[Libguestfs] [PATCH v6 31/41] daemon: Reimplement ‘btrfs_subvolume_list’ and ‘btrfs_subvolume_get_default’ in OCaml.
Richard W.M. Jones
rjones at redhat.com
Thu Jun 15 17:06:21 UTC 2017
---
daemon/Makefile.am | 2 +
daemon/btrfs.c | 175 ----------------------------------------------
daemon/btrfs.ml | 127 +++++++++++++++++++++++++++++++++
daemon/btrfs.mli | 26 +++++++
generator/actions_core.ml | 2 +
generator/daemon.ml | 5 +-
6 files changed, 160 insertions(+), 177 deletions(-)
diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 02afabcab..439c71bd3 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -259,6 +259,7 @@ guestfsd_CFLAGS = \
# https://caml.inria.fr/pub/docs/manual-ocaml/intfc.html
SOURCES_MLI = \
blkid.mli \
+ btrfs.mli \
chroot.mli \
sysroot.mli \
devsparts.mli \
@@ -283,6 +284,7 @@ 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 4f52b71e8..d9043d53c 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -41,11 +41,6 @@ GUESTFSD_EXT_CMD(str_mount, mount);
GUESTFSD_EXT_CMD(str_umount, umount);
GUESTFSD_EXT_CMD(str_btrfsimage, btrfs-image);
-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
@@ -483,137 +478,6 @@ 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, str_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)
{
@@ -649,45 +513,6 @@ 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, str_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..554212ccf
--- /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 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 with_mounted mountable f =
+ let tmpdir = sprintf "/tmp/%s" (String.random8 ()) 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
+
+ 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 () // mountable.m_device)
+
+ | MountableDevice ->
+ protect ~finally ~f:(
+ fun () ->
+ mkdir tmpdir 0o700;
+ ignore (command "mount" [mountable.m_device; tmpdir]);
+ f tmpdir
+ )
+
+ | MountableBtrfsVol subvol ->
+ protect ~finally ~f:(
+ fun () ->
+ mkdir tmpdir 0o700;
+ ignore (command "mount" ["-o"; "subvol=" ^ subvol (* XXX quoting? *);
+ mountable.m_device; tmpdir]);
+ f tmpdir
+ )
+
+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
+
+ (* 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.
+ *)
+ filter_map (
+ fun line ->
+ if line = "" then None
+ else 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
+
+ Some {
+ 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 (
diff --git a/generator/daemon.ml b/generator/daemon.ml
index 8cac5ccb1..83994e9d3 100644
--- a/generator/daemon.ml
+++ b/generator/daemon.ml
@@ -758,7 +758,7 @@ return_string_list (value retv)
| Int64 n -> pr "caml_copy_int64 (%s)" n
| String ((PlainString|Device|Pathname|Dev_or_Path), n) ->
pr "caml_copy_string (%s)" n
- | String (Mountable, n) ->
+ | String ((Mountable|Mountable_or_Path), n) ->
pr "copy_mountable (%s)" n
| String _ -> assert false
| OptString _ -> assert false
@@ -797,7 +797,8 @@ return_string_list (value retv)
pr " CAMLreturnT (int, 0);\n"
| RInt _ ->
pr " CAMLreturnT (int, Int_val (retv));\n"
- | RInt64 _ -> assert false
+ | RInt64 _ ->
+ pr " CAMLreturnT (int, Int64_val (retv));\n"
| RBool _ ->
pr " CAMLreturnT (int, Bool_val (retv));\n"
| RConstString _ -> assert false
--
2.13.0
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