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QFileSystemEngine: let cloneFile() inform QFile of permanent errors

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The Unix implementation in QFileSystemEngine::cloneFile() was unable to
tell the upper layer whether the failure was permanent (like ENOSPC and
EIO) or whether the fast copy attempt wasn't possible. This resulted in
QFile always retrying even after ENOSPC conditions.

This commit resolves that.

Change-Id: I38a830a99a0d38bcb51efffdf34bb7fead639496
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
This commit is contained in:
Thiago Macieira 2025-01-21 10:39:07 -08:00
parent e6e210c240
commit be2df3c6e0
8 changed files with 46 additions and 25 deletions
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4
src/corelib/io/qabstractfileengine.cpp
View File

@ -829,10 +829,10 @@ bool QAbstractFileEngine::unmap(uchar *address)
Returns \c true on success; otherwise, \c false is returned.
*/
bool QAbstractFileEngine::cloneTo(QAbstractFileEngine *target)
QAbstractFileEngine::TriStateResult QAbstractFileEngine::cloneTo(QAbstractFileEngine *target)
{
Q_UNUSED(target);
return false;
return TriStateResult::NotSupported;
}
/*!

7
src/corelib/io/qabstractfileengine_p.h
View File

@ -83,6 +83,11 @@ public:
OwnerGroup
};
enum class TriStateResult : qint8 {
NotSupported = -1,
Failed = 0,
Success = 1,
};
virtual ~QAbstractFileEngine();
@ -119,7 +124,7 @@ public:
virtual QDateTime fileTime(QFile::FileTime time) const;
virtual void setFileName(const QString &file);
virtual int handle() const;
virtual bool cloneTo(QAbstractFileEngine *target);
virtual TriStateResult cloneTo(QAbstractFileEngine *target);
bool atEnd() const;
uchar *map(qint64 offset, qint64 size, QFile::MemoryMapFlags flags);
bool unmap(uchar *ptr);

7
src/corelib/io/qfile.cpp
View File

@ -834,7 +834,12 @@ QFile::copy(const QString &newName)
out.close();
close();
} else {
if (!d->engine()->cloneTo(out.d_func()->engine())) {
QAbstractFileEngine::TriStateResult r = d->engine()->cloneTo(out.d_func()->engine());
if (r == QAbstractFileEngine::TriStateResult::Failed) {
d->setError(QFile::CopyError, tr("Could not copy to %1: %2")
.arg(newName, d->engine()->errorString()));
error = true;
} else if (r == QAbstractFileEngine::TriStateResult::NotSupported) {
char block[4096];
qint64 totalRead = 0;
out.setOpenMode(ReadWrite | Unbuffered);

4
src/corelib/io/qfilesystemengine_p.h
View File

@ -60,6 +60,8 @@ Q_CORE_EXPORT bool qt_isCaseSensitive(const QFileSystemEntry &entry, QFileSystem
class Q_AUTOTEST_EXPORT QFileSystemEngine
{
public:
using TriStateResult = QAbstractFileEngine::TriStateResult;
static bool isCaseSensitive(const QFileSystemEntry &entry, QFileSystemMetaData &data);
static QFileSystemEntry getLinkTarget(const QFileSystemEntry &link, QFileSystemMetaData &data);
@ -86,7 +88,7 @@ public:
static bool fillMetaData(const QFileSystemEntry &entry, QFileSystemMetaData &data,
QFileSystemMetaData::MetaDataFlags what);
#if defined(Q_OS_UNIX)
static bool cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData);
static TriStateResult cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData);
static bool fillMetaData(int fd, QFileSystemMetaData &data); // what = PosixStatFlags
static QByteArray id(int fd);
static bool setFileTime(int fd, const QDateTime &newDate,

34
src/corelib/io/qfilesystemengine_unix.cpp
View File

@ -1068,7 +1068,7 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
}
// static
bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData)
auto QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData) -> TriStateResult
{
QT_STATBUF statBuffer;
if (knownData.hasFlags(QFileSystemMetaData::PosixStatFlags) &&
@ -1076,12 +1076,14 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
statBuffer.st_mode = S_IFREG;
} else if (knownData.hasFlags(QFileSystemMetaData::PosixStatFlags) &&
knownData.isDirectory()) {
return false; // fcopyfile(3) returns success on directories
errno = EISDIR;
return TriStateResult::Failed; // fcopyfile(3) returns success on directories
} else if (QT_FSTAT(srcfd, &statBuffer) == -1) {
return false;
// errno was set
return TriStateResult::Failed;
} else if (!S_ISREG((statBuffer.st_mode))) {
// not a regular file, let QFile do the copy
return false;
return TriStateResult::NotSupported;
}
[[maybe_unused]] auto destinationIsEmpty = [dstfd]() {
@ -1093,7 +1095,7 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
#if defined(Q_OS_LINUX)
// first, try FICLONE (only works on regular files and only on certain fs)
if (::ioctl(dstfd, FICLONE, srcfd) == 0)
return true;
return TriStateResult::Success;
// Second, try sendfile (it can send to some special types too).
// sendfile(2) is limited in the kernel to 2G - 4k
@ -1102,30 +1104,34 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
ssize_t n = ::sendfile(dstfd, srcfd, nullptr, SendfileSize);
if (n == -1) {
// if we got an error here, give up and try at an upper layer
return false;
return TriStateResult::NotSupported;
}
while (n) {
n = ::sendfile(dstfd, srcfd, nullptr, SendfileSize);
if (n == -1) {
// uh oh, this is probably a real error (like ENOSPC), but we have
// no way to notify QFile of partial success, so just erase any work
// done (hopefully we won't get any errors, because there's nothing
// we can do about them)
// uh oh, this is probably a real error (like ENOSPC)
n = ftruncate(dstfd, 0);
n = lseek(srcfd, 0, SEEK_SET);
n = lseek(dstfd, 0, SEEK_SET);
return false;
return TriStateResult::Failed;
}
}
return true;
return TriStateResult::Success;
#elif defined(Q_OS_DARWIN)
// try fcopyfile
return fcopyfile(srcfd, dstfd, nullptr, COPYFILE_DATA | COPYFILE_STAT) == 0;
if (fcopyfile(srcfd, dstfd, nullptr, COPYFILE_DATA | COPYFILE_STAT) == 0)
return TriStateResult::Success;
switch (errno) {
case ENOTSUP:
case ENOMEM:
return TriStateResult::NotSupported; // let QFile try
}
return TriStateResult::Failed;
#else
Q_UNUSED(dstfd);
return false;
return TriStateResult::NotSupported;
#endif
}

2
src/corelib/io/qfsfileengine_p.h
View File

@ -93,7 +93,7 @@ public:
qint64 read(char *data, qint64 maxlen) override;
qint64 readLine(char *data, qint64 maxlen) override;
qint64 write(const char *data, qint64 len) override;
bool cloneTo(QAbstractFileEngine *target) override;
TriStateResult cloneTo(QAbstractFileEngine *target) override;
virtual bool isUnnamedFile() const
{ return false; }

9
src/corelib/io/qfsfileengine_unix.cpp
View File

@ -648,15 +648,18 @@ bool QFSFileEnginePrivate::unmap(uchar *ptr)
/*!
\reimp
*/
bool QFSFileEngine::cloneTo(QAbstractFileEngine *target)
QAbstractFileEngine::TriStateResult QFSFileEngine::cloneTo(QAbstractFileEngine *target)
{
Q_D(QFSFileEngine);
if ((target->fileFlags(LocalDiskFlag) & LocalDiskFlag) == 0)
return false;
return TriStateResult::NotSupported;
int srcfd = d->nativeHandle();
int dstfd = target->handle();
return QFileSystemEngine::cloneFile(srcfd, dstfd, d->metaData);
TriStateResult r = QFileSystemEngine::cloneFile(srcfd, dstfd, d->metaData);
if (r == TriStateResult::Failed)
setError(QFile::CopyError, qt_error_string(errno));
return r;
}
QT_END_NAMESPACE

4
src/corelib/io/qfsfileengine_win.cpp
View File

@ -897,12 +897,12 @@ bool QFSFileEnginePrivate::unmap(uchar *ptr)
/*!
\reimp
*/
bool QFSFileEngine::cloneTo(QAbstractFileEngine *target)
QAbstractFileEngine::TriStateResult QFSFileEngine::cloneTo(QAbstractFileEngine *target)
{
// There's some Windows Server 2016 API, but we won't
// bother with it.
Q_UNUSED(target);
return false;
return TriStateResult::NotSupported;
}
QT_END_NAMESPACE