virt-df: Use guestfs_max_disks instead of hard-coding limit of 25.

And comprehensively fix it so it works with > 26 disks.

3 files changed, 142 insertions, 49 deletions

diff --git a/df/df.c b/df/df.c
index f398d0c2..56a55cf1 100644
--- a/df/df.c
+++ b/df/df.c
@@ -30,6 +30,7 @@
 #endif
 
 #include "progname.h"
+#include "c-ctype.h"
 
 #include "guestfs.h"
 #include "options.h"
@@ -115,17 +116,50 @@ df_on_handle (const char *name, const char *uuid, char **devices, int offset)
   return ret;
 }
 
+/* dev is a device or partition name such as "/dev/sda" or "/dev/sda1".
+ * See if dev occurs somewhere in the list of devices.
+ */
 static int
 find_dev_in_devices (const char *dev, char **devices)
 {
-  size_t i;
+  guestfs_error_handler_cb old_error_cb;
+  void *old_error_data;
+  size_t i, len;
+  char *whole_disk;
+  int free_whole_disk;
+  int ret = 0;
+
+  /* Convert 'dev' to a whole disk name. */
+  len = strlen (dev);
+  if (len > 0 && c_isdigit (dev[len-1])) {
+    old_error_cb = guestfs_get_error_handler (g, &old_error_data);
+    guestfs_set_error_handler (g, NULL, NULL);
+
+    whole_disk = guestfs_part_to_dev (g, dev);
+
+    guestfs_set_error_handler (g, old_error_cb, old_error_data);
+
+    if (!whole_disk) /* probably an MD device or similar */
+      return 0;
+
+    free_whole_disk = 1;
+  }
+  else {
+    whole_disk = (char *) dev;
+    free_whole_disk = 0;
+  }
 
   for (i = 0; devices[i] != NULL; ++i) {
-    if (STRPREFIX (dev, devices[i]))
-      return 1;
+    if (STREQ (whole_disk, devices[i])) {
+      ret = 1;
+      break;
+    }
   }
 
-  return 0;
+  if (free_whole_disk)
+    free (whole_disk);
+
+  return ret;
 }
 
 static void
diff --git a/df/domains.c b/df/domains.c
index f2ee8546..2b1f4680 100644
--- a/df/domains.c
+++ b/df/domains.c
@@ -41,14 +41,6 @@
 
 #if defined(HAVE_LIBVIRT) && defined(HAVE_LIBXML2)
 
-/* Limit the number of devices we will ever add to the appliance.  The
- * overall limit in current libguestfs is 25: 26 = number of letters
- * in the English alphabet since we are only confident that
- * /dev/sd[a-z] will work because of various limits, minus 1 because
- * that may be used by the ext2 initial filesystem.  (RHBZ#635373).
- */
-#define MAX_DISKS 25
-
 /* The list of domains and disks that we build up in
  * get_domains_from_libvirt.
  */
@@ -94,9 +86,9 @@ free_domain (struct domain *domain)
   free (domain->uuid);
 }
 
-static void add_domains_by_id (virConnectPtr conn, int *ids, size_t n);
-static void add_domains_by_name (virConnectPtr conn, char **names, size_t n);
-static void add_domain (virDomainPtr dom);
+static void add_domains_by_id (virConnectPtr conn, int *ids, size_t n, size_t max_disks);
+static void add_domains_by_name (virConnectPtr conn, char **names, size_t n, size_t max_disks);
+static void add_domain (virDomainPtr dom, size_t max_disks);
 static int add_disk (guestfs_h *g, const char *filename, const char *format, int readonly, void *domain_vp);
 static void multi_df (struct domain *, size_t n, size_t *errors);
 
@@ -105,8 +97,13 @@ get_domains_from_libvirt (void)
 {
   virErrorPtr err;
   virConnectPtr conn;
-  int n;
-  size_t i, j, nr_disks_added, errors;
+  int n, r;
+  size_t i, j, nr_disks_added, errors, max_disks;
+
+  r = guestfs_max_disks (g);
+  if (r == -1)
+    exit (EXIT_FAILURE);
+  max_disks = (size_t) r;
 
   nr_domains = 0;
   domains = NULL;
@@ -140,7 +137,7 @@ get_domains_from_libvirt (void)
     exit (EXIT_FAILURE);
   }
 
-  add_domains_by_id (conn, ids, n);
+  add_domains_by_id (conn, ids, n, max_disks);
 
   n = virConnectNumOfDefinedDomains (conn);
   if (n == -1) {
@@ -161,7 +158,7 @@ get_domains_from_libvirt (void)
     exit (EXIT_FAILURE);
   }
 
-  add_domains_by_name (conn, names, n);
+  add_domains_by_name (conn, names, n, max_disks);
 
   /* You must free these even though the libvirt documentation doesn't
    * mention it.
@@ -182,7 +179,7 @@ get_domains_from_libvirt (void)
 
   /* To minimize the number of times we have to launch the appliance,
    * shuffle as many domains together as we can, but not exceeding
-   * MAX_DISKS per request.  If --one-per-guest was requested then only
+   * max_disks per request.  If --one-per-guest was requested then only
    * request disks from a single guest each time.
    * Interesting application for NP-complete knapsack problem here.
    */
@@ -196,7 +193,7 @@ get_domains_from_libvirt (void)
 
       /* Make a request with domains [i..j-1]. */
       for (j = i; j < nr_domains; ++j) {
-        if (nr_disks_added + domains[j].nr_disks > MAX_DISKS)
+        if (nr_disks_added + domains[j].nr_disks > max_disks)
           break;
         nr_disks_added += domains[j].nr_disks;
       }
@@ -219,7 +216,7 @@ get_domains_from_libvirt (void)
 }
 
 static void
-add_domains_by_id (virConnectPtr conn, int *ids, size_t n)
+add_domains_by_id (virConnectPtr conn, int *ids, size_t n, size_t max_disks)
 {
   size_t i;
   virDomainPtr dom;
@@ -228,7 +225,7 @@ add_domains_by_id (virConnectPtr conn, int *ids, size_t n)
     if (ids[i] != 0) {          /* RHBZ#538041 */
       dom = virDomainLookupByID (conn, ids[i]);
       if (dom) { /* transient errors are possible here, ignore them */
-        add_domain (dom);
+        add_domain (dom, max_disks);
         virDomainFree (dom);
       }
     }
@@ -236,7 +233,8 @@ add_domains_by_id (virConnectPtr conn, int *ids, size_t n)
 }
 
 static void
-add_domains_by_name (virConnectPtr conn, char **names, size_t n)
+add_domains_by_name (virConnectPtr conn, char **names, size_t n,
+                     size_t max_disks)
 {
   size_t i;
   virDomainPtr dom;
@@ -244,14 +242,14 @@ add_domains_by_name (virConnectPtr conn, char **names, size_t n)
   for (i = 0; i < n; ++i) {
     dom = virDomainLookupByName (conn, names[i]);
     if (dom) { /* transient errors are possible here, ignore them */
-      add_domain (dom);
+      add_domain (dom, max_disks);
       virDomainFree (dom);
     }
   }
 }
 
 static void
-add_domain (virDomainPtr dom)
+add_domain (virDomainPtr dom, size_t max_disks)
 {
   struct domain *domain;
 
@@ -287,10 +285,10 @@ add_domain (virDomainPtr dom)
     exit (EXIT_FAILURE);
   domain->nr_disks = n;
 
-  if (domain->nr_disks > MAX_DISKS) {
+  if (domain->nr_disks > max_disks) {
     fprintf (stderr,
-             _("%s: ignoring %s, it has too many disks (%zu > %d)\n"),
-             program_name, domain->name, domain->nr_disks, MAX_DISKS);
+             _("%s: ignoring %s, it has too many disks (%zu > %zu)\n"),
+             program_name, domain->name, domain->nr_disks, max_disks);
     free_domain (domain);
     nr_domains--;
     return;
diff --git a/df/output.c b/df/output.c
index ba513ded..5729dd4b 100644
--- a/df/output.c
+++ b/df/output.c
@@ -82,7 +82,7 @@ print_title (void)
   }
 }
 
-static void canonical_device (char *dev, int offset);
+static char *adjust_device_offset (const char *device, int offset);
 
 void
 print_stat (const char *name, const char *uuid_param,
@@ -102,13 +102,17 @@ print_stat (const char *name, const char *uuid_param,
   float percent;
   int hopts = human_round_to_nearest|human_autoscale|human_base_1024|human_SI;
   size_t i, len;
+  char *dev;
 
-  /* Make the device canonical. */
-  len = strlen (dev_param) + 1;
-  char dev[len];
-  strcpy (dev, dev_param);
-  if (offset >= 0)
-    canonical_device (dev, offset);
+  /* Make a canonical name, adjusting the device offset if necessary. */
+  dev = guestfs_canonical_device_name (g, dev_param);
+  if (!dev)
+    exit (EXIT_FAILURE);
+  if (offset >= 0) {
+    char *p = dev;
+    dev = adjust_device_offset (p, offset);
+    free (p);
+  }
 
   if (!inodes) {                /* 1K blocks */
     if (!human) {
@@ -190,20 +194,8 @@ print_stat (const char *name, const char *uuid_param,
 
     putchar ('\n');
   }
-}
 
-/* /dev/vda1 -> /dev/sda, adjusting the device offset. */
-static void
-canonical_device (char *dev, int offset)
-{
-  if (STRPREFIX (dev, "/dev/") &&
-      (dev[5] == 'h' || dev[5] == 'v') &&
-      dev[6] == 'd' &&
-      c_isalpha (dev[7]) &&
-      (c_isdigit (dev[8]) || dev[8] == '\0')) {
-    dev[5] = 's';
-    dev[7] -= offset;
-  }
+  free (dev);
 }
 
 /* Function to quote CSV fields on output without requiring an
@@ -241,3 +233,72 @@ write_csv_field (const char *field)
   }
   putchar ('"');
 }
+
+static char *drive_name (int index, char *ret);
+
+static char *
+adjust_device_offset (const char *device, int offset)
+{
+  int index;
+  int part_num;
+  char *whole_device;
+  int free_whole_device;
+  size_t len;
+  char *ret;
+
+  /* Could be a whole disk or a partition.  guestfs_device_index will
+   * only work with the whole disk name.
+   */
+  len = strlen (device);
+  if (len > 0 && c_isdigit (device[len-1])) {
+    whole_device = guestfs_part_to_dev (g, device);
+    if (whole_device == NULL)
+      exit (EXIT_FAILURE);
+    free_whole_device = 1;
+    part_num = guestfs_part_to_partnum (g, device);
+    if (part_num == -1)
+      exit (EXIT_FAILURE);
+  } else {
+    whole_device = (char *) device;
+    free_whole_device = 0;
+    part_num = 0;
+  }
+
+  index = guestfs_device_index (g, whole_device);
+  if (index == -1)
+    exit (EXIT_FAILURE);
+
+  if (free_whole_device)
+    free (whole_device);
+
+  assert (index >= offset);
+
+  index -= offset;
+
+  /* Construct the final device name. */
+  ret = malloc (128);
+  if (!ret) {
+    perror ("malloc");
+    exit (EXIT_FAILURE);
+  }
+
+  strcpy (ret, "/dev/sd");
+  drive_name (index, &ret[7]);
+  len = strlen (ret);
+  if (part_num > 0)
+    snprintf (&ret[len], 128-len, "%d", part_num);
+
+  return ret;
+}
+
+/* https://rwmj.wordpress.com/2011/01/09/how-are-linux-drives-named-beyond-drive-26-devsdz/ */
+static char *
+drive_name (int index, char *ret)
+{
+  if (index >= 26)
+    ret = drive_name (index/26 - 1, ret);
+  index %= 26;
+  *ret++ = 'a' + index;
+  *ret = '\0';
+  return ret;
+}