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dmsetup: display any message output from kernel

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Recent kernels allow messages to respond with a string.
Add dm_task_get_message_response() to libdevmapper to perform some
basic sanity checks and return this.
Have 'dmsetup message' display any response.

DM statistics will make extensive use of this.

(From Mikulas.)
This commit is contained in:
Alasdair G Kergon 2013-08-16 15:25:39 +01:00
parent cac49725c9
commit d8b781e8ab
4 changed files with 36 additions and 1 deletions
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2
WHATS_NEW_DM
View File

@ -1,5 +1,7 @@
Version 1.02.80 -
==================================
Display any output returned by 'dmsetup message'.
Add dm_task_get_message_response to libdevmapper.
Version 1.02.79 - 13th August 2013
==================================

26
libdm/ioctl/libdm-iface.c
View File

@ -1,6 +1,6 @@
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2012 Red Hat, Inc. All rights reserved.
* Copyright (C) 2004-2013 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
@ -700,6 +700,29 @@ struct dm_versions *dm_task_get_versions(struct dm_task *dmt)
dmt->dmi.v4->data_start);
}
const char *dm_task_get_message_response(struct dm_task *dmt)
{
const char *start, *end;
if (!(dmt->dmi.v4->flags & DM_DATA_OUT_FLAG))
return NULL;
start = (const char *) dmt->dmi.v4 + dmt->dmi.v4->data_start;
end = (const char *) dmt->dmi.v4 + dmt->dmi.v4->data_size;
if (end < start) {
log_error(INTERNAL_ERROR "Corrupted message structure returned: start %d > end %d", (int)dmt->dmi.v4->data_start, (int)dmt->dmi.v4->data_size);
return NULL;
}
if (!memchr(start, 0, end - start)) {
log_error(INTERNAL_ERROR "Message response doesn't contain terminating NUL character");
return NULL;
}
return start;
}
int dm_task_set_ro(struct dm_task *dmt)
{
dmt->read_only = 1;
@ -1867,6 +1890,7 @@ repeat_ioctl:
case DM_DEVICE_STATUS:
case DM_DEVICE_TABLE:
case DM_DEVICE_WAITEVENT:
case DM_DEVICE_TARGET_MSG:
_ioctl_buffer_double_factor++;
_dm_zfree_dmi(dmi);
goto repeat_ioctl;

1
libdm/libdevmapper.h
View File

@ -187,6 +187,7 @@ const char *dm_task_get_uuid(const struct dm_task *dmt);
struct dm_deps *dm_task_get_deps(struct dm_task *dmt);
struct dm_versions *dm_task_get_versions(struct dm_task *dmt);
const char *dm_task_get_message_response(struct dm_task *dmt);
/*
* These functions return device-mapper names based on the value

8
tools/dmsetup.c
View File

@ -770,6 +770,7 @@ static int _message(CMD_ARGS)
size_t sz = 1;
struct dm_task *dmt;
char *str;
const char *response;
if (!(dmt = dm_task_create(DM_DEVICE_TARGET_MSG)))
return 0;
@ -826,6 +827,13 @@ static int _message(CMD_ARGS)
if (!dm_task_run(dmt))
goto out;
if ((response = dm_task_get_message_response(dmt))) {
if (!*response || response[strlen(response) - 1] == '\n')
fputs(response, stdout);
else
puts(response);
}
r = 1;
out: