Added getenv, which takes a string and returns a string from the "unix"

environment.  
Example:
  (getenv "HOME") => "/Users/aghuloum"
  (getenv "FOO")  => ""

scheme/ikarus.main.ss

@@ -51,14 +51,14 @@
                      (let ([d (cdr args)])
                        (cond
                          [(null? d)
-                          (error #f "--script requires a script name")]
+                          (error 'ikarus "--script requires a script name")]
                          [else
                           (values '() (car d) 'script (cdr d))]))]
                     [(string=? (car args) "--r6rs-script")
                      (let ([d (cdr args)])
                        (cond
                          [(null? d)
-                          (error #f "--r6rs-script requires a script name")]
+                          (error 'ikarus "--r6rs-script requires a script name")]
                          [else
                           (values '() (car d) 'r6rs-script (cdr d))]))]
                     [else

scheme/ikarus.posix.ss

@@ -16,12 +16,12 @@
 
 (library (ikarus posix)
   (export posix-fork fork waitpid system file-exists? delete-file
-          env environ)
+          getenv env environ)
   (import 
     (rnrs bytevectors)
     (except (ikarus)
        posix-fork fork waitpid system file-exists? delete-file
-       env environ))
+       getenv env environ))
 
   (define posix-fork
     (lambda ()
@@ -96,6 +96,16 @@
                     [else "Unknown error while deleting"])
                   x)]))))
 
+  (define ($getenv-bv key)
+    (foreign-call "ikrt_getenv" key))
+  (define ($getenv-str key) 
+    (utf8->string ($getenv-bv (string->utf8 key))))
+
+  (define (getenv key)
+    (if (string? key)
+        ($getenv-str key)
+        (error 'getenv "the key is not a string" key)))
+
   (define env
     (let ()
       (define env

scheme/makefile.ss

@@ -1266,6 +1266,7 @@
     [string-normalize-nfkd                       r uc]
     [string-titlecase                            r uc]
     [string-upcase                               r uc]
+    [getenv                                      i]
     [char-ready?                                 ]
     [interaction-environment                     ]
     [load                                        i]

src/ikarus-runtime.c

@@ -1036,21 +1036,21 @@ ikrt_waitpid(ikp pid){
 }
 
 ikp 
-ikrt_getenv(ikp str, ikpcb* pcb){
-  fprintf(stderr, "getenv busted!\n");
-  exit(-1);
-  char* v = getenv((char*)str + off_bytevector_data);
+ikrt_getenv(ikp bv, ikpcb* pcb){
+  char* v = getenv((char*)bv + off_bytevector_data);
   if(v){
     int n = strlen(v);
-    ikp s = ik_unsafe_alloc(pcb, align(n+disp_string_data+1)) + string_tag;
-    ref(s, -string_tag) = fix(n);
-    memcpy(s+off_string_data, v, n+1);
+    ikp s = ik_safe_alloc(pcb, align(n+disp_bytevector_data+1))
+              + bytevector_tag;
+    ref(s, -bytevector_tag) = fix(n);
+    memcpy(s+off_bytevector_data, v, n+1);
     return s;
   } 
   else {
-    ikp s = ik_unsafe_alloc(pcb, align(disp_string_data+1)) + string_tag;
-    ref(s, -string_tag) = fix(0);
-    ref(s, off_string_data) = 0;
+    ikp s = ik_safe_alloc(pcb, align(disp_bytevector_data+1)) 
+          + bytevector_tag;
+    ref(s, -bytevector_tag) = fix(0);
+    ref(s, off_bytevector_data) = 0;
     return s;
   }
 }