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- /* Copyright (c) 2003-2004, Roger Dingledine
- * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file compat_compiler.h
- * \brief Utility macros to handle different features and behavior in different
- * compilers.
- **/
- #ifndef TOR_COMPAT_COMPILER_H
- #define TOR_COMPAT_COMPILER_H
- #include "orconfig.h"
- #include <inttypes.h>
- #if defined(__has_feature)
- # if __has_feature(address_sanitizer)
- /* Some of the fancy glibc strcmp() macros include references to memory that
- * clang rejects because it is off the end of a less-than-3. Clang hates this,
- * even though those references never actually happen. */
- # undef strcmp
- #endif /* __has_feature(address_sanitizer) */
- #endif /* defined(__has_feature) */
- #ifndef NULL_REP_IS_ZERO_BYTES
- #error "It seems your platform does not represent NULL as zero. We can't cope."
- #endif
- #ifndef DOUBLE_0_REP_IS_ZERO_BYTES
- #error "It seems your platform does not represent 0.0 as zeros. We can't cope."
- #endif
- #if 'a'!=97 || 'z'!=122 || 'A'!=65 || ' '!=32
- #error "It seems that you encode characters in something other than ASCII."
- #endif
- /* GCC can check printf and scanf types on arbitrary functions. */
- #ifdef __GNUC__
- #define CHECK_PRINTF(formatIdx, firstArg) \
- __attribute__ ((format(printf, formatIdx, firstArg)))
- #else
- #define CHECK_PRINTF(formatIdx, firstArg)
- #endif /* defined(__GNUC__) */
- #ifdef __GNUC__
- #define CHECK_SCANF(formatIdx, firstArg) \
- __attribute__ ((format(scanf, formatIdx, firstArg)))
- #else
- #define CHECK_SCANF(formatIdx, firstArg)
- #endif /* defined(__GNUC__) */
- /* What GCC do we have? */
- #ifdef __GNUC__
- #define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
- #else
- #define GCC_VERSION 0
- #endif
- /* Temporarily enable and disable warnings. */
- #ifdef __GNUC__
- # define PRAGMA_STRINGIFY_(s) #s
- # define PRAGMA_JOIN_STRINGIFY_(a,b) PRAGMA_STRINGIFY_(a ## b)
- /* Support for macro-generated pragmas (c99) */
- # define PRAGMA_(x) _Pragma (#x)
- # ifdef __clang__
- # define PRAGMA_DIAGNOSTIC_(x) PRAGMA_(clang diagnostic x)
- # else
- # define PRAGMA_DIAGNOSTIC_(x) PRAGMA_(GCC diagnostic x)
- # endif
- # if defined(__clang__) || GCC_VERSION >= 406
- /* we have push/pop support */
- # define DISABLE_GCC_WARNING(warningopt) \
- PRAGMA_DIAGNOSTIC_(push) \
- PRAGMA_DIAGNOSTIC_(ignored PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
- # define ENABLE_GCC_WARNING(warningopt) \
- PRAGMA_DIAGNOSTIC_(pop)
- #else /* !(defined(__clang__) || GCC_VERSION >= 406) */
- /* older version of gcc: no push/pop support. */
- # define DISABLE_GCC_WARNING(warningopt) \
- PRAGMA_DIAGNOSTIC_(ignored PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
- # define ENABLE_GCC_WARNING(warningopt) \
- PRAGMA_DIAGNOSTIC_(warning PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
- #endif /* defined(__clang__) || GCC_VERSION >= 406 */
- #else /* !(defined(__GNUC__)) */
- /* not gcc at all */
- # define DISABLE_GCC_WARNING(warning)
- # define ENABLE_GCC_WARNING(warning)
- #endif /* defined(__GNUC__) */
- /* inline is __inline on windows. */
- #ifdef _WIN32
- #define inline __inline
- #endif
- /* Try to get a reasonable __func__ substitute in place. */
- #if defined(_MSC_VER)
- #define __func__ __FUNCTION__
- #else
- /* For platforms where autoconf works, make sure __func__ is defined
- * sanely. */
- #ifndef HAVE_MACRO__func__
- #ifdef HAVE_MACRO__FUNCTION__
- #define __func__ __FUNCTION__
- #elif HAVE_MACRO__FUNC__
- #define __func__ __FUNC__
- #else
- #define __func__ "???"
- #endif /* defined(HAVE_MACRO__FUNCTION__) || ... */
- #endif /* !defined(HAVE_MACRO__func__) */
- #endif /* defined(_MSC_VER) */
- #ifdef ENUM_VALS_ARE_SIGNED
- #define ENUM_BF(t) unsigned
- #else
- /** Wrapper for having a bitfield of an enumerated type. Where possible, we
- * just use the enumerated type (so the compiler can help us and notice
- * problems), but if enumerated types are unsigned, we must use unsigned,
- * so that the loss of precision doesn't make large values negative. */
- #define ENUM_BF(t) t
- #endif /* defined(ENUM_VALS_ARE_SIGNED) */
- /* GCC has several useful attributes. */
- #if defined(__GNUC__) && __GNUC__ >= 3
- #define ATTR_NORETURN __attribute__((noreturn))
- #define ATTR_CONST __attribute__((const))
- #define ATTR_MALLOC __attribute__((malloc))
- #define ATTR_NORETURN __attribute__((noreturn))
- #define ATTR_WUR __attribute__((warn_unused_result))
- #define ATTR_UNUSED __attribute__ ((unused))
- /** Macro: Evaluates to <b>exp</b> and hints the compiler that the value
- * of <b>exp</b> will probably be true.
- *
- * In other words, "if (PREDICT_LIKELY(foo))" is the same as "if (foo)",
- * except that it tells the compiler that the branch will be taken most of the
- * time. This can generate slightly better code with some CPUs.
- */
- #define PREDICT_LIKELY(exp) __builtin_expect(!!(exp), 1)
- /** Macro: Evaluates to <b>exp</b> and hints the compiler that the value
- * of <b>exp</b> will probably be false.
- *
- * In other words, "if (PREDICT_UNLIKELY(foo))" is the same as "if (foo)",
- * except that it tells the compiler that the branch will usually not be
- * taken. This can generate slightly better code with some CPUs.
- */
- #define PREDICT_UNLIKELY(exp) __builtin_expect(!!(exp), 0)
- #else /* !(defined(__GNUC__) && __GNUC__ >= 3) */
- #define ATTR_NORETURN
- #define ATTR_CONST
- #define ATTR_MALLOC
- #define ATTR_NORETURN
- #define ATTR_UNUSED
- #define ATTR_WUR
- #define PREDICT_LIKELY(exp) (exp)
- #define PREDICT_UNLIKELY(exp) (exp)
- #endif /* defined(__GNUC__) && __GNUC__ >= 3 */
- /** Expands to a syntactically valid empty statement. */
- #define STMT_NIL (void)0
- /** Expands to a syntactically valid empty statement, explicitly (void)ing its
- * argument. */
- #define STMT_VOID(a) while (0) { (void)(a); }
- #ifdef __GNUC__
- /** STMT_BEGIN and STMT_END are used to wrap blocks inside macros so that
- * the macro can be used as if it were a single C statement. */
- #define STMT_BEGIN (void) ({
- #define STMT_END })
- #elif defined(sun) || defined(__sun__)
- #define STMT_BEGIN if (1) {
- #define STMT_END } else STMT_NIL
- #else
- #define STMT_BEGIN do {
- #define STMT_END } while (0)
- #endif /* defined(__GNUC__) || ... */
- /* Some tools (like coccinelle) don't like to see operators as macro
- * arguments. */
- #define OP_LT <
- #define OP_GT >
- #define OP_GE >=
- #define OP_LE <=
- #define OP_EQ ==
- #define OP_NE !=
- #if defined(__MINGW32__) || defined(__MINGW64__)
- #define MINGW_ANY
- #endif
- /** Macro: yield a pointer to the field at position <b>off</b> within the
- * structure <b>st</b>. Example:
- * <pre>
- * struct a { int foo; int bar; } x;
- * off_t bar_offset = offsetof(struct a, bar);
- * int *bar_p = STRUCT_VAR_P(&x, bar_offset);
- * *bar_p = 3;
- * </pre>
- */
- #define STRUCT_VAR_P(st, off) ((void*) ( ((char*)(st)) + (off) ) )
- /** Macro: yield a pointer to an enclosing structure given a pointer to
- * a substructure at offset <b>off</b>. Example:
- * <pre>
- * struct base { ... };
- * struct subtype { int x; struct base b; } x;
- * struct base *bp = &x.base;
- * struct *sp = SUBTYPE_P(bp, struct subtype, b);
- * </pre>
- */
- #define SUBTYPE_P(p, subtype, basemember) \
- ((void*) ( ((char*)(p)) - offsetof(subtype, basemember) ))
- /** Macro: Yields the number of elements in array x. */
- #define ARRAY_LENGTH(x) ((sizeof(x)) / sizeof(x[0]))
- /**
- * "Eat" a semicolon that somebody puts at the end of a top-level macro.
- *
- * Frequently, we want to declare a macro that people will use at file scope,
- * and we want to allow people to put a semicolon after the macro.
- *
- * This declaration of a struct can be repeated any number of times, and takes
- * a trailing semicolon afterwards.
- **/
- #define EAT_SEMICOLON \
- struct dummy_semicolon_eater__
- #endif /* !defined(TOR_COMPAT_H) */
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