cgroup: address some style+safety issues

three issues raised by Christian Seiler: use pid_t, use snprintf,
and use const.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index 0062571d44ac7ca083b8bd7378273156db038a6e..aaee546b929dc5ac9b13568371b12453a06853e5 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -542,11 +542,11 @@ struct cgroup_process_info *lxc_cgroup_process_info_get_self(struct cgroup_meta_
  * name is c1. .  We want to rename the cgroup directory to /sys/fs/cgroup/lxc/c1,
  * and return the string /sys/fs/cgroup/lxc/c1.
  */
-static char *cgroup_rename_nsgroup(char *mountpath, const char *oldname, int pid, const char *name)
+static char *cgroup_rename_nsgroup(const char *mountpath, const char *oldname, pid_t pid, const char *name)
 {
        char *dir, *fulloldpath;
        char *newname, *fullnewpath;
-       int len;
+       int len, newlen, ret;
 
        /*
         * if cgroup is mounted at /cgroup and task is in cgroup /ab/, pid 2375 and
@@ -559,8 +559,11 @@ static char *cgroup_rename_nsgroup(char *mountpath, const char *oldname, int pid
        dir = alloca(strlen(oldname) + 1);
        strcpy(dir, oldname);
 
-       fulloldpath = alloca(strlen(oldname) + strlen(mountpath) + 22);
-       sprintf(fulloldpath, "%s/%s/%d", mountpath, oldname, pid);
+       len = strlen(oldname) + strlen(mountpath) + 22;
+       fulloldpath = alloca(len);
+       ret = snprintf(fulloldpath, len, "%s/%s/%ld", mountpath, oldname, (unsigned long)pid);
+       if (ret < 0 || ret >= len)
+               return NULL;
 
        len = strlen(dir) + strlen(name) + 2;
        newname = malloc(len);
@@ -568,10 +571,19 @@ static char *cgroup_rename_nsgroup(char *mountpath, const char *oldname, int pid
                SYSERROR("Out of memory");
                return NULL;
        }
-       sprintf(newname, "%s/%s", dir, name);
+       ret = snprintf(newname, len, "%s/%s", dir, name);
+       if (ret < 0 || ret >= len) {
+               free(newname);
+               return NULL;
+       }
 
-       fullnewpath = alloca(strlen(mountpath) + len + 2);
-       sprintf(fullnewpath, "%s/%s", mountpath, newname);
+       newlen = strlen(mountpath) + len + 2;
+       fullnewpath = alloca(newlen);
+       ret = snprintf(fullnewpath, newlen, "%s/%s", mountpath, newname);
+       if (ret < 0 || ret >= newlen) {
+               free(newname);
+               return NULL;
+       }
 
        if (access(fullnewpath, F_OK) == 0) {
                if (rmdir(fullnewpath) != 0) {
@@ -592,7 +604,7 @@ static char *cgroup_rename_nsgroup(char *mountpath, const char *oldname, int pid
 }
 
 /* create a new cgroup */
-extern struct cgroup_process_info *lxc_cgroup_create(const char *name, const char *path_pattern, struct cgroup_meta_data *meta_data, const char *sub_pattern, int pid)
+extern struct cgroup_process_info *lxc_cgroup_create(const char *name, const char *path_pattern, struct cgroup_meta_data *meta_data, const char *sub_pattern, pid_t pid)
 {
        char **cgroup_path_components = NULL;
        char **p = NULL;
@@ -820,7 +832,7 @@ extern struct cgroup_process_info *lxc_cgroup_create(const char *name, const cha
                 * the cgroup name and record that.
                 */
                if (lxc_string_in_array("ns", (const char **)info_ptr->hierarchy->subsystems)) {
-                       char *tmp = cgroup_rename_nsgroup(info_ptr->designated_mount_point->mount_point,
+                       char *tmp = cgroup_rename_nsgroup((const char *)info_ptr->designated_mount_point->mount_point,
                                        info_ptr->cgroup_path, pid, name);
                        if (!tmp)
                                goto out_initial_error;