diff options
Diffstat (limited to 'Python/mystrtoul.c')
| -rw-r--r-- | Python/mystrtoul.c | 43 |
1 files changed, 33 insertions, 10 deletions
diff --git a/Python/mystrtoul.c b/Python/mystrtoul.c index 380b37da90..0dda4be2ee 100644 --- a/Python/mystrtoul.c +++ b/Python/mystrtoul.c @@ -17,7 +17,7 @@ #include <ctype.h> -#ifndef DONT_HAVE_ERRNO_H +#ifdef HAVE_ERRNO_H #include <errno.h> #endif @@ -69,11 +69,22 @@ static unsigned long smallmax[] = { * calculated by [int(math.floor(math.log(2**32, i))) for i in range(2, 37)]. * Note that this is pessimistic if sizeof(long) > 4. */ +#if SIZEOF_LONG == 4 static int digitlimit[] = { 0, 0, 32, 20, 16, 13, 12, 11, 10, 10, /* 0 - 9 */ 9, 9, 8, 8, 8, 8, 8, 7, 7, 7, /* 10 - 19 */ 7, 7, 7, 7, 6, 6, 6, 6, 6, 6, /* 20 - 29 */ 6, 6, 6, 6, 6, 6, 6}; /* 30 - 36 */ +#elif SIZEOF_LONG == 8 +/* [int(math.floor(math.log(2**64, i))) for i in range(2, 37)] */ +static int digitlimit[] = { + 0, 0, 64, 40, 32, 27, 24, 22, 21, 20, /* 0 - 9 */ + 19, 18, 17, 17, 16, 16, 16, 15, 15, 15, /* 10 - 19 */ + 14, 14, 14, 14, 13, 13, 13, 13, 13, 13, /* 20 - 29 */ + 13, 12, 12, 12, 12, 12, 12}; /* 30 - 36 */ +#else +#error "Need table for SIZEOF_LONG" +#endif /* ** strtoul @@ -184,10 +195,19 @@ overflowed: return (unsigned long)-1; } +/* Checking for overflow in PyOS_strtol is a PITA since C doesn't define + * anything about what happens when a signed integer operation overflows, + * and some compilers think they're doing you a favor by being "clever" + * then. Python assumes a 2's-complement representation, so that the bit + * pattern for the largest postive signed long is LONG_MAX, and for + * the smallest negative signed long is LONG_MAX + 1. + */ + long PyOS_strtol(char *str, char **ptr, int base) { long result; + unsigned long uresult; char sign; while (*str && isspace(Py_CHARMASK(*str))) @@ -197,17 +217,20 @@ PyOS_strtol(char *str, char **ptr, int base) if (sign == '+' || sign == '-') str++; - result = (long) PyOS_strtoul(str, ptr, base); + uresult = PyOS_strtoul(str, ptr, base); - /* Signal overflow if the result appears negative, - except for the largest negative integer */ - if (result < 0 && !(sign == '-' && result == -result)) { + if (uresult <= (unsigned long)LONG_MAX) { + result = (long)uresult; + if (sign == '-') + result = -result; + } + else if (sign == '-' && uresult == (unsigned long)LONG_MAX + 1) { + assert(LONG_MIN == -LONG_MAX-1); + result = LONG_MIN; + } + else { errno = ERANGE; - result = 0x7fffffff; + result = LONG_MAX; } - - if (sign == '-') - result = -result; - return result; } |