Add optional config file sections, selected with CHOOSE

Allows the user to define arbitrarily named optional sections
in the config file, and select which of those sections are used.

For example:

  OPTIONS=color
  CHOOSE=char A,char B

  [char A]
  OPTIONS=role:arc,race:dwa,align:law,gender:fem

  [char B]
  OPTIONS=role:wiz,race:elf,align:cha,gender:mal

src/files.c

@@ -198,6 +198,10 @@ STATIC_DCL void FDECL(set_symhandling, (char *, int));
 #ifdef NOCWD_ASSUMPTIONS
 STATIC_DCL void FDECL(adjust_prefix, (char *, int));
 #endif
+STATIC_DCL void NDECL(free_config_sections);
+STATIC_DCL char *FDECL(choose_random_part, (char *, char));
+STATIC_DCL boolean FDECL(is_config_section, (const char *));
+STATIC_DCL boolean FDECL(handle_config_section, (char *));
 #ifdef SELF_RECOVER
 STATIC_DCL boolean FDECL(copy_bytes, (int, int));
 #endif
@@ -205,6 +209,10 @@ STATIC_DCL boolean FDECL(copy_bytes, (int, int));
 STATIC_DCL int FDECL(open_levelfile_exclusively, (const char *, int, int));
 #endif
 
+
+static char *config_section_chosen = (char *) 0;
+static char *config_section_current = (char *) 0;
+
 /*
  * fname_encode()
  *
@@ -2130,6 +2138,91 @@ int prefixid;
 }
 #endif
 
+/* Choose at random one of the sep separated parts from str. Mangles str. */
+STATIC_OVL char *
+choose_random_part(str,sep)
+char *str;
+char sep;
+{
+    int nsep = 1;
+    int csep;
+    int len = 0;
+    char *begin = str;
+
+    if (!str)
+        return (char *) 0;
+
+    while (*str) {
+	if (*str == sep) nsep++;
+	str++;
+    }
+    csep = rn2(nsep);
+    str = begin;
+    while ((csep > 0) && *str) {
+	str++;
+	if (*str == sep) csep--;
+    }
+    if (*str) {
+	if (*str == sep) str++;
+	begin = str;
+	while (*str && *str != sep) {
+	    str++;
+	    len++;
+	}
+	*str = '\0';
+	if (len)
+            return begin;
+    }
+    return (char *) 0;
+}
+
+STATIC_OVL void
+free_config_sections()
+{
+    if (config_section_chosen) {
+        free(config_section_chosen);
+        config_section_chosen = NULL;
+    }
+    if (config_section_current) {
+        free(config_section_current);
+        config_section_current = NULL;
+    }
+}
+
+STATIC_OVL boolean
+is_config_section(str)
+const char *str;
+{
+    const char *a = rindex(str, ']');
+
+    return (a && *str == '[' && *(a+1) == '\0' && (int)(a - str) > 0);
+}
+
+STATIC_OVL boolean
+handle_config_section(buf)
+char *buf;
+{
+    if (is_config_section(buf)) {
+        char *send;
+        if (config_section_current) {
+            free(config_section_current);
+        }
+        config_section_current = dupstr(&buf[1]);
+        send = rindex(config_section_current, ']');
+        *send = '\0';
+        debugpline1("set config section: '%s'", config_section_current);
+        return TRUE;
+    }
+
+    if (config_section_current) {
+        if (!config_section_chosen)
+            return TRUE;
+        if (strcmp(config_section_current, config_section_chosen))
+            return TRUE;
+    }
+    return FALSE;
+}
+
 #define match_varname(INP, NAM, LEN) match_optname(INP, NAM, LEN, TRUE)
 
 int
@@ -2156,6 +2249,9 @@ int src;
     if (!*buf || *buf == '#' || !strcmp(buf, " "))
         return 1;
 
+    if (src != SET_IN_SYS && handle_config_section(buf))
+        return 1;
+
     /* find the '=' or ':' */
     bufp = index(buf, '=');
     altp = index(buf, ':');
@@ -2183,6 +2279,13 @@ int src;
         ++bufp; /* skip '='; parseoptions() handles spaces */
 
         parseoptions(bufp, TRUE, TRUE);
+    } else if (match_varname(buf, "CHOOSE", 6)) {
+        char *section;
+        if (config_section_chosen)
+            free(config_section_chosen);
+        section = choose_random_part(bufp, ',');
+        if (section)
+            config_section_chosen = dupstr(section);
     } else if (match_varname(buf, "AUTOPICKUP_EXCEPTION", 5)) {
         add_autopickup_exception(bufp);
     } else if (match_varname(buf, "BINDINGS", 4)) {
@@ -2642,6 +2745,7 @@ int src;
 
     /* begin detection of duplicate configfile options */
     set_duplicate_opt_detection(1);
+    free_config_sections();
 
     while (fgets(buf, sizeof buf, fp)) {
 #ifdef notyet
@@ -2665,6 +2769,7 @@ OR: Forbid multiline stuff for alternate config sources.
     }
     (void) fclose(fp);
 
+    free_config_sections();
     /* turn off detection of duplicate configfile options */
     set_duplicate_opt_detection(0);
     return rv;