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https://github.com/wolfpld/tracy.git
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ebf5ebd9bd
The old pre-flight truncated the output at startup with -f, so an interrupted capture lost the trace, and the probe fopen followed a symlink. The existing file is now moved to FILE~ for the duration of the capture and restored if the trace cannot be written.
93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
#include <cstdio>
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#include <cstdlib>
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#include <filesystem>
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#include <system_error>
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#include "CaptureFileBackup.hpp"
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namespace tracy
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{
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static std::filesystem::path s_backupPath, s_backupOf;
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static char s_errorBuf[512];
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OutputPrep PrepareOutputFile( const char* path, bool overwrite, const char** error )
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{
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std::error_code ec;
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const std::filesystem::path out( path );
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const auto st = std::filesystem::symlink_status( out, ec );
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const bool absent = st.type() == std::filesystem::file_type::not_found ||
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ec == std::errc::no_such_file_or_directory;
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if( ec && !absent )
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{
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snprintf( s_errorBuf, sizeof( s_errorBuf ), "cannot access output path %s: %s", path, ec.message().c_str() );
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*error = s_errorBuf;
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return OutputPrep::Unusable;
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}
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ec.clear();
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const bool exists = !absent;
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if( exists && !std::filesystem::is_regular_file( st ) )
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{
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snprintf( s_errorBuf, sizeof( s_errorBuf ), "output path %s exists and is not a regular file", path );
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*error = s_errorBuf;
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return OutputPrep::Unusable;
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}
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if( exists && !overwrite )
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{
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*error = nullptr;
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return OutputPrep::Exists;
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}
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FILE* probe = fopen( path, "ab" );
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if( !probe )
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{
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snprintf( s_errorBuf, sizeof( s_errorBuf ), "cannot open output file %s for writing", path );
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*error = s_errorBuf;
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return OutputPrep::Unusable;
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}
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fclose( probe );
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if( exists )
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{
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auto backup = out;
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backup += "~";
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std::filesystem::rename( out, backup, ec );
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if( ec )
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{
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snprintf( s_errorBuf, sizeof( s_errorBuf ), "cannot move existing %s out of the way: %s", path, ec.message().c_str() );
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*error = s_errorBuf;
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return OutputPrep::Unusable;
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}
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s_backupOf = out;
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s_backupPath = backup;
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atexit( RestoreOutputBackup );
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}
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else
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{
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std::filesystem::remove( out, ec );
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}
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*error = nullptr;
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return OutputPrep::Ok;
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}
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void RestoreOutputBackup()
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{
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if( s_backupOf.empty() ) return;
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std::error_code ec;
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std::filesystem::rename( s_backupPath, s_backupOf, ec );
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if( ec ) fprintf( stderr, "Could not restore %s from %s: %s\n", s_backupOf.string().c_str(), s_backupPath.string().c_str(), ec.message().c_str() );
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s_backupOf.clear();
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}
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void DiscardOutputBackup()
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{
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if( s_backupOf.empty() ) return;
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std::error_code ec;
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std::filesystem::remove( s_backupPath, ec );
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s_backupOf.clear();
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}
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}
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