[Libguestfs] [PATCH 2/8] New API: btrfs_subvolume_show
Richard W.M. Jones
rjones at redhat.com
Fri Dec 5 12:30:52 UTC 2014
On Tue, Dec 02, 2014 at 05:33:32PM +0800, Hu Tao wrote:
> btrfs_subvolume_show shows the detailed information of a subvolume or
> snapshot.
>
> Signed-off-by: Hu Tao <hutao at cn.fujitsu.com>
> ---
> daemon/btrfs.c | 185 +++++++++++++++++++++++++++++++++++++++++++++++++++
> generator/actions.ml | 9 +++
> src/MAX_PROC_NR | 2 +-
> 3 files changed, 195 insertions(+), 1 deletion(-)
>
> diff --git a/daemon/btrfs.c b/daemon/btrfs.c
> index 471cfbd..2cfb364 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);
> @@ -810,3 +812,186 @@ do_btrfs_fsck (const char *device, int64_t superblock, int repair)
>
> return 0;
> }
Ugh. 'btrfs' should have more easily parsable output.
> +/* 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)
Can you put the function name on a new line, so:
static char *
analyze_line (char *line, char **key, char **value)
The reason for this is to allow you to easily grep function
declarations in the source:
git grep ^analyze_line
> +{
> + 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;
> + }
> +
> + /* 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;
> + }
> +
> + /* If the path is the btrfs root, `btrfs subvolume show' reports:
> + * <path> is btrfs root
> + */
> + if (strstr (key, "is btrfs root") != NULL) {
> + reply_with_error ("%s is btrfs root", subvolume);
> + 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 80c7ea7..d5ec528 100644
> --- a/generator/actions.ml
> +++ b/generator/actions.ml
> @@ -12036,6 +12036,15 @@ 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";
> + 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
This desperately needs tests.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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