1 /* $NetBSD: cdefs.h,v 1.58 2004/12/11 05:59:00 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Berkeley Software Design, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)cdefs.h 8.8 (Berkeley) 1/9/95 35 */ 36 37 #ifndef _SYS_CDEFS_H_ 38 #define _SYS_CDEFS_H_ 39 40 /* 41 * Testing against Clang-specific extensions. 42 */ 43 #ifndef __has_extension 44 #define __has_extension __has_feature 45 #endif 46 #ifndef __has_feature 47 #define __has_feature(x) 0 48 #endif 49 #ifndef __has_include 50 #define __has_include(x) 0 51 #endif 52 #ifndef __has_builtin 53 #define __has_builtin(x) 0 54 #endif 55 #ifndef __has_attribute 56 #define __has_attribute(x) 0 57 #endif 58 59 #define __strong_alias(alias, sym) \ 60 __asm__(".global " #alias "\n" \ 61 #alias " = " #sym); 62 63 #if defined(__cplusplus) 64 #define __BEGIN_DECLS extern "C" { 65 #define __END_DECLS } 66 #else 67 #define __BEGIN_DECLS 68 #define __END_DECLS 69 #endif 70 71 #if defined(__cplusplus) 72 #define __BIONIC_CAST(_k,_t,_v) (_k<_t>(_v)) 73 #else 74 #define __BIONIC_CAST(_k,_t,_v) ((_t) (_v)) 75 #endif 76 77 /* 78 * The __CONCAT macro is used to concatenate parts of symbol names, e.g. 79 * with "#define OLD(foo) __CONCAT(old,foo)", OLD(foo) produces oldfoo. 80 * The __CONCAT macro is a bit tricky -- make sure you don't put spaces 81 * in between its arguments. __CONCAT can also concatenate double-quoted 82 * strings produced by the __STRING macro, but this only works with ANSI C. 83 */ 84 85 #define ___STRING(x) __STRING(x) 86 #define ___CONCAT(x,y) __CONCAT(x,y) 87 88 #if defined(__STDC__) || defined(__cplusplus) 89 #define __P(protos) protos /* full-blown ANSI C */ 90 #define __CONCAT(x,y) x ## y 91 #define __STRING(x) #x 92 93 #if defined(__cplusplus) 94 #define __inline inline /* convert to C++ keyword */ 95 #endif /* !__cplusplus */ 96 97 #else /* !(__STDC__ || __cplusplus) */ 98 #define __P(protos) () /* traditional C preprocessor */ 99 #define __CONCAT(x,y) x/**/y 100 #define __STRING(x) "x" 101 102 #endif /* !(__STDC__ || __cplusplus) */ 103 104 #define __always_inline __attribute__((__always_inline__)) 105 #define __attribute_const__ __attribute__((__const__)) 106 #define __attribute_pure__ __attribute__((__pure__)) 107 #define __dead __attribute__((__noreturn__)) 108 #define __noreturn __attribute__((__noreturn__)) 109 #define __mallocfunc __attribute__((__malloc__)) 110 #define __packed __attribute__((__packed__)) 111 #define __unused __attribute__((__unused__)) 112 #define __used __attribute__((__used__)) 113 114 /* 115 * _Nonnull is similar to the nonnull attribute in that it will instruct 116 * compilers to warn the user if it can prove that a null argument is being 117 * passed. Unlike the nonnull attribute, this annotation indicated that a value 118 * *should not* be null, not that it *cannot* be null, or even that the behavior 119 * is undefined. The important distinction is that the optimizer will perform 120 * surprising optimizations like the following: 121 * 122 * void foo(void*) __attribute__(nonnull, 1); 123 * 124 * int bar(int* p) { 125 * foo(p); 126 * 127 * // The following null check will be elided because nonnull attribute 128 * // means that, since we call foo with p, p can be assumed to not be 129 * // null. Thus this will crash if we are called with a null pointer. 130 * if (p != NULL) { 131 * return *p; 132 * } 133 * return 0; 134 * } 135 * 136 * int main() { 137 * return bar(NULL); 138 * } 139 * 140 * http://clang.llvm.org/docs/AttributeReference.html#nonnull 141 */ 142 #if !(defined(__clang__) && __has_feature(nullability)) 143 #define _Nonnull 144 #define _Nullable 145 #endif 146 147 #define __printflike(x, y) __attribute__((__format__(printf, x, y))) 148 #define __scanflike(x, y) __attribute__((__format__(scanf, x, y))) 149 150 /* 151 * GNU C version 2.96 added explicit branch prediction so that 152 * the CPU back-end can hint the processor and also so that 153 * code blocks can be reordered such that the predicted path 154 * sees a more linear flow, thus improving cache behavior, etc. 155 * 156 * The following two macros provide us with a way to use this 157 * compiler feature. Use __predict_true() if you expect the expression 158 * to evaluate to true, and __predict_false() if you expect the 159 * expression to evaluate to false. 160 * 161 * A few notes about usage: 162 * 163 * * Generally, __predict_false() error condition checks (unless 164 * you have some _strong_ reason to do otherwise, in which case 165 * document it), and/or __predict_true() `no-error' condition 166 * checks, assuming you want to optimize for the no-error case. 167 * 168 * * Other than that, if you don't know the likelihood of a test 169 * succeeding from empirical or other `hard' evidence, don't 170 * make predictions. 171 * 172 * * These are meant to be used in places that are run `a lot'. 173 * It is wasteful to make predictions in code that is run 174 * seldomly (e.g. at subsystem initialization time) as the 175 * basic block reordering that this affects can often generate 176 * larger code. 177 */ 178 #define __predict_true(exp) __builtin_expect((exp) != 0, 1) 179 #define __predict_false(exp) __builtin_expect((exp) != 0, 0) 180 181 #define __wur __attribute__((__warn_unused_result__)) 182 183 #ifdef __clang__ 184 # define __errorattr(msg) __attribute__((unavailable(msg))) 185 # define __warnattr(msg) __attribute__((deprecated(msg))) 186 # define __warnattr_real(msg) __attribute__((deprecated(msg))) 187 # define __enable_if(cond, msg) __attribute__((enable_if(cond, msg))) 188 #else 189 # define __errorattr(msg) __attribute__((__error__(msg))) 190 # define __warnattr(msg) __attribute__((__warning__(msg))) 191 # define __warnattr_real __warnattr 192 /* enable_if doesn't exist on other compilers; give an error if it's used. */ 193 194 /* errordecls really don't work as well in clang as they do in GCC. */ 195 # define __errordecl(name, msg) extern void name(void) __errorattr(msg) 196 #endif 197 198 #if defined(ANDROID_STRICT) 199 /* 200 * For things that are sketchy, but not necessarily an error. FIXME: Enable 201 * this. 202 */ 203 # define __warnattr_strict(msg) /* __warnattr(msg) */ 204 #else 205 # define __warnattr_strict(msg) 206 #endif 207 208 /* 209 * Some BSD source needs these macros. 210 * Originally they embedded the rcs versions of each source file 211 * in the generated binary. We strip strings during build anyway,. 212 */ 213 #define __IDSTRING(_prefix,_s) /* nothing */ 214 #define __COPYRIGHT(_s) /* nothing */ 215 #define __FBSDID(_s) /* nothing */ 216 #define __RCSID(_s) /* nothing */ 217 #define __SCCSID(_s) /* nothing */ 218 219 /* 220 * With bionic, you always get all C and POSIX API. 221 * 222 * If you want BSD and/or GNU extensions, _BSD_SOURCE and/or _GNU_SOURCE are 223 * expected to be defined by callers before *any* standard header file is 224 * included. 225 * 226 * In our header files we test against __USE_BSD and __USE_GNU. 227 */ 228 #if defined(_GNU_SOURCE) 229 # define __USE_BSD 1 230 # define __USE_GNU 1 231 #endif 232 233 #if defined(_BSD_SOURCE) 234 # define __USE_BSD 1 235 #endif 236 237 /* _FILE_OFFSET_BITS 64 support. */ 238 #if !defined(__LP64__) && defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64 239 #define __USE_FILE_OFFSET64 1 240 #define __RENAME_IF_FILE_OFFSET64(func) __RENAME(func) 241 #else 242 #define __RENAME_IF_FILE_OFFSET64(func) 243 #endif 244 245 #define __BIONIC__ 1 246 #include <android/api-level.h> 247 248 /* glibc compatibility. */ 249 #if defined(__LP64__) 250 #define __WORDSIZE 64 251 #else 252 #define __WORDSIZE 32 253 #endif 254 255 /* 256 * When _FORTIFY_SOURCE is defined, automatic bounds checking is 257 * added to commonly used libc functions. If a buffer overrun is 258 * detected, the program is safely aborted. 259 * 260 * https://android-developers.googleblog.com/2017/04/fortify-in-android.html 261 */ 262 263 #define __BIONIC_FORTIFY_UNKNOWN_SIZE ((size_t) -1) 264 265 #if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && defined(__OPTIMIZE__) && __OPTIMIZE__ > 0 266 # define __BIONIC_FORTIFY 1 267 # if _FORTIFY_SOURCE == 2 268 # define __bos_level 1 269 # else 270 # define __bos_level 0 271 # endif 272 # define __bosn(s, n) __builtin_object_size((s), (n)) 273 # define __bos(s) __bosn((s), __bos_level) 274 # define __bos0(s) __bosn((s), 0) 275 # if defined(__clang__) 276 # define __pass_object_size_n(n) __attribute__((pass_object_size(n))) 277 /* 278 * FORTIFY'ed functions all have either enable_if or pass_object_size, which 279 * makes taking their address impossible. Saying (&read)(foo, bar, baz); will 280 * therefore call the unFORTIFYed version of read. 281 */ 282 # define __call_bypassing_fortify(fn) (&fn) 283 /* 284 * Because clang-FORTIFY uses overloads, we can't mark functions as `extern 285 * inline` without making them available externally. 286 */ 287 # define __BIONIC_FORTIFY_INLINE static __inline__ __always_inline 288 /* Error functions don't have bodies, so they can just be static. */ 289 # define __BIONIC_ERROR_FUNCTION_VISIBILITY static 290 # else 291 /* 292 * Where they can, GCC and clang-style FORTIFY share implementations. 293 * So, make these nops in GCC. 294 */ 295 # define __pass_object_size_n(n) 296 # define __call_bypassing_fortify(fn) (fn) 297 /* __BIONIC_FORTIFY_NONSTATIC_INLINE is pointless in GCC's FORTIFY */ 298 # define __BIONIC_FORTIFY_INLINE extern __inline__ __always_inline __attribute__((gnu_inline)) __attribute__((__artificial__)) 299 # endif 300 #else 301 /* Further increase sharing for some inline functions */ 302 # define __pass_object_size_n(n) 303 #endif 304 #define __pass_object_size __pass_object_size_n(__bos_level) 305 #define __pass_object_size0 __pass_object_size_n(0) 306 307 /* 308 * Used to support clangisms with FORTIFY. Because these change how symbols are 309 * emitted, we need to ensure that bionic itself is built fortified. But lots 310 * of external code (especially stuff using configure) likes to declare 311 * functions directly, and they can't know that the overloadable attribute 312 * exists. This leads to errors like: 313 * 314 * dcigettext.c:151:7: error: redeclaration of 'getcwd' must have the 'overloadable' attribute 315 * char *getcwd (); 316 * ^ 317 * 318 * To avoid this and keep such software building, don't use overloadable if 319 * we're not using fortify. 320 */ 321 #if defined(__clang__) && defined(__BIONIC_FORTIFY) 322 # define __overloadable __attribute__((overloadable)) 323 /* We don't use __RENAME directly because on gcc this could result in unnecessary renames. */ 324 # define __RENAME_CLANG(x) __RENAME(x) 325 #else 326 # define __overloadable 327 # define __RENAME_CLANG(x) 328 #endif 329 330 /* Used to tag non-static symbols that are private and never exposed by the shared library. */ 331 #define __LIBC_HIDDEN__ __attribute__((visibility("hidden"))) 332 333 /* 334 * Used to tag symbols that should be hidden for 64-bit, 335 * but visible to preserve binary compatibility for LP32. 336 */ 337 #ifdef __LP64__ 338 #define __LIBC32_LEGACY_PUBLIC__ __attribute__((visibility("hidden"))) 339 #else 340 #define __LIBC32_LEGACY_PUBLIC__ __attribute__((visibility("default"))) 341 #endif 342 343 /* Used to rename functions so that the compiler emits a call to 'x' rather than the function this was applied to. */ 344 #define __RENAME(x) __asm__(#x) 345 346 #include <android/versioning.h> 347 348 #if __has_builtin(__builtin_umul_overflow) || __GNUC__ >= 5 349 #if defined(__LP64__) 350 #define __size_mul_overflow(a, b, result) __builtin_umull_overflow(a, b, result) 351 #else 352 #define __size_mul_overflow(a, b, result) __builtin_umul_overflow(a, b, result) 353 #endif 354 #else 355 extern __inline__ __always_inline __attribute__((gnu_inline)) 356 int __size_mul_overflow(__SIZE_TYPE__ a, __SIZE_TYPE__ b, __SIZE_TYPE__ *result) { 357 *result = a * b; 358 static const __SIZE_TYPE__ mul_no_overflow = 1UL << (sizeof(__SIZE_TYPE__) * 4); 359 return (a >= mul_no_overflow || b >= mul_no_overflow) && a > 0 && (__SIZE_TYPE__)-1 / a < b; 360 } 361 #endif 362 363 #if defined(__clang__) 364 /* 365 * Used when we need to check for overflow when multiplying x and y. This 366 * should only be used where __size_mul_overflow can not work, because it makes 367 * assumptions that __size_mul_overflow doesn't (x and y are positive, ...), 368 * *and* doesn't make use of compiler intrinsics, so it's probably slower than 369 * __size_mul_overflow. 370 */ 371 #define __unsafe_check_mul_overflow(x, y) ((__SIZE_TYPE__)-1 / (x) < (y)) 372 #endif 373 374 #endif /* !_SYS_CDEFS_H_ */ 375
