meson: add option for fexecve use

There are downsides to using fexecve:

when fexecve is used (for normal executables), /proc/pid/status shows Name: 3,
which means that ps -C foobar doesn't work. pidof works, because it checks
/proc/self/cmdline. /proc/self/exe also shows the correct link, but requires
privileges to read. /proc/self/comm also shows "3".

I think this can be considered a kernel deficiency: when O_CLOEXEC is used, this
"3" is completely meaningless. It could be any number. The kernel should use
argv[0] instead, which at least has *some* meaning.

I think the approach with fexecve/execveat is instersting, so let's provide it
as opt-in.

1 files changed, 2 insertions, 0 deletions

diff --git a/meson.build b/meson.build
index 68ead1f849..a800959ba9 100644
--- a/meson.build
+++ b/meson.build
@@ -215,6 +215,7 @@ conf.set_quoted('SYSTEM_SYSVRCND_PATH',                       sysvrcnd_path)
 conf.set_quoted('RC_LOCAL_PATH',                              get_option('rc-local'))
 
 conf.set('ANSI_OK_COLOR',                                     'ANSI_' + get_option('ok-color').underscorify().to_upper())
+conf.set10('ENABLE_FEXECVE',                                  get_option('fexecve'))
 
 conf.set_quoted('USER_CONFIG_UNIT_DIR',                       join_paths(pkgsysconfdir, 'user'))
 conf.set_quoted('USER_DATA_UNIT_DIR',                         userunitdir)
@@ -3787,6 +3788,7 @@ foreach tuple : [
         ['link-timesyncd-shared', get_option('link-timesyncd-shared')],
         ['kernel-install',        get_option('kernel-install')],
         ['systemd-analyze',  conf.get('ENABLE_ANALYZE') == 1],
+        ['fexecve'],
 ]
 
         if tuple.length() >= 2