From e3ebd50abde3b05db86c8965868c866152cd3287 Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Thu, 28 Apr 2022 13:16:54 +0100

Subject: [PATCH] New API: guestfs_device_name returning the drive name

For each drive added, return the name.  For example calling this with

index 0 will return the string "/dev/sda".  I called it

guestfs_device_name (not drive_name) for consistency with the existing

guestfs_device_index function.

You don't really need to call this function.  You can follow the

advice here:

https://libguestfs.org/guestfs.3.html#block-device-naming

and assume that drives are added with predictable names like

"/dev/sda", "/dev/sdb", etc.

However it's useful to expose the internal guestfs_int_drive_name

function since especially handling names beyond index 26 is tricky

(https://rwmj.wordpress.com/2011/01/09/how-are-linux-drives-named-beyond-drive-26-devsdz/)

Fixes: https://github.com/libguestfs/libguestfs/issues/80

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

(cherry picked from commit ac00e603f83802634f1d53b1629aee4670eaf31c)

---

 generator/actions_core.ml | 24 +++++++++++++++++++++++-

 lib/drives.c              | 15 +++++++++++++++

 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/generator/actions_core.ml b/generator/actions_core.ml

index ce9ee39cc..dc12fdc33 100644

--- a/generator/actions_core.ml

+++ b/generator/actions_core.ml

@@ -737,7 +737,29 @@ returns the index of the device in the list of devices.

 Index numbers start from 0.  The named device must exist,

 for example as a string returned from C<guestfs_list_devices>.

-See also C<guestfs_list_devices>, C<guestfs_part_to_dev>." };

+See also C<guestfs_list_devices>, C<guestfs_part_to_dev>,

+C<guestfs_device_name>." };

+

+  { defaults with

+    name = "device_name"; added = (1, 49, 1);

+    style = RString (RPlainString, "name"), [Int "index"], [];

+    tests = [

+      InitEmpty, Always, TestResult (

+        [["device_name"; "0"]], "STREQ (ret, \"/dev/sda\")"), [];

+      InitEmpty, Always, TestResult (

+        [["device_name"; "1"]], "STREQ (ret, \"/dev/sdb\")"), [];

+      InitEmpty, Always, TestLastFail (

+        [["device_name"; "99"]]), []

+    ];

+    shortdesc = "convert device index to name";

+    longdesc = "\

+This function takes a device index and returns the device

+name.  For example index C<0> will return the string C</dev/sda>.

+

+The drive index must have been added to the handle.

+

+See also C<guestfs_list_devices>, C<guestfs_part_to_dev>,

+C<guestfs_device_index>." };

   { defaults with

     name = "shutdown"; added = (1, 19, 16);

diff --git a/lib/drives.c b/lib/drives.c

index fd95308d2..a6179fc36 100644

--- a/lib/drives.c

+++ b/lib/drives.c

@@ -31,6 +31,7 @@

 #include <netdb.h>

 #include <arpa/inet.h>

 #include <assert.h>

+#include <errno.h>

 #include <libintl.h>

 #include "c-ctype.h"

@@ -1084,3 +1085,17 @@ guestfs_impl_device_index (guestfs_h *g, const char *device)

     error (g, _("%s: device not found"), device);

   return r;

 }

+

+char *

+guestfs_impl_device_name (guestfs_h *g, int index)

+{

+  char drive_name[64];

+

+  if (index < 0 || index >= g->nr_drives) {

+    guestfs_int_error_errno (g, EINVAL, _("drive index out of range"));

+    return NULL;

+  }

+

+  guestfs_int_drive_name (index, drive_name);

+  return safe_asprintf (g, "/dev/sd%s", drive_name);

+}

-- 

2.31.1