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GCC 3.4 introduced an attribute warn_unused_result to warn when a programmer discards the return value. Applying this judiciously across the codebase can help in fixing a lot of problems. At a high level, functions which return error codes should always be checked. More concretely, consider the functions ff_add_format and the like in avfilter/formats.h. A quick examination shows that a large portion of libavfilter fails to handle the associated errors, usually AVERROR(ENOMEM). The above example was where I observed the utility of this, but it should be useful in many places across the code base. Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
169 lines
4.4 KiB
C
169 lines
4.4 KiB
C
/*
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* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Macro definitions for various function/variable attributes
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*/
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#ifndef AVUTIL_ATTRIBUTES_H
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#define AVUTIL_ATTRIBUTES_H
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#ifdef __GNUC__
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# define AV_GCC_VERSION_AT_LEAST(x,y) (__GNUC__ > (x) || __GNUC__ == (x) && __GNUC_MINOR__ >= (y))
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# define AV_GCC_VERSION_AT_MOST(x,y) (__GNUC__ < (x) || __GNUC__ == (x) && __GNUC_MINOR__ <= (y))
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#else
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# define AV_GCC_VERSION_AT_LEAST(x,y) 0
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# define AV_GCC_VERSION_AT_MOST(x,y) 0
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#endif
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#ifndef av_always_inline
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#if AV_GCC_VERSION_AT_LEAST(3,1)
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# define av_always_inline __attribute__((always_inline)) inline
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#elif defined(_MSC_VER)
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# define av_always_inline __forceinline
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#else
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# define av_always_inline inline
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#endif
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#endif
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#ifndef av_extern_inline
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#if defined(__ICL) && __ICL >= 1210 || defined(__GNUC_STDC_INLINE__)
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# define av_extern_inline extern inline
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#else
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# define av_extern_inline inline
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#endif
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#endif
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#if AV_GCC_VERSION_AT_LEAST(3,4)
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# define av_warn_unused_result __attribute__((warn_unused_result))
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#else
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# define av_warn_unused_result
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#endif
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#if AV_GCC_VERSION_AT_LEAST(3,1)
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# define av_noinline __attribute__((noinline))
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#elif defined(_MSC_VER)
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# define av_noinline __declspec(noinline)
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#else
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# define av_noinline
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#endif
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#if AV_GCC_VERSION_AT_LEAST(3,1)
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# define av_pure __attribute__((pure))
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#else
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# define av_pure
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#endif
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#if AV_GCC_VERSION_AT_LEAST(2,6)
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# define av_const __attribute__((const))
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#else
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# define av_const
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#endif
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#if AV_GCC_VERSION_AT_LEAST(4,3)
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# define av_cold __attribute__((cold))
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#else
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# define av_cold
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#endif
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#if AV_GCC_VERSION_AT_LEAST(4,1) && !defined(__llvm__)
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# define av_flatten __attribute__((flatten))
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#else
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# define av_flatten
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#endif
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#if AV_GCC_VERSION_AT_LEAST(3,1)
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# define attribute_deprecated __attribute__((deprecated))
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#elif defined(_MSC_VER)
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# define attribute_deprecated __declspec(deprecated)
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#else
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# define attribute_deprecated
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#endif
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/**
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* Disable warnings about deprecated features
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* This is useful for sections of code kept for backward compatibility and
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* scheduled for removal.
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*/
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#ifndef AV_NOWARN_DEPRECATED
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#if AV_GCC_VERSION_AT_LEAST(4,6)
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# define AV_NOWARN_DEPRECATED(code) \
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_Pragma("GCC diagnostic push") \
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_Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") \
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code \
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_Pragma("GCC diagnostic pop")
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#elif defined(_MSC_VER)
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# define AV_NOWARN_DEPRECATED(code) \
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__pragma(warning(push)) \
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__pragma(warning(disable : 4996)) \
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code; \
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__pragma(warning(pop))
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#else
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# define AV_NOWARN_DEPRECATED(code) code
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#endif
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#endif
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#if defined(__GNUC__)
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# define av_unused __attribute__((unused))
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#else
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# define av_unused
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#endif
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/**
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* Mark a variable as used and prevent the compiler from optimizing it
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* away. This is useful for variables accessed only from inline
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* assembler without the compiler being aware.
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*/
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#if AV_GCC_VERSION_AT_LEAST(3,1)
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# define av_used __attribute__((used))
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#else
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# define av_used
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#endif
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#if AV_GCC_VERSION_AT_LEAST(3,3)
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# define av_alias __attribute__((may_alias))
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#else
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# define av_alias
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#endif
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER) && !defined(__clang__)
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# define av_uninit(x) x=x
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#else
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# define av_uninit(x) x
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#endif
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#ifdef __GNUC__
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# define av_builtin_constant_p __builtin_constant_p
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# define av_printf_format(fmtpos, attrpos) __attribute__((__format__(__printf__, fmtpos, attrpos)))
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#else
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# define av_builtin_constant_p(x) 0
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# define av_printf_format(fmtpos, attrpos)
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#endif
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#if AV_GCC_VERSION_AT_LEAST(2,5)
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# define av_noreturn __attribute__((noreturn))
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#else
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# define av_noreturn
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#endif
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#endif /* AVUTIL_ATTRIBUTES_H */
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