re PR libstdc++/12048 (unget does not work)

2003-09-03  Petur Runolfsson  <peturr02@ru.is>

	PR libstdc++/12048
	* include/ext/stdio_sync_filebuf.h
	(stdio_sync_filebuf::_M_unget_buf): Declare it.
	(stdio_sync_filebuf::stdio_sync_filebuf): Initialize _M_unget_buf.
	(stdio_sync_filebuf::uflow): Store the returned character in
	_M_unget_buf.
	(stdio_sync_filebuf::pbackfail): If argument is eof(), pass
	_M_unget_buf to syncungetc(). Set _M_unget_buf to eof().
	(stdio_sync_filebuf<char>::xsgetn): Store last read character in
	_M_unget_buf, if any, else eof().
	(stdio_sync_filebuf<wchar_t>::xsgetn: Store last read character in
	_M_unget_buf, if any, else eof().
	* testsuite/27_io/objects/char/12048.cc: Rename to...
	* testsuite/27_io/objects/char/12048-1.cc: ...this.
	* testsuite/27_io/objects/char/12048-2.cc: New test.
	* testsuite/27_io/objects/char/12048-3.cc: New test.
	* testsuite/27_io/objects/char/12048-4.cc: New test.
	* testsuite/27_io/objects/char/12048-5.cc: New test. XFAIL.
	* testsuite/27_io/objects/wchar_t/12048-1.cc: New test.
	* testsuite/27_io/objects/wchar_t/12048-2.cc: New test.
	* testsuite/27_io/objects/wchar_t/12048-3.cc: New test.
	* testsuite/27_io/objects/wchar_t/12048-4.cc: New test.
	* testsuite/27_io/objects/wchar_t/12048-5.cc: New test. XFAIL.
	* testsuite/ext/stdio_sync_filebuf_char.cc
	(test02, test03, test04, test05): New tests.
	* testsuite/ext/stdio_sync_filebuf_wchar_t.cc
	(test02, test03, test04, test05): New tests.

2003-09-03  Petur Runolfsson  <peturr02@ru.is>

	* docs/html/27_io/howto.html: setbuf(0, 0) has no effect on
	stringbuf or strstreambuf. Fix typos.

From-SVN: r71026

libstdc++-v3/ChangeLog

@@ -1,3 +1,38 @@
+2003-09-03  Petur Runolfsson  <peturr02@ru.is>
+
+	PR libstdc++/12048
+	* include/ext/stdio_sync_filebuf.h
+	(stdio_sync_filebuf::_M_unget_buf): Declare it.
+	(stdio_sync_filebuf::stdio_sync_filebuf): Initialize _M_unget_buf.
+	(stdio_sync_filebuf::uflow): Store the returned character in
+	_M_unget_buf.
+	(stdio_sync_filebuf::pbackfail): If argument is eof(), pass
+	_M_unget_buf to syncungetc(). Set _M_unget_buf to eof().
+	(stdio_sync_filebuf<char>::xsgetn): Store last read character in
+	_M_unget_buf, if any, else eof().
+	(stdio_sync_filebuf<wchar_t>::xsgetn: Store last read character in
+	_M_unget_buf, if any, else eof().
+	* testsuite/27_io/objects/char/12048.cc: Rename to...
+	* testsuite/27_io/objects/char/12048-1.cc: ...this.
+	* testsuite/27_io/objects/char/12048-2.cc: New test.
+	* testsuite/27_io/objects/char/12048-3.cc: New test.
+	* testsuite/27_io/objects/char/12048-4.cc: New test.
+	* testsuite/27_io/objects/char/12048-5.cc: New test. XFAIL.
+	* testsuite/27_io/objects/wchar_t/12048-1.cc: New test.
+	* testsuite/27_io/objects/wchar_t/12048-2.cc: New test.
+	* testsuite/27_io/objects/wchar_t/12048-3.cc: New test.
+	* testsuite/27_io/objects/wchar_t/12048-4.cc: New test.
+	* testsuite/27_io/objects/wchar_t/12048-5.cc: New test. XFAIL.
+	* testsuite/ext/stdio_sync_filebuf_char.cc
+	(test02, test03, test04, test05): New tests.
+	* testsuite/ext/stdio_sync_filebuf_wchar_t.cc
+	(test02, test03, test04, test05): New tests.
+
+2003-09-03  Petur Runolfsson  <peturr02@ru.is>
+
+	* docs/html/27_io/howto.html: setbuf(0, 0) has no effect on
+	stringbuf or strstreambuf. Fix typos.
+
 2003-09-02  Phil Edwards  <phil@codesourcery.com>
 
 	* acinclude.m4 (GLIBCXX_ENABLE_HOSTED):  #define _GLIBCXX_HOSTED

libstdc++-v3/docs/html/27_io/howto.html

@@ -185,9 +185,10 @@
       <code>setbuf()</code>-ish functions; the classes derived from
       <code>streambuf</code> each define behavior that &quot;makes 
       sense&quot; for that class:  an argument of (0,0) turns off buffering
-      for <code>filebuf</code> but has undefined behavior for its sibling
+      for <code>filebuf</code> but does nothing at all for its siblings
-      <code>stringbuf</code>, and specifying anything other than (0,0) has
+      <code>stringbuf</code> and <code>strstreambuf</code>, and specifying
-      varying effects.  Other user-defined class derived from streambuf can
+      anything other than (0,0) has varying effects.
+      User-defined classes derived from <code>streambuf</code> can
       do whatever they want.  (For <code>filebuf</code> and arguments for
       <code>(p,s)</code> other than zeros, libstdc++ does what you'd expect:
       the first <code>s</code> bytes of <code>p</code> are used as a buffer,

libstdc++-v3/include/ext/stdio_sync_filebuf.h

@@ -57,10 +57,7 @@ namespace __gnu_cxx
   template<typename _CharT, typename _Traits = std::char_traits<_CharT> >
     class stdio_sync_filebuf : public std::basic_streambuf<_CharT, _Traits>
     {
-    private:
+    public:
-      std::__c_file* const _M_file;
-
-     public:
       // Types:
       typedef _CharT                  	        	char_type;
       typedef _Traits		                    	traits_type;
@@ -68,8 +65,19 @@ namespace __gnu_cxx
       typedef typename traits_type::pos_type 		pos_type;
       typedef typename traits_type::off_type 		off_type;
 
+    private:
+      // Underlying stdio FILE
+      std::__c_file* const _M_file;
+      
+      // Last character gotten. This is used when pbackfail is
+      // called from basic_streambuf::sungetc()
+      int_type _M_unget_buf;
+
+    public:
       explicit 
-      stdio_sync_filebuf(std::__c_file* __f) : _M_file(__f) { }
+      stdio_sync_filebuf(std::__c_file* __f)
+      : _M_file(__f), _M_unget_buf(traits_type::eof())
+      { }
 
     protected:
 
@@ -91,11 +99,33 @@ namespace __gnu_cxx
 
       virtual int_type
       uflow()
-      { return this->syncgetc(); }
+      {
+	// Store the gotten character in case we need to unget it.
+	_M_unget_buf = this->syncgetc();
+	return _M_unget_buf;
+      }
 
       virtual int_type
       pbackfail(int_type __c = traits_type::eof())
-      { return this->syncungetc(__c); }
+      {
+	int_type __ret;
+	const int_type __eof = traits_type::eof();
+
+	// Check if the unget or putback was requested
+	if (traits_type::eq_int_type(__c, __eof)) // unget
+	  {
+	    if (!traits_type::eq_int_type(_M_unget_buf, __eof))
+	      __ret = this->syncungetc(_M_unget_buf);
+	    else // buffer invalid, fail.
+	      __ret = __eof;
+	  }
+	else // putback
+	  __ret = this->syncungetc(__c);
+
+	// The buffered character is no longer valid, discard it.
+	_M_unget_buf = __eof;
+	return __ret;
+      }
 
       virtual std::streamsize
       xsgetn(char_type* __s, std::streamsize __n);
@@ -179,7 +209,14 @@ namespace __gnu_cxx
   template<>
     inline std::streamsize
     stdio_sync_filebuf<char>::xsgetn(char* __s, std::streamsize __n)
-    { return std::fread(__s, 1, __n, _M_file); }
+    {
+      std::streamsize __ret = std::fread(__s, 1, __n, _M_file);
+      if (__ret > 0)
+	_M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
+      else
+	_M_unget_buf = traits_type::eof();
+      return __ret;
+    }
 
   template<>
     inline std::streamsize
@@ -213,9 +250,14 @@ namespace __gnu_cxx
 	  int_type __c = this->syncgetc();
 	  if (traits_type::eq_int_type(__c, __eof))
 	    break;
-	  *__s++ = __c;
+	  __s[__ret] = traits_type::to_char_type(__c);
 	  ++__ret;
 	}
+
+      if (__ret > 0)
+	_M_unget_buf = traits_type::to_int_type(__s[__ret - 1]);
+      else
+	_M_unget_buf = traits_type::eof();
       return __ret;
     }
       

libstdc++-v3/testsuite/ext/stdio_sync_filebuf_char.cc

@@ -52,13 +52,89 @@ void test01()
   VERIFY( sbuf.sgetn(buf, 5) == 5 );
   VERIFY( !memcmp(buf, c_lit + 3, 5) );
   VERIFY( getc(fin) == c_lit[8] );
-  VERIFY( sbuf.sungetc() == EOF );
 
   fclose(fin);
 }
 
+// libstdc++/12048
+void test02()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<char> sbuf(file);
+  int c1 = sbuf.sbumpc();
+  VERIFY( c1 != EOF );
+  int c2 = sbuf.sungetc();
+  VERIFY( c2 != EOF );
+  int c3 = sbuf.sbumpc();
+  VERIFY( c3 == c1 );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test03()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<char> sbuf(file);
+  int c1 = sbuf.sbumpc();
+  VERIFY( c1 != EOF );
+  int c2 = sbuf.sungetc();
+  VERIFY( c2 != EOF );
+  int c3 = std::fgetc(file);
+  VERIFY( c3 == c1 );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test04()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<char> sbuf(file);
+  char buf[2];
+  VERIFY( sbuf.sgetn(buf, 2) == 2 );
+  int c2 = sbuf.sungetc();
+  VERIFY( c2 != EOF );
+  int c3 = sbuf.sbumpc();
+  VERIFY( c3 == std::char_traits<char>::to_int_type(buf[1]) );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test05()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<char> sbuf(file);
+  char buf[2];
+  VERIFY( sbuf.sgetn(buf, 2) == 2 );
+  int c2 = sbuf.sungetc();
+  VERIFY( c2 != EOF );
+  int c3 = std::fgetc(file);
+  VERIFY( c3 == std::char_traits<char>::to_int_type(buf[1]) );
+
+  std::fclose(file);
+}
+
 int main ()
 {
   test01();
+  test02();
+  test03();
+  test04();
+  test05();
+
   return 0;
 }

libstdc++-v3/testsuite/ext/stdio_sync_filebuf_wchar_t.cc

@@ -53,13 +53,89 @@ void test01()
   VERIFY( wsbuf.sgetn(buf, 5) == 5 );
   VERIFY( !wmemcmp(buf, w_lit + 3, 5) );
   VERIFY( getwc(fin) == w_lit[8] );
-  VERIFY( wsbuf.sungetc() == WEOF );
 
   fclose(fin);
 }
 
+// libstdc++/12048
+void test02()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<wchar_t> sbuf(file);
+  std::wint_t c1 = sbuf.sbumpc();
+  VERIFY( c1 != WEOF );
+  std::wint_t c2 = sbuf.sungetc();
+  VERIFY( c2 != WEOF );
+  std::wint_t c3 = sbuf.sbumpc();
+  VERIFY( c3 == c1 );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test03()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<wchar_t> sbuf(file);
+  std::wint_t c1 = sbuf.sbumpc();
+  VERIFY( c1 != WEOF );
+  std::wint_t c2 = sbuf.sungetc();
+  VERIFY( c2 != WEOF );
+  std::wint_t c3 = std::fgetwc(file);
+  VERIFY( c3 == c1 );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test04()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<wchar_t> sbuf(file);
+  wchar_t buf[2];
+  VERIFY( sbuf.sgetn(buf, 2) == 2 );
+  std::wint_t c2 = sbuf.sungetc();
+  VERIFY( c2 != WEOF );
+  std::wint_t c3 = sbuf.sbumpc();
+  VERIFY( c3 == std::char_traits<wchar_t>::to_int_type(buf[1]) );
+
+  std::fclose(file);
+}
+
+// libstdc++/12048
+void test05()
+{
+  bool test = true;
+  const char* name = "cin_unget-1.txt";
+
+  std::FILE* file = std::fopen(name, "r");
+  __gnu_cxx::stdio_sync_filebuf<wchar_t> sbuf(file);
+  wchar_t buf[2];
+  VERIFY( sbuf.sgetn(buf, 2) == 2 );
+  std::wint_t c2 = sbuf.sungetc();
+  VERIFY( c2 != WEOF );
+  std::wint_t c3 = std::fgetwc(file);
+  VERIFY( c3 == std::char_traits<wchar_t>::to_int_type(buf[1]) );
+
+  std::fclose(file);
+}
+
 int main ()
 {
   test01();
+  test02();
+  test03();
+  test04();
+  test05();
+
   return 0;
 }