meson: unify handling of executable paths, provide options for all progs

This makes the meson build behave slightly differently than the autoconf-based
one, because we always first try to find the executable in the filesystem, and
fall back to the default. I think different handling of loadkeys, setfont, and
telinit was just a historical accident.

In addition to checking in $PATH, also check /usr/sbin/, /sbin for programs.
In Fedora $PATH includes /usr/sbin, (and /sbin is is a symlink to /usr/sbin),
but in Debian, those directories are not included in the path.

C.f. mesonbuild/meson#1576.

Also call all the options 'xxx-path' for clarity.

meson.build

@@ -134,7 +134,6 @@ conf.set_quoted('SYSTEM_CONFIG_UNIT_PATH',                    pkgsysconfdir + '/
 conf.set_quoted('SYSTEM_DATA_UNIT_PATH',                      systemunitdir)
 conf.set_quoted('SYSTEM_SYSVINIT_PATH',                       sysvinit_path)
 conf.set_quoted('SYSTEM_SYSVRCND_PATH',                       sysvrcnd_path)
-conf.set_quoted('TELINIT',                                    get_option('telinit'))
 conf.set_quoted('USER_CONFIG_UNIT_PATH',                      pkgsysconfdir + '/user')
 conf.set_quoted('USER_DATA_UNIT_PATH',                        userunitdir)
 conf.set_quoted('CERTIFICATE_ROOT',                           get_option('certificate-root'))
@@ -171,8 +170,6 @@ conf.set_quoted('SYSTEMD_EXPORT_PATH',                        rootlibexecdir + '
 conf.set_quoted('VENDOR_KEYRING_PATH',                        rootlibexecdir + '/import-pubring.gpg')
 conf.set_quoted('USER_KEYRING_PATH',                          pkgsysconfdir + '/import-pubring.gpg')
 conf.set_quoted('DOCUMENT_ROOT',                              pkgdatadir + '/gatewayd')
-conf.set_quoted('KBD_LOADKEYS',                               get_option('loadkeys'))
-conf.set_quoted('KBD_SETFONT',                                get_option('setfont'))
 
 conf.set_quoted('ABS_BUILD_DIR',                              meson.build_root())
 conf.set_quoted('ABS_SRC_DIR',                                meson.source_root())
@@ -382,19 +379,28 @@ awk = find_program('awk')
 m4 = find_program('m4')
 stat = find_program('stat')
 
-progs = [['quotaon',    '/usr/sbin/quotaon'   ],
-         ['quotacheck', '/usr/sbin/quotacheck'],
-         ['kill',       '/usr/bin/kill'       ],
-         ['kmod',       '/usr/bin/kmod'       ],
-         ['kexec',      '/usr/sbin/kexec'     ],
-         ['sulogin',    '/usr/sbin/sulogin'   ],
-         ['mount',      '/usr/bin/mount',     'MOUNT_PATH'],
-         ['umount',     '/usr/bin/umount',    'UMOUNT_PATH'],
+# if -Dxxx-path option is found, use that. Otherwise, check in $PATH,
+# /usr/sbin, /sbin, and fall back to the default from middle column.
+progs = [['telinit',    '/lib/sysvinit/telinit'],
+         ['quotaon',    '/usr/sbin/quotaon'    ],
+         ['quotacheck', '/usr/sbin/quotacheck' ],
+         ['kill',       '/usr/bin/kill'        ],
+         ['kmod',       '/usr/bin/kmod'        ],
+         ['kexec',      '/usr/sbin/kexec'      ],
+         ['sulogin',    '/usr/sbin/sulogin'    ],
+         ['mount',      '/usr/bin/mount',      'MOUNT_PATH'],
+         ['umount',     '/usr/bin/umount',     'UMOUNT_PATH'],
+         ['loadkeys',   '/usr/bin/loadkeys',   'KBD_LOADKEYS'],
+         ['setfont',    '/usr/bin/setfont',    'KBD_SETFONT'],
         ]
-
 foreach prog : progs
-  exe = find_program(prog[0], required: false)
-  path = exe.found() ? exe.path() : prog[1]
+  path = get_option(prog[0] + '-path')
+  if path != ''
+    message('Using @1@ for @0@'.format(prog[0], path))
+  else
+    exe = find_program(prog[0], '/usr/sbin/' + prog[0], '/sbin/' + prog[0], required: false)
+    path = exe.found() ? exe.path() : prog[1]
+  endif
   name = prog.length() > 2 ? prog[2] : prog[0].to_upper()
   conf.set_quoted(name, path)
 endforeach

meson_options.txt

@@ -7,13 +7,18 @@ option('sysvinit-path', type : 'string', value : '/etc/init.d',
        description : 'the directory where the SysV init scripts are located')
 option('sysvrcnd-path', type : 'string', value : '/etc/rc.d',
        description : 'the base directory for SysV rcN.d directories')
-option('telinit', type : 'string', value : '/lib/sysvinit/telinit',
-       description : 'path to telinit')
+option('telinit-path', type : 'string', description : 'path to telinit')
 
-option('loadkeys', type : 'string', value : '/usr/bin/loadkeys',
-       description : 'path to loadkeys')
-option('setfont', type : 'string', value : '/usr/bin/setfont',
-       description : 'path to setfont')
+option('quotaon-path', type : 'string', description : 'path to quotaon')
+option('quotacheck-path', type : 'string', description : 'path to quotacheck')
+option('kill-path', type : 'string', description : 'path to kill')
+option('kmod-path', type : 'string', description : 'path to kmod')
+option('kexec-path', type : 'string', description : 'path to kexec')
+option('sulogin-path', type : 'string', description : 'path to sulogin')
+option('mount-path', type : 'string', description : 'path to mount')
+option('umount-path', type : 'string', description : 'path to umount')
+option('loadkeys-path', type : 'string', description : 'path to loadkeys')
+option('setfont-path', type : 'string', description : 'path to setfont')
 
 option('utmp', type : 'boolean',
        description : 'support for utmp/wtmp log handling')