zend_multiply.h

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/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Sascha Schumann <sascha@schumann.cx>                        |
   |          Ard Biesheuvel <ard.biesheuvel@linaro.org>                  |
   +----------------------------------------------------------------------+
*/
 
#include "zend_portability.h"
 
#ifndef ZEND_MULTIPLY_H
#define ZEND_MULTIPLY_H
 
#if defined(PHP_HAVE_BUILTIN_SMULL_OVERFLOW) && SIZEOF_LONG == SIZEOF_ZEND_LONG
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    long __tmpvar;                                                  \
    if (((usedval) = __builtin_smull_overflow((a), (b), &__tmpvar))) {  \
        (dval) = (double) (a) * (double) (b);                       \
    }                                                               \
    else (lval) = __tmpvar;                                         \
} while (0)
 
#elif defined(PHP_HAVE_BUILTIN_SMULLL_OVERFLOW) && SIZEOF_LONG_LONG == SIZEOF_ZEND_LONG
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    long long __tmpvar;                                             \
    if (((usedval) = __builtin_smulll_overflow((a), (b), &__tmpvar))) { \
        (dval) = (double) (a) * (double) (b);                       \
    }                                                               \
    else (lval) = __tmpvar;                                         \
} while (0)
 
#elif (defined(__i386__) || defined(__x86_64__)) && defined(__GNUC__)
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    zend_long __tmpvar;                                                     \
    __asm__ ("imul %3,%0\n"                                         \
        "adc $0,%1"                                                 \
            : "=r"(__tmpvar),"=r"(usedval)                          \
            : "0"(a), "r"(b), "1"(0));                              \
    if (usedval) (dval) = (double) (a) * (double) (b);              \
    else (lval) = __tmpvar;                                         \
} while (0)
 
#elif defined(__arm__) && defined(__GNUC__)
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    zend_long __tmpvar;                                                     \
    __asm__("smull %0, %1, %2, %3\n"                                \
        "sub %1, %1, %0, asr #31"                                   \
            : "=r"(__tmpvar), "=r"(usedval)                         \
            : "r"(a), "r"(b));                                      \
    if (usedval) (dval) = (double) (a) * (double) (b);              \
    else (lval) = __tmpvar;                                         \
} while (0)
 
#elif defined(__aarch64__) && defined(__GNUC__)
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    zend_long __tmpvar;                                                     \
    __asm__("mul %0, %2, %3\n"                                      \
        "smulh %1, %2, %3\n"                                        \
        "sub %1, %1, %0, asr #63\n"                                 \
            : "=&r"(__tmpvar), "=&r"(usedval)                       \
            : "r"(a), "r"(b));                                      \
    if (usedval) (dval) = (double) (a) * (double) (b);              \
    else (lval) = __tmpvar;                                         \
} while (0)
 
#elif defined(ZEND_WIN32)
 
# ifdef _M_X64
#  pragma intrinsic(_mul128)
#  define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {       \
    __int64 __high; \
    __int64 __low = _mul128((a), (b), &__high); \
    if ((__low >> 63I64) == __high) { \
        (usedval) = 0; \
        (lval) = __low; \
    } else { \
        (usedval) = 1; \
        (dval) = (double)(a) * (double)(b); \
    } \
} while (0)
# elif defined(_M_ARM64)
#  pragma intrinsic(__mulh)
#  define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {       \
    __int64 __high = __mulh((a), (b)); \
    __int64 __low  = (a) * (b); \
    if ((__low >> 63I64) == __high) { \
        (usedval) = 0; \
        (lval) = __low; \
    } else { \
        (usedval) = 1; \
        (dval) = (double)(a) * (double)(b); \
    } \
} while (0)
# else
#  define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do { \
    zend_long   __lres  = (a) * (b);                                        \
    long double __dres  = (long double)(a) * (long double)(b);      \
    long double __delta = (long double) __lres - __dres;            \
    if ( ((usedval) = (( __dres + __delta ) != __dres))) {          \
        (dval) = __dres;                                            \
    } else {                                                        \
        (lval) = __lres;                                            \
    }                                                               \
} while (0)
# endif
 
#elif defined(__powerpc64__) && defined(__GNUC__)
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    long __low, __high;                     \
    __asm__("mulld %0,%2,%3\n\t"                    \
        "mulhd %1,%2,%3\n"                  \
        : "=&r"(__low), "=&r"(__high)               \
        : "r"(a), "r"(b));                  \
    if ((__low >> 63) != __high) {                  \
        (dval) = (double) (a) * (double) (b);           \
        (usedval) = 1;                      \
    } else {                            \
        (lval) = __low;                     \
        (usedval) = 0;                      \
    }                               \
} while (0)
 
#elif SIZEOF_ZEND_LONG == 4
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    int64_t __result = (int64_t) (a) * (int64_t) (b);               \
    if (__result > ZEND_LONG_MAX || __result < ZEND_LONG_MIN) {     \
        (dval) = (double) __result;                                 \
        (usedval) = 1;                                              \
    } else {                                                        \
        (lval) = (long) __result;                                   \
        (usedval) = 0;                                              \
    }                                                               \
} while (0)
 
#else
 
#define ZEND_SIGNED_MULTIPLY_LONG(a, b, lval, dval, usedval) do {   \
    long   __lres  = (a) * (b);                                     \
    long double __dres  = (long double)(a) * (long double)(b);      \
    long double __delta = (long double) __lres - __dres;            \
    if ( ((usedval) = (( __dres + __delta ) != __dres))) {          \
        (dval) = __dres;                                            \
    } else {                                                        \
        (lval) = __lres;                                            \
    }                                                               \
} while (0)
 
#endif
 
#if defined(__GNUC__) && (defined(__native_client__) || defined(i386))
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    size_t res = nmemb;
    size_t m_overflow = 0;
 
    if (ZEND_CONST_COND(offset == 0, 0)) {
        __asm__ ("mull %3\n\tadcl $0,%1"
         : "=&a"(res), "=&d" (m_overflow)
         : "%0"(res),
           "rm"(size));
    } else {
        __asm__ ("mull %3\n\taddl %4,%0\n\tadcl $0,%1"
         : "=&a"(res), "=&d" (m_overflow)
         : "%0"(res),
           "rm"(size),
           "rm"(offset));
    }
 
    if (UNEXPECTED(m_overflow)) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return res;
}
 
#elif defined(__GNUC__) && defined(__x86_64__)
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    size_t res = nmemb;
    zend_ulong m_overflow = 0;
 
#ifdef __ILP32__ /* x32 */
# define LP_SUFF "l"
#else /* amd64 */
# define LP_SUFF "q"
#endif
 
    if (ZEND_CONST_COND(offset == 0, 0)) {
        __asm__ ("mul" LP_SUFF  " %3\n\t"
            "adc $0,%1"
            : "=&a"(res), "=&d" (m_overflow)
            : "%0"(res),
              "rm"(size));
    } else {
        __asm__ ("mul" LP_SUFF  " %3\n\t"
            "add %4,%0\n\t"
            "adc $0,%1"
            : "=&a"(res), "=&d" (m_overflow)
            : "%0"(res),
              "rm"(size),
              "rm"(offset));
    }
#undef LP_SUFF
    if (UNEXPECTED(m_overflow)) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return res;
}
 
#elif defined(__GNUC__) && defined(__arm__)
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    size_t res;
    zend_ulong m_overflow;
 
    __asm__ ("umlal %0,%1,%2,%3"
        : "=r"(res), "=r"(m_overflow)
        : "r"(nmemb),
          "r"(size),
          "0"(offset),
          "1"(0));
 
    if (UNEXPECTED(m_overflow)) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return res;
}
 
#elif defined(__GNUC__) && defined(__aarch64__)
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    size_t res;
    zend_ulong m_overflow;
 
    __asm__ ("mul %0,%2,%3\n\tumulh %1,%2,%3\n\tadds %0,%0,%4\n\tadc %1,%1,xzr"
        : "=&r"(res), "=&r"(m_overflow)
        : "r"(nmemb),
          "r"(size),
          "r"(offset));
 
    if (UNEXPECTED(m_overflow)) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return res;
}
 
#elif defined(__GNUC__) && defined(__powerpc64__)
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
        size_t res;
        unsigned long m_overflow;
 
        __asm__ ("mulld %0,%2,%3\n\t"
                 "mulhdu %1,%2,%3\n\t"
                 "addc %0,%0,%4\n\t"
                 "addze %1,%1\n"
             : "=&r"(res), "=&r"(m_overflow)
             : "r"(nmemb),
               "r"(size),
               "r"(offset));
 
        if (UNEXPECTED(m_overflow)) {
                *overflow = 1;
                return 0;
        }
        *overflow = 0;
        return res;
}
 
#elif SIZEOF_SIZE_T == 4
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    uint64_t res = (uint64_t) nmemb * (uint64_t) size + (uint64_t) offset;
 
    if (UNEXPECTED(res > UINT64_C(0xFFFFFFFF))) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return (size_t) res;
}
 
#else
 
static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, size_t offset, bool *overflow)
{
    size_t res = nmemb * size + offset;
    double _d  = (double)nmemb * (double)size + (double)offset;
    double _delta = (double)res - _d;
 
    if (UNEXPECTED((_d + _delta ) != _d)) {
        *overflow = 1;
        return 0;
    }
    *overflow = 0;
    return res;
}
#endif
 
static zend_always_inline size_t zend_safe_address_guarded(size_t nmemb, size_t size, size_t offset)
{
    bool overflow;
    size_t ret = zend_safe_address(nmemb, size, offset, &overflow);
 
    if (UNEXPECTED(overflow)) {
        zend_error_noreturn(E_ERROR, "Possible integer overflow in memory allocation (%zu * %zu + %zu)", nmemb, size, offset);
        return 0;
    }
    return ret;
}
 
/* A bit more generic version of the same */
static zend_always_inline size_t zend_safe_addmult(size_t nmemb, size_t size, size_t offset, const char *message)
{
    bool overflow;
    size_t ret = zend_safe_address(nmemb, size, offset, &overflow);
 
    if (UNEXPECTED(overflow)) {
        zend_error_noreturn(E_ERROR, "Possible integer overflow in %s (%zu * %zu + %zu)", message, nmemb, size, offset);
        return 0;
    }
    return ret;
}
 
#endif /* ZEND_MULTIPLY_H */