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tmpfiles: add new "L+" command as stronger version of "L", that removes the destination before creating a symlink

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Also, make use of this for mtab as long as mount insists on creating it
even if we invoke it with "-n".
This commit is contained in:
Lennart Poettering 2014-06-16 13:21:07 +02:00
parent 45c196a76b
commit 2e78fa79bb
5 changed files with 103 additions and 46 deletions
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11
man/tmpfiles.d.xml
View file

@ -174,7 +174,16 @@ L /tmp/foobar - - - - /dev/null</programlisting>
<varlistentry>
<term><varname>L</varname></term>
<listitem><para>Create a symlink if it does not exist yet.</para></listitem>
<term><varname>L+</varname></term>
<listitem><para>Create a
symlink if it does not exist
yet. If suffixed with
<varname>+</varname> and a
file already exists where the
symlink is to be created it
will be removed and be
replaced by the
symlink.</para></listitem>
</varlistentry>
<varlistentry>

79
src/shared/util.c
View file

@ -4013,7 +4013,7 @@ int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
assert(_f);
assert(_temp_path);
t = strappend(path, ".XXXXXX");
t = tempfn_xxxxxx(path);
if (!t)
return -ENOMEM;
@ -4125,42 +4125,21 @@ int vt_disallocate(const char *name) {
}
int symlink_atomic(const char *from, const char *to) {
char *x;
_cleanup_free_ char *t;
const char *fn;
size_t k;
uint64_t u;
unsigned i;
int r;
_cleanup_free_ char *t = NULL;
assert(from);
assert(to);
t = new(char, strlen(to) + 1 + 16 + 1);
t = tempfn_random(to);
if (!t)
return -ENOMEM;
fn = basename(to);
k = fn-to;
memcpy(t, to, k);
t[k] = '.';
x = stpcpy(t+k+1, fn);
u = random_u64();
for (i = 0; i < 16; i++) {
*(x++) = hexchar(u & 0xF);
u >>= 4;
}
*x = 0;
if (symlink(from, t) < 0)
return -errno;
if (rename(t, to) < 0) {
r = -errno;
unlink(t);
return r;
unlink_noerrno(t);
return -errno;
}
return 0;
@ -6669,3 +6648,51 @@ int fflush_and_check(FILE *f) {
return 0;
}
char *tempfn_xxxxxx(const char *p) {
const char *fn;
char *t;
size_t k;
assert(p);
t = new(char, strlen(p) + 1 + 6 + 1);
if (!t)
return NULL;
fn = basename(p);
k = fn - p;
strcpy(stpcpy(stpcpy(mempcpy(t, p, k), "."), fn), "XXXXXX");
return t;
}
char *tempfn_random(const char *p) {
const char *fn;
char *t, *x;
uint64_t u;
size_t k;
unsigned i;
assert(p);
t = new(char, strlen(p) + 1 + 16 + 1);
if (!t)
return NULL;
fn = basename(p);
k = fn - p;
x = stpcpy(stpcpy(mempcpy(t, p, k), "."), fn);
u = random_u64();
for (i = 0; i < 16; i++) {
*(x++) = hexchar(u & 0xF);
u >>= 4;
}
*x = 0;
return t;
}

3
src/shared/util.h
View file

@ -948,3 +948,6 @@ int umount_recursive(const char *target, int flags);
int bind_remount_recursive(const char *prefix, bool ro);
int fflush_and_check(FILE *f);
char *tempfn_xxxxxx(const char *p);
char *tempfn_random(const char *p);

54
src/tmpfiles/tmpfiles.c
View file

@ -103,6 +103,8 @@ typedef struct Item {
bool keep_first_level:1;
bool force:1;
bool done:1;
} Item;
@ -746,31 +748,38 @@ static int create_item(Item *i) {
break;
case CREATE_SYMLINK: {
_cleanup_free_ char *x = NULL;
case CREATE_SYMLINK:
label_context_set(i->path, S_IFLNK);
r = symlink(i->argument, i->path);
label_context_clear();
if (r < 0 && errno != EEXIST) {
log_error("symlink(%s, %s) failed: %m", i->argument, i->path);
return -errno;
}
r = readlink_malloc(i->path, &x);
if (r < 0) {
log_error("readlink(%s) failed: %s", i->path, strerror(-r));
return -errno;
}
_cleanup_free_ char *x = NULL;
if (!streq(i->argument, x)) {
log_error("%s is not the right symlink.", i->path);
return -EEXIST;
if (errno != EEXIST) {
log_error("symlink(%s, %s) failed: %m", i->argument, i->path);
return -errno;
}
r = readlink_malloc(i->path, &x);
if (r < 0 || !streq(i->argument, x)) {
if (i->force) {
label_context_set(i->path, S_IFLNK);
r = symlink_atomic(i->argument, i->path);
label_context_clear();
if (r < 0) {
log_error("symlink(%s, %s) failed: %m", i->argument, i->path);
return -errno;
}
} else
log_debug("%s is not a symlink or does not point to the correct path.", i->path);
}
}
break;
}
case CREATE_BLOCK_DEVICE:
case CREATE_CHAR_DEVICE: {
@ -1135,10 +1144,17 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
return -EIO;
}
if (strlen(action) > 2 || (strlen(action) > 1 && action[1] != '!')) {
log_error("[%s:%u] Unknown modifier '%s'", fname, line, action);
if (isempty(action)) {
log_error("[%s:%u] Command too short '%s'.", fname, line, action);
return -EINVAL;
} else if (strlen(action) > 1 && !arg_boot)
}
if (strlen(action) > 1 && !in_charset(action+1, "!+")) {
log_error("[%s:%u] Unknown modifiers in command '%s'", fname, line, action);
return -EINVAL;
}
if (strchr(action+1, '!') && !arg_boot)
return 0;
type = action[0];
@ -1147,6 +1163,8 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
if (!i)
return log_oom();
i->force = !!strchr(action+1, '+');
r = specifier_printf(path, specifier_table, NULL, &i->path);
if (r < 0) {
log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, path);

2
tmpfiles.d/etc.conf
View file

@ -9,5 +9,5 @@
L /etc/os-release - - - - ../usr/lib/os-release
L /etc/localtime - - - - ../usr/share/zoneinfo/UTC
L /etc/mtab - - - - ../proc/self/mounts
L+ /etc/mtab - - - - ../proc/self/mounts
L /etc/resolv.conf - - - - ../run/systemd/resolve/resolv.conf