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-rw-r--r--balbir/api.c556
1 files changed, 556 insertions, 0 deletions
diff --git a/balbir/api.c b/balbir/api.c
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index 0000000..fce70a7
--- /dev/null
+++ b/balbir/api.c
@@ -0,0 +1,556 @@
+/*
+ * Copyright IBM Corporation. 2007
+ *
+ * Author: Dhaval Giani <dhaval@linux.vnet.ibm.com>
+ * Author: Balbir Singh <balbir@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * TODOs:
+ * 1. Convert comments to Docbook style.
+ * 2. Add more APIs for the control groups.
+ * 3. Handle the configuration related APIs.
+ * 4. Error handling.
+ *
+ * Code initiated and designed by Dhaval Giani. All faults are most likely
+ * his mistake.
+ */
+
+#include <errno.h>
+#include <libcgroup.h>
+#include <libcgroup-internal.h>
+#include <mntent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <fts.h>
+
+#ifndef PACKAGE_VERSION
+#define PACKAGE_VERSION 0.01
+#endif
+
+#define VERSION(ver) #ver
+
+/*
+ * Remember to bump this up for major API changes.
+ */
+const static char cg_version[] = VERSION(PACKAGE_VERSION);
+
+struct cg_mount_table_s cg_mount_table[CG_CONTROLLER_MAX];
+
+static int cg_chown_file(FTS *fts, FTSENT *ent, uid_t owner, gid_t group)
+{
+ int ret = 0;
+ const char *filename = fts->fts_path;
+ dbg("seeing file %s\n", filename);
+ switch (ent->fts_info) {
+ case FTS_ERR:
+ errno = ent->fts_errno;
+ break;
+ case FTS_D:
+ case FTS_DC:
+ case FTS_NSOK:
+ case FTS_NS:
+ case FTS_DNR:
+ case FTS_DP:
+ case FTS_F:
+ case FTS_DEFAULT:
+ ret = chown(filename, owner, group);
+ break;
+ }
+ return ret;
+}
+
+/*
+ * TODO: Need to decide a better place to put this function.
+ */
+static int cg_chown_recursive(char **path, uid_t owner, gid_t group)
+{
+ int ret = 0;
+ dbg("path is %s\n", *path);
+ FTS *fts = fts_open(path, FTS_PHYSICAL | FTS_NOCHDIR |
+ FTS_NOSTAT, NULL);
+ while (1) {
+ FTSENT *ent;
+ ent = fts_read(fts);
+ if (!ent) {
+ dbg("fts_read failed\n");
+ break;
+ }
+ ret = cg_chown_file(fts, ent, owner, group);
+ }
+ fts_close(fts);
+ return ret;
+}
+
+/**
+ * cgroup_init(), initializes the MOUNT_POINT.
+ * This code is not currently thread safe (hint: getmntent is not thread safe).
+ * This API is likely to change in the future to push state back to the caller
+ * to achieve thread safety. The code currently supports just one mount point.
+ * Complain if the cgroup filesystem controllers are bound to different mount
+ * points.
+ */
+int cgroup_init()
+{
+ FILE *proc_mount;
+ struct mntent *ent, *found_ent = NULL;
+ int found_mnt = 0;
+ int ret = 0;
+ char *mntent_tok;
+ static char *controllers[CG_CONTROLLER_MAX];
+ FILE *proc_cgroup;
+ char subsys_name[FILENAME_MAX];
+ int hierarchy, num_cgroups, enabled;
+ int i=0;
+ char *mntopt;
+ int err;
+
+ proc_cgroup = fopen("/proc/cgroups", "r");
+
+ if (!proc_cgroup)
+ return EIO;
+
+ /*
+ * The first line of the file has stuff we are not interested in.
+ * So just read it and discard the information.
+ *
+ * XX: fix the size for fgets
+ */
+ fgets(subsys_name, FILENAME_MAX, proc_cgroup);
+ while (!feof(proc_cgroup)) {
+ err = fscanf(proc_cgroup, "%s %d %d %d", subsys_name,
+ &hierarchy, &num_cgroups, &enabled);
+ if (err < 0)
+ break;
+ controllers[i] = (char *)malloc(strlen(subsys_name));
+ strcpy(controllers[i], subsys_name);
+ i++;
+ }
+ controllers[i] = NULL;
+ fclose(proc_cgroup);
+
+ proc_mount = fopen("/proc/mounts", "r");
+ if (proc_mount == NULL) {
+ return EIO;
+ }
+
+ while ((ent = getmntent(proc_mount)) != NULL) {
+ if (!strncmp(ent->mnt_type, "cgroup", strlen("cgroup"))) {
+ for (i = 0; controllers[i] != NULL; i++) {
+ mntopt = hasmntopt(ent, controllers[i]);
+ if (mntopt &&
+ strcmp(mntopt, controllers[i]) == 0) {
+ dbg("matched %s:%s\n", mntopt,
+ controllers[i]);
+ strcpy(cg_mount_table[found_mnt].name,
+ controllers[i]);
+ strcpy(cg_mount_table[found_mnt].path,
+ ent->mnt_dir);
+ dbg("Found cgroup option %s, "
+ " count %d\n",
+ ent->mnt_opts, found_mnt);
+ found_mnt++;
+ }
+ }
+ }
+ }
+
+ if (!found_mnt) {
+ cg_mount_table[0].name[0] = '\0';
+ return ECGROUPNOTMOUNTED;
+ }
+
+ found_mnt++;
+ cg_mount_table[found_mnt].name[0] = '\0';
+
+
+ fclose(proc_mount);
+ return ret;
+}
+
+static char **get_mounted_controllers(char *mountpoint)
+{
+ char **controllers;
+ int i, j;
+
+ i = 0;
+ j = 0;
+
+ controllers = (char **) malloc(sizeof(char *) * CG_CONTROLLER_MAX);
+
+ for (i = 0; i < CG_CONTROLLER_MAX && cg_mount_table[i].name != NULL;
+ i++) {
+ if (strcmp(cg_mount_table[i].name, mountpoint) == 0) {
+ controllers[j] = (char *)malloc(sizeof(char) *
+ FILENAME_MAX);
+ strcpy(controllers[j], cg_mount_table[i].name);
+ j++;
+ }
+ }
+ controllers[j] = (char *)malloc(sizeof(char) * FILENAME_MAX);
+ controllers[j][0] = '\0';
+
+ return controllers;
+}
+
+static int cg_test_mounted_fs()
+{
+ FILE *proc_mount;
+ struct mntent *ent;
+
+ proc_mount = fopen("/proc/mounts", "r");
+ if (proc_mount == NULL) {
+ return -1;
+ }
+ ent = getmntent(proc_mount);
+
+ while (strcmp(ent->mnt_type, "cgroup") !=0) {
+ ent = getmntent(proc_mount);
+ if (ent == NULL)
+ return 0;
+ }
+ fclose(proc_mount);
+ return 1;
+}
+
+static inline pid_t cg_gettid()
+{
+ return syscall(__NR_gettid);
+}
+
+static char* cg_build_path(char *name, char *path, char *type)
+{
+ int i;
+ for (i = 0; cg_mount_table[i].name[0] != '\0'; i++) {
+ if (strcmp(cg_mount_table[i].name, type) == 0) {
+ strcpy(path, cg_mount_table[i].path);
+ strcat(path, "/");
+ strcat(path, name);
+ strcat(path, "/");
+ return path;
+ }
+ }
+ return NULL;
+}
+
+/** cgroup_attach_task_pid is used to assign tasks to a cgroup.
+ * struct cgroup *cgroup: The cgroup to assign the thread to.
+ * pid_t tid: The thread to be assigned to the cgroup.
+ *
+ * returns 0 on success.
+ * returns ECGROUPNOTOWNER if the caller does not have access to the cgroup.
+ * returns ECGROUPNOTALLOWED for other causes of failure.
+ */
+int cgroup_attach_task_pid(struct cgroup *cgroup, pid_t tid)
+{
+ char path[FILENAME_MAX];
+ FILE *tasks;
+ int i;
+
+ if(!cgroup)
+ {
+ for(i = 0; i < CG_CONTROLLER_MAX &&
+ cg_mount_table[i].name[0]!='\0'; i++) {
+ if (!cg_build_path(cgroup->name, path, NULL))
+ continue;
+ strcat(path, "/tasks");
+
+ tasks = fopen(path, "w");
+ if (!tasks) {
+ switch (errno) {
+ case EPERM:
+ return ECGROUPNOTOWNER;
+ default:
+ return ECGROUPNOTALLOWED;
+ }
+ }
+ fprintf(tasks, "%d", tid);
+ fclose(tasks);
+ }
+ } else {
+ for( i = 0; i <= CG_CONTROLLER_MAX &&
+ cgroup->controller[i] != NULL ; i++) {
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[i]->name))
+ continue;
+
+ strcat(path, "/tasks");
+
+ tasks = fopen(path, "w");
+ if (!tasks) {
+ switch (errno) {
+ case EPERM:
+ return ECGROUPNOTOWNER;
+ default:
+ return ECGROUPNOTALLOWED;
+ }
+ }
+ fprintf(tasks, "%d", tid);
+ fclose(tasks);
+ }
+ }
+ return 0;
+
+}
+
+/** cgroup_attach_task is used to attach the current thread to a cgroup.
+ * struct cgroup *cgroup: The cgroup to assign the current thread to.
+ *
+ * See cg_attach_task_pid for return values.
+ */
+int cgroup_attach_task(struct cgroup *cgroup)
+{
+ pid_t tid = cg_gettid();
+ int error;
+
+ error = cgroup_attach_task_pid(cgroup, tid);
+
+ return error;
+}
+
+/*
+ * create_control_group()
+ * This is the basic function used to create the control group. This function
+ * just makes the group. It does not set any permissions, or any control values.
+ * The argument path is the fully qualified path name to make it generic.
+ */
+static int cg_create_control_group(char *path)
+{
+ int error;
+ if (!cg_test_mounted_fs())
+ return ECGROUPNOTMOUNTED;
+ error = mkdir(path, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
+ if (error) {
+ switch(errno) {
+ case EPERM:
+ return ECGROUPNOTOWNER;
+ default:
+ return ECGROUPNOTALLOWED;
+ }
+ }
+ return error;
+}
+
+/*
+ * set_control_value()
+ * This is the low level function for putting in a value in a control file.
+ * This function takes in the complete path and sets the value in val in that
+ * file.
+ */
+static int cg_set_control_value(char *path, char *val)
+{
+ int error;
+ FILE *control_file;
+ if (!cg_test_mounted_fs())
+ return ECGROUPNOTMOUNTED;
+
+ control_file = fopen(path, "a");
+
+ if (!control_file) {
+ if (errno == EPERM) {
+ /*
+ * We need to set the correct error value, does the
+ * group exist but we don't have the subsystem
+ * mounted at that point, or is it that the group
+ * does not exist. So we check if the tasks file
+ * exist. Before that, we need to extract the path.
+ */
+ int len = strlen(path);
+
+ while (*(path+len) != '/')
+ len--;
+ *(path+len+1) = '\0';
+ strcat(path, "tasks");
+ control_file = fopen(path, "r");
+ if (!control_file) {
+ if (errno == ENOENT)
+ return ECGROUPSUBSYSNOTMOUNTED;
+ }
+ fclose(control_file);
+ return ECGROUPNOTALLOWED;
+ }
+ return errno;
+ }
+
+ fprintf(control_file, "%s", val);
+ fclose(control_file);
+ return 0;
+}
+
+/** cgroup_modify_cgroup modifies the cgroup control files.
+ * struct cgroup *cgroup: The name will be the cgroup to be modified.
+ * The values will be the values to be modified, those not mentioned
+ * in the structure will not be modified.
+ *
+ * The uids cannot be modified yet.
+ *
+ * returns 0 on success.
+ *
+ */
+
+int cgroup_modify_cgroup(struct cgroup *cgroup)
+{
+ char path[FILENAME_MAX], base[FILENAME_MAX];
+ int i;
+ int error;
+
+ for (i = 0; i < CG_CONTROLLER_MAX && cgroup->controller[i];
+ i++, strcpy(path, base)) {
+ int j;
+ if (!cg_build_path(cgroup->name, base,
+ cgroup->controller[i]->name))
+ continue;
+ for(j = 0; j < CG_NV_MAX &&
+ cgroup->controller[i]->values[j];
+ j++, strcpy(path, base)) {
+ strcat(path, cgroup->controller[i]->values[j]->name);
+ error = cg_set_control_value(path,
+ cgroup->controller[i]->values[j]->value);
+ if (error)
+ goto err;
+ }
+ }
+ return 0;
+err:
+ return error;
+
+}
+
+/** cgroup_create_cgroup creates a new control group.
+ * struct cgroup *cgroup: The control group to be created
+ *
+ * returns 0 on success. We recommend calling cg_delete_cgroup
+ * if this routine fails. That should do the cleanup operation.
+ */
+int cgroup_create_cgroup(struct cgroup *cgroup, int ignore_ownership)
+{
+ char *fts_path[2], base[FILENAME_MAX], *path;
+ int i, j, k;
+ int error = 0;
+
+ fts_path[0] = (char *)malloc(FILENAME_MAX);
+ if (!fts_path[0])
+ return ENOMEM;
+ fts_path[1] = NULL;
+ path = fts_path[0];
+
+ /*
+ * XX: One important test to be done is to check, if you have multiple
+ * subsystems mounted at one point, all of them *have* be on the cgroup
+ * data structure. If not, we fail.
+ */
+ for (k = 0; k < CG_CONTROLLER_MAX && cgroup->controller[k]; k++) {
+ path[0] = '\0';
+
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[k]->name))
+ continue;
+
+ dbg("path is %s\n", path);
+ error = cg_create_control_group(path);
+ if (error)
+ goto err;
+
+ strcpy(base, path);
+
+ if (!ignore_ownership)
+ error = cg_chown_recursive(fts_path,
+ cgroup->control_uid, cgroup->control_gid);
+
+ if (error)
+ goto err;
+
+ for (j = 0; j < CG_NV_MAX && cgroup->controller[k]->values[j];
+ j++, strcpy(path, base)) {
+ strcat(path, cgroup->controller[k]->values[j]->name);
+ error = cg_set_control_value(path,
+ cgroup->controller[k]->values[j]->value);
+ /*
+ * Should we undo, what we've done in the loops above?
+ */
+ if (error)
+ goto err;
+ }
+
+ if (!ignore_ownership) {
+ strcpy(path, base);
+ strcat(path, "/tasks");
+ chown(path, cgroup->tasks_uid, cgroup->tasks_gid);
+ }
+ }
+
+err:
+ free(path);
+ return error;
+}
+
+/** cgroup_delete cgroup deletes a control group.
+ * struct cgroup *cgroup takes the group which is to be deleted.
+ *
+ * returns 0 on success.
+ */
+int cgroup_delete_cgroup(struct cgroup *cgroup, int ignore_migration)
+{
+ FILE *delete_tasks, *base_tasks = NULL;
+ int tids;
+ char path[FILENAME_MAX];
+ int error = ECGROUPNOTALLOWED;
+ int i;
+
+ for (i = 0; i < CG_CONTROLLER_MAX && cgroup->controller; i++) {
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[i]->name))
+ continue;
+ strcat(path, "../tasks");
+
+ base_tasks = fopen(path, "w");
+ if (!base_tasks)
+ goto base_open_err;
+
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[i]->name))
+ continue;
+
+ strcat(path, "tasks");
+
+ delete_tasks = fopen(path, "r");
+ if (!delete_tasks)
+ goto del_open_err;
+
+ while (!feof(delete_tasks)) {
+ fscanf(delete_tasks, "%d", &tids);
+ fprintf(base_tasks, "%d", tids);
+ }
+
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[i]->name))
+ continue;
+ error = rmdir(path);
+
+ fclose(delete_tasks);
+ }
+del_open_err:
+ if (base_tasks)
+ fclose(base_tasks);
+base_open_err:
+ if (ignore_migration) {
+ for (i = 0; cgroup->controller[i] != NULL; i++) {
+ if (!cg_build_path(cgroup->name, path,
+ cgroup->controller[i]->name))
+ continue;
+ error = rmdir(path);
+ }
+ }
+ return error;
+}
generated by cgit (git 2.34.1) at 2025-09-23 16:31:29 +0000