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From 691430206f1104b752b0e52386f317e639137788 Mon Sep 17 00:00:00 2001
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From: Jan Chaloupka <jchaloup@redhat.com>
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Date: Mon, 15 Sep 2014 13:29:39 +0200
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Subject: [PATCH] api.c: support for setting multiline values in control files
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As of now, libcgroup does not support multiline values setting from configuration files. i.e. values in a form:
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net_prio.ifpriomap="lo 7
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eth0 66
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eth1 5
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eth2 4
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eth3 3";
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Thus, setting of more network interfaces can not be done from configuration file. Or
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devices.allow="a *:* w
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c 8:* r";
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thus setting list of allow devices can not be set as well. The only way is to set it from userspace, e.g.:
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# echo "lo 7" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
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# echo "eth 0" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
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# echo "eth 1" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
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# echo "eth 2" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
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# echo "eth 3" > /sys/fs/cgroup/net_prio/testGroup/net_prio.ifpriomap
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This patch allows setting of multiline variables.
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How this support works:
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Multiline value is broken in lines and each line is set by write (man 2 write) syscall (without bufferring).
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This implies change of fopen with open, fclose with close.
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There is no control on multiline value, thus "eth0\n \t\n" can be set. However, setting
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of " \t" will fail as write command returns -1. Thus administrator has to set correct
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multiline values.
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Tested on virtual machine with fedora and rhel with network interface lo, eth0-eth3. Configuration file:
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# cat /etc/cgconfig.conf
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group testGroup {
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net_prio {
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net_prio.ifpriomap="lo 7
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eth0 66
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eth1 5
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eth2 4
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eth3 3";
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}
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}
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net_prio has to be created before:
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# modprobe netprio_cgroup
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# mkdir /sys/fs/cgroup/net_prio
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# mount -t cgroup -onet_prio none /sys/fs/cgroup/net_prio
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Changelog:
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test of success of strdup call
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free str_val before return (str_val is changing in while cycle,
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thus str_start_val points to the start of str_val before while)
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Signed-off-by: Jan Chaloupka <jchaloup@redhat.com>
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---
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src/api.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------
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1 file changed, 44 insertions(+), 6 deletions(-)
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diff --git a/src/api.c b/src/api.c
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index 5751b8f..d6c9d3a 100644
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--- a/src/api.c
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+++ b/src/api.c
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@@ -1495,13 +1495,18 @@ static int cg_create_control_group(const char *path)
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*/
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static int cg_set_control_value(char *path, const char *val)
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{
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- FILE *control_file = NULL;
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+ int ctl_file;
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+ char *str_val;
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+ char *str_val_start;
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+ char *pos;
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+ size_t len;
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+
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if (!cg_test_mounted_fs())
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return ECGROUPNOTMOUNTED;
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- control_file = fopen(path, "r+e");
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+ ctl_file = open(path, O_RDWR | O_CLOEXEC);
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- if (!control_file) {
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+ if (ctl_file == -1) {
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if (errno == EPERM) {
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/*
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* We need to set the correct error value, does the
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@@ -1512,6 +1517,7 @@ static int cg_set_control_value(char *path, const char *val)
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*/
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char *path_dir_end;
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char *tasks_path;
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+ FILE *control_file;
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path_dir_end = strrchr(path, '/');
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if (path_dir_end == NULL)
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@@ -1543,15 +1549,47 @@ static int cg_set_control_value(char *path, const char *val)
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return ECGROUPVALUENOTEXIST;
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}
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- if (fprintf(control_file, "%s", val) < 0) {
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+ /* Split the multiline value into lines. */
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+ /* One line is a special case of multiline value. */
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+ str_val = strdup(val);
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+ if (str_val == NULL) {
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last_errno = errno;
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- fclose(control_file);
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+ close(ctl_file);
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return ECGOTHER;
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}
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- if (fclose(control_file) < 0) {
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+
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+ str_val_start = str_val;
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+ pos = str_val;
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+
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+ do {
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+ str_val = pos;
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+ pos = strchr(str_val, '\n');
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+
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+ if (pos) {
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+ *pos = '\0';
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+ ++pos;
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+ }
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+
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+ len = strlen(str_val);
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+ if (len > 0) {
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+ if (write(ctl_file, str_val, len) == -1) {
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+ last_errno = errno;
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+ free(str_val_start);
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+ close(ctl_file);
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+ return ECGOTHER;
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+ }
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+ } else
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+ cgroup_warn("Warning: skipping empty line for %s\n",
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+ path);
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+ } while(pos);
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+
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+ if (close(ctl_file)) {
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last_errno = errno;
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+ free(str_val_start);
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return ECGOTHER;
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}
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+
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+ free(str_val_start);
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return 0;
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}
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--
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1.9.3
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