unicodeio.c: mark unused parameters

[gnulib.git] / lib / fwriteerror.c

diff --git a/lib/fwriteerror.c b/lib/fwriteerror.c
index a88c8e1..21bd098 100644 (file)
--- a/lib/fwriteerror.c
+++ b/lib/fwriteerror.c
@@ -1,11 +1,11 @@
 /* Detect write error on a stream.
-   Copyright (C) 2003-2005 Free Software Foundation, Inc.
+   Copyright (C) 2003-2006, 2008 Free Software Foundation, Inc.
    Written by Bruno Haible <bruno@clisp.org>, 2003.
 
-   This program is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -13,12 +13,9 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
 /* Specification.  */
 #include "fwriteerror.h"
@@ -26,16 +23,34 @@
 #include <errno.h>
 #include <stdbool.h>
 
-int
-fwriteerror (FILE *fp)
+static int
+do_fwriteerror (FILE *fp, bool ignore_ebadf)
 {
   /* State to allow multiple calls to fwriteerror (stdout).  */
   static bool stdout_closed = false;
 
-  if (fp == stdout && stdout_closed)
-    return 0;
+  if (fp == stdout)
+    {
+      if (stdout_closed)
+       return 0;
 
-  /* Need to
+      /* If we are closing stdout, don't attempt to do it later again.  */
+      stdout_closed = true;
+    }
+
+  /* This function returns an error indication if there was a previous failure
+     or if fclose failed, with two exceptions:
+       - Ignore an fclose failure if there was no previous error, no data
+        remains to be flushed, and fclose failed with EBADF.  That can
+        happen when a program like cp is invoked like this `cp a b >&-'
+        (i.e., with standard output closed) and doesn't generate any
+        output (hence no previous error and nothing to be flushed).
+       - Ignore an fclose failure due to EPIPE.  That can happen when a
+        program blocks or ignores SIGPIPE, and the output pipe or socket
+        has no readers now.  The EPIPE tells us that we should stop writing
+        to this output.  That's what we are doing anyway here.
+
+     Need to
      1. test the error indicator of the stream,
      2. flush the buffers both in userland and in the kernel, through fclose,
         testing for error again.  */
@@ -47,28 +62,63 @@ fwriteerror (FILE *fp)
   if (ferror (fp))
     {
       if (fflush (fp))
-       return -1; /* errno is set here */
+       goto close_preserving_errno; /* errno is set here */
       /* The stream had an error earlier, but its errno was lost.  If the
         error was not temporary, we can get the same errno by writing and
         flushing one more byte.  We can do so because at this point the
         stream's contents is garbage anyway.  */
       if (fputc ('\0', fp) == EOF)
-       return -1; /* errno is set here */
+       goto close_preserving_errno; /* errno is set here */
       if (fflush (fp))
-       return -1; /* errno is set here */
+       goto close_preserving_errno; /* errno is set here */
       /* Give up on errno.  */
       errno = 0;
-      return -1;
+      goto close_preserving_errno;
     }
 
-  /* If we are closing stdout, don't attempt to do it later again.  */
-  if (fp == stdout)
-    stdout_closed = true;
-
-  if (fclose (fp))
-    return -1; /* errno is set here */
+  if (ignore_ebadf)
+    {
+      /* We need an explicit fflush to tell whether some output was already
+        done on FP.  */
+      if (fflush (fp))
+       goto close_preserving_errno; /* errno is set here */
+      if (fclose (fp) && errno != EBADF)
+       goto got_errno; /* errno is set here */
+    }
+  else
+    {
+      if (fclose (fp))
+       goto got_errno; /* errno is set here */
+    }
 
   return 0;
+
+ close_preserving_errno:
+  /* There's an error.  Nevertheless call fclose(fp), for consistency
+     with the other cases.  */
+  {
+    int saved_errno = errno;
+    fclose (fp);
+    errno = saved_errno;
+  }
+ got_errno:
+  /* There's an error.  Ignore EPIPE.  */
+  if (errno == EPIPE)
+    return 0;
+  else
+    return -1;
+}
+
+int
+fwriteerror (FILE *fp)
+{
+  return do_fwriteerror (fp, false);
+}
+
+int
+fwriteerror_no_ebadf (FILE *fp)
+{
+  return do_fwriteerror (fp, true);
 }