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761da83ddd
min() and max() from the Linux kernel go through the trouble of
resulting in a constant expression if the arguments are constant
expressions, but they can't be used outside of a function due to their
use of ({ }). This means that they can't be used for, e.g., enumerators
or global arrays. Let's simplify min() and max() and instead add
explicit min_iconst() and max_iconst() macros that can be used
everywhere that an integer constant expression is required. We can then
use it in hash_table.h. While we're here, let's split these into their
own header file and document them better.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
// Copyright (c) Facebook, Inc. and its affiliates.
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// SPDX-License-Identifier: GPL-3.0+
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/**
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* @file
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*
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* Miscellanous utility functions.
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*
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* Several of these are taken from the Linux kernel source.
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*/
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#ifndef DRGN_UTIL_H
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#define DRGN_UTIL_H
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#include <assert.h>
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#include <errno.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#ifndef LIBDRGN_PUBLIC
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#define LIBDRGN_PUBLIC __attribute__((visibility("default")))
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#endif
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#ifdef NDEBUG
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#define UNREACHABLE() __builtin_unreachable()
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#else
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#define UNREACHABLE() assert(!"reachable")
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#endif
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#define likely(x) __builtin_expect(!!(x), 1)
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#define unlikely(x) __builtin_expect(!!(x), 0)
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#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER)
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#define __compiletime_error(message) __attribute__((__error__(message)))
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#else
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#define __compiletime_error(message)
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#endif
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#ifdef __OPTIMIZE__
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# define __compiletime_assert(condition, msg, prefix, suffix) \
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do { \
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extern void prefix ## suffix(void) __compiletime_error(msg); \
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if (!(condition)) \
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prefix ## suffix(); \
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} while (0)
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#else
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# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
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#endif
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#define _compiletime_assert(condition, msg, prefix, suffix) \
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__compiletime_assert(condition, msg, prefix, suffix)
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#define compiletime_assert(condition, msg) \
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_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
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#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
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#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
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#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
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#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
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#define container_of(ptr, type, member) ({ \
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void *__mptr = (void *)(ptr); \
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BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
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!__same_type(*(ptr), void), \
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"pointer type mismatch in container_of()"); \
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((type *)(__mptr - offsetof(type, member))); })
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static inline bool strstartswith(const char *s, const char *prefix)
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{
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return strncmp(s, prefix, strlen(prefix)) == 0;
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}
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static inline void *malloc_array(size_t nmemb, size_t size)
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{
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size_t bytes;
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if (__builtin_mul_overflow(nmemb, size, &bytes)) {
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errno = ENOMEM;
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return NULL;
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}
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return malloc(bytes);
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}
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static inline void *malloc64(uint64_t size)
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{
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if (size > SIZE_MAX)
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return NULL;
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return malloc(size);
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}
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#endif /* DRGN_UTIL_H */
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