Index: src/cgi.c
==================================================================
--- src/cgi.c
+++ src/cgi.c
@@ -949,17 +949,34 @@
   const char *zType;
   int len;
   const char *zRequestUri = cgi_parameter("REQUEST_URI",0);
   const char *zScriptName = cgi_parameter("SCRIPT_NAME",0);
   const char *zPathInfo = cgi_parameter("PATH_INFO",0);
+#ifdef _WIN32
+  const char *zServerSoftware = cgi_parameter("SERVER_SOFTWARE",0);
+#endif
 
 #ifdef FOSSIL_ENABLE_JSON
   json_main_bootstrap();
 #endif
   g.isHTTP = 1;
   cgi_destination(CGI_BODY);
   if( zScriptName==0 ) malformed_request("missing SCRIPT_NAME");
+#ifdef _WIN32
+  /* The Microsoft IIS web server does not define REQUEST_URI, instead it uses
+  ** PATH_INFO for virtually the same purpose.  Define REQUEST_URI the same as
+  ** PATH_INFO and redefine PATH_INFO with SCRIPT_NAME removed from the 
+  ** beginning. */
+  if( zServerSoftware && strstr(zServerSoftware, "Microsoft-IIS") ){
+    int i, j;
+    cgi_set_parameter("REQUEST_URI", zPathInfo);
+    for(i=0; zPathInfo[i]==zScriptName[i] && zPathInfo[i]; i++){}
+    for(j=i; zPathInfo[j] && zPathInfo[j]!='?'; j++){}
+    zPathInfo = mprintf("%.*s", j-i, zPathInfo+i);
+    cgi_replace_parameter("PATH_INFO", zPathInfo);
+  }
+#endif
   if( zRequestUri==0 ){
     const char *z = zPathInfo;
     if( zPathInfo==0 ){
       malformed_request("missing PATH_INFO and/or REQUEST_URI");
     }
@@ -1113,15 +1130,16 @@
     }
   }
 
   /* If no match is found and the name begins with an upper-case
   ** letter, then check to see if there is an environment variable
-  ** with the given name.
+  ** with the given name. Handle environment variables with empty values
+  ** the same as non-existent environment variables.
   */
   if( zName && fossil_isupper(zName[0]) ){
     const char *zValue = fossil_getenv(zName);
-    if( zValue ){
+    if( zValue && zValue[0] ){
       cgi_set_parameter_nocopy(zName, zValue, 0);
       CGIDEBUG(("env-match [%s] = [%s]\n", zName, zValue));
       return zValue;
     }
   }

Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -1994,21 +1994,26 @@
   char **azRedirect = 0;             /* List of repositories to redirect to */
   int nRedirect = 0;                 /* Number of entries in azRedirect */
   Glob *pFileGlob = 0;               /* Pattern for files */
   int allowRepoList = 0;             /* Allow lists of repository files */
   Blob config, line, key, value, value2;
-  if( g.argc==3 && fossil_strcmp(g.argv[1],"cgi")==0 ){
-    zFile = g.argv[2];
-  }else{
-    zFile = g.argv[1];
-  }
+  /* Initialize the CGI environment. */
   g.httpOut = stdout;
   g.httpIn = stdin;
   fossil_binary_mode(g.httpOut);
   fossil_binary_mode(g.httpIn);
   g.cgiOutput = 1;
   fossil_set_timeout(FOSSIL_DEFAULT_TIMEOUT);
+  /* Read and parse the CGI control file. */
+  if( g.argc==3 && fossil_strcmp(g.argv[1],"cgi")==0 ){
+    zFile = g.argv[2];
+  }else if( g.argc>=2 ){
+    zFile = g.argv[1];
+  }else{
+    cgi_panic("No CGI control file specified");
+  }
+  /* Read and parse the CGI control file. */
   blob_read_from_file(&config, zFile, ExtFILE);
   while( blob_line(&config, &line) ){
     if( !blob_token(&line, &key) ) continue;
     if( blob_buffer(&key)[0]=='#' ) continue;
     if( blob_eq(&key, "repository:") && blob_tail(&line, &value) ){