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machine-id-setup: simplifications

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This commit is contained in:
Lennart Poettering
2015-03-10 19:09:38 +01:00
parent d9dde2bb03
commit c6ac7e4b98
1 changed files with 141 additions and 143 deletions
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src/core/machine-id-setup.c
+141 -143
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@@ -40,6 +40,12 @@
static int shorten_uuid(char destination[34], const char source[36]) {
unsigned i, j;
assert(destination);
assert(source);
/* Converts a UUID into a machine ID, by lowercasing it and
* removing dashes. Validates everything. */
for (i = 0, j = 0; i < 36 && j < 32; i++) {
int t;
@@ -50,16 +56,53 @@ static int shorten_uuid(char destination[34], const char source[36]) {
destination[j++] = hexchar(t);
}
if (i == 36 && j == 32) {
destination[32] = '\n';
destination[33] = 0;
return 0;
}
if (i != 36 || j != 32)
return -EINVAL;
return -EINVAL;
destination[32] = '\n';
destination[33] = 0;
return 0;
}
static int generate(char id[34], const char *root) {
static int read_machine_id(int fd, char id[34]) {
char id_to_validate[34];
int r;
assert(fd >= 0);
assert(id);
/* Reads a machine ID from a file, validates it, and returns
* it. The returned ID ends in a newline. */
r = loop_read_exact(fd, id_to_validate, 33, false);
if (r < 0)
return r;
if (id_to_validate[32] != '\n')
return -EINVAL;
id_to_validate[32] = 0;
if (!id128_is_valid(id_to_validate))
return -EINVAL;
memcpy(id, id_to_validate, 32);
id[32] = '\n';
id[33] = 0;
return 0;
}
static int write_machine_id(int fd, char id[34]) {
assert(fd >= 0);
assert(id);
if (lseek(fd, 0, SEEK_SET) < 0)
return -errno;
return loop_write(fd, id, 33, false);
}
static int generate_machine_id(char id[34], const char *root) {
int fd, r;
unsigned char *p;
sd_id128_t buf;
@@ -76,18 +119,12 @@ static int generate(char id[34], const char *root) {
/* First, try reading the D-Bus machine id, unless it is a symlink */
fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd >= 0) {
r = loop_read_exact(fd, id, 33, false);
r = read_machine_id(fd, id);
safe_close(fd);
if (r >= 0 && id[32] == '\n') {
id[32] = 0;
if (id128_is_valid(id)) {
id[32] = '\n';
id[33] = 0;
log_info("Initializing machine ID from D-Bus machine ID.");
return 0;
}
if (r >= 0) {
log_info("Initializing machine ID from D-Bus machine ID.");
return 0;
}
}
@@ -101,12 +138,10 @@ static int generate(char id[34], const char *root) {
r = getenv_for_pid(1, "container_uuid", &e);
if (r > 0) {
if (strlen(e) >= 36) {
r = shorten_uuid(id, e);
if (r >= 0) {
log_info("Initializing machine ID from container UUID.");
return 0;
}
r = shorten_uuid(id, e);
if (r >= 0) {
log_info("Initializing machine ID from container UUID.");
return 0;
}
}
@@ -154,36 +189,96 @@ static int generate(char id[34], const char *root) {
return 0;
}
static int get_valid_machine_id(int fd, char id[34]) {
char id_to_validate[34];
int machine_id_setup(const char *root) {
const char *etc_machine_id, *run_machine_id;
_cleanup_close_ int fd = -1;
bool writable = true;
char id[34]; /* 32 + \n + \0 */
int r;
assert(fd >= 0);
assert(id);
if (isempty(root)) {
etc_machine_id = "/etc/machine-id";
run_machine_id = "/run/machine-id";
} else {
char *x;
if (loop_read_exact(fd, id_to_validate, 33, false) >= 0 &&
id_to_validate[32] == '\n') {
id_to_validate[32] = 0;
x = strjoina(root, "/etc/machine-id");
etc_machine_id = path_kill_slashes(x);
if (id128_is_valid(id_to_validate)) {
memcpy(id, id_to_validate, 32);
id[32] = '\n';
id[33] = 0;
return 0;
x = strjoina(root, "/run/machine-id");
run_machine_id = path_kill_slashes(x);
}
RUN_WITH_UMASK(0000) {
/* We create this 0444, to indicate that this isn't really
* something you should ever modify. Of course, since the file
* will be owned by root it doesn't matter much, but maybe
* people look. */
mkdir_parents(etc_machine_id, 0755);
fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
if (fd < 0) {
int old_errno = errno;
fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0) {
if (old_errno == EROFS && errno == ENOENT)
log_error_errno(errno,
"System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
"Booting up is supported only when:\n"
"1) /etc/machine-id exists and is populated.\n"
"2) /etc/machine-id exists and is empty.\n"
"3) /etc/machine-id is missing and /etc is writable.\n");
else
log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
return -errno;
}
writable = false;
}
}
return -EINVAL;
}
static int write_machine_id(int fd, char id[34]) {
assert(fd >= 0);
assert(id);
lseek(fd, 0, SEEK_SET);
if (loop_write(fd, id, 33, false) == 0)
if (read_machine_id(fd, id) >= 0)
return 0;
return -errno;
/* Hmm, so, the id currently stored is not useful, then let's
* generate one */
r = generate_machine_id(id, root);
if (r < 0)
return r;
if (writable)
if (write_machine_id(fd, id) >= 0)
return 0;
fd = safe_close(fd);
/* Hmm, we couldn't write it? So let's write it to
* /run/machine-id as a replacement */
RUN_WITH_UMASK(0022) {
r = write_string_file(run_machine_id, id);
}
if (r < 0) {
(void) unlink(run_machine_id);
return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
}
/* And now, let's mount it over */
if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {
(void) unlink_noerrno(run_machine_id);
return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
}
log_info("Installed transient %s file.", etc_machine_id);
/* Mark the mount read-only */
if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
return 0;
}
int machine_id_commit(const char *root) {
@@ -214,7 +309,7 @@ int machine_id_commit(const char *root) {
if (fd < 0)
return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
r = get_valid_machine_id(fd, id);
r = read_machine_id(fd, id);
if (r < 0)
return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);
@@ -264,100 +359,3 @@ int machine_id_commit(const char *root) {
return 0;
}
int machine_id_setup(const char *root) {
const char *etc_machine_id, *run_machine_id;
_cleanup_close_ int fd = -1;
bool writable = true;
struct stat st;
char id[34]; /* 32 + \n + \0 */
int r;
if (isempty(root)) {
etc_machine_id = "/etc/machine-id";
run_machine_id = "/run/machine-id";
} else {
char *x;
x = strjoina(root, "/etc/machine-id");
etc_machine_id = path_kill_slashes(x);
x = strjoina(root, "/run/machine-id");
run_machine_id = path_kill_slashes(x);
}
RUN_WITH_UMASK(0000) {
/* We create this 0444, to indicate that this isn't really
* something you should ever modify. Of course, since the file
* will be owned by root it doesn't matter much, but maybe
* people look. */
mkdir_parents(etc_machine_id, 0755);
fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
if (fd < 0) {
int old_errno = errno;
fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0) {
if (old_errno == EROFS && errno == ENOENT)
log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
"Booting up is supported only when:\n"
"1) /etc/machine-id exists and is populated.\n"
"2) /etc/machine-id exists and is empty.\n"
"3) /etc/machine-id is missing and /etc is writable.\n");
else
log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
return -errno;
}
writable = false;
}
}
if (fstat(fd, &st) < 0)
return log_error_errno(errno, "fstat() failed: %m");
if (S_ISREG(st.st_mode) && get_valid_machine_id(fd, id) == 0)
return 0;
/* Hmm, so, the id currently stored is not useful, then let's
* generate one */
r = generate(id, root);
if (r < 0)
return r;
if (S_ISREG(st.st_mode) && writable)
if (write_machine_id(fd, id) == 0)
return 0;
fd = safe_close(fd);
/* Hmm, we couldn't write it? So let's write it to
* /run/machine-id as a replacement */
RUN_WITH_UMASK(0022) {
r = write_string_file(run_machine_id, id);
}
if (r < 0) {
log_error_errno(r, "Cannot write %s: %m", run_machine_id);
unlink(run_machine_id);
return r;
}
/* And now, let's mount it over */
r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL);
if (r < 0) {
log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
unlink_noerrno(run_machine_id);
return -errno;
}
log_info("Installed transient %s file.", etc_machine_id);
/* Mark the mount read-only */
if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
return 0;
}