fix signed overflows at most-negative values in ato(i|l|ll)

[musl] / src / stdlib / atoi.c

#include <stdlib.h>
#include <ctype.h>

int atoi(const char *s)
{
        int n=0, neg=0;
        while (isspace(*s)) s++;
        switch (*s) {
        case '-': neg=1;
        case '+': s++;
        }
        /* Compute n as a negative number to avoid overflow on INT_MIN */
        while (isdigit(*s))
                n = 10*n - (*s++ - '0');
        return neg ? n : -n;
}