* 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.
This commit is contained in:
Corinna Vinschen
parent
a716252619
commit
c36cd56c54
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@ -1,3 +1,27 @@
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2011-06-17 Corinna Vinschen <corinna@vinschen.de>
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* fhandler.cc (fhandler_base::open): Drop local create_options variable.
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Use options member instead.
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* fhandler.h (class fhandler_base): Change type of access member to
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ACCESS_MASK. Change get_access and set_access methods accordingly.
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Add options member. Add get_options and set_options methods.
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(class fhandler_disk_file): Add prw_handle.
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(fhandler_disk_file::prw_open): Declare.
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(fhandler_disk_file::close): Declare.
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(fhandler_disk_file::dup): Declare.
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(fhandler_disk_file::fixup_after_fork): Declare.
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* fhandler_disk_file.cc (fhandler_disk_file::fhandler_disk_file):
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Initialize prw_handle to NULL.
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(fhandler_disk_file::close): Close prw_handle.
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(fhandler_disk_file::dup): New method.
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(fhandler_disk_file::fixup_after_fork): Set prw_handle to NULL since
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prw_handle is not inherited.
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(fhandler_disk_file::prw_open): New method. Add long comment to
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explain current behaviour.
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(fhandler_disk_file::pread): Revert previous change. Change to use
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prw_handle if possible.
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(fhandler_disk_file::pwrite): Change to use prw_handle if possible.
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2011-06-17 Corinna Vinschen <corinna@vinschen.de>
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* dcrt0.cc (dll_crt0_1): Call strace.dll_info after call to pinfo_init.
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@ -492,7 +492,6 @@ fhandler_base::open (int flags, mode_t mode)
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ULONG file_attributes = 0;
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ULONG shared = (get_major () == DEV_TAPE_MAJOR ? 0 : FILE_SHARE_VALID_FLAGS);
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ULONG create_disposition;
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ULONG create_options = FILE_OPEN_FOR_BACKUP_INTENT;
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OBJECT_ATTRIBUTES attr;
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IO_STATUS_BLOCK io;
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NTSTATUS status;
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@ -503,6 +502,7 @@ fhandler_base::open (int flags, mode_t mode)
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pc.get_object_attr (attr, *sec_none_cloexec (flags));
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options = FILE_OPEN_FOR_BACKUP_INTENT;
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switch (query_open ())
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{
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case query_read_control:
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@ -528,12 +528,12 @@ fhandler_base::open (int flags, mode_t mode)
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else
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access = GENERIC_READ | GENERIC_WRITE;
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if (flags & O_SYNC)
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create_options |= FILE_WRITE_THROUGH;
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options |= FILE_WRITE_THROUGH;
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if (flags & O_DIRECT)
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create_options |= FILE_NO_INTERMEDIATE_BUFFERING;
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options |= FILE_NO_INTERMEDIATE_BUFFERING;
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if (get_major () != DEV_SERIAL_MAJOR && get_major () != DEV_TAPE_MAJOR)
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{
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create_options |= FILE_SYNCHRONOUS_IO_NONALERT;
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options |= FILE_SYNCHRONOUS_IO_NONALERT;
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access |= SYNCHRONIZE;
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}
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break;
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@ -574,7 +574,7 @@ fhandler_base::open (int flags, mode_t mode)
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/* Add the reparse point flag to native symlinks, otherwise we open the
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target, not the symlink. This would break lstat. */
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if (pc.is_rep_symlink ())
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create_options |= FILE_OPEN_REPARSE_POINT;
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options |= FILE_OPEN_REPARSE_POINT;
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/* Starting with Windows 2000, when trying to overwrite an already
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existing file with FILE_ATTRIBUTE_HIDDEN and/or FILE_ATTRIBUTE_SYSTEM
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@ -626,7 +626,7 @@ fhandler_base::open (int flags, mode_t mode)
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}
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status = NtCreateFile (&fh, access, &attr, &io, NULL, file_attributes, shared,
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create_disposition, create_options, p, plen);
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create_disposition, options, p, plen);
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if (!NT_SUCCESS (status))
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{
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/* Trying to create a directory should return EISDIR, not ENOENT. */
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@ -672,7 +672,7 @@ done:
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debug_printf ("%x = NtCreateFile "
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"(%p, %x, %S, io, NULL, %x, %x, %x, %x, NULL, 0)",
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status, fh, access, pc.get_nt_native_path (), file_attributes,
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shared, create_disposition, create_options);
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shared, create_disposition, options);
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syscall_printf ("%d = fhandler_base::open (%S, %p)",
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res, pc.get_nt_native_path (), flags);
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@ -152,7 +152,9 @@ class fhandler_base
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} status, open_status;
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private:
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int access;
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ACCESS_MASK access;
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ULONG options;
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HANDLE io_handle;
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__ino64_t ino; /* file ID or hashed filename, depends on FS. */
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@ -206,8 +208,11 @@ class fhandler_base
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DWORD get_minor () { return dev ().get_minor (); }
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virtual int get_unit () { return dev ().get_minor (); }
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int get_access () const { return access; }
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void set_access (int x) { access = x; }
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ACCESS_MASK get_access () const { return access; }
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void set_access (ACCESS_MASK x) { access = x; }
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ULONG get_options () const { return options; }
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void set_options (ULONG x) { options = x; }
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int get_flags () { return openflags; }
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void set_flags (int x, int supplied_bin = 0);
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@ -801,13 +806,19 @@ class fhandler_dev_tape: public fhandler_dev_raw
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class fhandler_disk_file: public fhandler_base
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{
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HANDLE prw_handle;
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int readdir_helper (DIR *, dirent *, DWORD, DWORD, PUNICODE_STRING fname) __attribute__ ((regparm (3)));
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int prw_open (bool);
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public:
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fhandler_disk_file ();
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fhandler_disk_file (path_conv &pc);
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int open (int flags, mode_t mode);
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int close ();
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int dup (fhandler_base *child);
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void fixup_after_fork (HANDLE parent);
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int lock (int, struct __flock64 *);
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bool isdevice () const { return false; }
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int __stdcall fstat (struct __stat64 *buf) __attribute__ ((regparm (2)));
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@ -1356,12 +1356,12 @@ fhandler_base::utimens_fs (const struct timespec *tvp)
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}
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fhandler_disk_file::fhandler_disk_file () :
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fhandler_base ()
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fhandler_base (), prw_handle (NULL)
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{
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}
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fhandler_disk_file::fhandler_disk_file (path_conv &pc) :
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fhandler_base ()
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fhandler_base (), prw_handle (NULL)
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{
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set_name (pc);
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}
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@ -1372,6 +1372,35 @@ fhandler_disk_file::open (int flags, mode_t mode)
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return open_fs (flags, mode);
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}
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int
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fhandler_disk_file::close ()
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{
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if (prw_handle)
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NtClose (prw_handle);
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return fhandler_base::close ();
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}
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int
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fhandler_disk_file::dup (fhandler_base *child)
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{
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fhandler_disk_file *fhc = (fhandler_disk_file *) child;
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int ret = fhandler_base::dup (child);
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if (!ret && prw_handle
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&& !DuplicateHandle (GetCurrentProcess (), prw_handle,
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GetCurrentProcess (), &fhc->prw_handle,
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0, TRUE, DUPLICATE_SAME_ACCESS))
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prw_handle = NULL;
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return ret;
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}
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void
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fhandler_disk_file::fixup_after_fork (HANDLE parent)
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{
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prw_handle = NULL;
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fhandler_base::fixup_after_fork (parent);
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}
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int
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fhandler_base::open_fs (int flags, mode_t mode)
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{
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@ -1412,6 +1441,73 @@ out:
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return res;
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}
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/* POSIX demands that pread/pwrite don't change the current file position.
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While NtReadFile/NtWriteFile support atomic seek-and-io, both change the
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file pointer if the file handle has been opened for synchonous I/O.
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Using this handle for pread/pwrite would break atomicity, because the
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read/write operation would have to be followed by a seek back to the old
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file position. What we do is to open another handle to the file on the
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first call to either pread or pwrite. This is used for any subsequent
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pread/pwrite. Thus the current file position of the "normal" file
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handle is not touched.
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FIXME:
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Note that this is just a hack. The problem with this approach is that
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a change to the file permissions might disallow to open the file with
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the required permissions to read or write. This appears to be a border case,
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but that's exactly what git does. It creates the file for reading and
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writing and after writing it, it chmods the file to read-only. Then it
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calls pread on the file to examine the content. This works, but if git
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would use the original handle to pwrite to the file, it would be broken
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with our approach.
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One way to implement this is to open the pread/pwrite handle right at
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file open time. We would simply maintain two handles, which wouldn't
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be much of a problem given how we do that for other fhandler types as
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well.
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However, ultimately fhandler_disk_file should become a derived class of
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fhandler_base_overlapped. Each raw_read or raw_write would fetch the
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actual file position, read/write from there, and then set the file
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position again. Fortunately, while the file position is not maintained
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by the I/O manager, it can be fetched and set to a new value by all
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processes holding a handle to that file object. Pread and pwrite differ
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from raw_read and raw_write just by not touching the current file pos.
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Actually they could be merged with raw_read/raw_write if we add a position
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parameter to the latter. */
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int
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fhandler_disk_file::prw_open (bool write)
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{
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NTSTATUS status;
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IO_STATUS_BLOCK io;
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OBJECT_ATTRIBUTES attr;
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/* First try to open with the original access mask */
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ACCESS_MASK access = get_access ();
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pc.init_reopen_attr (&attr, get_handle ());
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status = NtOpenFile (&prw_handle, access, &attr, &io,
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FILE_SHARE_VALID_FLAGS, get_options ());
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if (status == STATUS_ACCESS_DENIED)
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{
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/* If we get an access denied, chmod has been called. Try again
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with just the required rights to perform the called function. */
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access &= write ? ~GENERIC_READ : ~GENERIC_WRITE;
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status = NtOpenFile (&prw_handle, access, &attr, &io,
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FILE_SHARE_VALID_FLAGS, get_options ());
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}
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debug_printf ("%x = NtOpenFile (%p, %x, %S, io, %x, %x)",
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status, prw_handle, access, pc.get_nt_native_path (),
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FILE_SHARE_VALID_FLAGS, get_options ());
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if (!NT_SUCCESS (status))
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{
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__seterrno_from_nt_status (status);
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return -1;
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}
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return 0;
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}
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ssize_t __stdcall
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fhandler_disk_file::pread (void *buf, size_t count, _off64_t offset)
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{
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@ -1429,7 +1525,9 @@ fhandler_disk_file::pread (void *buf, size_t count, _off64_t offset)
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IO_STATUS_BLOCK io;
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LARGE_INTEGER off = { QuadPart:offset };
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status = NtReadFile (get_handle (), NULL, NULL, NULL, &io, buf, count,
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if (!prw_handle && prw_open (false))
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goto non_atomic;
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status = NtReadFile (prw_handle, NULL, NULL, NULL, &io, buf, count,
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&off, NULL);
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if (!NT_SUCCESS (status))
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{
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@ -1440,15 +1538,15 @@ fhandler_disk_file::pread (void *buf, size_t count, _off64_t offset)
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}
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if (status == (NTSTATUS) STATUS_ACCESS_VIOLATION)
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{
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if (is_at_eof (get_handle ()))
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if (is_at_eof (prw_handle))
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return 0;
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switch (mmap_is_attached_or_noreserve (buf, count))
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{
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case MMAP_NORESERVE_COMMITED:
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status = NtReadFile (get_handle (), NULL, NULL, NULL, &io,
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status = NtReadFile (prw_handle, NULL, NULL, NULL, &io,
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buf, count, &off, NULL);
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if (NT_SUCCESS (status))
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goto success;
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return io.Information;
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break;
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case MMAP_RAISE_SIGBUS:
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raise (SIGBUS);
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@ -1459,12 +1557,9 @@ fhandler_disk_file::pread (void *buf, size_t count, _off64_t offset)
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__seterrno_from_nt_status (status);
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return -1;
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}
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success:
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lseek (-io.Information, SEEK_CUR);
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return io.Information;
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}
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non_atomic:
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/* Text mode stays slow and non-atomic. */
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ssize_t res;
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_off64_t curpos = lseek (0, SEEK_CUR);
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@ -1499,7 +1594,9 @@ fhandler_disk_file::pwrite (void *buf, size_t count, _off64_t offset)
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IO_STATUS_BLOCK io;
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LARGE_INTEGER off = { QuadPart:offset };
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status = NtWriteFile (get_handle (), NULL, NULL, NULL, &io, buf, count,
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if (!prw_handle && prw_open (true))
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goto non_atomic;
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status = NtWriteFile (prw_handle, NULL, NULL, NULL, &io, buf, count,
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&off, NULL);
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if (!NT_SUCCESS (status))
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{
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@ -1508,6 +1605,8 @@ fhandler_disk_file::pwrite (void *buf, size_t count, _off64_t offset)
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}
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return io.Information;
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}
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non_atomic:
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/* Text mode stays slow and non-atomic. */
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int res;
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_off64_t curpos = lseek (0, SEEK_CUR);
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