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LibC: Fix strtol() handling of invalid characters

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Rewrite this function to go from left-to-right instead of right-to-left
since this allows us to accumulate valid characters before encountering
any invalid ones.

This fixes parsing of strings emitted by GCC, like "1, %0|%0, %1}". :^)
This commit is contained in:
Andreas Kling 2019-08-24 12:37:58 +02:00
parent 56eaf9b033
commit d3a8fe70a2
1 changed files with 69 additions and 29 deletions
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98
Libraries/LibC/stdlib.cpp
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@ -329,49 +329,89 @@ size_t mbstowcs(wchar_t*, const char*, size_t)
ASSERT_NOT_REACHED(); ASSERT_NOT_REACHED();
} }
long strtol(const char* str, char** endptr, int base) long strtol(const char* nptr, char** endptr, int base)
{ {
int sign = 1; errno = 0;
while (isspace(*str))
str++; if (base < 0 || base == 1 || base > 36) {
if (*str == '-' || *str == '+') { errno = EINVAL;
if (*str == '-') if (endptr)
sign = -1; *endptr = const_cast<char*>(nptr);
str++; return 0;
} }
const char* p = nptr;
while (isspace(*p))
++p;
bool is_negative = false;
if (*p == '-') {
is_negative = true;
++p;
} else {
if (*p == '+')
++p;
}
if (base == 0 || base == 16) { if (base == 0 || base == 16) {
if (base == 0) if (base == 0)
base = 10; base = 10;
if (*str == '0') { if (*p == '0') {
str++; if (*(p + 1) == 'X' || *(p + 1) == 'x') {
if (*str == 'X' || *str == 'x') { p += 2;
str++;
base = 16; base = 16;
} else if (base != 16) { } else if (base != 16) {
base = 8; base = 8;
} }
} }
} }
size_t length = strlen(str);
const char* estr = str + length - 1; long cutoff_point = is_negative ? (LONG_MIN / base) : (LONG_MAX / base);
long track = 1; int max_valid_digit_at_cutoff_point = is_negative ? (LONG_MIN % base) : (LONG_MAX % base);
long num = 0; long num = 0;
while (estr >= str) {
if ((*estr >= '0' && *estr <= '9') || (base > 10 && (*estr >= 'A' && *estr <= 'Z'))) { bool has_overflowed = false;
int digit_value = *estr - '0'; unsigned digits_consumed = 0;
if (*estr >= 'A' && *estr <= 'Z')
digit_value = 10 + (*estr - 'A'); for (;;) {
num += (track *= base) / base * digit_value; char ch = *(p++);
int digit;
if (isdigit(ch))
digit = ch - '0';
else if (islower(ch))
digit = ch - ('a' - 10);
else if (isupper(ch))
digit = ch - ('A' - 10);
else
break;
if (digit >= base)
break;
if (has_overflowed)
continue;
bool is_past_cutoff = is_negative ? num < cutoff_point : num > cutoff_point;
if (is_past_cutoff || (num == cutoff_point && digit > max_valid_digit_at_cutoff_point)) {
has_overflowed = true;
num = is_negative ? LONG_MIN : LONG_MAX;
errno = ERANGE;
} else { } else {
if (endptr) num *= base;
*endptr = const_cast<char*>(estr); num += is_negative ? -digit : digit;
return 0; ++digits_consumed;
};
estr--;
} }
if (endptr) }
*endptr = const_cast<char*>(str + length);
return num * sign; if (endptr) {
if (has_overflowed || digits_consumed > 0)
*endptr = const_cast<char*>(p - 1);
else
*endptr = const_cast<char*>(nptr);
}
return num;
} }
unsigned long strtoul(const char* str, char** endptr, int base) unsigned long strtoul(const char* str, char** endptr, int base)