[Libguestfs] [PATCH v3 15/23] daemon: Reimplement ‘btrfs_subvolume_list’ and ‘btrfs_subvolume_get_default’ in OCaml.

--- daemon/Makefile.am | 2 + daemon/btrfs.c | 175 ---------------------------------------------- daemon/btrfs.ml | 127 +++++++++++++++++++++++++++++++++ daemon/btrfs.mli | 26 +++++++ generator/actions_core.ml | 2 + 5 files changed, 157 insertions(+), 175 deletions(-) diff --git a/daemon/Makefile.am b/daemon/Makefile.am index 873f6b394..9971a45a7 100644 --- a/daemon/Makefile.am +++ b/daemon/Makefile.am @@ -243,6 +243,7 @@ guestfsd_CFLAGS = \ # https://caml.inria.fr/pub/docs/manual-ocaml/intfc.html SOURCES_MLI = \ blkid.mli \ + btrfs.mli \ chroot.mli \ sysroot.mli \ devsparts.mli \ @@ -268,6 +269,7 @@ SOURCES_ML = \ mountable.ml \ chroot.ml \ blkid.ml \ + btrfs.ml \ devsparts.ml \ file.ml \ filearch.ml \ diff --git a/daemon/btrfs.c b/daemon/btrfs.c index 00c9b3c75..f11902b21 100644 --- a/daemon/btrfs.c +++ b/daemon/btrfs.c @@ -33,11 +33,6 @@ #include "c-ctype.h" #include "ignore-value.h" -COMPILE_REGEXP (re_btrfs_subvolume_list, - "ID\\s+(\\d+).*\\s" - "top level\\s+(\\d+).*\\s" - "path\\s(.*)", - 0) COMPILE_REGEXP (re_btrfs_balance_status, "Balance on '.*' is (.*)", 0) int @@ -475,137 +470,6 @@ umount (char *fs_buf, const mountable_t *fs) return 0; } -guestfs_int_btrfssubvolume_list * -do_btrfs_subvolume_list (const mountable_t *fs) -{ - CLEANUP_FREE_STRING_LIST char **lines = NULL; - size_t i = 0; - const size_t MAX_ARGS = 64; - const char *argv[MAX_ARGS]; - - /* Execute 'btrfs subvolume list <fs>', and split the output into lines */ - { - char *fs_buf = mount (fs); - - if (!fs_buf) - return NULL; - - ADD_ARG (argv, i, "btrfs"); - ADD_ARG (argv, i, "subvolume"); - ADD_ARG (argv, i, "list"); - ADD_ARG (argv, i, fs_buf); - ADD_ARG (argv, i, NULL); - - CLEANUP_FREE char *out = NULL, *errout = NULL; - int r = commandv (&out, &errout, argv); - - if (umount (fs_buf, fs) != 0) - return NULL; - - if (r == -1) { - CLEANUP_FREE char *fs_desc = mountable_to_string (fs); - if (fs_desc == NULL) { - fprintf (stderr, "malloc: %m"); - } - reply_with_error ("%s: %s", fs_desc ? fs_desc : "malloc", errout); - return NULL; - } - - lines = split_lines (out); - if (!lines) return NULL; - } - - /* Output is: - * - * ID 256 gen 30 top level 5 path test1 - * ID 257 gen 30 top level 5 path dir/test2 - * ID 258 gen 30 top level 5 path test3 - * - * "ID <n>" is the subvolume ID. - * "gen <n>" is the generation when the root was created or last - * updated. - * "top level <n>" is the top level subvolume ID. - * "path <str>" is the subvolume path, relative to the top of the - * filesystem. - * - * Note that the order that each of the above is fixed, but - * different versions of btrfs may display different sets of data. - * Specifically, older versions of btrfs do not display gen. - */ - - guestfs_int_btrfssubvolume_list *ret = NULL; - - const size_t nr_subvolumes = guestfs_int_count_strings (lines); - - ret = malloc (sizeof *ret); - if (!ret) { - reply_with_perror ("malloc"); - return NULL; - } - - ret->guestfs_int_btrfssubvolume_list_len = nr_subvolumes; - ret->guestfs_int_btrfssubvolume_list_val = - calloc (nr_subvolumes, sizeof (struct guestfs_int_btrfssubvolume)); - if (ret->guestfs_int_btrfssubvolume_list_val == NULL) { - reply_with_perror ("calloc"); - goto error; - } - - for (i = 0; i < nr_subvolumes; ++i) { - /* To avoid allocations, reuse the 'line' buffer to store the - * path. Thus we don't need to free 'line', since it will be - * freed by the calling (XDR) code. - */ - char *line = lines[i]; -#define N_MATCHES 4 - int ovector[N_MATCHES * 3]; - - if (pcre_exec (re_btrfs_subvolume_list, NULL, line, strlen (line), 0, 0, - ovector, N_MATCHES * 3) < 0) -#undef N_MATCHES - { - unexpected_output: - reply_with_error ("unexpected output from 'btrfs subvolume list' command: %s", line); - goto error; - } - - struct guestfs_int_btrfssubvolume *this = - &ret->guestfs_int_btrfssubvolume_list_val[i]; - -#if __WORDSIZE == 64 -#define XSTRTOU64 xstrtoul -#else -#define XSTRTOU64 xstrtoull -#endif - - if (XSTRTOU64 (line + ovector[2], NULL, 10, - &this->btrfssubvolume_id, NULL) != LONGINT_OK) - goto unexpected_output; - if (XSTRTOU64 (line + ovector[4], NULL, 10, - &this->btrfssubvolume_top_level_id, NULL) != LONGINT_OK) - goto unexpected_output; - -#undef XSTRTOU64 - - this->btrfssubvolume_path = - strndup (line + ovector[6], ovector[7] - ovector[6]); - if (this->btrfssubvolume_path == NULL) - goto error; - } - - return ret; - - error: - if (ret->guestfs_int_btrfssubvolume_list_val) { - for (i = 0; i < nr_subvolumes; ++i) - free (ret->guestfs_int_btrfssubvolume_list_val[i].btrfssubvolume_path); - free (ret->guestfs_int_btrfssubvolume_list_val); - } - free (ret); - - return NULL; -} - int do_btrfs_subvolume_set_default (int64_t id, const char *fs) { @@ -641,45 +505,6 @@ do_btrfs_subvolume_set_default (int64_t id, const char *fs) return 0; } -int64_t -do_btrfs_subvolume_get_default (const mountable_t *fs) -{ - const size_t MAX_ARGS = 64; - const char *argv[MAX_ARGS]; - size_t i = 0; - char *fs_buf = NULL; - CLEANUP_FREE char *err = NULL; - CLEANUP_FREE char *out = NULL; - int r; - int64_t ret = -1; - - fs_buf = mount (fs); - if (fs_buf == NULL) - goto error; - - ADD_ARG (argv, i, "btrfs"); - ADD_ARG (argv, i, "subvolume"); - ADD_ARG (argv, i, "get-default"); - ADD_ARG (argv, i, fs_buf); - ADD_ARG (argv, i, NULL); - - r = commandv (&out, &err, argv); - if (r == -1) { - reply_with_error ("%s: %s", fs_buf, err); - goto error; - } - if (sscanf (out, "ID %" SCNi64, &ret) != 1) { - reply_with_error ("%s: could not parse subvolume id: %s", argv[0], out); - ret = -1; - goto error; - } - - error: - if (fs_buf && umount (fs_buf, fs) != 0) - return -1; - return ret; -} - int do_btrfs_filesystem_sync (const char *fs) { diff --git a/daemon/btrfs.ml b/daemon/btrfs.ml new file mode 100644 index 000000000..fc02abefa --- /dev/null +++ b/daemon/btrfs.ml @@ -0,0 +1,127 @@ +(* guestfs-inspection + * Copyright (C) 2009-2017 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. + *) + +open Printf +open Scanf +open Unix + +open Std_utils +open Unix_utils + +open Mountable +open Utils + +include Structs + +(* In order to examine subvolumes, quota and other things, the btrfs + * filesystem has to be mounted. However we're passed a mountable + * in these cases, so we must mount the filesystem. But we cannot + * mount it under the sysroot, as something else might be mounted + * there so this function mounts the filesystem on a temporary + * directory and ensures it is always unmounted afterwards. + *) +let rec with_mounted mountable f = + let _with_mounted mount_cmd f = + let tmpdir = Mkdtemp.temp_dir "btrfs" in + + (* This is the cleanup function which is called to unmount and + * remove the temporary directory. This is called on error and + * ordinary exit paths. + *) + let finally () = + ignore (Sys.command (sprintf "umount %s" (quote tmpdir))); + rmdir tmpdir + in + + protect ~finally ~f:(fun () -> mount_cmd tmpdir; f tmpdir) + in + + match mountable.m_type with + | MountablePath -> + (* This corner-case happens for Mountable_or_Path parameters, where + * a path was supplied by the caller. The path (the m_device + * field) is relative to the sysroot. + *) + f (Sysroot.sysroot_path mountable.m_device) + + | MountableDevice -> + let cmd tmpdir = + ignore (command "mount" [mountable.m_device; tmpdir]) in + _with_mounted cmd f + + | MountableBtrfsVol subvol -> + let cmd tmpdir = + ignore (command "mount" ["-o"; "subvol=" ^ subvol (* XXX quoting? *); + mountable.m_device; tmpdir]) in + _with_mounted cmd f + +let re_btrfs_subvolume_list = + Str.regexp ("ID[ \t]+\\([0-9]+\\).*[ \t]" ^ + "top level[ \t]+\\([0-9]+\\).*[ \t]" ^ + "path[ \t]+\\(.*\\)") + +let btrfs_subvolume_list mountable = + (* Execute 'btrfs subvolume list <fs>', and split the output into lines *) + let lines = + with_mounted mountable ( + fun mp -> command "btrfs" ["subvolume"; "list"; mp] + ) in + let lines = String.nsplit "\n" lines in + let lines = List.filter ((<>) "") lines in + + (* Output is: + * + * ID 256 gen 30 top level 5 path test1 + * ID 257 gen 30 top level 5 path dir/test2 + * ID 258 gen 30 top level 5 path test3 + * + * "ID <n>" is the subvolume ID. + * "gen <n>" is the generation when the root was created or last + * updated. + * "top level <n>" is the top level subvolume ID. + * "path <str>" is the subvolume path, relative to the top of the + * filesystem. + * + * Note that the order that each of the above is fixed, but + * different versions of btrfs may display different sets of data. + * Specifically, older versions of btrfs do not display gen. + *) + List.map ( + fun line -> + if Str.string_match re_btrfs_subvolume_list line 0 then ( + let id = Int64.of_string (Str.matched_group 1 line) + and top_level_id = Int64.of_string (Str.matched_group 2 line) + and path = Str.matched_group 3 line in + + { + btrfssubvolume_id = id; + btrfssubvolume_top_level_id = top_level_id; + btrfssubvolume_path = path + } + ) + else + failwithf "unexpected output from 'btrfs subvolume list' command: %s" + line + ) lines + +let btrfs_subvolume_get_default mountable = + let out = + with_mounted mountable ( + fun mp -> command "btrfs" ["subvolume"; "get-default"; mp] + ) in + sscanf out "ID %Ld" identity diff --git a/daemon/btrfs.mli b/daemon/btrfs.mli new file mode 100644 index 000000000..55a38e42d --- /dev/null +++ b/daemon/btrfs.mli @@ -0,0 +1,26 @@ +(* guestfs-inspection + * Copyright (C) 2009-2017 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. + *) + +type btrfssubvolume = { + btrfssubvolume_id : int64; + btrfssubvolume_top_level_id : int64; + btrfssubvolume_path : string; +} + +val btrfs_subvolume_list : Mountable.t -> btrfssubvolume list +val btrfs_subvolume_get_default : Mountable.t -> int64 diff --git a/generator/actions_core.ml b/generator/actions_core.ml index 140ba6c1b..bd3c21d3b 100644 --- a/generator/actions_core.ml +++ b/generator/actions_core.ml @@ -7304,6 +7304,7 @@ created subvolume will be added to." }; { defaults with name = "btrfs_subvolume_list"; added = (1, 17, 35); style = RStructList ("subvolumes", "btrfssubvolume"), [String (Mountable_or_Path, "fs")], []; + impl = OCaml "Btrfs.btrfs_subvolume_list"; optional = Some "btrfs"; camel_name = "BTRFSSubvolumeList"; test_excuse = "tested in tests/btrfs"; shortdesc = "list btrfs snapshots and subvolumes"; @@ -8783,6 +8784,7 @@ This uses the L<blockdev(8)> command." }; { defaults with name = "btrfs_subvolume_get_default"; added = (1, 29, 17); style = RInt64 "id", [String (Mountable_or_Path, "fs")], []; + impl = OCaml "Btrfs.btrfs_subvolume_get_default"; optional = Some "btrfs"; camel_name = "BTRFSSubvolumeGetDefault"; tests = [ InitPartition, Always, TestResult ( -- 2.13.2