O_RDONLY/O_WRONLY/O_RDWR portability.

p4raw-id: //depot/perl@14445

diff --git a/doio.c b/doio.c
index ca15cd7..ab74d4a 100644 (file)
--- a/doio.c
+++ b/doio.c
@@ -140,18 +140,44 @@ Perl_do_openn(pTHX_ GV *gv, register char *name, I32 len, int as_raw,
     if (as_raw) {
         /* sysopen style args, i.e. integer mode and permissions */
        STRLEN ix = 0;
-       if (num_svs != 0) {
-            Perl_croak(aTHX_ "panic: sysopen with multiple args");
-       }
-       if (rawmode & (O_WRONLY|O_RDWR|O_CREAT
+       int appendtrunc =
+            0
 #ifdef O_APPEND        /* Not fully portable. */
-                      |O_APPEND
+            |O_APPEND
 #endif
 #ifdef O_TRUNC /* Not fully portable. */
-                      |O_TRUNC
+            |O_TRUNC
 #endif
-                      ))
-           TAINT_PROPER("sysopen");
+            ;
+       int modifyingmode =
+            O_WRONLY|O_RDWR|O_CREAT|appendtrunc;
+       int ismodifying;
+
+       if (num_svs != 0) {
+            Perl_croak(aTHX_ "panic: sysopen with multiple args");
+       }
+       /* It's not always
+
+          O_RDONLY 0
+          O_WRONLY 1
+          O_RDWR   2
+
+          It might be (in OS/390 and Mac OS Classic it is)
+
+          O_WRONLY 1
+          O_RDONLY 2
+          O_RDWR   3
+
+          This means that simple & with O_RDWR would look
+          like O_RDONLY is present.  Therefore we have to
+          be more careful.
+       */
+       if ((ismodifying = (rawmode & modifyingmode))) {
+            if ((ismodifying & O_WRONLY) == O_WRONLY ||
+                (ismodifying & O_RDWR)   == O_RDWR   ||
+                (ismodifying & (O_CREAT|appendtrunc)))
+                 TAINT_PROPER("sysopen");
+       }
        mode[ix++] = '#'; /* Marker to openn to use numeric "sysopen" */
 
 #if defined(USE_64_BIT_RAWIO) && defined(O_LARGEFILE)