Re: Comparing binary files with Diff 3.2 compiled with MinGW

> From: Bruno Haible <[email protected]>
> Cc: [email protected], Eli Zaretskii <[email protected]>, [email protected]
> Date: Sun, 13 May 2012 04:00:25 +0200
> 
> > 'set_binary_mode' would be OK
> 
> Good. New proposal attached below.

And here's the patch for Diffutils' io.c to go with the new proposal:

2012-05-13  Eli Zaretskii  <[email protected]>

	* src/io.c: Include binary-io.h.
	(sip, read_files): Switch file I/O to binary mode and back as
	appropriate, to support binary files on systems that distinguish
	between text and binary I/O.

--- src/io.c~0	2011-08-15 08:24:38.000000000 +0300
+++ src/io.c	2012-05-13 21:38:39.795500000 +0300
@@ -22,6 +22,7 @@
 #include <cmpbuf.h>
 #include <file-type.h>
 #include <xalloc.h>
+#include <binary-io.h>
 
 /* Rotate an unsigned value to the left.  */
 #define ROL(v, n) ((v) << (n) | (v) >> (sizeof (v) * CHAR_BIT - (n)))
@@ -110,12 +111,25 @@ sip (struct file_data *current, bool ski
       if (! skip_test)
 	{
 	  /* Check first part of file to see if it's a binary file.  */
-
-	  /* FIXME: if O_BINARY, this should revert to text mode
-	     if the file is not binary.  */
+	  bool binary_file;
+	  int prev_mode = set_binary_mode (current->desc, O_BINARY);
 
 	  file_block_read (current, current->bufsize);
-	  return binary_file_p (current->buffer, current->buffered);
+	  binary_file = binary_file_p (current->buffer, current->buffered);
+	  if (prev_mode != O_BINARY)
+	    {
+	      /* Revert to text mode and seek back to the beginning to
+		 reread the file.  Use relative seek, since file
+		 descriptors like stdin might not start at offset
+		 zero.  */
+
+	      if (lseek (current->desc, -current->buffered, SEEK_CUR) == -1)
+		pfatal_with_name (current->name);
+	      (void) set_binary_mode (current->desc, O_TEXT);
+              current->buffered = 0;
+              current->eof = false;
+	    }
+	  return binary_file;
 	}
     }
 
@@ -761,7 +775,8 @@ read_files (struct file_data filevec[], 
     }
   if (appears_binary)
     {
-      /* FIXME: If O_BINARY, this should set both files to binary mode.  */
+      (void) set_binary_mode (filevec[0].desc, O_BINARY);
+      (void) set_binary_mode (filevec[1].desc, O_BINARY);
       return true;
     }