systemd: do not require absolute paths in ExecStart

Absolute paths make everything simple and quick, but sometimes this requirement
can be annoying. A good example is calling 'test', which will be located in
/usr/bin/ or /bin depending on the distro. The need the provide the full path
makes it harder a portable unit file in such cases.

This patch uses a fixed search path (DEFAULT_PATH which was already used as the
default value of $PATH), and if a non-absolute file name is found, it is
immediately resolved to a full path using this search path when the unit is
loaded. After that, everything behaves as if an absolute path was specified. In
particular, the executable must exist when the unit is loaded.

diff --git a/src/basic/path-util.h b/src/basic/path-util.h
index 7415248aec880a7c0ca018106b971702ca200073..8af04569bf6c133c060527a82310106010ac216b 100644 (file)
--- a/src/basic/path-util.h
+++ b/src/basic/path-util.h
@@ -5,6 +5,19 @@
   This file is part of systemd.
 
   Copyright 2010-2012 Lennart Poettering
+
+  elogind is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  elogind is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with elogind; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
 #include <alloca.h>
@@ -17,17 +30,23 @@
 
 #if HAVE_SPLIT_BIN
 #  define PATH_SBIN_BIN(x) x "sbin:" x "bin"
+#  define PATH0_SBIN_BIN(x) x "sbin\0" x "bin"
 #else
+#  define PATH0_SBIN_BIN(x) x "bin"
 #  define PATH_SBIN_BIN(x) x "bin"
 #endif
 
 #define DEFAULT_PATH_NORMAL PATH_SBIN_BIN("/usr/local/") ":" PATH_SBIN_BIN("/usr/")
+#define DEFAULT_PATH0_NORMAL PATH0_SBIN_BIN("/usr/local/") "\0" PATH0_SBIN_BIN("/usr/")
 #define DEFAULT_PATH_SPLIT_USR DEFAULT_PATH_NORMAL ":" PATH_SBIN_BIN("/")
+#define DEFAULT_PATH0_SPLIT_USR DEFAULT_PATH0_NORMAL "\0" PATH0_SBIN_BIN("/")
 
 #if HAVE_SPLIT_USR
 #  define DEFAULT_PATH DEFAULT_PATH_SPLIT_USR
+#  define DEFAULT_PATH_NULSTR DEFAULT_PATH0_SPLIT_USR
 #else
 #  define DEFAULT_PATH DEFAULT_PATH_NORMAL
+#  define DEFAULT_PATH_NULSTR DEFAULT_PATH0_NORMAL
 #endif
 
 bool is_path(const char *p) _pure_;