2011-06-17 Corinna Vinschen <corinna@vinschen.de>
+ * fhandler.cc (fhandler_base::open): Drop local create_options variable.
+ Use options member instead.
+ * fhandler.h (class fhandler_base): Change type of access member to
+ ACCESS_MASK. Change get_access and set_access methods accordingly.
+ Add options member. Add get_options and set_options methods.
+ (class fhandler_disk_file): Add prw_handle.
+ (fhandler_disk_file::prw_open): Declare.
+ (fhandler_disk_file::close): Declare.
+ (fhandler_disk_file::dup): Declare.
+ (fhandler_disk_file::fixup_after_fork): Declare.
+ * fhandler_disk_file.cc (fhandler_disk_file::fhandler_disk_file):
+ Initialize prw_handle to NULL.
+ (fhandler_disk_file::close): Close prw_handle.
+ (fhandler_disk_file::dup): New method.
+ (fhandler_disk_file::fixup_after_fork): Set prw_handle to NULL since
+ prw_handle is not inherited.
+ (fhandler_disk_file::prw_open): New method. Add long comment to
+ explain current behaviour.
+ (fhandler_disk_file::pread): Revert previous change. Change to use
+ prw_handle if possible.
+ (fhandler_disk_file::pwrite): Change to use prw_handle if possible.
+
+2011-06-17 Corinna Vinschen <corinna@vinschen.de>
+
* dcrt0.cc (dll_crt0_1): Call strace.dll_info after call to pinfo_init.
* strace.cc (strace::hello): Drop printing DLL information here since
application info is not always available at this point.
ULONG file_attributes = 0;
ULONG shared = (get_major () == DEV_TAPE_MAJOR ? 0 : FILE_SHARE_VALID_FLAGS);
ULONG create_disposition;
- ULONG create_options = FILE_OPEN_FOR_BACKUP_INTENT;
OBJECT_ATTRIBUTES attr;
IO_STATUS_BLOCK io;
NTSTATUS status;
pc.get_object_attr (attr, *sec_none_cloexec (flags));
+ options = FILE_OPEN_FOR_BACKUP_INTENT;
switch (query_open ())
{
case query_read_control:
else
access = GENERIC_READ | GENERIC_WRITE;
if (flags & O_SYNC)
- create_options |= FILE_WRITE_THROUGH;
+ options |= FILE_WRITE_THROUGH;
if (flags & O_DIRECT)
- create_options |= FILE_NO_INTERMEDIATE_BUFFERING;
+ options |= FILE_NO_INTERMEDIATE_BUFFERING;
if (get_major () != DEV_SERIAL_MAJOR && get_major () != DEV_TAPE_MAJOR)
{
- create_options |= FILE_SYNCHRONOUS_IO_NONALERT;
+ options |= FILE_SYNCHRONOUS_IO_NONALERT;
access |= SYNCHRONIZE;
}
break;
/* Add the reparse point flag to native symlinks, otherwise we open the
target, not the symlink. This would break lstat. */
if (pc.is_rep_symlink ())
- create_options |= FILE_OPEN_REPARSE_POINT;
+ options |= FILE_OPEN_REPARSE_POINT;
/* Starting with Windows 2000, when trying to overwrite an already
existing file with FILE_ATTRIBUTE_HIDDEN and/or FILE_ATTRIBUTE_SYSTEM
}
status = NtCreateFile (&fh, access, &attr, &io, NULL, file_attributes, shared,
- create_disposition, create_options, p, plen);
+ create_disposition, options, p, plen);
if (!NT_SUCCESS (status))
{
/* Trying to create a directory should return EISDIR, not ENOENT. */
debug_printf ("%x = NtCreateFile "
"(%p, %x, %S, io, NULL, %x, %x, %x, %x, NULL, 0)",
status, fh, access, pc.get_nt_native_path (), file_attributes,
- shared, create_disposition, create_options);
+ shared, create_disposition, options);
syscall_printf ("%d = fhandler_base::open (%S, %p)",
res, pc.get_nt_native_path (), flags);
}
fhandler_disk_file::fhandler_disk_file () :
- fhandler_base ()
+ fhandler_base (), prw_handle (NULL)
{
}
fhandler_disk_file::fhandler_disk_file (path_conv &pc) :
- fhandler_base ()
+ fhandler_base (), prw_handle (NULL)
{
set_name (pc);
}
}
int
+fhandler_disk_file::close ()
+{
+ if (prw_handle)
+ NtClose (prw_handle);
+ return fhandler_base::close ();
+}
+
+int
+fhandler_disk_file::dup (fhandler_base *child)
+{
+ fhandler_disk_file *fhc = (fhandler_disk_file *) child;
+
+ int ret = fhandler_base::dup (child);
+ if (!ret && prw_handle
+ && !DuplicateHandle (GetCurrentProcess (), prw_handle,
+ GetCurrentProcess (), &fhc->prw_handle,
+ 0, TRUE, DUPLICATE_SAME_ACCESS))
+ prw_handle = NULL;
+ return ret;
+}
+
+void
+fhandler_disk_file::fixup_after_fork (HANDLE parent)
+{
+ prw_handle = NULL;
+ fhandler_base::fixup_after_fork (parent);
+}
+
+int
fhandler_base::open_fs (int flags, mode_t mode)
{
/* Unfortunately NT allows to open directories for writing, but that's
return res;
}
+/* POSIX demands that pread/pwrite don't change the current file position.
+ While NtReadFile/NtWriteFile support atomic seek-and-io, both change the
+ file pointer if the file handle has been opened for synchonous I/O.
+ Using this handle for pread/pwrite would break atomicity, because the
+ read/write operation would have to be followed by a seek back to the old
+ file position. What we do is to open another handle to the file on the
+ first call to either pread or pwrite. This is used for any subsequent
+ pread/pwrite. Thus the current file position of the "normal" file
+ handle is not touched.
+
+ FIXME:
+
+ Note that this is just a hack. The problem with this approach is that
+ a change to the file permissions might disallow to open the file with
+ the required permissions to read or write. This appears to be a border case,
+ but that's exactly what git does. It creates the file for reading and
+ writing and after writing it, it chmods the file to read-only. Then it
+ calls pread on the file to examine the content. This works, but if git
+ would use the original handle to pwrite to the file, it would be broken
+ with our approach.
+
+ One way to implement this is to open the pread/pwrite handle right at
+ file open time. We would simply maintain two handles, which wouldn't
+ be much of a problem given how we do that for other fhandler types as
+ well.
+
+ However, ultimately fhandler_disk_file should become a derived class of
+ fhandler_base_overlapped. Each raw_read or raw_write would fetch the
+ actual file position, read/write from there, and then set the file
+ position again. Fortunately, while the file position is not maintained
+ by the I/O manager, it can be fetched and set to a new value by all
+ processes holding a handle to that file object. Pread and pwrite differ
+ from raw_read and raw_write just by not touching the current file pos.
+ Actually they could be merged with raw_read/raw_write if we add a position
+ parameter to the latter. */
+
+int
+fhandler_disk_file::prw_open (bool write)
+{
+ NTSTATUS status;
+ IO_STATUS_BLOCK io;
+ OBJECT_ATTRIBUTES attr;
+
+ /* First try to open with the original access mask */
+ ACCESS_MASK access = get_access ();
+ pc.init_reopen_attr (&attr, get_handle ());
+ status = NtOpenFile (&prw_handle, access, &attr, &io,
+ FILE_SHARE_VALID_FLAGS, get_options ());
+ if (status == STATUS_ACCESS_DENIED)
+ {
+ /* If we get an access denied, chmod has been called. Try again
+ with just the required rights to perform the called function. */
+ access &= write ? ~GENERIC_READ : ~GENERIC_WRITE;
+ status = NtOpenFile (&prw_handle, access, &attr, &io,
+ FILE_SHARE_VALID_FLAGS, get_options ());
+ }
+ debug_printf ("%x = NtOpenFile (%p, %x, %S, io, %x, %x)",
+ status, prw_handle, access, pc.get_nt_native_path (),
+ FILE_SHARE_VALID_FLAGS, get_options ());
+ if (!NT_SUCCESS (status))
+ {
+ __seterrno_from_nt_status (status);
+ return -1;
+ }
+ return 0;
+}
+
ssize_t __stdcall
fhandler_disk_file::pread (void *buf, size_t count, _off64_t offset)
{
IO_STATUS_BLOCK io;
LARGE_INTEGER off = { QuadPart:offset };
- status = NtReadFile (get_handle (), NULL, NULL, NULL, &io, buf, count,
+ if (!prw_handle && prw_open (false))
+ goto non_atomic;
+ status = NtReadFile (prw_handle, NULL, NULL, NULL, &io, buf, count,
&off, NULL);
if (!NT_SUCCESS (status))
{
}
if (status == (NTSTATUS) STATUS_ACCESS_VIOLATION)
{
- if (is_at_eof (get_handle ()))
+ if (is_at_eof (prw_handle))
return 0;
switch (mmap_is_attached_or_noreserve (buf, count))
{
case MMAP_NORESERVE_COMMITED:
- status = NtReadFile (get_handle (), NULL, NULL, NULL, &io,
+ status = NtReadFile (prw_handle, NULL, NULL, NULL, &io,
buf, count, &off, NULL);
if (NT_SUCCESS (status))
- goto success;
+ return io.Information;
break;
case MMAP_RAISE_SIGBUS:
raise (SIGBUS);
__seterrno_from_nt_status (status);
return -1;
}
-
-success:
- lseek (-io.Information, SEEK_CUR);
- return io.Information;
}
+non_atomic:
/* Text mode stays slow and non-atomic. */
ssize_t res;
_off64_t curpos = lseek (0, SEEK_CUR);
IO_STATUS_BLOCK io;
LARGE_INTEGER off = { QuadPart:offset };
- status = NtWriteFile (get_handle (), NULL, NULL, NULL, &io, buf, count,
+ if (!prw_handle && prw_open (true))
+ goto non_atomic;
+ status = NtWriteFile (prw_handle, NULL, NULL, NULL, &io, buf, count,
&off, NULL);
if (!NT_SUCCESS (status))
{
}
return io.Information;
}
+
+non_atomic:
/* Text mode stays slow and non-atomic. */
int res;
_off64_t curpos = lseek (0, SEEK_CUR);
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