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QFileSystemEngineUnix: Don't stat before retrieving working path.

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This is entirely unnecessary. If the path is bad, then getcwd and friends will
fail. Doing an extra stat imposes an extra performance overhead without reason.

Trivia: A dive into Qt's history shows that the stat dates back to:
  Sat Aug 12 14:24:36 1995 +0100
The original purpose of the stat was to avoid calling getcwd unless the path had
actually changed. Subsequently, the caching was removed, but the stat remained.

Change-Id: Ia4598dc74ded36516b3e10e7ab0eb5a6a5690466
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Robin Burchell 2014-12-08 03:00:04 -08:00
parent 015002fec9
commit 99e69dce78
1 changed files with 21 additions and 28 deletions
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49
src/corelib/io/qfilesystemengine_unix.cpp
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@ -723,36 +723,29 @@ bool QFileSystemEngine::setCurrentPath(const QFileSystemEntry &path)
QFileSystemEntry QFileSystemEngine::currentPath()
{
QFileSystemEntry result;
QT_STATBUF st;
if (QT_STAT(".", &st) == 0) {
#if defined(__GLIBC__) && !defined(PATH_MAX)
char *currentName = ::get_current_dir_name();
if (currentName) {
result = QFileSystemEntry(QByteArray(currentName), QFileSystemEntry::FromNativePath());
::free(currentName);
}
#else
char currentName[PATH_MAX+1];
if (::getcwd(currentName, PATH_MAX)) {
#if defined(Q_OS_VXWORKS) && defined(VXWORKS_VXSIM)
QByteArray dir(currentName);
if (dir.indexOf(':') < dir.indexOf('/'))
dir.remove(0, dir.indexOf(':')+1);
qstrncpy(currentName, dir.constData(), PATH_MAX);
#endif
result = QFileSystemEntry(QByteArray(currentName), QFileSystemEntry::FromNativePath());
}
# if defined(QT_DEBUG)
if (result.isEmpty())
qWarning("QFileSystemEngine::currentPath: getcwd() failed");
# endif
#endif
} else {
# if defined(QT_DEBUG)
qWarning("QFileSystemEngine::currentPath: stat(\".\") failed");
# endif
char *currentName = ::get_current_dir_name();
if (currentName) {
result = QFileSystemEntry(QByteArray(currentName), QFileSystemEntry::FromNativePath());
::free(currentName);
}
#else
char currentName[PATH_MAX+1];
if (::getcwd(currentName, PATH_MAX)) {
#if defined(Q_OS_VXWORKS) && defined(VXWORKS_VXSIM)
QByteArray dir(currentName);
if (dir.indexOf(':') < dir.indexOf('/'))
dir.remove(0, dir.indexOf(':')+1);
qstrncpy(currentName, dir.constData(), PATH_MAX);
#endif
result = QFileSystemEntry(QByteArray(currentName), QFileSystemEntry::FromNativePath());
}
# if defined(QT_DEBUG)
if (result.isEmpty())
qWarning("QFileSystemEngine::currentPath: getcwd() failed");
# endif
#endif
return result;
}
QT_END_NAMESPACE