radix = 10;
}
number_start = text;
do {
unsigned long long digit;
if (*text >= '0' && *text <= '9') {
digit = *text - '0';
} else if (radix > 10) {
if (*text >= 'A' && *text < 'A' + (radix - 10)) {
digit = 10 + (*text - 'A');
} else if (*text >= 'a' && *text < 'a' + (radix - 10)) {
digit = 10 + (*text - 'a');
} else {
break;
}
} else {
break;
}
if (value != 0 && radix > ullong_max / value) {
overflow = true;
} else {
value *= radix;
if (digit > ullong_max - value) {
overflow = true;
} else {
value += digit;
}
}
++text;
} while (count == 0 || (text - text_start) != count);
}
if (text == number_start) { // no number was parsed, so no characters were consumed
text = text_start;
}
if (overflow) {
if (negative) {
value = 0;
} else {
value = ullong_max;
}
} else if (value == 0) {
negative = false;
}
*valuep = value;
*negativep = negative;
return text - text_start;
}
#endif
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOL) || !defined(HAVE_STRTOUL) || !defined(HAVE_STRTOD)
static size_t SDL_ScanLong(const char *text, int count, int radix, long *valuep)
{
@@ -563,39 +648,16 @@ static size_t SDL_ScanLongLong(const char *text, int count, int radix, long long
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOULL)
static size_t SDL_ScanUnsignedLongLong(const char *text, int count, int radix, unsigned long long *valuep)
{
const char *textstart = text;
unsigned long long value = 0;
if (*text == '-') {
return SDL_ScanLongLong(text, count, radix, (long long *)valuep);
}
if (radix == 16 && SDL_strncmp(text, "0x", 2) == 0) {
text += 2;
}
for (;;) {
int v;
if (SDL_isdigit((unsigned char)*text)) {
v = *text - '0';
} else if (radix == 16 && SDL_isupperhex(*text)) {
v = 10 + (*text - 'A');
} else if (radix == 16 && SDL_islowerhex(*text)) {
v = 10 + (*text - 'a');
bool negative;
size_t len = SDL_ScanUnsignedLongLongInternal(text, count, radix, valuep, &negative);
if (negative) {
if (*valuep == 0) {
*valuep = ~0ULL; // ULLONG_MAX
} else {
break;
}
value *= radix;
value += v;
++text;
if (count > 0 && (text - textstart) == count) {
break;
*valuep = 0ULL - *valuep;
}
}
if (valuep && text > textstart) {
*valuep = value;
}
return text - textstart;
return len;
}
#endif
@@ -1292,18 +1354,8 @@ unsigned long long SDL_strtoull(const char *string, char **endp, int base)
#ifdef HAVE_STRTOULL
return strtoull(string, endp, base);
#else
size_t len;
unsigned long long value = 0;
if (!base) {
if ((SDL_strlen(string) > 2) && (SDL_strncasecmp(string, "0x", 2) == 0)) {
base = 16;
} else {
base = 10;
}
}
len = SDL_ScanUnsignedLongLong(string, 0, base, &value);
size_t len = SDL_ScanUnsignedLongLong(string, 0, base, &value);
if (endp) {
*endp = (char *)string + len;
}