Re: Comparing binary files with Diff 3.2 compiled with MinGW

[Eli Zaretskii]

> From: Bruno Haible <address@hidden>
> Cc: address@hidden, Eli Zaretskii <address@hidden>, address@hidden
> 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  <address@hidden>

        * 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;
     }