mirror of
https://github.com/JakeHillion/drgn.git
synced 2024-12-23 09:43:06 +00:00
d1745755f1
Also:
* Rename struct string to struct nstring and move it to its own header.
* Fix scripts/iwyu.py, which was broken by commit 5541fad063 ("Fix
some flake8 errors").
* Add workarounds for a few outstanding include-what-you-use issues.
There is still a false positive for
include-what-you-use/include-what-you-use#970, but hopefully that is
fixed soon.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
149 lines
4.1 KiB
C
149 lines
4.1 KiB
C
// Copyright (c) Facebook, Inc. and its affiliates.
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// SPDX-License-Identifier: GPL-3.0-or-later
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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 HOST_LITTLE_ENDIAN (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
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/**
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* Switch statement with an enum controlling expression that must have a case
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* for every enumeration value and a default case.
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*/
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#define SWITCH_ENUM_DEFAULT(expr, ...) { \
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_Pragma("GCC diagnostic push"); \
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_Pragma("GCC diagnostic error \"-Wswitch-enum\""); \
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_Pragma("GCC diagnostic error \"-Wswitch-default\""); \
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switch (expr) { \
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__VA_ARGS__ \
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} \
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_Pragma("GCC diagnostic pop"); \
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}
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/**
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* Switch statement with an enum controlling expression that must have a case
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* for every enumeration value. The expression is assumed to have a valid
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* enumeration value. Cases which are assumed not to be possible can be placed
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* at the end of the statement.
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*/
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#define SWITCH_ENUM(expr, ...) \
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SWITCH_ENUM_DEFAULT(expr, \
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__VA_ARGS__ \
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default: UNREACHABLE(); \
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)
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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 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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static inline void *memdup(void *ptr, size_t size)
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{
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void *copy = malloc(size);
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if (copy)
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memcpy(copy, ptr, size);
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return copy;
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}
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/** Return the maximum value of an @p n-byte unsigned integer. */
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static inline uint64_t uint_max(int n)
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{
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assert(n >= 1 && n <= 8);
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return UINT64_MAX >> (64 - 8 * n);
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}
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/**
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* Safely add to a pointer which may be `NULL`.
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*
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* `NULL + 0` is undefined behavior, but it often arises naturally, like when
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* computing the end of a dynamic array: `arr + length`. This works around the
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* undefined behavior: `add_to_possibly_null_pointer(NULL, 0)` is defined as
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* `NULL`.
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*
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* A more natural definition would be `i == 0 ? ptr : ptr + i`, but some
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* versions of GCC and Clang generate an unnecessary branch or conditional move
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* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97225).
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*/
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#define add_to_possibly_null_pointer(ptr, i) \
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((typeof(ptr))((uintptr_t)(ptr) + (i) * sizeof(*(ptr))))
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#endif /* DRGN_UTIL_H */
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