| #include <stdio.h> |
| #include <unistd.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <errno.h> |
| #include <signal.h> |
| #include <dirent.h> |
| #include <sys/fcntl.h> |
| #include <sys/stat.h> |
| #include <sys/param.h> |
| #include "init.h" |
| #include "os.h" |
| #include "user.h" |
| |
| #define UML_DIR "~/.uml/" |
| |
| #define UMID_LEN 64 |
| |
| /* Changed by set_umid, which is run early in boot */ |
| static char umid[UMID_LEN] = { 0 }; |
| |
| /* Changed by set_uml_dir and make_uml_dir, which are run early in boot */ |
| static char *uml_dir = UML_DIR; |
| |
| static int __init make_uml_dir(void) |
| { |
| char dir[512] = { '\0' }; |
| int len, err; |
| |
| if(*uml_dir == '~'){ |
| char *home = getenv("HOME"); |
| |
| err = -ENOENT; |
| if(home == NULL){ |
| printk("make_uml_dir : no value in environment for " |
| "$HOME\n"); |
| goto err; |
| } |
| strlcpy(dir, home, sizeof(dir)); |
| uml_dir++; |
| } |
| strlcat(dir, uml_dir, sizeof(dir)); |
| len = strlen(dir); |
| if (len > 0 && dir[len - 1] != '/') |
| strlcat(dir, "/", sizeof(dir)); |
| |
| err = -ENOMEM; |
| uml_dir = malloc(strlen(dir) + 1); |
| if (uml_dir == NULL) { |
| printf("make_uml_dir : malloc failed, errno = %d\n", errno); |
| goto err; |
| } |
| strcpy(uml_dir, dir); |
| |
| if((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)){ |
| printf("Failed to mkdir '%s': %s\n", uml_dir, strerror(errno)); |
| err = -errno; |
| goto err_free; |
| } |
| return 0; |
| |
| err_free: |
| free(uml_dir); |
| err: |
| uml_dir = NULL; |
| return err; |
| } |
| |
| /* |
| * Unlinks the files contained in @dir and then removes @dir. |
| * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We |
| * ignore ENOENT errors for anything (they happen, strangely enough - possibly due |
| * to races between multiple dying UML threads). |
| */ |
| static int remove_files_and_dir(char *dir) |
| { |
| DIR *directory; |
| struct dirent *ent; |
| int len; |
| char file[256]; |
| int ret; |
| |
| directory = opendir(dir); |
| if (directory == NULL) { |
| if (errno != ENOENT) |
| return -errno; |
| else |
| return 0; |
| } |
| |
| while ((ent = readdir(directory)) != NULL) { |
| if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, "..")) |
| continue; |
| len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1; |
| if (len > sizeof(file)) { |
| ret = -E2BIG; |
| goto out; |
| } |
| |
| sprintf(file, "%s/%s", dir, ent->d_name); |
| if (unlink(file) < 0 && errno != ENOENT) { |
| ret = -errno; |
| goto out; |
| } |
| } |
| |
| if (rmdir(dir) < 0 && errno != ENOENT) { |
| ret = -errno; |
| goto out; |
| } |
| |
| ret = 0; |
| out: |
| closedir(directory); |
| return ret; |
| } |
| |
| /* This says that there isn't already a user of the specified directory even if |
| * there are errors during the checking. This is because if these errors |
| * happen, the directory is unusable by the pre-existing UML, so we might as |
| * well take it over. This could happen either by |
| * the existing UML somehow corrupting its umid directory |
| * something other than UML sticking stuff in the directory |
| * this boot racing with a shutdown of the other UML |
| * In any of these cases, the directory isn't useful for anything else. |
| * |
| * Boolean return: 1 if in use, 0 otherwise. |
| */ |
| static inline int is_umdir_used(char *dir) |
| { |
| char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; |
| char pid[sizeof("nnnnn\0")], *end; |
| int dead, fd, p, n, err; |
| |
| n = snprintf(file, sizeof(file), "%s/pid", dir); |
| if(n >= sizeof(file)){ |
| printk("is_umdir_used - pid filename too long\n"); |
| err = -E2BIG; |
| goto out; |
| } |
| |
| dead = 0; |
| fd = open(file, O_RDONLY); |
| if(fd < 0) { |
| fd = -errno; |
| if(fd != -ENOENT){ |
| printk("is_umdir_used : couldn't open pid file '%s', " |
| "err = %d\n", file, -fd); |
| } |
| goto out; |
| } |
| |
| err = 0; |
| n = read(fd, pid, sizeof(pid)); |
| if(n < 0){ |
| printk("is_umdir_used : couldn't read pid file '%s', " |
| "err = %d\n", file, errno); |
| goto out_close; |
| } else if(n == 0){ |
| printk("is_umdir_used : couldn't read pid file '%s', " |
| "0-byte read\n", file); |
| goto out_close; |
| } |
| |
| p = strtoul(pid, &end, 0); |
| if(end == pid){ |
| printk("is_umdir_used : couldn't parse pid file '%s', " |
| "errno = %d\n", file, errno); |
| goto out_close; |
| } |
| |
| if((kill(p, 0) == 0) || (errno != ESRCH)){ |
| printk("umid \"%s\" is already in use by pid %d\n", umid, p); |
| return 1; |
| } |
| |
| out_close: |
| close(fd); |
| out: |
| return 0; |
| } |
| |
| /* |
| * Try to remove the directory @dir unless it's in use. |
| * Precondition: @dir exists. |
| * Returns 0 for success, < 0 for failure in removal or if the directory is in |
| * use. |
| */ |
| static int umdir_take_if_dead(char *dir) |
| { |
| int ret; |
| if (is_umdir_used(dir)) |
| return -EEXIST; |
| |
| ret = remove_files_and_dir(dir); |
| if (ret) { |
| printk("is_umdir_used - remove_files_and_dir failed with " |
| "err = %d\n", ret); |
| } |
| return ret; |
| } |
| |
| static void __init create_pid_file(void) |
| { |
| char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; |
| char pid[sizeof("nnnnn\0")]; |
| int fd, n; |
| |
| if(umid_file_name("pid", file, sizeof(file))) |
| return; |
| |
| fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644); |
| if(fd < 0){ |
| printk("Open of machine pid file \"%s\" failed: %s\n", |
| file, strerror(errno)); |
| return; |
| } |
| |
| snprintf(pid, sizeof(pid), "%d\n", getpid()); |
| n = write(fd, pid, strlen(pid)); |
| if(n != strlen(pid)) |
| printk("Write of pid file failed - err = %d\n", errno); |
| |
| close(fd); |
| } |
| |
| int __init set_umid(char *name) |
| { |
| if(strlen(name) > UMID_LEN - 1) |
| return -E2BIG; |
| |
| strlcpy(umid, name, sizeof(umid)); |
| |
| return 0; |
| } |
| |
| /* Changed in make_umid, which is called during early boot */ |
| static int umid_setup = 0; |
| |
| int __init make_umid(void) |
| { |
| int fd, err; |
| char tmp[256]; |
| |
| if(umid_setup) |
| return 0; |
| |
| make_uml_dir(); |
| |
| if(*umid == '\0'){ |
| strlcpy(tmp, uml_dir, sizeof(tmp)); |
| strlcat(tmp, "XXXXXX", sizeof(tmp)); |
| fd = mkstemp(tmp); |
| if(fd < 0){ |
| printk("make_umid - mkstemp(%s) failed: %s\n", |
| tmp, strerror(errno)); |
| err = -errno; |
| goto err; |
| } |
| |
| close(fd); |
| |
| set_umid(&tmp[strlen(uml_dir)]); |
| |
| /* There's a nice tiny little race between this unlink and |
| * the mkdir below. It'd be nice if there were a mkstemp |
| * for directories. |
| */ |
| if(unlink(tmp)){ |
| err = -errno; |
| goto err; |
| } |
| } |
| |
| snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid); |
| err = mkdir(tmp, 0777); |
| if(err < 0){ |
| err = -errno; |
| if(err != -EEXIST) |
| goto err; |
| |
| if (umdir_take_if_dead(tmp) < 0) |
| goto err; |
| |
| err = mkdir(tmp, 0777); |
| } |
| if(err){ |
| err = -errno; |
| printk("Failed to create '%s' - err = %d\n", umid, -errno); |
| goto err; |
| } |
| |
| umid_setup = 1; |
| |
| create_pid_file(); |
| |
| err = 0; |
| err: |
| return err; |
| } |
| |
| static int __init make_umid_init(void) |
| { |
| if(!make_umid()) |
| return 0; |
| |
| /* If initializing with the given umid failed, then try again with |
| * a random one. |
| */ |
| printk("Failed to initialize umid \"%s\", trying with a random umid\n", |
| umid); |
| *umid = '\0'; |
| make_umid(); |
| |
| return 0; |
| } |
| |
| __initcall(make_umid_init); |
| |
| int __init umid_file_name(char *name, char *buf, int len) |
| { |
| int n, err; |
| |
| err = make_umid(); |
| if(err) |
| return err; |
| |
| n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name); |
| if(n >= len){ |
| printk("umid_file_name : buffer too short\n"); |
| return -E2BIG; |
| } |
| |
| return 0; |
| } |
| |
| char *get_umid(void) |
| { |
| return umid; |
| } |
| |
| static int __init set_uml_dir(char *name, int *add) |
| { |
| if(*name == '\0'){ |
| printf("uml_dir can't be an empty string\n"); |
| return 0; |
| } |
| |
| if(name[strlen(name) - 1] == '/'){ |
| uml_dir = name; |
| return 0; |
| } |
| |
| uml_dir = malloc(strlen(name) + 2); |
| if(uml_dir == NULL){ |
| printf("Failed to malloc uml_dir - error = %d\n", errno); |
| |
| /* Return 0 here because do_initcalls doesn't look at |
| * the return value. |
| */ |
| return 0; |
| } |
| sprintf(uml_dir, "%s/", name); |
| |
| return 0; |
| } |
| |
| __uml_setup("uml_dir=", set_uml_dir, |
| "uml_dir=<directory>\n" |
| " The location to place the pid and umid files.\n\n" |
| ); |
| |
| static void remove_umid_dir(void) |
| { |
| char dir[strlen(uml_dir) + UMID_LEN + 1], err; |
| |
| sprintf(dir, "%s%s", uml_dir, umid); |
| err = remove_files_and_dir(dir); |
| if(err) |
| printf("remove_umid_dir - remove_files_and_dir failed with " |
| "err = %d\n", err); |
| } |
| |
| __uml_exitcall(remove_umid_dir); |