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Atomic implementation of create file and obtain handle for Win/Symbian 

Besides generating a unique name, createFileFromTemplate now also
acquires a file handle on all platforms. The file engine's native handle
is passed by reference and modified in place.

This fixes a long standing security issue on Windows.

On Windows and Symbian platforms we directly use the "native" file path
when processing the template and generating the unique name. Since the
native encoding is known, conversions at this point are safe.

Errors other than "file exists" are propagated to Q(Temporary)File,
and result in a failure in open(). The changes also unify error handling
and should give consistent behaviour across all platforms.

Worthy of note, there's a change in behaviour on Windows and Symbian:
fileNames returned by QTemporaryFile on Windows and Symbian are always
absolute after open has been called. This has to do with how
QFileSystemEntry::nativeFilePath works on these platforms. (Test was
updated to reflect change in behaviour.)

Reviewed-by: Gareth Stockwell
Reviewed-by: Shane Kearns
(cherry picked from commit ff9b69838ec146aeb43d4af8a03043f9c5f0454d)

Conflicts:

	tests/auto/qtemporaryfile/tst_qtemporaryfile.cpp

Change-Id: Ibc9affb321ea4f4b193efc1f7336c9770b43d8df
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
bb10
João Abecasis 2011-08-05 10:45:08 +02:00 committed by Qt by Nokia
parent a4a09488ee
commit f4f729cb7b
2 changed files with 123 additions and 61 deletions
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153
src/corelib/io/qtemporaryfile.cpp
View File

@ -49,6 +49,11 @@
#include "private/qfile_p.h"
#include "private/qabstractfileengine_p.h"
#include "private/qfsfileengine_p.h"
#include "private/qsystemerror_p.h"
#if defined(Q_OS_SYMBIAN)
#include "private/qcore_symbian_p.h"
#endif
#if !defined(Q_OS_WIN) && !defined(Q_OS_SYMBIAN)
#include "private/qcore_unix_p.h" // overrides QT_OPEN
@ -83,9 +88,20 @@ struct QConcatenable<Char>
}
};
# ifdef Q_OS_WIN
typedef HANDLE NativeFileHandle;
# else // Q_OS_SYMBIAN
# ifdef SYMBIAN_ENABLE_64_BIT_FILE_SERVER_API
typedef RFile64 NativeFileHandle;
# else
typedef RFile NativeFileHandle;
# endif
# endif
#else // POSIX
typedef char Char;
typedef char Latin1Char;
typedef int NativeFileHandle;
#endif
struct Placeholder
@ -161,8 +177,9 @@ struct QConcatenable<Placeholder>
handle otherwise. In both cases, the string in \a path will be changed and
contain the generated path name.
*/
static int createFileFromTemplate(QFileSystemEntry::NativePath &path,
size_t pos, size_t length)
static bool createFileFromTemplate(NativeFileHandle &file,
QFileSystemEntry::NativePath &path, size_t pos, size_t length,
QSystemError &error)
{
Q_ASSERT(length != 0);
Q_ASSERT(pos < size_t(path.length()));
@ -192,21 +209,50 @@ static int createFileFromTemplate(QFileSystemEntry::NativePath &path,
}
}
#ifdef Q_OS_SYMBIAN
RFs& fs = qt_s60GetRFs();
#endif
for (;;) {
// Atomically create file and obtain handle
#if !defined(Q_OS_WIN) && !defined(Q_OS_SYMBIAN)
{
int fd = QT_OPEN(path.constData(),
QT_OPEN_CREAT | O_EXCL | QT_OPEN_RDWR | QT_OPEN_LARGEFILE,
0600);
if (fd != -1)
return fd;
if (errno != EEXIST)
return -1;
#if defined(Q_OS_WIN)
file = CreateFile((const wchar_t *)path.constData(),
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, CREATE_NEW,
FILE_ATTRIBUTE_NORMAL, NULL);
if (file != INVALID_HANDLE_VALUE)
return true;
DWORD err = GetLastError();
if (err != ERROR_FILE_EXISTS) {
error = QSystemError(err, QSystemError::NativeError);
return false;
}
#elif defined(Q_OS_SYMBIAN)
TInt err = file.Create(fs, qt_QString2TPtrC(path),
EFileRead | EFileWrite | EFileShareReadersOrWriters);
if (err == KErrNone)
return true;
if (err != KErrAlreadyExists) {
error = QSystemError(err, QSystemError::NativeError);
return false;
}
#else // POSIX
file = QT_OPEN(path.constData(),
QT_OPEN_CREAT | O_EXCL | QT_OPEN_RDWR | QT_OPEN_LARGEFILE,
0600);
if (file != -1)
return true;
int err = errno;
if (err != EEXIST) {
error = QSystemError(err, QSystemError::NativeError);
return false;
}
#else
if (!QFileInfo(path).exists())
return 1;
#endif
/* tricky little algorwwithm for backward compatibility */
@ -217,8 +263,11 @@ static int createFileFromTemplate(QFileSystemEntry::NativePath &path,
case 'Z':
// Rollover, advance next character
*iter = Latin1Char('a');
if (++iter == placeholderEnd)
return -1;
if (++iter == placeholderEnd) {
// Out of alternatives. Return file exists error, previously set.
error = QSystemError(err, QSystemError::NativeError);
return false;
}
continue;
@ -319,7 +368,14 @@ bool QTemporaryFileEngine::open(QIODevice::OpenMode openMode)
if (!filePathIsTemplate)
return QFSFileEngine::open(openMode);
const QString qfilename = d->fileEntry.filePath();
const QString qfilename =
#if !defined(Q_OS_WIN) && !defined(Q_OS_SYMBIAN)
// Since the native encoding is out of our control, we need to process
// the path as UTF-16 before doing any conversions
d->fileEntry.filePath();
#else
d->fileEntry.nativeFilePath();
#endif
// Find placeholder string.
uint phPos = qfilename.length();
@ -333,8 +389,14 @@ bool QTemporaryFileEngine::open(QIODevice::OpenMode openMode)
continue;
}
if (qfilename[phPos] == QLatin1Char('/')
|| phLength >= 6) {
if (phLength >= 6
|| qfilename[phPos] ==
#if !defined(Q_OS_WIN) && !defined(Q_OS_SYMBIAN)
QLatin1Char('/')
#else
QLatin1Char('\\')
#endif
) {
++phPos;
break;
}
@ -366,44 +428,35 @@ bool QTemporaryFileEngine::open(QIODevice::OpenMode openMode)
filename = qfilename % Latin1Char('.') % Placeholder(phLength);
} else
filename = qfilename;
// No native separators, not a "native path"
#endif
int fd = createFileFromTemplate(filename, phPos, phLength);
QSystemError error;
#if defined(Q_OS_WIN)
NativeFileHandle &file = d->fileHandle;
#elif defined(Q_OS_SYMBIAN)
NativeFileHandle &file = d->symbianFile;
#else // POSIX
NativeFileHandle &file = d->fd;
#endif
#if !defined(Q_OS_WIN) && !defined(Q_OS_SYMBIAN)
if (fd != -1) {
// First open the fd as an external file descriptor to
// initialize the engine properly.
if (QFSFileEngine::open(openMode, fd)) {
// Allow the engine to close the handle even if it's "external".
d->closeFileHandle = true;
// Restore the file names (open() resets them).
d->fileEntry = QFileSystemEntry(QString::fromLocal8Bit(filename.constData(), filename.length())); //note that filename is NOT a native path
filePathIsTemplate = false;
return true;
}
QT_CLOSE(fd);
}
setError(errno == EMFILE ? QFile::ResourceError : QFile::OpenError, qt_error_string(errno));
return false;
#else
if (fd == -1)
if (!createFileFromTemplate(file, filename, phPos, phLength, error)) {
setError(QFile::OpenError, error.toString());
return false;
d->fileEntry = QFileSystemEntry(filename, QFileSystemEntry::FromInternalPath());
if (QFSFileEngine::open(openMode)) {
filePathIsTemplate = false;
return true;
}
d->fileEntry = QFileSystemEntry(qfilename, QFileSystemEntry::FromInternalPath());
return false;
d->fileEntry = QFileSystemEntry(filename, QFileSystemEntry::FromNativePath());
#if !defined(Q_OS_WIN)
d->closeFileHandle = true;
#endif
filePathIsTemplate = false;
d->openMode = openMode;
d->lastFlushFailed = false;
d->tried_stat = 0;
return true;
}
bool QTemporaryFileEngine::remove()

31
tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
View File

@ -199,11 +199,12 @@ void tst_QTemporaryFile::fileTemplate()
QCOMPARE(file.open(), true);
QString fileName = QFileInfo(file).fileName();
if (prefix.length())
QCOMPARE(file.fileName().left(prefix.length()), prefix);
QCOMPARE(fileName.left(prefix.length()), prefix);
if (suffix.length())
QCOMPARE(file.fileName().right(suffix.length()), suffix);
QCOMPARE(fileName.right(suffix.length()), suffix);
}
@ -716,20 +717,28 @@ void tst_QTemporaryFile::QTBUG_4796()
<< file5.fileName()
<< file6.fileName();
QVERIFY(file1.fileName().startsWith(fileTemplate1 + QLatin1Char('.')));
QVERIFY(file2.fileName().startsWith(fileTemplate2 + QLatin1Char('.')));
QVERIFY(file5.fileName().startsWith("test-XXXXXX/" + fileTemplate1 + QLatin1Char('.')));
QVERIFY(file6.fileName().startsWith("test-XXXXXX/" + prefix));
QDir currentDir;
QString fileName1 = currentDir.relativeFilePath(file1.fileName());
QString fileName2 = currentDir.relativeFilePath(file2.fileName());
QString fileName3 = currentDir.relativeFilePath(file3.fileName());
QString fileName4 = currentDir.relativeFilePath(file4.fileName());
QString fileName5 = currentDir.relativeFilePath(file5.fileName());
QString fileName6 = currentDir.relativeFilePath(file6.fileName());
QVERIFY(fileName1.startsWith(fileTemplate1 + QLatin1Char('.')));
QVERIFY(fileName2.startsWith(fileTemplate2 + QLatin1Char('.')));
QVERIFY(fileName5.startsWith("test-XXXXXX/" + fileTemplate1 + QLatin1Char('.')));
QVERIFY(fileName6.startsWith("test-XXXXXX/" + prefix));
if (!prefix.isEmpty()) {
QVERIFY(file3.fileName().startsWith(prefix));
QVERIFY(file4.fileName().startsWith(prefix));
QVERIFY(fileName3.startsWith(prefix));
QVERIFY(fileName4.startsWith(prefix));
}
if (!suffix.isEmpty()) {
QVERIFY(file3.fileName().endsWith(suffix));
QVERIFY(file4.fileName().endsWith(suffix));
QVERIFY(file6.fileName().endsWith(suffix));
QVERIFY(fileName3.endsWith(suffix));
QVERIFY(fileName4.endsWith(suffix));
QVERIFY(fileName6.endsWith(suffix));
}
}
}