configure option --enable-relpath

add relative path ../lib to spinit for codemodels
and search path in ivars.c, independently from
install path which has to be an absolute path

configure.ac

@@ -171,6 +171,10 @@ AC_ARG_ENABLE([help],
 AC_ARG_ENABLE([xgraph],
     [AS_HELP_STRING([--enable-xgraph], [Enable xgraph compilation.])])
 
+# --enable-relpath: Relative path for binary and data. Default is "no".
+# ngspice shared may want relative paths for spinit etc.
+AC_ARG_ENABLE([relpath],
+    [AS_HELP_STRING([--enable-relpath], [Enable relative paths for spinit etc.])])
 # --with-readline:  Includes GNU readline support into CLI.  Default is "no".
 AC_ARG_WITH([readline],
     [AS_HELP_STRING([--with-readline[=yes/no]], [Enable GNU readline support for CLI. Default=no.])])
@@ -774,8 +778,15 @@ if test "x$getopt_long" = xtrue; then
     AC_DEFINE([HAVE_GETOPT_LONG], [1], [Have fcn getopt_long()])
 fi
 
+AM_CONDITIONAL([RELPATH], [test "x$enable_relpath" = xyes])
+if test "x$enable_relpath" = xyes; then
+    AC_DEFINE_UNQUOTED([NGSPICEBINDIR], ["`echo ../bin`"], [Define the directory for executables])
+    AC_DEFINE_UNQUOTED([NGSPICEDATADIR], ["`echo ../share/ngspice`"], [Define the directory for architecture independent data files])
+    AC_DEFINE([HAS_RELPATH], [1], [rel. path of libraries and scripts])
+else
 AC_DEFINE_UNQUOTED([NGSPICEBINDIR], ["`echo $dprefix/bin`"], [Define the directory for executables])
 AC_DEFINE_UNQUOTED([NGSPICEDATADIR], ["`echo $dprefix/share/ngspice`"], [Define the directory for architecture independent data files])
+fi
 AC_DEFINE_UNQUOTED([NGSPICEBUILDDATE], ["`date`"], [Define the build date])
 
 if test "x$with_wingui" = xyes; then

src/Makefile.am

@@ -293,13 +293,19 @@ ngspice.idx: ngmakeidx$(EXEEXT) $(srcdir)/ngspice.txt
 endif !SHWIN
 endif !WINGUI
 
+if RELPATH
+spinitpath=../lib/ngspice
+endif RELPATH
+if !RELPATH
+spinitpath=$(pkglibdir)
+endif !RELPATH
 
 ## create spinit at compile time, see
 ##   (info "(autoconf) Installation Directory Variables")
 
 edit = sed \
 	-e 's|@XSPICEINIT[@]|$(XSPICEINIT)|g' \
-	-e 's|@pkglibdir[@]|$(pkglibdir)|g'
+	-e 's|@pkglibdir[@]|$(spinitpath)|g'
 
 spinit tclspinit : Makefile
 	rm -f $@ $@.tmp

src/misc/ivars.c

@@ -33,16 +33,30 @@ mkvar(char **p, char *path_prefix, char *var_dir, char *env_var)
         *p = tprintf("%s%s%s", path_prefix, DIR_PATHSEP, var_dir);
 }
 
+    /* $dprefix has been set to /usr/local or C:/Spice (Windows) in configure.ac,
+    or to <path> given by prefix="<path>" as parameter to ./configure command.
+    NGSPICEBINDIR has been set to $dprefix/bin in config.h.
+    NGSPICEDATADIR has been set to $dprefix/share/ngspice in config.h.
+    If --enable-relpath is selected as paramter to the ./configure command, then
+    NGSPICEBINDIR is set to ../bin in config.h.
+    NGSPICEDATADIR is set to ../share/ngspice in config.h.
+    Spice_Exec_Dir has been set to NGSPICEBINDIR in conf.c,
+    may be overridden here by environmental variable SPICE_EXEC_DIR.
+    Spice_Lib_Dir has been set to NGSPICEDATADIR in conf.c,
+    may be overridden here by environmental variable SPICE_LIB_DIR.
+    The search path for codemodels in spinit contains $dprefix, or, if --enable-relpath
+    is given, to ../lib, set by src/makefile.am. With Visual C, it is set manually by
+    an entry to ngspice\visualc\src\include\ngspice\config.h.*/
 void
 ivars(char *argv0)
 {
     char *temp=NULL;
-	 /* $dprefix has been set to /usr/local or C:/Spice (Windows) in configure.ac,
-    NGSPICEBINDIR has been set to $dprefix/bin in configure.ac, 
-    Spice_Exec_Dir has been set to NGSPICEBINDIR in conf.c,
-    may be overridden here by environmental variable SPICE_EXEC_DIR */
-    env_overr(&Spice_Exec_Dir, "SPICE_EXEC_DIR");
+
+#ifdef HAS_RELPATH
+    Spice_Lib_Dir = temp = copy("../share/ngspice");
+#else
     env_overr(&Spice_Lib_Dir, "SPICE_LIB_DIR");
+#endif
 
     /* for printing a news file */
     mkvar(&News_File, Spice_Lib_Dir, "news", "SPICE_NEWS");
@@ -52,6 +66,7 @@ ivars(char *argv0)
     mkvar(&Lib_Path, Spice_Lib_Dir, "scripts", "SPICE_SCRIPTS");
     /* used to call ngspice with aspice command, not used in Windows mode */
     mkvar(&Spice_Path, Spice_Exec_Dir, "ngspice", "SPICE_PATH");
+    tfree(temp);
     /* may be used to store input files (*.lib, *.include, ...) */
     /* get directory where ngspice resides */
 #if defined (HAS_WINGUI) || defined (__MINGW32__) || defined (_MSC_VER)