[libvirt] [PATCH v2] daemon: add option to read host uuid from /etc/machine-id
Nikolay Shirokovskiy
nshirokovskiy at virtuozzo.com
Mon May 2 12:30:56 UTC 2016
Daemon config parameter switch between reading host uuid
either from smbios or machine-id:
host_uuid_source = "smbios|machine-id"
Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
difference from version 1:
* move file reading function to virfile.c and generalize it
* change comments and documentation as suggested by reviewer (see NOTES)
NOTES
Cole, I eventually found the way you suggested to document host_uuid
slightly misguided. It sounds like it is applied only if
dmidecode fail. So documentation is slightly different from
that is your reply.
daemon/libvirtd-config.c | 2 ++
daemon/libvirtd-config.h | 1 +
daemon/libvirtd.c | 38 +++++++++++++++++++++++++++++++++++---
daemon/libvirtd.conf | 15 +++++++++++----
src/libvirt_private.syms | 2 ++
src/util/virfile.c | 24 ++++++++++++++++++++++++
src/util/virfile.h | 2 ++
src/util/viruuid.c | 11 ++---------
8 files changed, 79 insertions(+), 16 deletions(-)
diff --git a/daemon/libvirtd-config.c b/daemon/libvirtd-config.c
index 7a448f9..45280e9 100644
--- a/daemon/libvirtd-config.c
+++ b/daemon/libvirtd-config.c
@@ -374,6 +374,7 @@ daemonConfigFree(struct daemonConfig *data)
VIR_FREE(data->crl_file);
VIR_FREE(data->host_uuid);
+ VIR_FREE(data->host_uuid_source);
VIR_FREE(data->log_filters);
VIR_FREE(data->log_outputs);
@@ -463,6 +464,7 @@ daemonConfigLoadOptions(struct daemonConfig *data,
GET_CONF_UINT(conf, filename, audit_logging);
GET_CONF_STR(conf, filename, host_uuid);
+ GET_CONF_STR(conf, filename, host_uuid_source);
GET_CONF_UINT(conf, filename, log_level);
GET_CONF_STR(conf, filename, log_filters);
diff --git a/daemon/libvirtd-config.h b/daemon/libvirtd-config.h
index 3e1971d..672e9ad 100644
--- a/daemon/libvirtd-config.h
+++ b/daemon/libvirtd-config.h
@@ -28,6 +28,7 @@
struct daemonConfig {
char *host_uuid;
+ char *host_uuid_source;
int listen_tls;
int listen_tcp;
diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c
index 7ec02ad..a489136 100644
--- a/daemon/libvirtd.c
+++ b/daemon/libvirtd.c
@@ -1076,6 +1076,39 @@ static int migrateProfile(void)
return ret;
}
+static int
+daemonSetupHostUUID(const struct daemonConfig *config)
+{
+ static const char *machine_id = "/etc/machine-id";
+ char buf[VIR_UUID_STRING_BUFLEN];
+ const char *uuid;
+
+ if (config->host_uuid) {
+ uuid = config->host_uuid;
+ } else if (!config->host_uuid_source ||
+ STREQ(config->host_uuid_source, "smbios")) {
+ /* smbios UUID is fetched on demand in virGetHostUUID */
+ return 0;
+ } else if (STREQ(config->host_uuid_source, "machine-id")) {
+ if (virFileReadBufQuiet(machine_id, buf, sizeof(buf)) < 0) {
+ VIR_ERROR(_("Can't read %s"), machine_id);
+ return -1;
+ }
+
+ uuid = buf;
+ } else {
+ VIR_ERROR(_("invalid UUID source: %s"), config->host_uuid_source);
+ return -1;
+ }
+
+ if (virSetHostUUIDStr(uuid)) {
+ VIR_ERROR(_("invalid host UUID: %s"), uuid);
+ return -1;
+ }
+
+ return 0;
+}
+
/* Print command-line usage. */
static void
daemonUsage(const char *argv0, bool privileged)
@@ -1295,9 +1328,8 @@ int main(int argc, char **argv) {
exit(EXIT_FAILURE);
}
- if (config->host_uuid &&
- virSetHostUUIDStr(config->host_uuid) < 0) {
- VIR_ERROR(_("invalid host UUID: %s"), config->host_uuid);
+ if (daemonSetupHostUUID(config) < 0) {
+ VIR_ERROR(_("Can't setup host uuid"));
exit(EXIT_FAILURE);
}
diff --git a/daemon/libvirtd.conf b/daemon/libvirtd.conf
index d2c439c..1c1fa7f 100644
--- a/daemon/libvirtd.conf
+++ b/daemon/libvirtd.conf
@@ -410,10 +410,16 @@
###################################################################
# UUID of the host:
-# Provide the UUID of the host here in case the command
-# 'dmidecode -s system-uuid' does not provide a valid uuid. In case
-# 'dmidecode' does not provide a valid UUID and none is provided here, a
-# temporary UUID will be generated.
+# Host UUID is read from one of the sources specified in host_uuid_source.
+#
+# - 'smbios': fetch the UUID from 'dmidecode -s system-uuid'
+# - 'machine-id': fetch the UUID from /etc/machine-id
+#
+# The host_uuid_source default is 'smbios'. If 'dmidecode' does not provide
+# a valid UUID a temporary UUID will be generated.
+#
+# Another option is to specify host UUID in host_uuid.
+#
# Keep the format of the example UUID below. UUID must not have all digits
# be the same.
@@ -421,6 +427,7 @@
# it with the output of the 'uuidgen' command and then
# uncomment this entry
#host_uuid = "00000000-0000-0000-0000-000000000000"
+#host_uuid_source = "smbios"
###################################################################
# Keepalive protocol:
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0de35ef..98e9ac5 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1510,6 +1510,7 @@ virFileOpenTty;
virFilePrintf;
virFileReadAll;
virFileReadAllQuiet;
+virFileReadBufQuiet;
virFileReadHeaderFD;
virFileReadLimFD;
virFileRelLinkPointsTo;
@@ -2537,6 +2538,7 @@ virUUIDFormat;
virUUIDGenerate;
virUUIDIsValid;
virUUIDParse;
+virUUIDRead;
# util/virxml.h
diff --git a/src/util/virfile.c b/src/util/virfile.c
index 730c08d..4d7b510 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -1401,6 +1401,30 @@ virFileReadAllQuiet(const char *path, int maxlen, char **buf)
return len;
}
+/* Read @file into preallocated buffer @buf of size @len.
+ * Return value is -errno in case of errors and size
+ * of data read (no trailing zero) in case of success.
+ * If there is more data then @len - 1 then data will be
+ * truncated. */
+int
+virFileReadBufQuiet(const char *file, char *buf, int len)
+{
+ int fd;
+ ssize_t sz;
+
+ fd = open(file, O_RDONLY);
+ if (fd < 0)
+ return -errno;
+
+ sz = saferead(fd, buf, len - 1);
+ VIR_FORCE_CLOSE(fd);
+ if (sz < 0)
+ return -errno;
+
+ buf[sz] = '\0';
+ return sz;
+}
+
/* Truncate @path and write @str to it. If @mode is 0, ensure that
@path exists; otherwise, use @mode if @path must be created.
Return 0 for success, nonzero for failure.
diff --git a/src/util/virfile.h b/src/util/virfile.h
index 312f226..dc62eab 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -131,6 +131,8 @@ int virFileReadAll(const char *path, int maxlen, char **buf)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
int virFileReadAllQuiet(const char *path, int maxlen, char **buf)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3);
+int virFileReadBufQuiet(const char *file, char *buf, int len)
+ ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
int virFileWriteStr(const char *path, const char *str, mode_t mode)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
diff --git a/src/util/viruuid.c b/src/util/viruuid.c
index 16e57db..3cbaae0 100644
--- a/src/util/viruuid.c
+++ b/src/util/viruuid.c
@@ -231,15 +231,8 @@ getDMISystemUUID(char *uuid, int len)
};
while (paths[i]) {
- int fd = open(paths[i], O_RDONLY);
- if (fd >= 0) {
- if (saferead(fd, uuid, len - 1) == len - 1) {
- uuid[len - 1] = '\0';
- VIR_FORCE_CLOSE(fd);
- return 0;
- }
- VIR_FORCE_CLOSE(fd);
- }
+ if (virFileReadBufQuiet(paths[i], uuid, len) == len - 1)
+ return 0;
i++;
}
--
1.8.3.1
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