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[PATCH v2] POSIX ACL support
|
From: |
Romain Francoise |
|
Subject: |
[PATCH v2] POSIX ACL support |
|
Date: |
Sun, 02 Dec 2012 21:04:19 +0100 |
Hi,
Thanks to everyone who commented on the first version of this patch.
This is another iteration with the following changes:
- C-level functions renamed to `file-acl' and `set-file-acl' in hope that
they can be used with non-POSIX ACL implementations; conversely the
parts of the implementation that are POSIX ACL specific are now inside
HAVE_POSIX_ACL
- the additional argument to `copy-file' has been dropped, the existing
argument `preserve-selinux-context' has been turned into a more generic
`preserve-extended-attributes' argument which does both SELinux and ACL
- new functions `file-extended-attributes' and `set-file-extended-attributes'
have been added to make the implementation cleaner in files.el, handling
both SELinux context and ACL entries (do they need to be documented in
the Elisp manual?)
Tested again on GNU/Linux with libacl, and FreeBSD.
Comments welcome!
Thanks,
diff --git a/configure.ac b/configure.ac
index 085ca83..7d533fa 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
@@ -2170,6 +2171,23 @@ fi
AC_SUBST(LIBGNUTLS_LIBS)
AC_SUBST(LIBGNUTLS_CFLAGS)
+dnl POSIX ACL support: provided by libacl on GNU/Linux, by libc on FreeBSD.
+HAVE_POSIX_ACL=no
+LIBACL_LIBS=
+if test "${with_acl}" = "yes"; then
+ AC_CHECK_LIB([acl], [acl_set_file], HAVE_POSIX_ACL=yes, HAVE_POSIX_ACL=no)
+ if test "$HAVE_POSIX_ACL" = yes; then
+ AC_DEFINE(HAVE_POSIX_ACL, 1, [Define to 1 if using POSIX ACL support.])
+ LIBACL_LIBS=-lacl
+ else
+ AC_CHECK_FUNC(acl_set_file, HAVE_POSIX_ACL=yes, HAVE_POSIX_ACL=no)
+ if test "$HAVE_POSIX_ACL" = yes; then
+ AC_DEFINE(HAVE_POSIX_ACL, 1, [Define to 1 if using POSIX 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
diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index a5710c7..ce2ebee 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -1350,6 +1350,22 @@ 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 ACL entries
+ If Emacs has been compiled with ACL support, you can use the function
address@hidden to retrieve a file's ACL entries. The format is
+platform-specific; on GNU/Linux and BSD, Emacs uses the POSIX ACL
+interface. For the function @code{set-file-acl}, see @ref{Changing
+Files}.
+
address@hidden file-acl filename
+This function returns the ACL entries of the file @var{filename}.
+The return value is a string containing the textual representation of
+the ACL entries.
+
+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
@@ -1539,9 +1555,10 @@ address@hidden, we attempt to copy the user and group
ownership of the
file. This works only on some operating systems, and only if you have
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-extended-attributes} is
address@hidden, and Emacs has been built with the appropriate support,
+this function attempts to copy the file's extended attributes, such as
+its SELinux context and ACL entries (@pxref{File Attributes}).
@end deffn
@deffn Command make-symbolic-link filename newname &optional ok-if-exists
@@ -1682,6 +1699,14 @@ nothing if SELinux is disabled, or if Emacs was compiled
without
SELinux support.
@end defun
address@hidden set-file-acl filename acl-string
+This function sets the ACL entries of the file @var{filename} to
address@hidden @xref{File Attributes}, for a brief description of
+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 1bb140c..0bcdc7d 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3878,6 +3878,27 @@ Interactively, confirmation is required unless you
supply a prefix argument."
;; the one at the old location.
(vc-find-file-hook))
+(defun file-extended-attributes (filename)
+ "Return an alist of extended attributes of file FILENAME.
+
+Extended attributes are platform-specific metadata about the file,
+such as SELinux context, list of ACL entries, etc."
+ `((acl . ,(file-acl filename))
+ (selinux-context . ,(file-selinux-context filename))))
+
+(defun set-file-extended-attributes (filename attributes)
+ "Set extended attributes of file FILENAME to ATTRIBUTES.
+
+ATTRIBUTES must be an alist of file attributes as returned by
+`file-extended-attributes'."
+ (dolist (elt attributes)
+ (let ((attr (car elt))
+ (val (cdr elt)))
+ (cond ((eq attr 'acl)
+ (set-file-acl filename val))
+ ((eq attr 'selinux-context)
+ (set-file-selinux-context filename val))))))
+
(defun backup-buffer ()
"Make a backup of the disk file visited by the current buffer, if
appropriate.
This is normally done before saving the buffer the first time.
@@ -3887,13 +3908,14 @@ 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 EXTENDED-ATTRIBUTES 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.
+EXTENDED-ATTRIBUTES is the result of `file-extended-attributes'
+on the original file; this means that the caller, after saving
+the buffer, should change the extended attributes of the new file
+to agree with the old attributes.
BACKUPNAME is the backup file name, which is the old file renamed."
(if (and make-backup-files (not backup-inhibited)
(not buffer-backed-up)
@@ -3922,7 +3944,8 @@ 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)))
+ (extended-attributes
+ (file-extended-attributes buffer-file-name)))
;; Actually write the back up file.
(condition-case ()
(if (or file-precious-flag
@@ -3942,10 +3965,12 @@ 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 extended-attributes)
;; rename-file should delete old backup.
(rename-file real-file-name backupname t)
- (setq setmodes (list modes context backupname)))
+ (setq setmodes (list modes extended-attributes
+ backupname)))
(file-error
;; If trouble writing the backup, write it in
;; .emacs.d/%backup%.
@@ -3953,7 +3978,8 @@ 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 extended-attributes)))
(setq buffer-backed-up t)
;; Now delete the old versions, if desired.
(if delete-old-versions
@@ -3965,7 +3991,7 @@ 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 extended-attributes)
(let ((umask (default-file-modes)))
(unwind-protect
(progn
@@ -3993,8 +4019,8 @@ BACKUPNAME is the backup file name, which is the old file
renamed."
(set-default-file-modes umask)))
(and modes
(set-file-modes to-name (logand modes #o1777)))
- (and context
- (set-file-selinux-context to-name context)))
+ (and extended-attributes
+ (set-file-extended-attributes to-name extended-attributes)))
(defvar file-name-version-regexp
"\\(?:~\\|\\.~[-[:alnum:]:address@hidden(?:~[[:digit:]]+\\)?~\\)"
@@ -4570,7 +4596,8 @@ 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-extended-attributes buffer-file-name
+ (nth 1 setmodes)))
(error nil))))
;; If the auto-save file was recent before this command,
;; delete it now.
@@ -4583,7 +4610,8 @@ 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 EXTENDED-ATTRIBUTES BACKUPNAME), like
+;; backup-buffer.
(defun basic-save-buffer-1 ()
(prog1
(if save-buffer-coding-system
@@ -4595,7 +4623,8 @@ 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 EXTENDED-ATTRIBUTES BACKUPNAME), like
+;; backup-buffer.
(defun basic-save-buffer-2 ()
(let (tempsetmodes setmodes)
(if (not (file-writable-p buffer-file-name))
@@ -4670,7 +4699,7 @@ Before and after saving the buffer, this function runs
(setq setmodes (or setmodes
(list (or (file-modes buffer-file-name)
(logand ?\666 umask))
- (file-selinux-context buffer-file-name)
+ (file-extended-attributes buffer-file-name)
buffer-file-name)))
;; We succeeded in writing the temp file,
;; so rename it.
@@ -4682,10 +4711,10 @@ Before and after saving the buffer, this function runs
(cond ((and tempsetmodes (not setmodes))
;; Change the mode back, after writing.
(setq setmodes (list (file-modes buffer-file-name)
- (file-selinux-context buffer-file-name)
+ (file-extended-attributes 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-extended-attributes buffer-file-name (nth 1
setmodes)))))
(let (success)
(unwind-protect
(progn
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 48dbf20..9b5d96a 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_POSIX_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_acl;
+static Lisp_Object Qset_file_acl;
static Lisp_Object Qfile_newer_than_file_p;
Lisp_Object Qinsert_file_contents;
Lisp_Object Qwrite_region;
@@ -1881,9 +1887,10 @@ A prefix arg makes KEEP-TIME non-nil.
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)
+If PRESERVE-EXTENDED-ATTRIBUTES is non-nil, we try to copy additional
+attributes of FILE to NEWNAME, such as its SELinux context and ACL
+entries (depending on how Emacs was built). */)
+ (Lisp_Object file, Lisp_Object newname, Lisp_Object ok_if_already_exists,
Lisp_Object keep_time, Lisp_Object preserve_uid_gid, Lisp_Object
preserve_extended_attributes)
{
int ifd, ofd;
int n;
@@ -1898,6 +1905,9 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
security_context_t con;
int conlength = 0;
#endif
+#ifdef HAVE_POSIX_ACL
+ acl_t acl = NULL;
+#endif
encoded_file = encoded_newname = Qnil;
GCPRO4 (file, newname, encoded_file, encoded_newname);
@@ -1920,7 +1930,7 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
if (!NILP (handler))
RETURN_UNGCPRO (call7 (handler, Qcopy_file, file, newname,
ok_if_already_exists, keep_time, preserve_uid_gid,
- preserve_selinux_context));
+ preserve_extended_attributes));
encoded_file = ENCODE_FILE (file);
encoded_newname = ENCODE_FILE (newname);
@@ -1974,14 +1984,23 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
copyable by us. */
input_file_statable_p = (fstat (ifd, &st) >= 0);
-#if HAVE_LIBSELINUX
- if (!NILP (preserve_selinux_context) && is_selinux_enabled ())
+ if (!NILP (preserve_extended_attributes))
{
- conlength = fgetfilecon (ifd, &con);
- if (conlength == -1)
- report_file_error ("Doing fgetfilecon", Fcons (file, Qnil));
- }
+#if HAVE_LIBSELINUX
+ if (is_selinux_enabled ())
+ {
+ conlength = fgetfilecon (ifd, &con);
+ if (conlength == -1)
+ report_file_error ("Doing fgetfilecon", Fcons (file, Qnil));
+ }
+#endif
+
+#ifdef HAVE_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)
@@ -2071,6 +2090,17 @@ on the system, we copy the SELinux context of FILE to
NEWNAME. */)
}
#endif
+#ifdef HAVE_POSIX_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))
@@ -2960,6 +2990,104 @@ compiled with SELinux support. */)
return Qnil;
}
+DEFUN ("file-acl", Ffile_acl, Sfile_acl, 1, 1, 0,
+ doc: /* Return 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_POSIX_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_acl);
+ if (!NILP (handler))
+ return call2 (handler, Qfile_acl, absname);
+
+#ifdef HAVE_POSIX_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-acl", Fset_file_acl, Sset_file_acl,
+ 2, 2, 0,
+ doc: /* Set ACL of file named FILENAME to ACL-STRING.
+ACL-STRING should contain the textual representation of the ACL
+entries in a format suitable for the platform.
+
+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_POSIX_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_acl);
+ if (!NILP (handler))
+ return call3 (handler, Qset_file_acl, absname, acl_string);
+
+#ifdef HAVE_POSIX_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. */)
@@ -5838,6 +5966,8 @@ This includes interactive calls to `delete-file' and
defsubr (&Sset_file_modes);
defsubr (&Sset_file_times);
defsubr (&Sfile_selinux_context);
+ defsubr (&Sfile_acl);
+ defsubr (&Sset_file_acl);
defsubr (&Sset_file_selinux_context);
defsubr (&Sset_default_file_modes);
defsubr (&Sdefault_file_modes);
Re: [PATCH v2] POSIX ACL support, Romain Francoise, 2012/12/06