util: use gcc builtins to better check array sizes

[mirror_ovs.git] / lib / util.h

/*
 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef UTIL_H
#define UTIL_H 1

#include <limits.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "compiler.h"
#include "openvswitch/types.h"

#ifndef va_copy
#ifdef __va_copy
#define va_copy __va_copy
#else
#define va_copy(dst, src) ((dst) = (src))
#endif
#endif

#ifdef __CHECKER__
#define BUILD_ASSERT(EXPR) ((void) 0)
#define BUILD_ASSERT_DECL(EXPR) extern int (*build_assert(void))[1]
#elif !defined(__cplusplus)
/* Build-time assertion building block. */
#define BUILD_ASSERT__(EXPR) \
        sizeof(struct { unsigned int build_assert_failed : (EXPR) ? 1 : -1; })

/* Build-time assertion for use in a statement context. */
#define BUILD_ASSERT(EXPR) (void) BUILD_ASSERT__(EXPR)

/* Build-time assertion for use in a declaration context. */
#define BUILD_ASSERT_DECL(EXPR) \
        extern int (*build_assert(void))[BUILD_ASSERT__(EXPR)]
#else /* __cplusplus */
#include <boost/static_assert.hpp>
#define BUILD_ASSERT BOOST_STATIC_ASSERT
#define BUILD_ASSERT_DECL BOOST_STATIC_ASSERT
#endif /* __cplusplus */

#ifdef __GNUC__
#define BUILD_ASSERT_GCCONLY(EXPR) BUILD_ASSERT(EXPR)
#define BUILD_ASSERT_DECL_GCCONLY(EXPR) BUILD_ASSERT_DECL(EXPR)
#else
#define BUILD_ASSERT_GCCONLY(EXPR) ((void) 0)
#define BUILD_ASSERT_DECL_GCCONLY(EXPR) ((void) 0)
#endif

/* Like the standard assert macro, except:
 *
 *   - Writes the failure message to the log.
 *
 *   - Not affected by NDEBUG. */
#define ovs_assert(CONDITION)                                           \
    if (!OVS_LIKELY(CONDITION)) {                                       \
        ovs_assert_failure(SOURCE_LOCATOR, __func__, #CONDITION);       \
    }
void ovs_assert_failure(const char *, const char *, const char *) NO_RETURN;

/* Casts 'pointer' to 'type' and issues a compiler warning if the cast changes
 * anything other than an outermost "const" or "volatile" qualifier.
 *
 * The cast to int is present only to suppress an "expression using sizeof
 * bool" warning from "sparse" (see
 * http://permalink.gmane.org/gmane.comp.parsers.sparse/2967). */
#define CONST_CAST(TYPE, POINTER)                               \
    ((void) sizeof ((int) ((POINTER) == (TYPE) (POINTER))),     \
     (TYPE) (POINTER))

extern const char *program_name;

#define __ARRAY_SIZE_NOCHECK(ARRAY) (sizeof(ARRAY) / sizeof((ARRAY)[0]))
#ifdef __GNUC__
/* return 0 for array types, 1 otherwise */
#define __ARRAY_CHECK(ARRAY) 					\
    !__builtin_types_compatible_p(typeof(ARRAY), typeof(&ARRAY[0]))

/* compile-time fail if not array */
#define __ARRAY_FAIL(ARRAY) (sizeof(char[-2*!__ARRAY_CHECK(ARRAY)]))
#define __ARRAY_SIZE(ARRAY)					\
    __builtin_choose_expr(__ARRAY_CHECK(ARRAY),			\
        __ARRAY_SIZE_NOCHECK(ARRAY), __ARRAY_FAIL(ARRAY))
#else
#define __ARRAY_SIZE(ARRAY) __ARRAY_SIZE_NOCHECK(ARRAY)
#endif

/* Returns the number of elements in ARRAY. */
#define ARRAY_SIZE(ARRAY) __ARRAY_SIZE(ARRAY)

/* Returns X / Y, rounding up.  X must be nonnegative to round correctly. */
#define DIV_ROUND_UP(X, Y) (((X) + ((Y) - 1)) / (Y))

/* Returns X rounded up to the nearest multiple of Y. */
#define ROUND_UP(X, Y) (DIV_ROUND_UP(X, Y) * (Y))

/* Returns X rounded down to the nearest multiple of Y. */
#define ROUND_DOWN(X, Y) ((X) / (Y) * (Y))

/* Returns true if X is a power of 2, otherwise false. */
#define IS_POW2(X) ((X) && !((X) & ((X) - 1)))

static inline bool
is_pow2(uintmax_t x)
{
    return IS_POW2(x);
}

/* Returns X rounded up to a power of 2.  X must be a constant expression. */
#define ROUND_UP_POW2(X) RUP2__(X)
#define RUP2__(X) (RUP2_1(X) + 1)
#define RUP2_1(X) (RUP2_2(X) | (RUP2_2(X) >> 16))
#define RUP2_2(X) (RUP2_3(X) | (RUP2_3(X) >> 8))
#define RUP2_3(X) (RUP2_4(X) | (RUP2_4(X) >> 4))
#define RUP2_4(X) (RUP2_5(X) | (RUP2_5(X) >> 2))
#define RUP2_5(X) (RUP2_6(X) | (RUP2_6(X) >> 1))
#define RUP2_6(X) ((X) - 1)

/* Returns X rounded down to a power of 2.  X must be a constant expression. */
#define ROUND_DOWN_POW2(X) RDP2__(X)
#define RDP2__(X) (RDP2_1(X) - (RDP2_1(X) >> 1))
#define RDP2_1(X) (RDP2_2(X) | (RDP2_2(X) >> 16))
#define RDP2_2(X) (RDP2_3(X) | (RDP2_3(X) >> 8))
#define RDP2_3(X) (RDP2_4(X) | (RDP2_4(X) >> 4))
#define RDP2_4(X) (RDP2_5(X) | (RDP2_5(X) >> 2))
#define RDP2_5(X) (      (X) | (      (X) >> 1))

#ifndef MIN
#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
#endif

#ifndef MAX
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
#endif

#define NOT_REACHED() abort()

/* Expands to a string that looks like "<file>:<line>", e.g. "tmp.c:10".
 *
 * See http://c-faq.com/ansi/stringize.html for an explanation of STRINGIZE and
 * STRINGIZE2. */
#define SOURCE_LOCATOR __FILE__ ":" STRINGIZE(__LINE__)
#define STRINGIZE(ARG) STRINGIZE2(ARG)
#define STRINGIZE2(ARG) #ARG

/* Given a pointer-typed lvalue OBJECT, expands to a pointer type that may be
 * assigned to OBJECT. */
#ifdef __GNUC__
#define OVS_TYPEOF(OBJECT) typeof(OBJECT)
#else
#define OVS_TYPEOF(OBJECT) void *
#endif

/* Given OBJECT of type pointer-to-structure, expands to the offset of MEMBER
 * within an instance of the structure.
 *
 * The GCC-specific version avoids the technicality of undefined behavior if
 * OBJECT is null, invalid, or not yet initialized.  This makes some static
 * checkers (like Coverity) happier.  But the non-GCC version does not actually
 * dereference any pointer, so it would be surprising for it to cause any
 * problems in practice.
 */
#ifdef __GNUC__
#define OBJECT_OFFSETOF(OBJECT, MEMBER) offsetof(typeof(*(OBJECT)), MEMBER)
#else
#define OBJECT_OFFSETOF(OBJECT, MEMBER) \
    ((char *) &(OBJECT)->MEMBER - (char *) (OBJECT))
#endif

/* Given POINTER, the address of the given MEMBER in a STRUCT object, returns
   the STRUCT object. */
#define CONTAINER_OF(POINTER, STRUCT, MEMBER)                           \
        ((STRUCT *) (void *) ((char *) (POINTER) - offsetof (STRUCT, MEMBER)))

/* Given POINTER, the address of the given MEMBER within an object of the type
 * that that OBJECT points to, returns OBJECT as an assignment-compatible
 * pointer type (either the correct pointer type or "void *").  OBJECT must be
 * an lvalue.
 *
 * This is the same as CONTAINER_OF except that it infers the structure type
 * from the type of '*OBJECT'. */
#define OBJECT_CONTAINING(POINTER, OBJECT, MEMBER)                      \
    ((OVS_TYPEOF(OBJECT)) (void *)                                      \
     ((char *) (POINTER) - OBJECT_OFFSETOF(OBJECT, MEMBER)))

/* Given POINTER, the address of the given MEMBER within an object of the type
 * that that OBJECT points to, assigns the address of the outer object to
 * OBJECT, which must be an lvalue.
 *
 * Evaluates to (void) 0 as the result is not to be used. */
#define ASSIGN_CONTAINER(OBJECT, POINTER, MEMBER) \
    ((OBJECT) = OBJECT_CONTAINING(POINTER, OBJECT, MEMBER), (void) 0)

/* Given ATTR, and TYPE, cast the ATTR to TYPE by first casting ATTR to
 * (void *). This is to suppress the alignment warning issued by clang. */
#define ALIGNED_CAST(TYPE, ATTR) ((TYPE) (void *) (ATTR))

#ifdef  __cplusplus
extern "C" {
#endif

void set_program_name__(const char *name, const char *version,
                        const char *date, const char *time);
#define set_program_name(name) \
        set_program_name__(name, VERSION, __DATE__, __TIME__)

const char *get_subprogram_name(void);
void set_subprogram_name(const char *name);

const char *get_program_version(void);
void ovs_print_version(uint8_t min_ofp, uint8_t max_ofp);

void out_of_memory(void) NO_RETURN;
void *xmalloc(size_t) MALLOC_LIKE;
void *xcalloc(size_t, size_t) MALLOC_LIKE;
void *xzalloc(size_t) MALLOC_LIKE;
void *xrealloc(void *, size_t);
void *xmemdup(const void *, size_t) MALLOC_LIKE;
char *xmemdup0(const char *, size_t) MALLOC_LIKE;
char *xstrdup(const char *) MALLOC_LIKE;
char *xasprintf(const char *format, ...) PRINTF_FORMAT(1, 2) MALLOC_LIKE;
char *xvasprintf(const char *format, va_list) PRINTF_FORMAT(1, 0) MALLOC_LIKE;
void *x2nrealloc(void *p, size_t *n, size_t s);

void ovs_strlcpy(char *dst, const char *src, size_t size);
void ovs_strzcpy(char *dst, const char *src, size_t size);

void ovs_abort(int err_no, const char *format, ...)
    PRINTF_FORMAT(2, 3) NO_RETURN;
void ovs_abort_valist(int err_no, const char *format, va_list)
    PRINTF_FORMAT(2, 0) NO_RETURN;
void ovs_fatal(int err_no, const char *format, ...)
    PRINTF_FORMAT(2, 3) NO_RETURN;
void ovs_fatal_valist(int err_no, const char *format, va_list)
    PRINTF_FORMAT(2, 0) NO_RETURN;
void ovs_error(int err_no, const char *format, ...) PRINTF_FORMAT(2, 3);
void ovs_error_valist(int err_no, const char *format, va_list)
    PRINTF_FORMAT(2, 0);
const char *ovs_retval_to_string(int);
const char *ovs_strerror(int);
void ovs_hex_dump(FILE *, const void *, size_t, uintptr_t offset, bool ascii);

bool str_to_int(const char *, int base, int *);
bool str_to_long(const char *, int base, long *);
bool str_to_llong(const char *, int base, long long *);
bool str_to_uint(const char *, int base, unsigned int *);
bool str_to_ulong(const char *, int base, unsigned long *);
bool str_to_ullong(const char *, int base, unsigned long long *);

bool str_to_double(const char *, double *);

int hexit_value(int c);
unsigned int hexits_value(const char *s, size_t n, bool *ok);

const char *english_list_delimiter(size_t index, size_t total);

char *get_cwd(void);
char *dir_name(const char *file_name);
char *base_name(const char *file_name);
char *abs_file_name(const char *dir, const char *file_name);

char *xreadlink(const char *filename);
char *follow_symlinks(const char *filename);

void ignore(bool x OVS_UNUSED);
\f
/* Bitwise tests. */

/* Returns the number of trailing 0-bits in 'n'.  Undefined if 'n' == 0.
 *
 * This compiles to a single machine instruction ("bsf") with GCC on x86. */
#if !defined(UINT_MAX) || !defined(UINT32_MAX)
#error "Someone screwed up the #includes."
#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
static inline int
raw_ctz(uint32_t n)
{
    return __builtin_ctz(n);
}
#else
/* Defined in util.c. */
int raw_ctz(uint32_t n);
#endif

/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
static inline int
ctz(uint32_t n)
{
    return n ? raw_ctz(n) : 32;
}

int log_2_floor(uint32_t);
int log_2_ceil(uint32_t);
unsigned int popcount(uint32_t);

/* Returns the rightmost 1-bit in 'x' (e.g. 01011000 => 00001000), or 0 if 'x'
 * is 0. */
static inline uintmax_t
rightmost_1bit(uintmax_t x)
{
    return x & -x;
}

/* Returns 'x' with its rightmost 1-bit changed to a zero (e.g. 01011000 =>
 * 01010000), or 0 if 'x' is 0. */
static inline uintmax_t
zero_rightmost_1bit(uintmax_t x)
{
    return x & (x - 1);
}

/* Returns the index of the rightmost 1-bit in 'x' (e.g. 01011000 => 3), or 32
 * if 'x' is 0.
 *
 * Unlike the other functions for rightmost 1-bits, this function only works
 * with 32-bit integers. */
static inline uint32_t
rightmost_1bit_idx(uint32_t x)
{
    return x ? ctz(x) : 32;
}

/* Returns the index of the rightmost 1-bit in 'x' (e.g. 01011000 => 6), or 32
 * if 'x' is 0.
 *
 * This function only works with 32-bit integers. */
static inline uint32_t
leftmost_1bit_idx(uint32_t x)
{
    return x ? log_2_floor(x) : 32;
}
\f
bool is_all_zeros(const uint8_t *, size_t);
bool is_all_ones(const uint8_t *, size_t);
void bitwise_copy(const void *src, unsigned int src_len, unsigned int src_ofs,
                  void *dst, unsigned int dst_len, unsigned int dst_ofs,
                  unsigned int n_bits);
void bitwise_zero(void *dst_, unsigned int dst_len, unsigned dst_ofs,
                  unsigned int n_bits);
void bitwise_one(void *dst_, unsigned int dst_len, unsigned dst_ofs,
                 unsigned int n_bits);
bool bitwise_is_all_zeros(const void *, unsigned int len, unsigned int ofs,
                          unsigned int n_bits);
void bitwise_put(uint64_t value,
                 void *dst, unsigned int dst_len, unsigned int dst_ofs,
                 unsigned int n_bits);
uint64_t bitwise_get(const void *src, unsigned int src_len,
                     unsigned int src_ofs, unsigned int n_bits);

#ifdef  __cplusplus
}
#endif

#endif /* util.h */