New API: md-stat.

This returns information about the underlying devices of an MD
(software RAID) device.

1 files changed, 172 insertions, 0 deletions

diff --git a/daemon/md.c b/daemon/md.c
index 265f4f4c..0e2f7048 100644
--- a/daemon/md.c
+++ b/daemon/md.c
@@ -329,3 +329,175 @@ do_md_stop(const char *md)
   free (err);
   return 0;
 }
+
+static size_t
+count_spaces (const char *line)
+{
+  size_t r = 0;
+  while (*line) {
+    if (*line == ' ')
+      r++;
+    line++;
+  }
+  return r;
+}
+
+/* Parse a line like: "active raid1 sdb1[0] sdc1[1](F)" */
+static guestfs_int_mdstat_list *
+parse_md_stat_line (char *line)
+{
+  guestfs_int_mdstat_list *ret;
+  guestfs_int_mdstat *t;
+  size_t spaces, n, i, len;
+  char *next;
+  char *p, *q;
+
+  ret = malloc (sizeof *ret);
+  if (!ret) {
+    reply_with_perror ("malloc");
+    return NULL;
+  }
+
+  /* We don't know exactly how many entries we will need yet, but we
+   * can estimate it, and this will always be an over-estimate.
+   */
+  spaces = count_spaces (line);
+  ret->guestfs_int_mdstat_list_val =
+    calloc (spaces+1, sizeof (struct guestfs_int_mdstat));
+  if (ret->guestfs_int_mdstat_list_val == NULL) {
+    reply_with_perror ("malloc");
+    free (ret);
+    return NULL;
+  }
+
+  for (n = 0; *line; line = next) {
+    len = strcspn (line, " ");
+    if (line[len] == '\0')
+      next = &line[len];
+    else {
+      line[len] = '\0';
+      next = &line[len+1];
+    }
+
+    if (verbose)
+      printf ("mdstat: %s\n", line);
+
+    /* Looking for entries that contain "[..]", skip ones which don't. */
+    p = strchr (line, '[');
+    if (p == NULL)
+      continue;
+    q = strchr (line, ']');
+    if (q == NULL)
+      continue;
+    if (p > q)
+      continue;
+
+    ret->guestfs_int_mdstat_list_len = n+1;
+    t = &ret->guestfs_int_mdstat_list_val[n];
+
+    /* Device name is everything before the '[' character, but we
+     * need to prefix with /dev/.
+     */
+    if (p == line) {
+      reply_with_error ("device entry is too short: %s", line);
+      goto error;
+    }
+
+    *p = '\0';
+    if (asprintf (&t->mdstat_device, "/dev/%s", line) == -1) {
+      reply_with_perror ("asprintf");
+      goto error;
+    }
+
+    /* Device index is the number after '['. */
+    line = p+1;
+    *q = '\0';
+    if (sscanf (line, "%" SCNi32, &t->mdstat_index) != 1) {
+      reply_with_error ("not a device number: %s", line);
+      goto error;
+    }
+
+    /* Looking for flags "(F)(S)...". */
+    line = q+1;
+    len = strlen (line);
+    t->mdstat_flags = malloc (len+1);
+    if (!t->mdstat_flags) {
+      reply_with_error ("malloc");
+      goto error;
+    }
+
+    for (i = 0; *line; line++) {
+      if (c_isalpha (*line))
+        t->mdstat_flags[i++] = *line;
+    }
+    t->mdstat_flags[i] = '\0';
+
+    n++;
+  }
+
+  return ret;
+
+ error:
+  for (i = 0; i <= spaces; ++i) {
+    free (ret->guestfs_int_mdstat_list_val[i].mdstat_device);
+    free (ret->guestfs_int_mdstat_list_val[i].mdstat_flags);
+  }
+  free (ret->guestfs_int_mdstat_list_val);
+  free (ret);
+  return NULL;
+}
+
+extern guestfs_int_mdstat_list *
+do_md_stat (const char *md)
+{
+  size_t mdlen;
+  FILE *fp;
+  char *line = NULL;
+  size_t len = 0;
+  ssize_t n;
+  guestfs_int_mdstat_list *ret = NULL;
+
+  if (STRPREFIX (md, "/dev/"))
+    md += 5;
+  mdlen = strlen (md);
+
+  fp = fopen ("/proc/mdstat", "r");
+  if (fp == NULL) {
+    reply_with_perror ("fopen: %s", "/proc/mdstat");
+    return NULL;
+  }
+
+  /* Search for a line which begins with "<md> : ". */
+  while ((n = getline (&line, &len, fp)) != -1) {
+    if (STRPREFIX (line, md) &&
+        line[mdlen] == ' ' && line[mdlen+1] == ':' && line[mdlen+2] == ' ') {
+      /* Found it. */
+      ret = parse_md_stat_line (&line[mdlen+3]);
+      if (!ret) {
+        free (line);
+        fclose (fp);
+        return NULL;
+      }
+
+      /* Stop parsing the mdstat file after we've found the line
+       * we are interested in.
+       */
+      break;
+    }
+  }
+
+  free (line);
+
+  if (fclose (fp) == EOF) {
+    reply_with_perror ("fclose: %s", "/proc/mdstat");
+    return NULL;
+  }
+
+  /* Did we find the line? */
+  if (!ret) {
+    reply_with_error ("%s: MD device not found", md);
+    return NULL;
+  }
+
+  return ret;
+}