Implement CLASH_DETECTION for MS-Windows.
src/filelock.c [WINDOWSNT]: Include w32.h. (MAKE_LOCK_NAME): Don't use 'lock', it clashes with MS runtime function of that name. Up-case the macro arguments. (IS_LOCK_FILE): New macro. (fill_in_lock_file_name): Use IS_LOCK_FILE instead of S_ISLNK. (create_lock_file): New function, with body extracted from lock_file_1. [WINDOWSNT]: Implement lock files by writing a regular file with the lock information as its contents. (read_lock_data): New function, on Posix platforms just calls emacs_readlinkat. [WINDOWSNT]: Read the lock info from the file. (current_lock_owner): Call read_lock_data instead of calling emacs_readlinkat directly. (lock_file) [WINDOWSNT]: Run the file name through dostounix_filename. src/w32proc.c (sys_kill): Support the case of SIG = 0, in which case just check if the process by that PID exists. src/w32.c (sys_open): Don't reset the _O_CREAT flag if _O_EXCL is also present, as doing so will fail to error out if the file already exists. src/makefile.w32-in ($(BLD)/filelock.$(O)): Depend on src/w32.h. nt/inc/ms-w32.h (BOOT_TIME_FILE): Define. nt/config.nt (CLASH_DETECTION): Define to 1. lisp/emacs-lisp/bytecomp.el (byte-recompile-directory): Reject files that match "\`\.#", to avoid compiling lock files, even if they are readable (as they are on MS-Windows). doc/emacs/files.texi (Interlocking): Don't refer to symlinks as the exclusive means of locking files. etc/NEWS: Mention support for lock files on MS-Windows.
This commit is contained in:
Eli Zaretskii
parent
aec32f66d0
commit
343a2aefb5
13 changed files with 215 additions and 34 deletions
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@ -1,3 +1,8 @@
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2013-02-25 Eli Zaretskii <eliz@gnu.org>
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* files.texi (Interlocking): Don't refer to symlinks as the
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exclusive means of locking files.
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2013-02-22 Glenn Morris <rgm@gnu.org>
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* ack.texi (Acknowledgments):
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@ -734,10 +734,10 @@ file.
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@cindex locking files
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When you make the first modification in an Emacs buffer that is
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visiting a file, Emacs records that the file is @dfn{locked} by you.
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(It does this by creating a specially-named symbolic link in the same
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directory.) Emacs removes the lock when you save the changes. The
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idea is that the file is locked whenever an Emacs buffer visiting it
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has unsaved changes.
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(It does this by creating a specially-named symbolic link or regular
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file with special contents in the same directory.) Emacs removes the
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lock when you save the changes. The idea is that the file is locked
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whenever an Emacs buffer visiting it has unsaved changes.
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@vindex create-lockfiles
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You can prevent the creation of lock files by setting the variable
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@ -774,14 +774,14 @@ multiple names, Emacs does not prevent two users from editing it
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simultaneously under different names.
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A lock file cannot be written in some circumstances, e.g., if Emacs
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lacks the system permissions or the system does not support symbolic
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links. In these cases, Emacs can still detect the collision when you
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try to save a file, by checking the file's last-modification date. If
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the file has changed since the last time Emacs visited or saved it,
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that implies that changes have been made in some other way, and will
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be lost if Emacs proceeds with saving. Emacs then displays a warning
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message and asks for confirmation before saving; answer @kbd{yes} to
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save, and @kbd{no} or @kbd{C-g} cancel the save.
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lacks the system permissions or cannot create lock files for some
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other reason. In these cases, Emacs can still detect the collision
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when you try to save a file, by checking the file's last-modification
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date. If the file has changed since the last time Emacs visited or
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saved it, that implies that changes have been made in some other way,
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and will be lost if Emacs proceeds with saving. Emacs then displays a
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warning message and asks for confirmation before saving; answer
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@kbd{yes} to save, and @kbd{no} or @kbd{C-g} cancel the save.
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If you are notified that simultaneous editing has already taken
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place, one way to compare the buffer to its file is the @kbd{M-x
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7
etc/NEWS
7
etc/NEWS
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@ -348,6 +348,13 @@ Setting it has no effect, and %t in the mode-line format is ignored.
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Likewise, `file-name-buffer-file-type-alist' is now obsolete, and
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modifying it has no effect.
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---
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** Lock files now work on MS-Windows.
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This allows to avoid losing your edits if the same file is being
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edited in another Emacs session or by another user. See the node
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"Interlocking" in the Emacs User Manual for the details. To disable
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file locking, customize `create-lockfiles' to nil.
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** Improved fullscreen support on Mac OS X.
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Both native (>= OSX 10.7) and "old style" fullscreen are supported.
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Customize `ns-use-native-fullscreen' to change style. For >= 10.7
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@ -1,3 +1,9 @@
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2013-02-25 Eli Zaretskii <eliz@gnu.org>
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* emacs-lisp/bytecomp.el (byte-recompile-directory): Reject files
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that match "\`\.#", to avoid compiling lock files, even if they
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are readable (as they are on MS-Windows).
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2013-02-25 Stefan Monnier <monnier@iro.umontreal.ca>
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* files.el (basic-save-buffer): Remove redundant directory-creation.
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@ -1594,7 +1594,9 @@ that already has a `.elc' file."
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(setq directories (nconc directories (list source))))
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;; It is an ordinary file. Decide whether to compile it.
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(if (and (string-match emacs-lisp-file-regexp source)
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;; The next 2 tests avoid compiling lock files
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(file-readable-p source)
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(not (string-match "\\`\\.#" file))
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(not (auto-save-file-name-p source))
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(not (string-equal dir-locals-file
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(file-name-nondirectory source))))
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@ -1,3 +1,9 @@
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2013-02-25 Eli Zaretskii <eliz@gnu.org>
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* inc/ms-w32.h (BOOT_TIME_FILE): Define.
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* config.nt (CLASH_DETECTION): Define to 1.
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2013-02-16 Eli Zaretskii <eliz@gnu.org>
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* inc/ms-w32.h (__STDC__): Fiddle with value only for MSVC.
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@ -75,7 +75,7 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
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/* Define if you want lock files to be written, so that Emacs can tell
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instantly when you try to modify a file that someone else has modified in
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his/her Emacs. */
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#undef CLASH_DETECTION
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#define CLASH_DETECTION 1
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/* Short copyright string for this version of Emacs. */
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#define COPYRIGHT "Copyright (C) 2013 Free Software Foundation, Inc."
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@ -70,6 +70,18 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
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#define HAVE___BUILTIN_UNWIND_INIT 1
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#endif
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/* This isn't perfect, as some systems might have the page file in
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another place. Also, I suspect that the time stamp of that file
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might also change when Windows enlarges the file due to
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insufficient VM. Still, this seems to be the most reliable way;
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the alternative (of using GetSystemTimes) won't work on laptops
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that hibernate, because the system clock is stopped then. Other
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possibility would be to run "net statistics workstation" and parse
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the output, but that's gross. So this should do; if the file is
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not there, the boot time will be returned as zero, and filelock.c
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already handles that. */
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#define BOOT_TIME_FILE "C:/pagefile.sys"
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/* ============================================================ */
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/* Here, add any special hacks needed to make Emacs work on this
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@ -1,5 +1,33 @@
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2013-02-25 Eli Zaretskii <eliz@gnu.org>
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Implement CLASH_DETECTION for MS-Windows.
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* filelock.c [WINDOWSNT]: Include w32.h.
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(MAKE_LOCK_NAME): Don't use 'lock', it clashes with MS runtime
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function of that name. Up-case the macro arguments.
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(IS_LOCK_FILE): New macro.
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(fill_in_lock_file_name): Use IS_LOCK_FILE instead of S_ISLNK.
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(create_lock_file): New function, with body extracted from
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lock_file_1.
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[WINDOWSNT]: Implement lock files by writing a regular file with
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the lock information as its contents.
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(read_lock_data): New function, on Posix platforms just calls
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emacs_readlinkat.
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[WINDOWSNT]: Read the lock info from the file.
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(current_lock_owner): Call read_lock_data instead of calling
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emacs_readlinkat directly.
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(lock_file) [WINDOWSNT]: Run the file name through
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dostounix_filename.
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* w32proc.c (sys_kill): Support the case of SIG = 0, in which case
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just check if the process by that PID exists.
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* w32.c (sys_open): Don't reset the _O_CREAT flag if _O_EXCL is
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also present, as doing so will fail to error out if the file
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already exists.
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* makefile.w32-in ($(BLD)/filelock.$(O)): Depend on src/w32.h.
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* textprop.c (Fadd_text_properties, Fremove_text_properties)
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(Fremove_list_of_text_properties): Skip all of the intervals in
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the region between START and END that already have resp. don't
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113
src/filelock.c
113
src/filelock.c
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@ -43,6 +43,9 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
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#include "buffer.h"
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#include "coding.h"
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#include "systime.h"
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#ifdef WINDOWSNT
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#include "w32.h" /* for dostounix_filename */
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#endif
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#ifdef CLASH_DETECTION
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@ -288,13 +291,22 @@ typedef struct
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#define FREE_LOCK_INFO(i) do { xfree ((i).user); xfree ((i).host); } while (0)
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/* Write the name of the lock file for FN into LFNAME. Length will be
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that of FN plus two more for the leading `.#' plus 1 for the
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trailing period plus one for the digit after it plus one for the
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null. */
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#define MAKE_LOCK_NAME(lock, file) \
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(lock = alloca (SBYTES (file) + 2 + 1 + 1 + 1), \
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fill_in_lock_file_name (lock, (file)))
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/* Write the name of the lock file for FNAME into LOCKNAME. Length
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will be that of FN plus two more for the leading `.#' plus 1 for
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the trailing period plus one for the digit after it plus one for
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the null. */
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#define MAKE_LOCK_NAME(LOCKNAME, FNAME) \
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(LOCKNAME = alloca (SBYTES (FNAME) + 2 + 1 + 1 + 1), \
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fill_in_lock_file_name (LOCKNAME, (FNAME)))
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#ifdef WINDOWSNT
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/* 256 chars for user, 1024 chars for host, 10 digits for each of 2 int's. */
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#define MAX_LFINFO (256 + 1024 + 10 + 10 + 2)
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/* min size: .@PID */
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#define IS_LOCK_FILE(ST) (MAX_LFINFO >= (ST).st_size && (ST).st_size >= 3)
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#else
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#define IS_LOCK_FILE(ST) S_ISLNK ((ST).st_mode)
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#endif
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static void
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fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn)
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@ -318,7 +330,7 @@ fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn)
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p = lockfile + length + 2;
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while (lstat (lockfile, &st) == 0 && !S_ISLNK (st.st_mode))
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while (lstat (lockfile, &st) == 0 && !IS_LOCK_FILE (st))
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{
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if (count > 9)
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{
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@ -329,6 +341,49 @@ fill_in_lock_file_name (register char *lockfile, register Lisp_Object fn)
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}
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}
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static int
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create_lock_file (char *lfname, char *lock_info_str, bool force)
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{
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int err;
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#ifdef WINDOWSNT
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/* Symlinks are supported only by latest versions of Windows, and
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creating them is a privileged operation that often triggers UAC
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elevation prompts. Therefore, instead of using symlinks, we
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create a regular file with the lock info written as its
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contents. */
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{
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int fd = emacs_open (lfname, O_WRONLY | O_BINARY | O_CREAT | O_EXCL,
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S_IREAD | S_IWRITE);
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if (fd < 0 && errno == EEXIST && force)
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fd = emacs_open (lfname, O_WRONLY | O_BINARY | O_TRUNC,
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S_IREAD | S_IWRITE);
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if (fd >= 0)
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{
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ssize_t lock_info_len = strlen (lock_info_str);
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err = 0;
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if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len)
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err = -1;
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if (emacs_close (fd))
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err = -1;
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}
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else
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err = -1;
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}
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#else
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err = symlink (lock_info_str, lfname);
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if (errno == EEXIST && force)
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{
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unlink (lfname);
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err = symlink (lock_info_str, lfname);
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}
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#endif
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return err;
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}
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/* Lock the lock file named LFNAME.
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If FORCE, do so even if it is already locked.
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Return true if successful. */
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@ -355,13 +410,7 @@ lock_file_1 (char *lfname, bool force)
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esprintf (lock_info_str, boot ? "%s@%s.%"pMd":%"pMd : "%s@%s.%"pMd,
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user_name, host_name, pid, boot);
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err = symlink (lock_info_str, lfname);
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if (errno == EEXIST && force)
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{
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unlink (lfname);
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err = symlink (lock_info_str, lfname);
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}
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err = create_lock_file (lfname, lock_info_str, force);
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symlink_errno = errno;
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SAFE_FREE ();
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@ -377,6 +426,32 @@ within_one_second (time_t a, time_t b)
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return (a - b >= -1 && a - b <= 1);
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}
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static Lisp_Object
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read_lock_data (char *lfname)
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{
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#ifndef WINDOWSNT
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return emacs_readlinkat (AT_FDCWD, lfname);
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#else
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int fd = emacs_open (lfname, O_RDONLY | O_BINARY, S_IREAD);
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ssize_t nbytes;
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char lfinfo[MAX_LFINFO + 1];
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if (fd < 0)
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return Qnil;
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nbytes = emacs_read (fd, lfinfo, MAX_LFINFO);
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emacs_close (fd);
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if (nbytes > 0)
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{
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lfinfo[nbytes] = '\0';
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return build_string (lfinfo);
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}
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else
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return Qnil;
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#endif
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}
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/* Return 0 if nobody owns the lock file LFNAME or the lock is obsolete,
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1 if another process owns it (and set OWNER (if non-null) to info),
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2 if the current process owns it,
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@ -390,7 +465,7 @@ current_lock_owner (lock_info_type *owner, char *lfname)
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lock_info_type local_owner;
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intmax_t n;
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char *at, *dot, *colon;
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Lisp_Object lfinfo_object = emacs_readlinkat (AT_FDCWD, lfname);
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Lisp_Object lfinfo_object = read_lock_data (lfname);
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char *lfinfo;
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struct gcpro gcpro1;
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@ -552,6 +627,12 @@ lock_file (Lisp_Object fn)
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orig_fn = fn;
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GCPRO1 (fn);
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fn = Fexpand_file_name (fn, Qnil);
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#ifdef WINDOWSNT
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/* Ensure we have only '/' separators, to avoid problems with
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looking (inside fill_in_lock_file_name) for backslashes in file
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names encoded by some DBCS codepage. */
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dostounix_filename (SSDATA (fn), 1);
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#endif
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encoded_fn = ENCODE_FILE (fn);
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/* Create the name of the lock-file for file fn */
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@ -864,6 +864,7 @@ $(BLD)/fileio.$(O) : \
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$(BLD)/filelock.$(O) : \
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$(SRC)/filelock.c \
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$(SRC)/w32.h \
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$(NT_INC)/pwd.h \
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$(NT_INC)/sys/file.h \
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$(NT_INC)/sys/stat.h \
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11
src/w32.c
11
src/w32.c
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@ -3402,10 +3402,13 @@ int
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sys_open (const char * path, int oflag, int mode)
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{
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const char* mpath = map_w32_filename (path, NULL);
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/* Try to open file without _O_CREAT, to be able to write to hidden
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and system files. Force all file handles to be
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non-inheritable. */
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int res = _open (mpath, (oflag & ~_O_CREAT) | _O_NOINHERIT, mode);
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int res = -1;
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/* If possible, try to open file without _O_CREAT, to be able to
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write to existing hidden and system files. Force all file
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handles to be non-inheritable. */
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if ((oflag & (_O_CREAT | _O_EXCL)) != (_O_CREAT | _O_EXCL))
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res = _open (mpath, (oflag & ~_O_CREAT) | _O_NOINHERIT, mode);
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if (res < 0)
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res = _open (mpath, oflag | _O_NOINHERIT, mode);
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if (res >= 0 && res < MAXDESC)
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|
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@ -2263,12 +2263,42 @@ sys_kill (pid_t pid, int sig)
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pid = -pid;
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/* Only handle signals that will result in the process dying */
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if (sig != SIGINT && sig != SIGKILL && sig != SIGQUIT && sig != SIGHUP)
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if (sig != 0
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||||
&& sig != SIGINT && sig != SIGKILL && sig != SIGQUIT && sig != SIGHUP)
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{
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errno = EINVAL;
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return -1;
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}
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|
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if (sig == 0)
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{
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/* It will take _some_ time before PID 4 or less on Windows will
|
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be Emacs... */
|
||||
if (pid <= 4)
|
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{
|
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errno = EPERM;
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return -1;
|
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}
|
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proc_hand = OpenProcess (PROCESS_QUERY_INFORMATION, 0, pid);
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if (proc_hand == NULL)
|
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{
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DWORD err = GetLastError ();
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|
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switch (err)
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{
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case ERROR_ACCESS_DENIED: /* existing process, but access denied */
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errno = EPERM;
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return -1;
|
||||
case ERROR_INVALID_PARAMETER: /* process PID does not exist */
|
||||
errno = ESRCH;
|
||||
return -1;
|
||||
}
|
||||
}
|
||||
else
|
||||
CloseHandle (proc_hand);
|
||||
return 0;
|
||||
}
|
||||
|
||||
cp = find_child_pid (pid);
|
||||
if (cp == NULL)
|
||||
{
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue