[Libguestfs] [PATCH v2 03/11] New API: btrfs_subvolume_show

Hu Tao
Thu, 11 Dec 2014 06:11:31 -0000

btrfs_subvolume_show shows the detailed information of a subvolume or
snapshot.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
 daemon/btrfs.c       | 194 +++++++++++++++++++++++++++++++++++++++++++++++++++
 generator/actions.ml |  25 +++++++
 src/MAX_PROC_NR      |   2 +-
 3 files changed, 220 insertions(+), 1 deletion(-)

diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index 9f4c5f4..9e32e11 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -24,11 +24,13 @@
 #include <pcre.h>
 #include <string.h>
 #include <unistd.h>
+#include <assert.h>

 #include "daemon.h"
 #include "actions.h"
 #include "optgroups.h"
 #include "xstrtol.h"
+#include "c-ctype.h"

 GUESTFSD_EXT_CMD(str_btrfs, btrfs);
 GUESTFSD_EXT_CMD(str_btrfstune, btrfstune);
@@ -819,3 +821,195 @@ do_btrfs_fsck (const char *device, int64_t superblock, int
repair)

   return 0;
 }
+
+/* analyze_line: analyze one line contains key:value pair.
+ * returns the next position following \n.
+ */
+static char *
+analyze_line (char *line, char **key, char **value)
+{
+  char *p = line;
+  char *next = NULL;
+  char delimiter = ':';
+  char *del_pos = NULL;
+
+  if (!line || *line == '\0') {
+    *key = NULL;
+    *value = NULL;
+    return NULL;
+  }
+
+  next = strchr (p, '\n');
+  if (next) {
+    *next = '\0';
+    ++next;
+  }
+
+  /* leading spaces and tabs */
+  while (*p && c_isspace (*p))
+    ++p;
+
+  assert (key);
+  if (*p == delimiter)
+    *key = NULL;
+  else
+    *key = p;
+
+  del_pos = strchr (p, delimiter);
+  if (del_pos) {
+    *del_pos = '\0';
+
+    /* leading spaces and tabs */
+    do {
+      ++del_pos;
+    } while (*del_pos && c_isspace (*del_pos));
+    assert (value);
+    *value = del_pos;
+  } else
+    *value = NULL;
+
+  return next;
+}
+
+char **
+do_btrfs_subvolume_show (const char *subvolume)
+{
+  const size_t MAX_ARGS = 64;
+  const char *argv[MAX_ARGS];
+  size_t i = 0;
+  CLEANUP_FREE char *subvolume_buf = NULL;
+  CLEANUP_FREE char *err = NULL;
+  CLEANUP_FREE char *out = NULL;
+  char *p, *key = NULL, *value = NULL;
+  DECLARE_STRINGSBUF (ret);
+  int r;
+
+  subvolume_buf = sysroot_path (subvolume);
+  if (subvolume_buf == NULL) {
+    reply_with_perror ("malloc");
+    return NULL;
+  }
+
+  ADD_ARG (argv, i, str_btrfs);
+  ADD_ARG (argv, i, "subvolume");
+  ADD_ARG (argv, i, "show");
+  ADD_ARG (argv, i, subvolume_buf);
+  ADD_ARG (argv, i, NULL);
+
+  r = commandv (&out, &err, argv);
+  if (r == -1) {
+    reply_with_error ("%s: %s", subvolume, err);
+    return NULL;
+  }
+
+  /* If the path is the btrfs root, `btrfs subvolume show' reports:
+   *   <path> is btrfs root
+   */
+  if (out && strstr (out, "is btrfs root") != NULL) {
+    reply_with_error ("%s is btrfs root", subvolume);
+    return NULL;
+  }
+
+  /* If the path is a normal directory, `btrfs subvolume show' reports:
+   *   ERROR: <path> is not a subvolume
+   */
+  if (err && strstr (err, "is not a subvolume")) {
+    reply_with_error ("%s is not a subvolume", subvolume);
+    return NULL;
+  }
+
+  /* Output is:
+   *
+   * /
+   *         Name:                   root
+   *         uuid:                   c875169e-cf4e-a04d-9959-b667dec36234
+   *         Parent uuid:            -
+   *         Creation time:          2014-11-13 10:13:08
+   *         Object ID:              256
+   *         Generation (Gen):       6579
+   *         Gen at creation:        5
+   *         Parent:                 5
+   *         Top Level:              5
+   *         Flags:                  -
+   *         Snapshot(s):
+   *                                 snapshots/test1
+   *                                 snapshots/test2
+   *                                 snapshots/test3
+   *
+   */
+  p = analyze_line(out, &key, &value);
+  if (!p) {
+    reply_with_error ("truncated output: %s", out);
+    return NULL;
+  }
+
+  /* The first line is the path of the subvolume. */
+  if (key && !value) {
+    if (add_string (&ret, "path") == -1)
+      return NULL;
+    if (add_string (&ret, key) == -1)
+      return NULL;
+  } else {
+    if (add_string (&ret, key) == -1)
+      return NULL;
+    if (add_string (&ret, value) == -1)
+      return NULL;
+  }
+
+  /* Read the lines and split into "key: value". */
+  p = analyze_line(p, &key, &value);
+  while (key) {
+    /* snapshot is special, see the output above */
+    if (STREQLEN (key, "Snapshot(s)", sizeof
("Snapshot(s)") - 1)) {
+      char *ss = NULL;
+      int ss_len = 0;
+
+      if (add_string (&ret, key) == -1)
+        return NULL;
+
+      p = analyze_line(p, &key, &value);
+
+      while (key && !value) {
+          ss = realloc (ss, ss_len + strlen (key) + 1);
+          if (!ss)
+            return NULL;
+
+          if (ss_len != 0)
+            ss[ss_len++] = ',';
+
+          memcpy (ss + ss_len, key, strlen (key));
+          ss_len += strlen (key);
+          ss[ss_len] = '\0';
+
+          p = analyze_line(p, &key, &value);
+      }
+
+      if (ss) {
+        if (add_string_nodup (&ret, ss) == -1) {
+          free (ss);
+          return NULL;
+        }
+      } else {
+        if (add_string (&ret, "") == -1)
+          return NULL;
+      }
+    } else {
+      if (add_string (&ret, key ? key : "") == -1)
+        return NULL;
+      if (value && !STREQ(value, "-")) {
+        if (add_string (&ret, value) == -1)
+          return NULL;
+      } else {
+        if (add_string (&ret, "") == -1)
+          return NULL;
+      }
+
+      p = analyze_line(p, &key, &value);
+    }
+  }
+
+  if (end_stringsbuf (&ret) == -1)
+    return NULL;
+
+  return ret.argv;
+}
diff --git a/generator/actions.ml b/generator/actions.ml
index 4e47a02..1ea19f7 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12050,6 +12050,31 @@ This uses the L<blockdev(8)> command." };
     longdesc = "\
 Get the default subvolume or snapshot of a filesystem mounted at
C<mountpoint>." };

+  { defaults with
+    name = "btrfs_subvolume_show";
+    style = RHashtable "btrfssubvolumeinfo", [Pathname
"subvolume"], [];
+    proc_nr = Some 426;
+    optional = Some "btrfs"; camel_name =
"BTRFSSubvolumeShow";
+    tests = [
+      InitPartition, Always, TestLastFail (
+        [["mkfs_btrfs"; "/dev/sda1"; "";
""; "NOARG"; ""; "NOARG";
"NOARG"; ""; ""];
+         ["mount"; "/dev/sda1"; "/"];
+         ["btrfs_subvolume_show"; "/"]]), [];
+      InitPartition, Always, TestRun (
+        [["mkfs_btrfs"; "/dev/sda1"; "";
""; "NOARG"; ""; "NOARG";
"NOARG"; ""; ""];
+         ["mount"; "/dev/sda1"; "/"];
+         ["btrfs_subvolume_create"; "/sub1";
"NOARG"];
+         ["btrfs_subvolume_show"; "/sub1"]]), [];
+      InitPartition, Always, TestLastFail (
+        [["mkfs_btrfs"; "/dev/sda1"; "";
""; "NOARG"; ""; "NOARG";
"NOARG"; ""; ""];
+         ["mount"; "/dev/sda1"; "/"];
+         ["mkdir"; "/dir1"];
+         ["btrfs_subvolume_show"; "/dir1"]]), [];
+    ];
+    shortdesc = "return detailed information of the subvolume";
+    longdesc = "\
+Return detailed information of the subvolume." };
+
 ]

 (* Non-API meta-commands available only in guestfish.
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 5e4a522..9f51d08 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-425
+426
--
1.9.3