Re: [Libguestfs] RFC: copy-attributes command

Hi, attached there is a prototype of patch for adding a new copy-attributes command. Such command would allow copy the attributes of a "file" to another, so for example in guestfish: copy-attributes foo bar permissions:true xattributes:false would only copy the permissions of foo to bar, not copying its extended attributes too.

Just few notes: - my first daemon command, so possibly I could be missing something - copy_xattrs is in xattr.c to avoid spreading the usage of xattr API in many places - copy_xattrs does a bit of code repetition with other stuff in xattr.c, but I'm not sure how to avoid it without making the xattr listing code (getxattrs) a bit more complex that what it is already Comments? -- Pino Toscano

diff --git a/daemon/daemon.h b/daemon/daemon.h index b77d764..6535658 100644 --- a/daemon/daemon.h +++ b/daemon/daemon.h @@ -231,6 +231,9 @@ extern void journal_finalize (void); /*-- in proto.c --*/ extern void main_loop (int sock) __attribute__((noreturn)); +/*-- in xattr.c --*/ +extern int copy_xattrs (const char *src, const char *dest); + /* ordinary daemon functions use these to indicate errors * NB: you don't need to prefix the string with the current command, * it is added automatically by the client-side RPC stubs. diff --git a/daemon/file.c b/daemon/file.c index f348f87..fd6da71 100644 --- a/daemon/file.c +++ b/daemon/file.c @@ -28,6 +28,7 @@ #include "guestfs_protocol.h" #include "daemon.h" #include "actions.h" +#include "optgroups.h" GUESTFSD_EXT_CMD(str_file, file); GUESTFSD_EXT_CMD(str_zcat, zcat); @@ -584,3 +585,46 @@ do_filesize (const char *path) return buf.st_size; } + +int +do_copy_attributes (const char *src, const char *dest, int permissions, int xattributes) +{ + int r; + struct stat srcstat, deststat; + + CHROOT_IN; + r = stat (src, &srcstat); + CHROOT_OUT; + + if (r == -1) { + reply_with_perror ("stat: %s", src); + return -1; + } + + CHROOT_IN; + r = stat (dest, &deststat); + CHROOT_OUT; + + if (r == -1) { + reply_with_perror ("stat: %s", dest); + return -1; + } + + if (permissions && ((srcstat.st_mode & 0777) != (deststat.st_mode & 0777))) { + CHROOT_IN; + r = chmod (dest, (srcstat.st_mode & 0777));

+ CHROOT_OUT; + + if (r == -1) { + reply_with_perror ("chmod: %s", dest); + return -1; + } + } + + if (xattributes && optgroup_linuxxattrs_available ()) { + if (!copy_xattrs (src, dest)) + return -1; + } + + return 0; +} diff --git a/daemon/xattr.c b/daemon/xattr.c index af8bfd4..97a94d5 100644 --- a/daemon/xattr.c +++ b/daemon/xattr.c @@ -545,8 +545,98 @@ do_lgetxattr (const char *path, const char *name, size_t *size_r) return buf; /* caller frees */ } +int +copy_xattrs (const char *src, const char *dest) +{ +#if defined(HAVE_LISTXATTR) && defined(HAVE_GETXATTR) && defined(HAVE_SETXATTR)

+ ssize_t len, vlen, ret; + CLEANUP_FREE char *buf = NULL, *attrval = NULL; + size_t i, attrval_len = 0; + + CHROOT_IN; + len = listxattr (src, NULL, 0); + CHROOT_OUT; + if (len == -1) { + reply_with_perror ("listxattr: %s", src); + goto error; + } + + buf = malloc (len); + if (buf == NULL) { + reply_with_perror ("malloc"); + goto error; + } + + CHROOT_IN; + len = listxattr (src, buf, len); + CHROOT_OUT; + if (len == -1) { + reply_with_perror ("listxattr: %s", src); + goto error; + } + + /* What we get from the kernel is a string "foo\0bar\0baz" of length + * len. + */ + for (i = 0; i < (size_t) len; i += strlen (&buf[i]) + 1) { + CHROOT_IN; + vlen = getxattr (src, &buf[i], NULL, 0); + CHROOT_OUT; + if (vlen == -1) { + reply_with_perror ("getxattr: %s, %s", src, &buf[i]); + goto error; + } + + if (vlen > XATTR_SIZE_MAX) { + /* The next call to getxattr will fail anyway, so ... */ + reply_with_error ("extended attribute is too large"); + goto error; + } + + if (vlen > attrval_len) { + char *new = realloc (attrval, vlen); + if (new == NULL) { + reply_with_perror ("realloc"); + goto error; + } + attrval = new; + attrval_len = vlen; + } + + CHROOT_IN; + vlen = getxattr (src, &buf[i], attrval, vlen); + CHROOT_OUT; + if (vlen == -1) { + reply_with_perror ("getxattr: %s, %s", src, &buf[i]); + goto error; + } + + CHROOT_IN; + ret = setxattr (dest, &buf[i], attrval, vlen, 0); + CHROOT_OUT; + if (vlen == -1) { + reply_with_perror ("setxattr: %s, %s", dest, &buf[i]); + goto error; + } + }

+ return 1; + + error: + return 0; +#else + return 0; +#endif +} + #else /* no xattr.h */ OPTGROUP_LINUXXATTRS_NOT_AVAILABLE +int +copy_xattrs (const char *src, const char *dest) +{ + abort (); +} + #endif /* no xattr.h */ diff --git a/fish/Makefile.am b/fish/Makefile.am index bd0485f..fb0e99e 100644 --- a/fish/Makefile.am +++ b/fish/Makefile.am @@ -279,6 +279,7 @@ if ENABLE_APPLIANCE TESTS += \ test-copy.sh \ test-edit.sh \ + test-file-attrs.sh \ test-find0.sh \ test-inspect.sh \ test-glob.sh \ diff --git a/fish/test-file-attrs.sh b/fish/test-file-attrs.sh new file mode 100755 index 0000000..85c6d29 --- /dev/null +++ b/fish/test-file-attrs.sh @@ -0,0 +1,118 @@ +#!/bin/bash - +# libguestfs +# Copyright (C) 2014 Red Hat Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + +# Test guestfish file attributes commands (chmod, copy-attributes, etc). + +set -e +export LANG=C + +rm -f test.out + +$VG ./guestfish > test.out <<EOF +scratch 50MB +run +part-disk /dev/sda mbr +mkfs ext2 /dev/sda1 +mount /dev/sda1 / + +touch /foo +touch /bar +chmod 0712 /foo +stat /foo | grep mode: +copy-attributes /foo /bar permissions:true +stat /bar | grep mode: +EOF + +if [ "$(cat test.out)" != "mode: 33226 +mode: 33226" ]; then + echo "$0: unexpected output:" + cat test.out + exit 1 +fi + +$VG ./guestfish > test.out <<EOF +scratch 50MB +run

+part-disk /dev/sda mbr +mkfs ext2 /dev/sda1 +mount /dev/sda1 / + +touch /foo +touch /bar +setxattr user.test foo 3 /foo +setxattr user.test2 secondtest 10 /foo +setxattr user.foo another 7 /bar +lxattrlist / "foo bar" +copy-attributes /foo /bar xattributes:true +lxattrlist / "foo bar" +EOF + +if [ "$(cat test.out)" != "[0] = { + attrname: + attrval: 2\x00 +} +[1] = { + attrname: user.test + attrval: foo +} +[2] = { + attrname: user.test2 + attrval: secondtest +} +[3] = { + attrname: + attrval: 1\x00 +} +[4] = { + attrname: user.foo + attrval: another +} +[0] = { + attrname: + attrval: 2\x00 +} +[1] = { + attrname: user.test + attrval: foo +} +[2] = { + attrname: user.test2 + attrval: secondtest +} +[3] = { + attrname: + attrval: 3\x00 +} +[4] = { + attrname: user.foo + attrval: another +} +[5] = { + attrname: user.test + attrval: foo +} +[6] = { + attrname: user.test2 + attrval: secondtest +}" ]; then + echo "$0: unexpected output:" + cat test.out + exit 1 +fi + +rm test.out diff --git a/generator/actions.ml b/generator/actions.ml index 9fa7acb..676a3ea 100644 --- a/generator/actions.ml +++ b/generator/actions.ml @@ -11647,6 +11647,28 @@ This function is used internally when setting up the appliance." }; This function is used internally when closing the appliance. Note it's only called when ./configure --enable-valgrind-daemon is used." }; + { defaults with + name = "copy_attributes"; + style = RErr, [Pathname "src"; Pathname "dest"], [OBool "permissions"; OBool "xattributes"]; + proc_nr = Some 415; + shortdesc = "copy the attributes of a path (file/directory) to another"; + longdesc = "\ +Copy the attributes of a path (which can be a file or a directory) +to another path. + +By default B<no> attribute is copied; you have to specify which attributes +to copy enabling the optional arguments:

+=over 4 + +=item C<permissions> + +Copy the UNIX permissions from C<source> to C<destination>. + +=item C<xattributes> + +Copy the extended attributes from C<source> to C<destination>." }; + ] (* Non-API meta-commands available only in guestfish. diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR index d1b9f6a..21c8d99 100644 --- a/src/MAX_PROC_NR +++ b/src/MAX_PROC_NR @@ -1 +1 @@ -414 +415