Create a new tag v0.1b

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>



git-svn-id: https://libcg.svn.sourceforge.net/svnroot/libcg/tags/v0.1b@50 4f4bb910-9a46-0410-90c8-c897d4f1cd53

1 files changed, 556 insertions, 0 deletions

diff --git a/balbir/api.c b/balbir/api.c
new file mode 100644
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;
+}