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Merge topic 'fix-atomic-rename-on-Windows'

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59b568e Fix cmSystemTools::RenameFile race on Windows
This commit is contained in:
Brad King 2013-02-05 14:46:27 -05:00 committed by CMake Topic Stage
commit 9ff34ff2fd
1 changed files with 20 additions and 31 deletions
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53
Source/cmSystemTools.cxx
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@ -1180,46 +1180,35 @@ bool cmSystemTools::CopyFileIfDifferent(const char* source,
bool cmSystemTools::RenameFile(const char* oldname, const char* newname) bool cmSystemTools::RenameFile(const char* oldname, const char* newname)
{ {
#ifdef _WIN32 #ifdef _WIN32
/* On Windows the move functions will not replace existing files. # ifndef INVALID_FILE_ATTRIBUTES
Check if the destination exists. */ # define INVALID_FILE_ATTRIBUTES ((DWORD)-1)
struct stat newFile; # endif
if(stat(newname, &newFile) == 0) /* Windows MoveFileEx may not replace read-only or in-use files. If it
fails then remove the read-only attribute from any existing destination.
Try multiple times since we may be racing against another process
creating/opening the destination file just before our MoveFileEx. */
int tries = 5;
while(!MoveFileEx(oldname, newname, MOVEFILE_REPLACE_EXISTING) && --tries)
{ {
/* The destination exists. We have to replace it carefully. The // Try again only if failure was due to access permissions.
MoveFileEx function does what we need but is not available on if(GetLastError() != ERROR_ACCESS_DENIED)
Win9x. */
OSVERSIONINFO osv;
DWORD attrs;
/* Make sure the destination is not read only. */
attrs = GetFileAttributes(newname);
if(attrs & FILE_ATTRIBUTE_READONLY)
{ {
return false;
}
DWORD attrs = GetFileAttributes(newname);
if((attrs != INVALID_FILE_ATTRIBUTES) &&
(attrs & FILE_ATTRIBUTE_READONLY))
{
// Remove the read-only attribute from the destination file.
SetFileAttributes(newname, attrs & ~FILE_ATTRIBUTE_READONLY); SetFileAttributes(newname, attrs & ~FILE_ATTRIBUTE_READONLY);
} }
/* Check the windows version number. */
osv.dwOSVersionInfoSize = sizeof(osv);
GetVersionEx(&osv);
if(osv.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS)
{
/* This is Win9x. There is no MoveFileEx implementation. We
cannot quite rename the file atomically. Just delete the
destination and then move the file. */
DeleteFile(newname);
return MoveFile(oldname, newname) != 0;
}
else else
{ {
/* This is not Win9x. Use the MoveFileEx implementation. */ // The file may be temporarily in use so wait a bit.
return MoveFileEx(oldname, newname, MOVEFILE_REPLACE_EXISTING) != 0; cmSystemTools::Delay(100);
} }
} }
else return tries > 0;
{
/* The destination does not exist. Just move the file. */
return MoveFile(oldname, newname) != 0;
}
#else #else
/* On UNIX we have an OS-provided call to do this atomically. */ /* On UNIX we have an OS-provided call to do this atomically. */
return rename(oldname, newname) == 0; return rename(oldname, newname) == 0;