vsnprintf.c: fix string precision

* vsnprintf.c (BSD_vfprintf): fix string width when precision is
  given.  as the result of `memchr` is NULL or its offset from the
  start cannot exceed the size, the comparison was always false.
  [ruby-core:62737] [Bug #9861]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46098 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,10 @@
+Sun May 25 11:56:33 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vsnprintf.c (BSD_vfprintf): fix string width when precision is
+	  given.  as the result of `memchr` is NULL or its offset from the
+	  start cannot exceed the size, the comparison was always false.
+	  [ruby-core:62737] [Bug #9861]
+
 Sun May 25 11:32:42 2014  Zachary Scott  <e@zzak.io>
 
 	* lib/yaml.rb: Remove Psych::EngineManager [Bug #8344]

ext/-test-/printf/printf.c

@@ -42,18 +42,23 @@ utoa(char *p, char *e, unsigned int x)
 static VALUE
 printf_test_call(int argc, VALUE *argv, VALUE self)
 {
-    VALUE opt, type, num;
+    VALUE opt, type, num, result;
     char format[sizeof(int) * 6 + 8], *p = format, cnv;
     int n;
+    const char *s;
 
     rb_scan_args(argc, argv, "2:", &type, &num, &opt);
     Check_Type(type, T_STRING);
     if (RSTRING_LEN(type) != 1) rb_raise(rb_eArgError, "wrong length(%ld)", RSTRING_LEN(type));
     switch (cnv = RSTRING_PTR(type)[0]) {
-      case 'd': case 'x': case 'o': case 'X': break;
+      case 'd': case 'x': case 'o': case 'X':
+	n = NUM2INT(num);
+	break;
+      case 's':
+	s = StringValueCStr(num);
+	break;
       default: rb_raise(rb_eArgError, "wrong conversion(%c)", cnv);
     }
-    n = NUM2INT(num);
     *p++ = '%';
     if (!NIL_P(opt)) {
 	VALUE v;
@@ -84,8 +89,13 @@ printf_test_call(int argc, VALUE *argv, VALUE self)
     }
     *p++ = cnv;
     *p++ = '\0';
-    return rb_assoc_new(rb_enc_sprintf(rb_usascii_encoding(), format, n),
-			rb_usascii_str_new_cstr(format));
+    if (cnv == 's') {
+	result = rb_enc_sprintf(rb_usascii_encoding(), format, s);
+    }
+    else {
+	result = rb_enc_sprintf(rb_usascii_encoding(), format, n);
+    }
+    return rb_assoc_new(result, rb_usascii_str_new_cstr(format));
 }
 
 void

test/-ext-/test_printf.rb

@@ -181,4 +181,10 @@ class Test_SPrintf < Test::Unit::TestCase
                                             zero: zr, width: width,
                                             prec: prec))
   }
+
+  def test_string_prec
+    assert_equal("a", Bug::Printf.("s", "a", prec: 3)[0])
+    assert_equal("  a", Bug::Printf.("s", "a", width: 3, prec: 3)[0])
+    assert_equal("a  ", Bug::Printf.("s", "a", minus: true, width: 3, prec: 3)[0])
+  end
 end

vsnprintf.c

@@ -993,7 +993,7 @@ fp_begin:		_double = va_arg(ap, double);
 				 */
 				const char *p = (char *)memchr(cp, 0, prec);
 
-				if (p != NULL && (p - cp) > prec)
+				if (p != NULL && (p - cp) < prec)
 					size = (int)(p - cp);
 				else
 					size = prec;