Fix pointer/int cast warnings on 64-bit Windows

On 64-bit Windows, `long` is 32 bits wide and can't hold a pointer.
Switch to ptrdiff_t instead which should be the same size as a pointer
on every somewhat sane platform without requiring C99 types like
intptr_t.

Fixes bug 788312.

Thanks to J. Peter Mugaas for the report and initial patch.

1 files changed, 6 insertions, 5 deletions

diff --git a/xmlIO.c b/xmlIO.c
index 6891ff9a..5902f627 100644
--- a/xmlIO.c
+++ b/xmlIO.c
@@ -12,6 +12,7 @@
 #include "libxml.h"
 
 #include <string.h>
+#include <stddef.h>
 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
@@ -826,7 +827,7 @@ static int
 xmlFdRead (void * context, char * buffer, int len) {
     int ret;
 
-    ret = read((int) (long) context, &buffer[0], len);
+    ret = read((int) (ptrdiff_t) context, &buffer[0], len);
     if (ret < 0) xmlIOErr(0, "read()");
     return(ret);
 }
@@ -847,7 +848,7 @@ xmlFdWrite (void * context, const char * buffer, int len) {
     int ret = 0;
 
     if (len > 0) {
-	ret = write((int) (long) context, &buffer[0], len);
+	ret = write((int) (ptrdiff_t) context, &buffer[0], len);
 	if (ret < 0) xmlIOErr(0, "write()");
     }
     return(ret);
@@ -865,7 +866,7 @@ xmlFdWrite (void * context, const char * buffer, int len) {
 static int
 xmlFdClose (void * context) {
     int ret;
-    ret = close((int) (long) context);
+    ret = close((int) (ptrdiff_t) context);
     if (ret < 0) xmlIOErr(0, "close()");
     return(ret);
 }
@@ -3008,7 +3009,7 @@ xmlParserInputBufferCreateFd(int fd, xmlCharEncoding enc) {
 
     ret = xmlAllocParserInputBuffer(enc);
     if (ret != NULL) {
-        ret->context = (void *) (long) fd;
+        ret->context = (void *) (ptrdiff_t) fd;
 	ret->readcallback = xmlFdRead;
 	ret->closecallback = xmlFdClose;
     }
@@ -3114,7 +3115,7 @@ xmlOutputBufferCreateFd(int fd, xmlCharEncodingHandlerPtr encoder) {
 
     ret = xmlAllocOutputBufferInternal(encoder);
     if (ret != NULL) {
-        ret->context = (void *) (long) fd;
+        ret->context = (void *) (ptrdiff_t) fd;
 	ret->writecallback = xmlFdWrite;
 	ret->closecallback = NULL;
     }