As of now, libcgroup does not support multiline values setting from
configuration files. i.e. values in a form:
net_prio.ifpriomap="lo 7
eth0 66
eth1 5
eth2 4
eth3 3";
Thus, setting of more network interfaces can not be done from configuration
file. Or
devices.allow="a *:* w
c 8:* r";
thus setting list of allow devices can not be set as well. The only way is to
set it from userspace, e.g.:
# echo "lo 7" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
# echo "eth 0" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
# echo "eth 1" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
# echo "eth 2" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
# echo "eth 3" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
This patch allows setting of multiline variables.
How this support works:
Multiline value is broken in lines and each line is set by write (man 2 write)
syscall (without bufferring).
This implies change of fopen with open, fclose with close.
There is no control on multiline value, thus "eth0\n \t\n" can be set.
However, setting
of " \t" will fail as write command returns -1. Thus administrator has to set
correct
multiline values.
Tested on virtual machine with fedora and rhel with network interface lo,
eth0-eth3. Configuration file:
# cat /etc/cgconfig.conf
group testGroup {
net_prio {
net_prio.ifpriomap="lo 7
eth0 66
eth1 5
eth2 4
eth3 3";
}
}
net_prio has to be created before:
# modprobe netprio_cgroup
# mkdir /sys/fs/cgroup/net_prio
# mount -t cgroup -onet_prio none /sys/fs/cgroup/net_prio
Changelog:
test of success of strdup call
free str_val before return (str_val is changing in while cycle,
thus str_start_val points to the start of str_val before while)
Signed-off-by: Jan Chaloupka <jchal...@redhat.com>
---
src/api.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 44 insertions(+), 6 deletions(-)
diff --git a/src/api.c b/src/api.c
index 5751b8f..d6c9d3a 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1495,13 +1495,18 @@ static int cg_create_control_group(const char *path)
*/
static int cg_set_control_value(char *path, const char *val)
{
- FILE *control_file = NULL;
+ int ctl_file;
+ char *str_val;
+ char *str_val_start;
+ char *pos;
+ size_t len;
+
if (!cg_test_mounted_fs())
return ECGROUPNOTMOUNTED;
- control_file = fopen(path, "r+e");
+ ctl_file = open(path, O_RDWR | O_CLOEXEC);
- if (!control_file) {
+ if (ctl_file == -1) {
if (errno == EPERM) {
/*
* We need to set the correct error value, does the
@@ -1512,6 +1517,7 @@ static int cg_set_control_value(char *path, const char
*val)
*/
char *path_dir_end;
char *tasks_path;
+ FILE *control_file;
path_dir_end = strrchr(path, '/');
if (path_dir_end == NULL)
@@ -1543,15 +1549,47 @@ static int cg_set_control_value(char *path, const char
*val)
return ECGROUPVALUENOTEXIST;
}
- if (fprintf(control_file, "%s", val) < 0) {
+ /* Split the multiline value into lines. */
+ /* One line is a special case of multiline value. */
+ str_val = strdup(val);
+ if (str_val == NULL) {
last_errno = errno;
- fclose(control_file);
+ close(ctl_file);
return ECGOTHER;
}
- if (fclose(control_file) < 0) {
+
+ str_val_start = str_val;
+ pos = str_val;
+
+ do {
+ str_val = pos;
+ pos = strchr(str_val, '\n');
+
+ if (pos) {
+ *pos = '\0';
+ ++pos;
+ }
+
+ len = strlen(str_val);
+ if (len > 0) {
+ if (write(ctl_file, str_val, len) == -1) {
+ last_errno = errno;
+ free(str_val_start);
+ close(ctl_file);
+ return ECGOTHER;
+ }
+ } else
+ cgroup_warn("Warning: skipping empty line for %s\n",
+ path);
+ } while(pos);
+
+ if (close(ctl_file)) {
last_errno = errno;
+ free(str_val_start);
return ECGOTHER;
}
+
+ free(str_val_start);
return 0;
}
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