tree-wide: introduce new safe_fork() helper and port everything over

This adds a new safe_fork() wrapper around fork() and makes use of it
everywhere. The new wrapper does a couple of things we previously did
manually and separately in a safer, more correct and automatic way:

1. Optionally resets signal handlers/mask in the child

2. Sets a name on all processes we fork off right after forking off (and
   the patch assigns useful names for all processes we fork off now,
   following a systematic naming scheme: always enclosed in () – in order
   to indicate that these are not proper, exec()ed processes, but only
   forked off children, and if the process is long-running with only our
   own code, without execve()'ing something else, it gets am "sd-" prefix.)

3. Optionally closes all file descriptors in the child

4. Optionally sets a PR_SET_DEATHSIG to SIGTERM in the child, in a safe
   way so that the parent dying before this happens being handled
   safely.

5. Optionally reopens the logs

6. Optionally connects stdin/stdout/stderr to /dev/null

7. Debug logs about the forked off processes.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/core/unit.h b/src/core/unit.h
index fdd82315ba..80585ac1c8 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -782,7 +782,7 @@ bool unit_shall_confirm_spawn(Unit *u);
 
 void unit_set_exec_params(Unit *s, ExecParameters *p);
 
-int unit_fork_helper_process(Unit *u, pid_t *ret);
+int unit_fork_helper_process(Unit *u, const char *name, pid_t *ret);
 
 void unit_remove_dependencies(Unit *u, UnitDependencyMask mask);