2010.02.26 08:11 "[Tiff] Patch for tif_unix.c", by Eric Doenges

Hi,

I have a small patch for tif_unix.c that I would like to see included in libtiff 4.0 if possible. The problem is that tif_unix.c assumes that read() and write() will be able to read and write the number of requested bytes in one go. While this assumption seems to hold (for disk files) on all Unix systems I have ever worked on, it is not guaranteed by POSIX, and we do have one system (TI TMS320C6X using TI's compiler and C runtime) where file I/O can only be done in small chunks (256 bytes in this case).

With kind regards,
Eric Dönges
--
Dr. Eric Dönges doenges@mvtec.com

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Index: libtiff/tif_unix.c

=================================================================== RCS file: /cvs/maptools/cvsroot/libtiff/libtiff/tif_unix.c,v retrieving revision 1.21

diff -u -r1.21 tif_unix.c

--- libtiff/tif_unix.c  18 Jul 2007 13:46:41 -0000      1.21
+++ libtiff/tif_unix.c  26 Feb 2010 07:49:36 -0000

@@ -58,25 +58,43 @@
 static tmsize_t
 _tiffReadProc(thandle_t fd, void* buf, tmsize_t size)
 {

• size_t size_io = (size_t) size;
• if ((tmsize_t) size_io != size)
• {
• errno=EINVAL;
• return (tmsize_t) -1;
• }
• return ((tmsize_t) read((int) fd, buf, size_io));

+        size_t bytes, total, size_io = (size_t) size;
+        if ((tmsize_t) size_io != size)
+        {
+                errno=EINVAL;
+                return (tmsize_t) -1;
+        }
+
+        for (total = 0; total < size_io; total += bytes)
+        {
+                if (0 > (bytes = read((int) fd, (char *) buf + total,
+                                      size_io - total)))

+                        return (tmsize_t) -1;
+                else if (0 == bytes)
+                        break;
+        }
+        return (tmsize_t) total;
 }

 static tmsize_t
 _tiffWriteProc(thandle_t fd, void* buf, tmsize_t size)
 {
-       size_t size_io = (size_t) size;
-       if ((tmsize_t) size_io != size)
-       {
-               errno=EINVAL;
-               return (tmsize_t) -1;
-       }
-       return ((tmsize_t) write((int) fd, buf, size_io));

+        size_t bytes, total, size_io = (size_t) size;
+        if ((tmsize_t) size_io != size)
+        {
+                errno=EINVAL;
+                return (tmsize_t) -1;
+        }
+
+        for (total = 0; total < size_io; total += bytes)
+        {
+                if (0 > (bytes = write((int) fd, (char *) buf + total,
+                                       size_io - total)))
+                        return (tmsize_t)-1;
+                else if (0 == bytes)
+                        break;
+        }
+        return (tmsize_t) total;

 }

 static uint64