[Patch] Fix first part of libstdc++/13731

[Paolo Carlini <pcarlini at suse dot de>]

Hi everyone, hi Loren,

this is the first part, dealing with write (the second part will affect
writev, and therefore xsputn).

I briefly recall that this work is needed because, when pipes are involved,
and n > PIPE_BUF, partial but succesful writes are possible: therefore we
must iterate 'til completion or error.

I would like you all to stress test in mainline this first part for a few
days, in the meanwhile work on the second part, which is less 
straighforward,
but still manageable since our writev are always of 1 or 2 buffers, not
fully general.

Tested x86-linux.

Paolo.

////////////////
2004-02-11  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/13731 (first part: write)
	* config/io/basic_file_stdio.h (__basic_file<char>::xwrite):
	New, declare.
	* config/io/basic_file_stdio.cc (__basic_file<char>::xwrite):
	Define it: a wrapper around write() handling partial write.
	(__basic_file<char>::xsputn): Use it.
	(__basic_file<char>::xsputn_2): Likewise.

diff -prN libstdc++-v3-orig/config/io/basic_file_stdio.cc libstdc++-v3/config/io/basic_file_stdio.cc
*** libstdc++-v3-orig/config/io/basic_file_stdio.cc	Thu Feb  5 21:11:32 2004
--- libstdc++-v3/config/io/basic_file_stdio.cc	Wed Feb 11 18:52:16 2004
*************** namespace std 
*** 200,215 ****
      while (__ret == -1L && errno == EINTR);
      return __ret;
    }
!     
!   streamsize 
!   __basic_file<char>::xsputn(const char* __s, streamsize __n)
    {
!     streamsize __ret;
!     do
!       __ret = write(this->fd(), __s, __n);
!     while (__ret == -1L && errno == EINTR);
!     return __ret;
    }
  
    streamsize 
    __basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
--- 200,227 ----
      while (__ret == -1L && errno == EINTR);
      return __ret;
    }
! 
!   // Wrapper handling partial write.
!   streamsize
!   __basic_file<char>::xwrite(const char* __s, streamsize __n)
    {
!     streamsize __nleft = __n;
!     while (__nleft > 0)
!       {
! 	const streamsize __ret = write(this->fd(), __s, __nleft);
! 	if (__ret == -1L && errno == EINTR)
! 	  continue;
! 	else if (__ret == -1L)
! 	  break;
! 	__nleft -= __ret;
! 	__s += __ret;
!       }
!     return __n - __nleft;
    }
+  
+   streamsize 
+   __basic_file<char>::xsputn(const char* __s, streamsize __n)
+   { return __basic_file<char>::xwrite(__s, __n); }
  
    streamsize 
    __basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
*************** namespace std 
*** 228,246 ****
      while (__ret == -1L && errno == EINTR);
  #else
      if (__n1)
!       do
! 	__ret = write(this->fd(), __s1, __n1);
!       while (__ret == -1L && errno == EINTR);
  
      if (__ret == __n1)
!       {
! 	do
! 	  __ret = write(this->fd(), __s2, __n2);
! 	while (__ret == -1L && errno == EINTR);
! 	
! 	if (__ret != -1L)
! 	  __ret += __n1;
!       }
  #endif
      return __ret;
    }
--- 240,249 ----
      while (__ret == -1L && errno == EINTR);
  #else
      if (__n1)
!       __ret = __basic_file<char>::xwrite(__s1, __n1);
  
      if (__ret == __n1)
!       __ret += __basic_file<char>::xwrite(__s2, __n2);
  #endif
      return __ret;
    }
diff -prN libstdc++-v3-orig/config/io/basic_file_stdio.h libstdc++-v3/config/io/basic_file_stdio.h
*** libstdc++-v3-orig/config/io/basic_file_stdio.h	Thu Feb  5 06:24:17 2004
--- libstdc++-v3/config/io/basic_file_stdio.h	Wed Feb 11 17:59:49 2004
*************** namespace std 
*** 84,89 ****
--- 84,92 ----
        ~__basic_file();
  
        streamsize 
+       xwrite(const char* __s, streamsize __n);
+ 
+       streamsize 
        xsputn(const char* __s, streamsize __n);
  
        streamsize