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[PATCH] POSIX ACL support
|
From: |
Romain Francoise |
|
Subject: |
[PATCH] POSIX ACL support |
|
Date: |
Sun, 18 Nov 2012 23:27:22 +0100 |
Hi,
The following patch adds support for preserving POSIX ACL entries of
files, which at the moment are lost when Emacs saves a buffer (unless
`backup-by-copying' is set). This is a similar problem as preserving the
SELinux context, and as a consequence the implementation is also very
similar.
Only the "portable" interface is used, I tested this patch successfully on
GNU/Linux (using libacl) and FreeBSD.
Comments welcome!
Thanks,
diff --git a/configure.ac b/configure.ac
index 1884cc7..fb5d8dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -184,6 +184,7 @@ OPTION_DEFAULT_ON([dbus],[don't compile with D-Bus support])
OPTION_DEFAULT_ON([gconf],[don't compile with GConf support])
OPTION_DEFAULT_ON([gsettings],[don't compile with GSettings support])
OPTION_DEFAULT_ON([selinux],[don't compile with SELinux support])
+OPTION_DEFAULT_ON([acl],[don't compile with ACL support])
OPTION_DEFAULT_ON([gnutls],[don't use -lgnutls for SSL/TLS support])
## For the times when you want to build Emacs but don't have
@@ -2151,6 +2152,24 @@ fi
AC_SUBST(LIBGNUTLS_LIBS)
AC_SUBST(LIBGNUTLS_CFLAGS)
+dnl On GNU/Linux, ACL support is provided by libacl. On BSD,
+dnl ACL support is directly provided by libc.
+HAVE_ACL=no
+LIBACL_LIBS=
+if test "${with_acl}" = "yes"; then
+ AC_CHECK_LIB([acl], [acl_set_file], HAVE_ACL=yes, HAVE_ACL=no)
+ if test "$HAVE_ACL" = yes; then
+ AC_DEFINE(HAVE_ACL, 1, [Define to 1 if using ACL support.])
+ LIBACL_LIBS=-lacl
+ else
+ AC_CHECK_FUNC(acl_set_file, HAVE_ACL=yes, HAVE_ACL=no)
+ if test "$HAVE_ACL" = yes; then
+ AC_DEFINE(HAVE_ACL, 1, [Define to 1 if using ACL support.])
+ fi
+ fi
+fi
+AC_SUBST(LIBACL_LIBS)
+
dnl Do not put whitespace before the #include statements below.
dnl Older compilers (eg sunos4 cc) choke on it.
HAVE_XAW3D=no
@@ -4435,6 +4454,7 @@ echo " Does Emacs use -ldbus?
${HAVE_DBUS}"
echo " Does Emacs use -lgconf? ${HAVE_GCONF}"
echo " Does Emacs use GSettings?
${HAVE_GSETTINGS}"
echo " Does Emacs use -lselinux?
${HAVE_LIBSELINUX}"
+echo " Does Emacs use ACL support? ${HAVE_ACL}"
echo " Does Emacs use -lgnutls? ${HAVE_GNUTLS}"
echo " Does Emacs use -lxml2?
${HAVE_LIBXML2}"
diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index a5710c7..03fe290 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -1350,6 +1350,24 @@ not support SELinux, or if Emacs was not compiled with
SELinux
support, then the return value is @code{(nil nil nil nil)}.
@end defun
address@hidden POSIX ACL
+ Several operating systems, like GNU/Linux and BSD, support
+fine-grained discretionary access rights for files and directories using
+the POSIX ACL interface. If Emacs has been compiled with ACL support,
+you can use the function @code{file-posix-acl} to retrieve a file's ACL
+entries. For the function @code{set-file-posix-acl}, see @ref{Changing
+Files}.
+
address@hidden file-posix-acl filename
+This function returns the POSIX ACL entries of the file @var{filename}.
+The return value is a string containing the textual representation of
+the ACL entries. See the @file{acl} man page for details about this
+representation.
+
+If the file does not exist or is inaccessible, of if Emacs was not
+compiled with ACL support, then the return value is @code{nil}.
address@hidden defun
+
@node Locating Files
@subsection How to Locate Files in Standard Places
@cindex locate file in path
@@ -1542,6 +1560,10 @@ the correct permissions to do so.
If the optional argument @var{preserve-selinux} is address@hidden, and
Emacs has been compiled with SELinux support, this function attempts
to copy the file's SELinux context (@pxref{File Attributes}).
+
+If the optional argument @var{preserve-posix-acl} is address@hidden, and
+Emacs has been compiled with ACL support, this function attempts to copy
+the file's POSIX ACL entries (@pxref{File Attributes}).
@end deffn
@deffn Command make-symbolic-link filename newname &optional ok-if-exists
@@ -1682,6 +1704,14 @@ nothing if SELinux is disabled, or if Emacs was compiled
without
SELinux support.
@end defun
address@hidden set-file-posix-acl filename acl-string
+This function sets the POSIX ACL entries of the file @var{filename} to
address@hidden @xref{File Attributes}, for a brief description of
+POSIX ACLs. The @var{acl-string} argument should be a string containing
+the textual representation of the desired ACL entries. The function
+does nothing if Emacs was compiled without ACL support.
address@hidden defun
+
@node File Names
@section File Names
@cindex file names
diff --git a/lisp/files.el b/lisp/files.el
index 8e8a178..e507894 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3878,13 +3878,14 @@ variable `make-backup-files'. If it's done by
renaming, then the file is
no longer accessible under its old name.
The value is non-nil after a backup was made by renaming.
-It has the form (MODES SELINUXCONTEXT BACKUPNAME).
+It has the form (MODES SELINUXCONTEXT ACL BACKUPNAME).
MODES is the result of `file-modes' on the original
file; this means that the caller, after saving the buffer, should change
the modes of the new file to agree with the old modes.
SELINUXCONTEXT is the result of `file-selinux-context' on the original
file; this means that the caller, after saving the buffer, should change
the SELinux context of the new file to agree with the old context.
+Similarly, ACL is the result of `file-posix-acl' on the original file.
BACKUPNAME is the backup file name, which is the old file renamed."
(if (and make-backup-files (not backup-inhibited)
(not buffer-backed-up)
@@ -3913,7 +3914,8 @@ BACKUPNAME is the backup file name, which is the old file
renamed."
(y-or-n-p (format "Delete excess backup
versions of %s? "
real-file-name)))))
(modes (file-modes buffer-file-name))
- (context (file-selinux-context buffer-file-name)))
+ (context (file-selinux-context buffer-file-name))
+ (acl (file-posix-acl buffer-file-name)))
;; Actually write the back up file.
(condition-case ()
(if (or file-precious-flag
@@ -3933,10 +3935,10 @@ BACKUPNAME is the backup file name, which is the old
file renamed."
(<= (nth 2 attr)
backup-by-copying-when-privileged-mismatch)))
(or (nth 9 attr)
(not (file-ownership-preserved-p
real-file-name)))))))
- (backup-buffer-copy real-file-name backupname modes
context)
+ (backup-buffer-copy real-file-name backupname modes
context acl)
;; rename-file should delete old backup.
(rename-file real-file-name backupname t)
- (setq setmodes (list modes context backupname)))
+ (setq setmodes (list modes context acl backupname)))
(file-error
;; If trouble writing the backup, write it in
;; .emacs.d/%backup%.
@@ -3944,7 +3946,7 @@ BACKUPNAME is the backup file name, which is the old file
renamed."
(message "Cannot write backup file; backing up in %s"
backupname)
(sleep-for 1)
- (backup-buffer-copy real-file-name backupname modes
context)))
+ (backup-buffer-copy real-file-name backupname modes
context acl)))
(setq buffer-backed-up t)
;; Now delete the old versions, if desired.
(if delete-old-versions
@@ -3956,7 +3958,7 @@ BACKUPNAME is the backup file name, which is the old file
renamed."
setmodes)
(file-error nil))))))
-(defun backup-buffer-copy (from-name to-name modes context)
+(defun backup-buffer-copy (from-name to-name modes context acl)
(let ((umask (default-file-modes)))
(unwind-protect
(progn
@@ -3985,7 +3987,9 @@ BACKUPNAME is the backup file name, which is the old file
renamed."
(and modes
(set-file-modes to-name (logand modes #o1777)))
(and context
- (set-file-selinux-context to-name context)))
+ (set-file-selinux-context to-name context))
+ (and acl
+ (set-file-posix-acl to-name acl)))
(defvar file-name-version-regexp
"\\(?:~\\|\\.~[-[:alnum:]:address@hidden(?:~[[:digit:]]+\\)?~\\)"
@@ -4561,7 +4565,8 @@ Before and after saving the buffer, this function runs
(condition-case ()
(progn
(set-file-modes buffer-file-name (car setmodes))
- (set-file-selinux-context buffer-file-name (nth 1
setmodes)))
+ (set-file-selinux-context buffer-file-name (nth 1
setmodes))
+ (set-file-posix-acl buffer-file-name (nth 2 setmodes)))
(error nil))))
;; If the auto-save file was recent before this command,
;; delete it now.
@@ -4574,7 +4579,7 @@ Before and after saving the buffer, this function runs
;; This does the "real job" of writing a buffer into its visited file
;; and making a backup file. This is what is normally done
;; but inhibited if one of write-file-functions returns non-nil.
-;; It returns a value (MODES SELINUXCONTEXT BACKUPNAME), like backup-buffer.
+;; It returns a value (MODES SELINUXCONTEXT ACL BACKUPNAME), like
backup-buffer.
(defun basic-save-buffer-1 ()
(prog1
(if save-buffer-coding-system
@@ -4586,7 +4591,7 @@ Before and after saving the buffer, this function runs
(setq buffer-file-coding-system-explicit
(cons last-coding-system-used nil)))))
-;; This returns a value (MODES SELINUXCONTEXT BACKUPNAME), like backup-buffer.
+;; This returns a value (MODES SELINUXCONTEXT ACL BACKUPNAME), like
backup-buffer.
(defun basic-save-buffer-2 ()
(let (tempsetmodes setmodes)
(if (not (file-writable-p buffer-file-name))
@@ -4659,9 +4664,10 @@ Before and after saving the buffer, this function runs
;; Since we have created an entirely new file,
;; make sure it gets the right permission bits set.
(setq setmodes (or setmodes
- (list (or (file-modes buffer-file-name)
+ (list (or (file-modes buffer-file-name)
(logand ?\666 umask))
(file-selinux-context buffer-file-name)
+ (file-posix-acl buffer-file-name)
buffer-file-name)))
;; We succeeded in writing the temp file,
;; so rename it.
@@ -4674,9 +4680,11 @@ Before and after saving the buffer, this function runs
;; Change the mode back, after writing.
(setq setmodes (list (file-modes buffer-file-name)
(file-selinux-context buffer-file-name)
+ (file-posix-acl buffer-file-name)
buffer-file-name))
(set-file-modes buffer-file-name (logior (car setmodes) 128))
- (set-file-selinux-context buffer-file-name (nth 1 setmodes)))))
+ (set-file-selinux-context buffer-file-name (nth 1 setmodes))
+ (set-file-posix-acl (nth 2 setmodes)))))
(let (success)
(unwind-protect
(progn
@@ -4690,7 +4698,7 @@ Before and after saving the buffer, this function runs
;; the backup by renaming, undo the backing-up.
(and setmodes (not success)
(progn
- (rename-file (nth 2 setmodes) buffer-file-name t)
+ (rename-file (nth 3 setmodes) buffer-file-name t)
(setq buffer-backed-up nil))))))
setmodes))
diff --git a/src/Makefile.in b/src/Makefile.in
index d034ad0..060d62a 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -283,6 +283,8 @@ LIBSELINUX_LIBS = @LIBSELINUX_LIBS@
LIBGNUTLS_LIBS = @LIBGNUTLS_LIBS@
LIBGNUTLS_CFLAGS = @LIBGNUTLS_CFLAGS@
+LIBACL_LIBS = @LIBACL_LIBS@
+
LIB_PTHREAD_SIGMASK = @LIB_PTHREAD_SIGMASK@
INTERVALS_H = dispextern.h intervals.h composite.h
@@ -398,7 +400,7 @@ LIBES = $(LIBS) $(W32_LIBS) $(LIBX_BASE) $(LIBIMAGE) \
$(LIBXML2_LIBS) $(LIBGPM) $(LIBRESOLV) $(LIBS_SYSTEM) \
$(LIBS_TERMCAP) $(GETLOADAVG_LIBS) $(SETTINGS_LIBS) $(LIBSELINUX_LIBS) \
$(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
- $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(LIB_PTHREAD_SIGMASK) \
+ $(LIBACL_LIBS) $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(LIB_PTHREAD_SIGMASK) \
$(LIB_GCC) $(LIB_MATH) $(LIB_STANDARD) $(LIB_GCC)
all: emacs$(EXEEXT) $(OTHER_FILES)
diff --git a/src/fileio.c b/src/fileio.c
index 572f6d8..7654668 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -36,6 +36,10 @@ along with GNU Emacs. If not, see
<http://www.gnu.org/licenses/>. */
#include <selinux/context.h>
#endif
+#ifdef HAVE_ACL
+#include <sys/acl.h>
+#endif
+
#include <c-ctype.h>
#include "lisp.h"
@@ -236,6 +240,8 @@ static Lisp_Object Qset_file_modes;
static Lisp_Object Qset_file_times;
static Lisp_Object Qfile_selinux_context;
static Lisp_Object Qset_file_selinux_context;
+static Lisp_Object Qfile_posix_acl;
+static Lisp_Object Qset_file_posix_acl;
static Lisp_Object Qfile_newer_than_file_p;
Lisp_Object Qinsert_file_contents;
Lisp_Object Qwrite_region;
@@ -1829,7 +1835,7 @@ barf_or_query_if_file_exists (Lisp_Object absname, const
char *querystring,
return;
}
-DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6,
+DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 7,
"fCopy file: \nGCopy %s to file: \np\nP",
doc: /* Copy FILE to NEWNAME. Both args must be strings.
If NEWNAME names a directory, copy FILE there.
@@ -1854,8 +1860,11 @@ If PRESERVE-UID-GID is non-nil, we try to transfer the
uid and gid of FILE to NEWNAME.
If PRESERVE-SELINUX-CONTEXT is non-nil and SELinux is enabled
-on the system, we copy the SELinux context of FILE to NEWNAME. */)
- (Lisp_Object file, Lisp_Object newname, Lisp_Object ok_if_already_exists,
Lisp_Object keep_time, Lisp_Object preserve_uid_gid, Lisp_Object
preserve_selinux_context)
+on the system, we copy the SELinux context of FILE to NEWNAME.
+
+If PRESERVE-POSIX-ACL is non-nil and Emacs is built with ACL support,
+we copy the ACL of FILE to NEWNAME. */)
+ (Lisp_Object file, Lisp_Object newname, Lisp_Object ok_if_already_exists,
Lisp_Object keep_time, Lisp_Object preserve_uid_gid, Lisp_Object
preserve_selinux_context, Lisp_Object preserve_posix_acl)
{
int ifd, ofd;
int n;
@@ -1870,6 +1879,9 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
security_context_t con;
int conlength = 0;
#endif
+#ifdef HAVE_ACL
+ acl_t acl = NULL;
+#endif
encoded_file = encoded_newname = Qnil;
GCPRO4 (file, newname, encoded_file, encoded_newname);
@@ -1955,6 +1967,15 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
}
#endif
+#ifdef HAVE_ACL
+ if (!NILP (preserve_posix_acl))
+ {
+ acl = acl_get_fd (ifd);
+ if (acl == NULL && errno != ENOTSUP)
+ report_file_error ("Getting ACL", Fcons (file, Qnil));
+ }
+#endif
+
if (out_st.st_mode != 0
&& st.st_dev == out_st.st_dev && st.st_ino == out_st.st_ino)
{
@@ -2045,6 +2066,17 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
}
#endif
+#ifdef HAVE_ACL
+ if (acl != NULL)
+ {
+ bool fail = acl_set_fd (ofd, acl) != 0;
+ if (fail && errno != ENOTSUP)
+ report_file_error ("Setting ACL", Fcons (newname, Qnil));
+
+ acl_free (acl);
+ }
+#endif
+
if (input_file_statable_p)
{
if (!NILP (keep_time))
@@ -2262,7 +2294,7 @@ This is what happens in interactive use with M-x. */)
have copy-file prompt again. */
Fcopy_file (file, newname,
NILP (ok_if_already_exists) ? Qnil : Qt,
- Qt, Qt, Qt);
+ Qt, Qt, Qt, Qt);
count = SPECPDL_INDEX ();
specbind (Qdelete_by_moving_to_trash, Qnil);
@@ -2934,6 +2966,104 @@ compiled with SELinux support. */)
return Qnil;
}
+DEFUN ("file-posix-acl", Ffile_posix_acl, Sfile_posix_acl, 1, 1, 0,
+ doc: /* Return POSIX ACL entries of file named FILENAME, as a string.
+Return nil if file does not exist or is not accessible, or if Emacs was
+not compiled with ACL support. */)
+ (Lisp_Object filename)
+{
+ Lisp_Object absname;
+ Lisp_Object handler;
+#ifdef HAVE_ACL
+ acl_t acl;
+ Lisp_Object acl_string;
+ char *str;
+#endif
+
+ absname = expand_and_dir_to_file (filename,
+ BVAR (current_buffer, directory));
+
+ /* If the file name has special constructs in it,
+ call the corresponding file handler. */
+ handler = Ffind_file_name_handler (absname, Qfile_posix_acl);
+ if (!NILP (handler))
+ return call2 (handler, Qfile_posix_acl, absname);
+
+#ifdef HAVE_ACL
+ absname = ENCODE_FILE (absname);
+
+ acl = acl_get_file (SSDATA (absname), ACL_TYPE_ACCESS);
+ if (acl == NULL)
+ return Qnil;
+
+ str = acl_to_text (acl, NULL);
+ if (str == NULL)
+ {
+ acl_free (acl);
+ return Qnil;
+ }
+
+ acl_string = build_string (str);
+ acl_free (str);
+ acl_free (acl);
+
+ return acl_string;
+#endif
+
+ return Qnil;
+}
+
+DEFUN ("set-file-posix-acl", Fset_file_posix_acl, Sset_file_posix_acl,
+ 2, 2, 0,
+ doc: /* Set POSIX ACL of file named FILENAME to ACL-STRING.
+ACL-STRING should contain the textual representation of the ACL
+entries in either long or short form.
+
+This function does nothing if Emacs was not compiled with ACL
+support. */)
+ (Lisp_Object filename, Lisp_Object acl_string)
+{
+ Lisp_Object absname;
+ Lisp_Object handler;
+#ifdef HAVE_ACL
+ Lisp_Object encoded_absname;
+ acl_t acl;
+ bool fail;
+#endif
+
+ absname = Fexpand_file_name (filename, BVAR (current_buffer, directory));
+
+ /* If the file name has special constructs in it,
+ call the corresponding file handler. */
+ handler = Ffind_file_name_handler (absname, Qset_file_posix_acl);
+ if (!NILP (handler))
+ return call3 (handler, Qset_file_posix_acl, absname, acl_string);
+
+#ifdef HAVE_ACL
+ if (STRINGP (acl_string))
+ {
+ acl = acl_from_text (SSDATA (acl_string));
+ if (acl == NULL)
+ {
+ report_file_error ("Converting ACL", Fcons (absname, Qnil));
+ return Qnil;
+ }
+
+ encoded_absname = ENCODE_FILE (absname);
+
+ fail = (acl_set_file (SSDATA (encoded_absname), ACL_TYPE_ACCESS,
+ acl)
+ != 0);
+ if (fail && errno != ENOTSUP)
+ report_file_error ("Setting ACL", Fcons (absname, Qnil));
+
+ acl_free (acl);
+ }
+#endif
+
+ return Qnil;
+}
+
DEFUN ("file-modes", Ffile_modes, Sfile_modes, 1, 1, 0,
doc: /* Return mode bits of file named FILENAME, as an integer.
Return nil, if file does not exist or is not accessible. */)
@@ -5812,6 +5942,8 @@ This includes interactive calls to `delete-file' and
defsubr (&Sset_file_modes);
defsubr (&Sset_file_times);
defsubr (&Sfile_selinux_context);
+ defsubr (&Sfile_posix_acl);
+ defsubr (&Sset_file_posix_acl);
defsubr (&Sset_file_selinux_context);
defsubr (&Sset_default_file_modes);
defsubr (&Sdefault_file_modes);
- [PATCH] POSIX ACL support,
Romain Francoise <=