mirror of
https://github.com/xen-project/xen.git
synced 2026-10-29 18:50:05 +01:00
Ian Campbell
382c72d83a
The underlying code paths in tap_ctl_create attempt to handle both *devpath == NULL (by allocating) and *devpath != NULL (caller provided name) and if they allocate tend to write the return immediately before doing other potentially error generating tasks. All of which makes handling this at a lower level rather more complicated than handling it in the error path of libxl__blktap_devpath. Note that libxl__blktap_devpath initialises devpath to NULL and if the earlier GCSPRINTF succeeds then the value is returned earlier. Therefore if we make it to the call to tap_ctl_create then devpath is still NULL on entry, therefore on the error path devpath is either still NULL or has been set to a freshly allocated value by tap_ctl_create. Since free(NULL) is fine it is sufficient to just free(devpath). I also considered adding a non-NULL devnull to the gc, even on failure, but that would have required a comment to explain the apparently strange behaviour. Compile tested only. CID: 1215177 Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Acked-by: Wei Liu <wei.liu2@citrix.com>
95 lines
2.3 KiB
C
95 lines
2.3 KiB
C
/*
|
|
* Copyright (C) 2010 Advanced Micro Devices
|
|
* Author Christoph Egger <Christoph.Egger@amd.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU Lesser General Public License as published
|
|
* by the Free Software Foundation; version 2.1 only.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU Lesser General Public License for more details.
|
|
*/
|
|
|
|
#include "libxl_osdeps.h" /* must come before any other headers */
|
|
#include "libxl_internal.h"
|
|
|
|
#include "tap-ctl.h"
|
|
|
|
int libxl__blktap_enabled(libxl__gc *gc)
|
|
{
|
|
const char *msg;
|
|
return !tap_ctl_check(&msg);
|
|
}
|
|
|
|
char *libxl__blktap_devpath(libxl__gc *gc,
|
|
const char *disk,
|
|
libxl_disk_format format)
|
|
{
|
|
const char *type;
|
|
char *params, *devname = NULL;
|
|
tap_list_t tap;
|
|
int err;
|
|
|
|
type = libxl__device_disk_string_of_format(format);
|
|
err = tap_ctl_find(type, disk, &tap);
|
|
if (err == 0) {
|
|
devname = GCSPRINTF("/dev/xen/blktap-2/tapdev%d", tap.minor);
|
|
if (devname)
|
|
return devname;
|
|
}
|
|
|
|
params = GCSPRINTF("%s:%s", type, disk);
|
|
err = tap_ctl_create(params, &devname);
|
|
if (!err) {
|
|
libxl__ptr_add(gc, devname);
|
|
return devname;
|
|
}
|
|
|
|
free(devname);
|
|
return NULL;
|
|
}
|
|
|
|
|
|
int libxl__device_destroy_tapdisk(libxl__gc *gc, const char *params)
|
|
{
|
|
char *type, *disk;
|
|
int err;
|
|
tap_list_t tap;
|
|
|
|
type = libxl__strdup(gc, params);
|
|
|
|
disk = strchr(type, ':');
|
|
if (!disk) {
|
|
LOG(ERROR, "Unable to parse params %s", params);
|
|
return ERROR_INVAL;
|
|
}
|
|
|
|
*disk++ = '\0';
|
|
|
|
err = tap_ctl_find(type, disk, &tap);
|
|
if (err < 0) {
|
|
/* returns -errno */
|
|
LOGEV(ERROR, -err, "Unable to find type %s disk %s", type, disk);
|
|
return ERROR_FAIL;
|
|
}
|
|
|
|
err = tap_ctl_destroy(tap.id, tap.minor);
|
|
if (err < 0) {
|
|
LOGEV(ERROR, -err, "Failed to destroy tap device id %d minor %d",
|
|
tap.id, tap.minor);
|
|
return ERROR_FAIL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Local variables:
|
|
* mode: C
|
|
* c-basic-offset: 4
|
|
* indent-tabs-mode: nil
|
|
* End:
|
|
*/
|