Enhance the search path for .spiceinit (spice.rc):

- in the directory from where the netlist has been loaded
- in a user provided path read from environmental variable SPICE_USERINIT_DIR,
- in the current directory,
- in the the HOME directory,
- in the USERPROFILE directory. */
In shared ngspice the first line shall read
- in the directory Infile_Path received from the caller (sent before initialization)

src/main.c

@@ -1252,11 +1252,30 @@ int main(int argc, char **argv)
     else {
         if (readinit) {
             /* load user's initialisation file
-              try accessing the initialisation file .spiceinit in a user provided
-              path read from environmental variable SPICE_USERINIT_DIR,
-              if that fails try the alternate name spice.rc, then look into
-              the current directory, then the HOME directory, then into USERPROFILE */
+              try accessing the initialisation file .spiceinit
+              (If it fails, try the alternate name spice.rc):
+              - in the directory from where the netlist has been loaded
+              - in a user provided path read from environmental variable SPICE_USERINIT_DIR,
+              - in the current directory,
+              - in the the HOME directory,
+              - in the USERPROFILE directory. */
             do {
+                {
+                    if (optind <= argc) {
+                        char* inpath = ngdirname(argv[optind]);
+                        if (inpath) {
+                            if (read_initialisation_file(inpath, INITSTR) != FALSE) {
+                                FREE(inpath);
+                                break;
+                            }
+                            if (read_initialisation_file(inpath, ALT_INITSTR) != FALSE) {
+                                FREE(inpath);
+                                break;
+                            }
+                            FREE(inpath);
+                        }
+                    }
+                }
                 {
                     const char* const userinit = getenv("SPICE_USERINIT_DIR");
                     if (userinit) {

src/sharedspice.c

@@ -975,13 +975,26 @@ ngSpice_Init(SendChar* printfcn, SendStat* statusfcn, ControlledExit* ngspiceexi
     }
 #else /* ~ HAVE_PWD_H */
     /* load user's initialisation file
-       try accessing the initialisation file .spiceinit in a user provided
-       path read from environmental variable SPICE_USERINIT_DIR,
-       if that fails try the alternate name spice.rc, then look into
-       the current directory, then the HOME directory, then into USERPROFILE.
+      try accessing the initialisation file .spiceinit
+      (If it fails, try the alternate name spice.rc):
+      - in the directory Infile_Path received from the caller (sent before initialization)
+      - in a user provided path read from environmental variable SPICE_USERINIT_DIR,
+      - in the current directory,
+      - in the the HOME directory,
+      - in the USERPROFILE directory.
       Don't read .spiceinit, if ngSpice_nospiceinit() has been called. */
     if (!cp_getvar("no_spiceinit", CP_BOOL, NULL, 0)) {
         do {
+            {
+                if (Infile_Path) {
+                    if (read_initialisation_file(Infile_Path, INITSTR) != FALSE) {
+                        break;
+                    }
+                    if (read_initialisation_file(Infile_Path, ALT_INITSTR) != FALSE) {
+                        break;
+                    }
+                }
+            }
             {
                 const char* const userinit = getenv("SPICE_USERINIT_DIR");
                 if (userinit) {