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Systemd/unit.c

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/*-*- Mode: C; c-basic-offset: 8 -*-*/
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/timerfd.h>
#include <sys/poll.h>
#include <stdlib.h>
#include <unistd.h>
#include "set.h"
#include "unit.h"
#include "macro.h"
#include "strv.h"
#include "load-fragment.h"
#include "load-dropin.h"
#include "log.h"
const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX] = {
[UNIT_SERVICE] = &service_vtable,
[UNIT_TIMER] = &timer_vtable,
[UNIT_SOCKET] = &socket_vtable,
[UNIT_TARGET] = &target_vtable,
[UNIT_DEVICE] = &device_vtable,
[UNIT_MOUNT] = &mount_vtable,
[UNIT_AUTOMOUNT] = &automount_vtable,
[UNIT_SNAPSHOT] = &snapshot_vtable
};
UnitType unit_name_to_type(const char *n) {
UnitType t;
assert(n);
for (t = 0; t < _UNIT_TYPE_MAX; t++)
if (endswith(n, unit_vtable[t]->suffix))
return t;
return _UNIT_TYPE_INVALID;
}
#define VALID_CHARS \
"0123456789" \
"abcdefghijklmnopqrstuvwxyz" \
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
"-_.\\"
bool unit_name_is_valid(const char *n) {
UnitType t;
const char *e, *i;
assert(n);
if (strlen(n) >= UNIT_NAME_MAX)
return false;
t = unit_name_to_type(n);
if (t < 0 || t >= _UNIT_TYPE_MAX)
return false;
if (!(e = strrchr(n, '.')))
return false;
if (e == n)
return false;
for (i = n; i < e; i++)
if (!strchr(VALID_CHARS, *i))
return false;
return true;
}
char *unit_name_change_suffix(const char *n, const char *suffix) {
char *e, *r;
size_t a, b;
assert(n);
assert(unit_name_is_valid(n));
assert(suffix);
assert_se(e = strrchr(n, '.'));
a = e - n;
b = strlen(suffix);
if (!(r = new(char, a + b + 1)))
return NULL;
memcpy(r, n, a);
memcpy(r+a, suffix, b+1);
return r;
}
Unit *unit_new(Manager *m) {
Unit *u;
assert(m);
if (!(u = new0(Unit, 1)))
return NULL;
if (!(u->meta.names = set_new(string_hash_func, string_compare_func))) {
free(u);
return NULL;
}
u->meta.manager = m;
u->meta.type = _UNIT_TYPE_INVALID;
return u;
}
int unit_add_name(Unit *u, const char *text) {
UnitType t;
char *s;
int r;
assert(u);
assert(text);
if (!unit_name_is_valid(text))
return -EINVAL;
if ((t = unit_name_to_type(text)) == _UNIT_TYPE_INVALID)
return -EINVAL;
if (u->meta.type != _UNIT_TYPE_INVALID && t != u->meta.type)
return -EINVAL;
if (!(s = strdup(text)))
return -ENOMEM;
if ((r = set_put(u->meta.names, s)) < 0) {
free(s);
if (r == -EEXIST)
return 0;
return r;
}
if ((r = hashmap_put(u->meta.manager->units, s, u)) < 0) {
set_remove(u->meta.names, s);
free(s);
return r;
}
u->meta.type = t;
if (!u->meta.id)
u->meta.id = s;
return 0;
}
int unit_choose_id(Unit *u, const char *name) {
char *s;
assert(u);
assert(name);
/* Selects one of the names of this unit as the id */
if (!(s = set_get(u->meta.names, (char*) name)))
return -ENOENT;
u->meta.id = s;
return 0;
}
int unit_set_description(Unit *u, const char *description) {
char *s;
assert(u);
if (!(s = strdup(description)))
return -ENOMEM;
free(u->meta.description);
u->meta.description = s;
return 0;
}
void unit_add_to_load_queue(Unit *u) {
assert(u);
if (u->meta.load_state != UNIT_STUB || u->meta.in_load_queue)
return;
LIST_PREPEND(Meta, load_queue, u->meta.manager->load_queue, &u->meta);
u->meta.in_load_queue = true;
}
static void bidi_set_free(Unit *u, Set *s) {
Iterator i;
Unit *other;
assert(u);
/* Frees the set and makes sure we are dropped from the
* inverse pointers */
SET_FOREACH(other, s, i) {
UnitDependency d;
for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
set_remove(other->meta.dependencies[d], u);
}
set_free(s);
}
void unit_free(Unit *u) {
UnitDependency d;
Iterator i;
char *t;
assert(u);
/* Detach from next 'bigger' objects */
SET_FOREACH(t, u->meta.names, i)
hashmap_remove_value(u->meta.manager->units, t, u);
if (u->meta.in_load_queue)
LIST_REMOVE(Meta, load_queue, u->meta.manager->load_queue, &u->meta);
if (u->meta.load_state == UNIT_LOADED)
if (UNIT_VTABLE(u)->done)
UNIT_VTABLE(u)->done(u);
/* Free data and next 'smaller' objects */
if (u->meta.job)
job_free(u->meta.job);
for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
bidi_set_free(u, u->meta.dependencies[d]);
free(u->meta.description);
free(u->meta.load_path);
while ((t = set_steal_first(u->meta.names)))
free(t);
set_free(u->meta.names);
free(u);
}
UnitActiveState unit_active_state(Unit *u) {
assert(u);
if (u->meta.load_state != UNIT_LOADED)
return UNIT_INACTIVE;
return UNIT_VTABLE(u)->active_state(u);
}
static int ensure_merge(Set **s, Set *other) {
if (!other)
return 0;
if (*s)
return set_merge(*s, other);
if (!(*s = set_copy(other)))
return -ENOMEM;
return 0;
}
/* FIXME: Does not rollback on failure! Needs to fix special unit
* pointers. Needs to merge names and dependencies properly.*/
int unit_merge(Unit *u, Unit *other) {
int r;
UnitDependency d;
assert(u);
assert(other);
assert(u->meta.manager == other->meta.manager);
/* This merges 'other' into 'unit'. FIXME: This does not
* rollback on failure. */
if (u->meta.type != u->meta.type)
return -EINVAL;
if (u->meta.load_state != UNIT_STUB)
return -EINVAL;
/* Merge names */
if ((r = ensure_merge(&u->meta.names, other->meta.names)) < 0)
return r;
/* Merge dependencies */
for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++)
/* fixme, the inverse mapping is missing */
if ((r = ensure_merge(&u->meta.dependencies[d], other->meta.dependencies[d])) < 0)
return r;
return 0;
}
const char* unit_id(Unit *u) {
assert(u);
if (u->meta.id)
return u->meta.id;
return set_first(u->meta.names);
}
const char *unit_description(Unit *u) {
assert(u);
if (u->meta.description)
return u->meta.description;
return unit_id(u);
}
void unit_dump(Unit *u, FILE *f, const char *prefix) {
static const char* const load_state_table[_UNIT_LOAD_STATE_MAX] = {
[UNIT_STUB] = "stub",
[UNIT_LOADED] = "loaded",
[UNIT_FAILED] = "failed"
};
static const char* const active_state_table[_UNIT_ACTIVE_STATE_MAX] = {
[UNIT_ACTIVE] = "active",
[UNIT_INACTIVE] = "inactive",
[UNIT_ACTIVATING] = "activating",
[UNIT_DEACTIVATING] = "deactivating"
};
static const char* const dependency_table[_UNIT_DEPENDENCY_MAX] = {
[UNIT_REQUIRES] = "Requires",
[UNIT_SOFT_REQUIRES] = "SoftRequires",
[UNIT_WANTS] = "Wants",
[UNIT_REQUISITE] = "Requisite",
[UNIT_SOFT_REQUISITE] = "SoftRequisite",
[UNIT_REQUIRED_BY] = "RequiredBy",
[UNIT_SOFT_REQUIRED_BY] = "SoftRequiredBy",
[UNIT_WANTED_BY] = "WantedBy",
[UNIT_CONFLICTS] = "Conflicts",
[UNIT_BEFORE] = "Before",
[UNIT_AFTER] = "After",
};
char *t;
UnitDependency d;
Iterator i;
char *prefix2;
assert(u);
if (!prefix)
prefix = "";
prefix2 = strappend(prefix, "\t");
if (!prefix2)
prefix2 = "";
fprintf(f,
"%s→ Unit %s:\n"
"%s\tDescription: %s\n"
"%s\tUnit Load State: %s\n"
"%s\tUnit Active State: %s\n",
prefix, unit_id(u),
prefix, unit_description(u),
prefix, load_state_table[u->meta.load_state],
prefix, active_state_table[unit_active_state(u)]);
if (u->meta.load_path)
fprintf(f, "%s\tLoad Path: %s\n", prefix, u->meta.load_path);
SET_FOREACH(t, u->meta.names, i)
fprintf(f, "%s\tName: %s\n", prefix, t);
for (d = 0; d < _UNIT_DEPENDENCY_MAX; d++) {
Unit *other;
if (set_isempty(u->meta.dependencies[d]))
continue;
SET_FOREACH(other, u->meta.dependencies[d], i)
fprintf(f, "%s\t%s: %s\n", prefix, dependency_table[d], unit_id(other));
}
if (UNIT_VTABLE(u)->dump)
UNIT_VTABLE(u)->dump(u, f, prefix2);
if (u->meta.job)
job_dump(u->meta.job, f, prefix2);
free(prefix2);
}
/* Common implementation for multiple backends */
int unit_load_fragment_and_dropin(Unit *u) {
int r, ret;
assert(u);
/* Load a .socket file */
if ((r = unit_load_fragment(u)) < 0)
return r;
ret = r > 0;
/* Load drop-in directory data */
if ((r = unit_load_dropin(u)) < 0)
return r;
return ret;
}
int unit_load(Unit *u) {
int r;
assert(u);
if (u->meta.in_load_queue) {
LIST_REMOVE(Meta, load_queue, u->meta.manager->load_queue, &u->meta);
u->meta.in_load_queue = false;
}
if (u->meta.load_state != UNIT_STUB)
return 0;
if (UNIT_VTABLE(u)->init)
if ((r = UNIT_VTABLE(u)->init(u)) < 0)
goto fail;
u->meta.load_state = UNIT_LOADED;
return 0;
fail:
u->meta.load_state = UNIT_FAILED;
return r;
}
/* Errors:
* -EBADR: This unit type does not support starting.
* -EALREADY: Unit is already started.
* -EAGAIN: An operation is already in progress. Retry later.
*/
int unit_start(Unit *u) {
UnitActiveState state;
assert(u);
if (!UNIT_VTABLE(u)->start)
return -EBADR;
state = unit_active_state(u);
if (UNIT_IS_ACTIVE_OR_RELOADING(state))
return -EALREADY;
/* We don't suppress calls to ->start() here when we are
* already starting, to allow this request to be used as a
* "hurry up" call, for example when the unit is in some "auto
* restart" state where it waits for a holdoff timer to elapse
* before it will start again. */
return UNIT_VTABLE(u)->start(u);
}
bool unit_can_start(Unit *u) {
assert(u);
return !!UNIT_VTABLE(u)->start;
}
/* Errors:
* -EBADR: This unit type does not support stopping.
* -EALREADY: Unit is already stopped.
* -EAGAIN: An operation is already in progress. Retry later.
*/
int unit_stop(Unit *u) {
UnitActiveState state;
assert(u);
if (!UNIT_VTABLE(u)->stop)
return -EBADR;
state = unit_active_state(u);
if (state == UNIT_INACTIVE)
return -EALREADY;
if (state == UNIT_DEACTIVATING)
return 0;
return UNIT_VTABLE(u)->stop(u);
}
/* Errors:
* -EBADR: This unit type does not support reloading.
* -ENOEXEC: Unit is not started.
* -EAGAIN: An operation is already in progress. Retry later.
*/
int unit_reload(Unit *u) {
UnitActiveState state;
assert(u);
if (!unit_can_reload(u))
return -EBADR;
state = unit_active_state(u);
if (unit_active_state(u) == UNIT_ACTIVE_RELOADING)
return -EALREADY;
if (unit_active_state(u) != UNIT_ACTIVE)
return -ENOEXEC;
return UNIT_VTABLE(u)->reload(u);
}
bool unit_can_reload(Unit *u) {
assert(u);
if (!UNIT_VTABLE(u)->reload)
return false;
if (!UNIT_VTABLE(u)->can_reload)
return true;
return UNIT_VTABLE(u)->can_reload(u);
}
static void retroactively_start_dependencies(Unit *u) {
Iterator i;
Unit *other;
assert(u);
assert(UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(u)));
SET_FOREACH(other, u->meta.dependencies[UNIT_REQUIRES], i)
if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_START, other, JOB_REPLACE, true, NULL);
SET_FOREACH(other, u->meta.dependencies[UNIT_SOFT_REQUIRES], i)
if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_START, other, JOB_FAIL, false, NULL);
SET_FOREACH(other, u->meta.dependencies[UNIT_REQUISITE], i)
if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_START, other, JOB_REPLACE, true, NULL);
SET_FOREACH(other, u->meta.dependencies[UNIT_WANTS], i)
if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_START, other, JOB_FAIL, false, NULL);
SET_FOREACH(other, u->meta.dependencies[UNIT_CONFLICTS], i)
if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_STOP, other, JOB_REPLACE, true, NULL);
}
static void retroactively_stop_dependencies(Unit *u) {
Iterator i;
Unit *other;
assert(u);
assert(UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(u)));
SET_FOREACH(other, u->meta.dependencies[UNIT_REQUIRED_BY], i)
if (!UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(other)))
manager_add_job(u->meta.manager, JOB_STOP, other, JOB_REPLACE, true, NULL);
}
void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns) {
assert(u);
assert(os < _UNIT_ACTIVE_STATE_MAX);
assert(ns < _UNIT_ACTIVE_STATE_MAX);
assert(!(os == UNIT_ACTIVE && ns == UNIT_ACTIVATING));
assert(!(os == UNIT_INACTIVE && ns == UNIT_DEACTIVATING));
if (os == ns)
return;
if (!UNIT_IS_ACTIVE_OR_RELOADING(os) && UNIT_IS_ACTIVE_OR_RELOADING(ns))
u->meta.active_enter_timestamp = now(CLOCK_REALTIME);
else if (UNIT_IS_ACTIVE_OR_RELOADING(os) && !UNIT_IS_ACTIVE_OR_RELOADING(ns))
u->meta.active_exit_timestamp = now(CLOCK_REALTIME);
if (u->meta.job) {
if (u->meta.job->state == JOB_WAITING)
/* So we reached a different state for this
* job. Let's see if we can run it now if it
* failed previously due to EAGAIN. */
job_schedule_run(u->meta.job);
else {
assert(u->meta.job->state == JOB_RUNNING);
/* Let's check whether this state change
* constitutes a finished job, or maybe
* cotradicts a running job and hence needs to
* invalidate jobs. */
switch (u->meta.job->type) {
case JOB_START:
case JOB_VERIFY_ACTIVE:
if (UNIT_IS_ACTIVE_OR_RELOADING(ns)) {
job_finish_and_invalidate(u->meta.job, true);
return;
} else if (ns == UNIT_ACTIVATING)
return;
else
job_finish_and_invalidate(u->meta.job, false);
break;
case JOB_RELOAD:
case JOB_RELOAD_OR_START:
if (ns == UNIT_ACTIVE) {
job_finish_and_invalidate(u->meta.job, true);
return;
} else if (ns == UNIT_ACTIVATING || ns == UNIT_ACTIVE_RELOADING)
return;
else
job_finish_and_invalidate(u->meta.job, false);
break;
case JOB_STOP:
case JOB_RESTART:
case JOB_TRY_RESTART:
if (ns == UNIT_INACTIVE) {
job_finish_and_invalidate(u->meta.job, true);
return;
} else if (ns == UNIT_DEACTIVATING)
return;
else
job_finish_and_invalidate(u->meta.job, false);
break;
default:
assert_not_reached("Job type unknown");
}
}
}
/* If this state change happened without being requested by a
* job, then let's retroactively start or stop dependencies */
if (UNIT_IS_INACTIVE_OR_DEACTIVATING(os) && UNIT_IS_ACTIVE_OR_ACTIVATING(ns))
retroactively_start_dependencies(u);
else if (UNIT_IS_ACTIVE_OR_ACTIVATING(os) && UNIT_IS_INACTIVE_OR_DEACTIVATING(ns))
retroactively_stop_dependencies(u);
}
int unit_watch_fd(Unit *u, int fd, uint32_t events, Watch *w) {
struct epoll_event ev;
assert(u);
assert(fd >= 0);
assert(w);
assert(w->type == WATCH_INVALID || (w->type == WATCH_FD && w->fd == fd && w->unit == u));
zero(ev);
ev.data.ptr = w;
ev.events = events;
if (epoll_ctl(u->meta.manager->epoll_fd,
w->type == WATCH_INVALID ? EPOLL_CTL_ADD : EPOLL_CTL_MOD,
fd,
&ev) < 0)
return -errno;
w->fd = fd;
w->type = WATCH_FD;
w->unit = u;
return 0;
}
void unit_unwatch_fd(Unit *u, Watch *w) {
assert(u);
assert(w);
if (w->type == WATCH_INVALID)
return;
assert(w->type == WATCH_FD && w->unit == u);
assert_se(epoll_ctl(u->meta.manager->epoll_fd, EPOLL_CTL_DEL, w->fd, NULL) >= 0);
w->fd = -1;
w->type = WATCH_INVALID;
w->unit = NULL;
}
int unit_watch_pid(Unit *u, pid_t pid) {
assert(u);
assert(pid >= 1);
return hashmap_put(u->meta.manager->watch_pids, UINT32_TO_PTR(pid), u);
}
void unit_unwatch_pid(Unit *u, pid_t pid) {
assert(u);
assert(pid >= 1);
hashmap_remove(u->meta.manager->watch_pids, UINT32_TO_PTR(pid));
}
int unit_watch_timer(Unit *u, usec_t delay, Watch *w) {
struct itimerspec its;
int flags, fd;
bool ours;
assert(u);
assert(w);
assert(w->type == WATCH_INVALID || (w->type == WATCH_TIMER && w->unit == u));
/* This will try to reuse the old timer if there is one */
if (w->type == WATCH_TIMER) {
ours = false;
fd = w->fd;
} else {
ours = true;
if ((fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC)) < 0)
return -errno;
}
zero(its);
if (delay <= 0) {
/* Set absolute time in the past, but not 0, since we
* don't want to disarm the timer */
its.it_value.tv_sec = 0;
its.it_value.tv_nsec = 1;
flags = TFD_TIMER_ABSTIME;
} else {
timespec_store(&its.it_value, delay);
flags = 0;
}
/* This will also flush the elapse counter */
if (timerfd_settime(fd, flags, &its, NULL) < 0)
goto fail;
if (w->type == WATCH_INVALID) {
struct epoll_event ev;
zero(ev);
ev.data.ptr = w;
ev.events = POLLIN;
if (epoll_ctl(u->meta.manager->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
goto fail;
}
w->fd = fd;
w->type = WATCH_TIMER;
w->unit = u;
return 0;
fail:
if (ours)
assert_se(close_nointr(fd) == 0);
return -errno;
}
void unit_unwatch_timer(Unit *u, Watch *w) {
assert(u);
assert(w);
if (w->type == WATCH_INVALID)
return;
assert(w->type == WATCH_TIMER && w->unit == u);
assert_se(epoll_ctl(u->meta.manager->epoll_fd, EPOLL_CTL_DEL, w->fd, NULL) >= 0);
assert_se(close_nointr(w->fd) == 0);
w->fd = -1;
w->type = WATCH_INVALID;
w->unit = NULL;
}
bool unit_job_is_applicable(Unit *u, JobType j) {
assert(u);
assert(j >= 0 && j < _JOB_TYPE_MAX);
switch (j) {
case JOB_VERIFY_ACTIVE:
case JOB_START:
return true;
case JOB_STOP:
case JOB_RESTART:
case JOB_TRY_RESTART:
return unit_can_start(u);
case JOB_RELOAD:
return unit_can_reload(u);
case JOB_RELOAD_OR_START:
return unit_can_reload(u) && unit_can_start(u);
default:
assert_not_reached("Invalid job type");
}
}
int unit_add_dependency(Unit *u, UnitDependency d, Unit *other) {
static const UnitDependency inverse_table[_UNIT_DEPENDENCY_MAX] = {
[UNIT_REQUIRES] = UNIT_REQUIRED_BY,
[UNIT_SOFT_REQUIRES] = UNIT_SOFT_REQUIRED_BY,
[UNIT_WANTS] = UNIT_WANTED_BY,
[UNIT_REQUISITE] = UNIT_REQUIRED_BY,
[UNIT_SOFT_REQUISITE] = UNIT_SOFT_REQUIRED_BY,
[UNIT_REQUIRED_BY] = _UNIT_DEPENDENCY_INVALID,
[UNIT_SOFT_REQUIRED_BY] = _UNIT_DEPENDENCY_INVALID,
[UNIT_WANTED_BY] = _UNIT_DEPENDENCY_INVALID,
[UNIT_CONFLICTS] = UNIT_CONFLICTS,
[UNIT_BEFORE] = UNIT_AFTER,
[UNIT_AFTER] = UNIT_BEFORE
};
int r;
assert(u);
assert(d >= 0 && d < _UNIT_DEPENDENCY_MAX);
assert(inverse_table[d] != _UNIT_DEPENDENCY_INVALID);
assert(other);
/* We won't allow dependencies on ourselves. We will not
* consider them an error however. */
if (u == other)
return 0;
if ((r = set_ensure_allocated(&u->meta.dependencies[d], trivial_hash_func, trivial_compare_func)) < 0)
return r;
if ((r = set_ensure_allocated(&other->meta.dependencies[inverse_table[d]], trivial_hash_func, trivial_compare_func)) < 0)
return r;
if ((r = set_put(u->meta.dependencies[d], other)) < 0)
return r;
if ((r = set_put(other->meta.dependencies[inverse_table[d]], u)) < 0) {
set_remove(u->meta.dependencies[d], other);
return r;
}
return 0;
}
int unit_add_dependency_by_name(Unit *u, UnitDependency d, const char *name) {
Unit *other;
int r;
if ((r = manager_load_unit(u->meta.manager, name, &other)) < 0)
return r;
if ((r = unit_add_dependency(u, d, other)) < 0)
return r;
return 0;
}
const char *unit_path(void) {
char *e;
if ((e = getenv("UNIT_PATH")))
if (path_is_absolute(e))
return e;
return UNIT_PATH;
}
int set_unit_path(const char *p) {
char *cwd, *c;
int r;
/* This is mostly for debug purposes */
if (path_is_absolute(p)) {
if (!(c = strdup(p)))
return -ENOMEM;
} else {
if (!(cwd = get_current_dir_name()))
return -errno;
r = asprintf(&c, "%s/%s", cwd, p);
free(cwd);
if (r < 0)
return -ENOMEM;
}
if (setenv("UNIT_PATH", c, 0) < 0) {
r = -errno;
free(c);
return r;
}
return 0;
}
char *unit_name_escape_path(const char *prefix, const char *path, const char *suffix) {
char *r, *t;
const char *f;
size_t a, b, c;
assert(path);
/* Takes a path and a suffix and prefix and makes a nice
* string suitable as unit name of it, escaping all weird
* chars on the way.
*
* / becomes ., and all chars not alloweed in a unit name get
* escaped as \xFF, including \ and ., of course. This
* escaping is hence reversible.
*/
if (!prefix)
prefix = "";
if (!suffix)
suffix = "";
a = strlen(prefix);
b = strlen(path);
c = strlen(suffix);
if (!(r = new(char, a+b*4+c+1)))
return NULL;
memcpy(r, prefix, a);
for (f = path, t = r+a; *f; f++) {
if (*f == '/')
*(t++) = '.';
else if (*f == '.' || *f == '\\' || !strchr(VALID_CHARS, *f)) {
*(t++) = '\\';
*(t++) = 'x';
*(t++) = hexchar(*f > 4);
*(t++) = hexchar(*f);
} else
*(t++) = *f;
}
memcpy(t, suffix, c+1);
return r;
}
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