nostril/compiler.h
William Casarin 009af9ed5b initial commit
Signed-off-by: William Casarin <jb55@jb55.com>
2022-04-14 07:52:29 -07:00

86 lines
2.3 KiB
C

#ifndef COMPILER_H
#define COMPILER_H
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#if HAVE_UNALIGNED_ACCESS
#define alignment_ok(p, n) 1
#else
#define alignment_ok(p, n) ((size_t)(p) % (n) == 0)
#endif
#define UNUSED __attribute__((__unused__))
/**
* BUILD_ASSERT - assert a build-time dependency.
* @cond: the compile-time condition which must be true.
*
* Your compile will fail if the condition isn't true, or can't be evaluated
* by the compiler. This can only be used within a function.
*
* Example:
* #include <stddef.h>
* ...
* static char *foo_to_char(struct foo *foo)
* {
* // This code needs string to be at start of foo.
* BUILD_ASSERT(offsetof(struct foo, string) == 0);
* return (char *)foo;
* }
*/
#define BUILD_ASSERT(cond) \
do { (void) sizeof(char [1 - 2*!(cond)]); } while(0)
/**
* BUILD_ASSERT_OR_ZERO - assert a build-time dependency, as an expression.
* @cond: the compile-time condition which must be true.
*
* Your compile will fail if the condition isn't true, or can't be evaluated
* by the compiler. This can be used in an expression: its value is "0".
*
* Example:
* #define foo_to_char(foo) \
* ((char *)(foo) \
* + BUILD_ASSERT_OR_ZERO(offsetof(struct foo, string) == 0))
*/
#define BUILD_ASSERT_OR_ZERO(cond) \
(sizeof(char [1 - 2*!(cond)]) - 1)
#define memclear(mem, size) memset(mem, 0, size)
#define memclear_2(m1, s1, m2, s2) { memclear(m1, s1); memclear(m2, s2); }
#define memclear_3(m1, s1, m2, s2, m3, s3) { memclear(m1, s1); memclear(m2, s2); memclear(m3, s3); }
static inline void *memcheck_(const void *data, size_t len)
{
(void)len;
return (void *)data;
}
#if HAVE_TYPEOF
/**
* memcheck - check that a memory region is initialized
* @data: start of region
* @len: length in bytes
*
* When running under valgrind, this causes an error to be printed
* if the entire region is not defined. Otherwise valgrind only
* reports an error when an undefined value is used for a branch, or
* written out.
*
* Example:
* // Search for space, but make sure it's all initialized.
* if (memchr(memcheck(somebytes, bytes_len), ' ', bytes_len)) {
* printf("space was found!\n");
* }
*/
#define memcheck(data, len) ((__typeof__((data)+0))memcheck_((data), (len)))
#else
#define memcheck(data, len) memcheck_((data), (len))
#endif
#endif /* COMPILER_H */