From b562983222fa84d834035402ffa56ded4d212fc9 Mon Sep 17 00:00:00 2001
From: "C. Masloch" <pushbx@ulukai.org>
Date: Sat, 21 May 2022 15:29:51 +0200
Subject: [PATCH] config: add the CONFIG, ALTCONFIG, and OLDCONFIG kernel
 command line commands

CONFIG takes precedence and is by default initialised
to the empty string, that is, skipped. ALTCONFIG is
used to specify the 'alternative' filename and defaults
to fdconfig.sys. Finally, OLDCONFIG defaults to the
config.sys filename.
---
 kernel/config.c | 78 ++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 61 insertions(+), 17 deletions(-)

diff --git a/kernel/config.c b/kernel/config.c
index 04569ce..4643a6d 100644
--- a/kernel/config.c
+++ b/kernel/config.c
@@ -62,6 +62,8 @@ STATIC struct MenuSelector MenuStruct[MENULINESMAX] BSS_INIT({0});
 
 int nMenuLine BSS_INIT(0);
 int MenuColor = -1;
+extern UBYTE kernel_command_line[256];
+extern int kernel_command_line_length;
 
 STATIC void WriteMenuLine(struct MenuSelector *menu)
 {
@@ -800,6 +802,26 @@ copy_char:
 #endif
 
 
+static unsigned check_config_commandline(char ** pointer, char * cc,
+	char const * commandbuffer, char const * command);
+static unsigned check_config_commandline(char ** pointer, char * cc,
+	char const * commandbuffer, char const * command) {
+  unsigned length = strlen(command);
+  if (memcmp(commandbuffer, command, length) == 0
+      && (commandbuffer[length] == '\t'
+          || commandbuffer[length] == ' '
+          || commandbuffer[length] == '='
+          || commandbuffer[length] == 0)) {
+    for (cc += length; *cc == '\t' || *cc == ' '; ++cc);
+    if (*cc == '=') ++cc;
+    for (; *cc == '\t' || *cc == ' '; ++cc);
+    *pointer = cc;
+    return 1;
+  }
+  return 0;
+}
+
+
 VOID DoConfig(int nPass)
 {
   BYTE *pLine;
@@ -838,20 +860,46 @@ VOID DoConfig(int nPass)
 #endif
   }
 
+  {
+    char * pp = kernel_command_line;
+    char * cc;
+    unsigned ii;
+    static char commandbuffer[256];
+    char * end = &kernel_command_line[kernel_command_line_length];
+    char * configfile = "";
+    char * altconfigfile = "fdconfig.sys";
+    char * oldconfigfile = "config.sys";
+    struct { char ** pointer; char const * command; }
+      configcommands[] = {
+        { &configfile, "CONFIG" },
+        { &altconfigfile, "ALTCONFIG" },
+        { &oldconfigfile, "OLDCONFIG" },
+        { NULL, NULL }
+        };
+    for (; pp < end; pp += strlen(pp) + 1) {
+      for (cc = pp; *cc == '\t' || *cc == ' '; ++cc);
+      strcpy(commandbuffer, cc);
+      strupr(commandbuffer);
+      for (ii = 0; configcommands[ii].pointer != NULL; ++ii)
+        if (check_config_commandline(configcommands[ii].pointer,
+          cc, commandbuffer, configcommands[ii].command))
+          break;
+    }
 
-  /* Check to see if we have a config.sys file.  If not, just     */
-  /* exit since we don't force the user to have one (but 1st      */
-  /* also process MEMDISK passed config options if present).      */
-  if ((nFileDesc = open("fdconfig.sys", 0)) >= 0)
-  {
-    DebugPrintf(("Reading FDCONFIG.SYS...\n"));
-  }
-  else
-  {
-    DebugPrintf(("FDCONFIG.SYS not found\n"));
-    if ((nFileDesc = open("config.sys", 0)) < 0)
-    {
-      DebugPrintf(("CONFIG.SYS not found\n"));
+    /* Check to see if we have a config.sys file.  If not, just     */
+    /* exit since we don't force the user to have one (but 1st      */
+    /* also process MEMDISK passed config options if present).      */
+    for (ii = 0; configcommands[ii].pointer != NULL; ++ii) {
+      if (**configcommands[ii].pointer != '\0') {
+        if ((nFileDesc = open(*configcommands[ii].pointer, 0)) >= 0) {
+          DebugPrintf(("Reading \"%s\"...\n", *configcommands[ii].pointer));
+          break;
+        } else {
+          DebugPrintf(("\"%s\" not found\n", *configcommands[ii].pointer));
+        }
+      }
+    }
+    if (configcommands[ii].pointer == NULL) {
       /* at this point no config file was found, may return early */
 #ifdef MEMDISK_ARGS
       /* if memdisk in use then only assume end of file reached and proceed, else return early */
@@ -861,10 +909,6 @@ VOID DoConfig(int nPass)
 #endif
         return;
     }
-    else
-    {
-      DebugPrintf(("Reading CONFIG.SYS...\n"));
-    }
   }
 
   nCfgLine = 0;  /* keep track of which line in file for errors   */