From 3cc5ddcac142317709aa235a27d8ce0a84140150 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 24 May 2012 03:07:49 +0000
Subject: Bug #6487

* io.c (io_strip_bom): check EOF.  [Bug #6487][ruby-core:45203]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35766 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 io.c | 68 +++++++++++++++++++++++++++++++++-----------------------------------
 1 file changed, 33 insertions(+), 35 deletions(-)

(limited to 'io.c')

diff --git a/io.c b/io.c
index e5e77be5cb..c935ff1a3f 100644
--- a/io.c
+++ b/io.c
@@ -5099,65 +5099,63 @@ static void io_encoding_set(rb_io_t *, VALUE, VALUE, VALUE);
 static int
 io_strip_bom(VALUE io)
 {
-    int b1, b2, b3, b4;
-    switch (b1 = FIX2INT(rb_io_getbyte(io))) {
-      case 0xEF:
-	b2 = FIX2INT(rb_io_getbyte(io));
-	if (b2 == 0xBB) {
-	    b3 = FIX2INT(rb_io_getbyte(io));
-	    if (b3 == 0xBF) {
+    VALUE b1, b2, b3, b4;
+
+    if (NIL_P(b1 = rb_io_getbyte(io))) return 0;
+    switch (b1) {
+      case INT2FIX(0xEF):
+	if (NIL_P(b2 = rb_io_getbyte(io))) break;
+	if (b2 == INT2FIX(0xBB) && !NIL_P(b3 = rb_io_getbyte(io))) {
+	    if (b3 == INT2FIX(0xBF)) {
 		return rb_utf8_encindex();
 	    }
-	    rb_io_ungetbyte(io, INT2FIX(b3));
+	    rb_io_ungetbyte(io, b3);
 	}
-	rb_io_ungetbyte(io, INT2FIX(b2));
+	rb_io_ungetbyte(io, b2);
 	break;
 
-      case 0xFE:
-	b2 = FIX2INT(rb_io_getbyte(io));
-	if (b2 == 0xFF) {
+      case INT2FIX(0xFE):
+	if (NIL_P(b2 = rb_io_getbyte(io))) break;
+	if (b2 == INT2FIX(0xFF)) {
 	    return rb_enc_find_index("UTF-16BE");
 	}
-	rb_io_ungetbyte(io, INT2FIX(b2));
+	rb_io_ungetbyte(io, b2);
 	break;
 
-      case 0xFF:
-	b2 = FIX2INT(rb_io_getbyte(io));
-	if (b2 == 0xFE) {
-	    b3 = FIX2INT(rb_io_getbyte(io));
-	    if (b3 == 0) {
-		b4 = FIX2INT(rb_io_getbyte(io));
-		if (b4 == 0) {
+      case INT2FIX(0xFF):
+	if (NIL_P(b2 = rb_io_getbyte(io))) break;
+	if (b2 == INT2FIX(0xFE)) {
+	    b3 = rb_io_getbyte(io);
+	    if (b3 == INT2FIX(0) && !NIL_P(b4 = rb_io_getbyte(io))) {
+		if (b4 == INT2FIX(0)) {
 		    return rb_enc_find_index("UTF-32LE");
 		}
-		rb_io_ungetbyte(io, INT2FIX(b4));
+		rb_io_ungetbyte(io, b4);
+		rb_io_ungetbyte(io, b3);
 	    }
 	    else {
-		rb_io_ungetbyte(io, INT2FIX(b3));
+		rb_io_ungetbyte(io, b3);
 		return rb_enc_find_index("UTF-16LE");
 	    }
-	    rb_io_ungetbyte(io, INT2FIX(b3));
 	}
-	rb_io_ungetbyte(io, INT2FIX(b2));
+	rb_io_ungetbyte(io, b2);
 	break;
 
-      case 0:
-	b2 = FIX2INT(rb_io_getbyte(io));
-	if (b2 == 0) {
-	    b3 = FIX2INT(rb_io_getbyte(io));
-	    if (b3 == 0xFE) {
-		b4 = FIX2INT(rb_io_getbyte(io));
-		if (b4 == 0xFF) {
+      case INT2FIX(0):
+	if (NIL_P(b2 = rb_io_getbyte(io))) break;
+	if (b2 == INT2FIX(0) && !NIL_P(b3 = rb_io_getbyte(io))) {
+	    if (b3 == INT2FIX(0xFE) && !NIL_P(b4 = rb_io_getbyte(io))) {
+		if (b4 == INT2FIX(0xFF)) {
 		    return rb_enc_find_index("UTF-32BE");
 		}
-		rb_io_ungetbyte(io, INT2FIX(b4));
+		rb_io_ungetbyte(io, b4);
 	    }
-	    rb_io_ungetbyte(io, INT2FIX(b3));
+	    rb_io_ungetbyte(io, b3);
 	}
-	rb_io_ungetbyte(io, INT2FIX(b2));
+	rb_io_ungetbyte(io, b2);
 	break;
     }
-    rb_io_ungetbyte(io, INT2FIX(b1));
+    rb_io_ungetbyte(io, b1);
     return 0;
 }
 
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