Eliminate -Wsign-compare compiler warnings

This was due to an API inconsistency which can be safely worked around.
Hopefully we'll remember to fix the API next time we come to break
things.

diff --git a/libusb/libusb.h b/libusb/libusb.h
index 27b3612..b3c9089 100644 (file)
--- a/libusb/libusb.h
+++ b/libusb/libusb.h
@@ -25,6 +25,7 @@
 #include <sys/time.h>
 #include <sys/types.h>
 #include <time.h>
+#include <limits.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -1053,11 +1054,19 @@ static inline unsigned char *libusb_get_iso_packet_buffer(
 {
        int i;
        size_t offset = 0;
+       int _packet;
 
-       if (packet >= transfer->num_iso_packets)
+       /* oops..slight bug in the API. packet is an unsigned int, but we use
+        * signed integers almost everywhere else. range-check and convert to
+        * signed to avoid compiler warnings. FIXME for libusb-2. */
+       if (packet > INT_MAX)
                return NULL;
+       _packet = packet;
 
-       for (i = 0; i < packet; i++)
+       if (_packet >= transfer->num_iso_packets)
+               return NULL;
+
+       for (i = 0; i < _packet; i++)
                offset += transfer->iso_packet_desc[i].length;
 
        return transfer->buffer + offset;
@@ -1085,10 +1094,19 @@ static inline unsigned char *libusb_get_iso_packet_buffer(
 static inline unsigned char *libusb_get_iso_packet_buffer_simple(
        struct libusb_transfer *transfer, unsigned int packet)
 {
-       if (packet >= transfer->num_iso_packets)
+       int _packet;
+
+       /* oops..slight bug in the API. packet is an unsigned int, but we use
+        * signed integers almost everywhere else. range-check and convert to
+        * signed to avoid compiler warnings. FIXME for libusb-2. */
+       if (packet > INT_MAX)
+               return NULL;
+       _packet = packet;
+
+       if (_packet >= transfer->num_iso_packets)
                return NULL;
 
-       return transfer->buffer + (transfer->iso_packet_desc[0].length * packet);
+       return transfer->buffer + (transfer->iso_packet_desc[0].length * _packet);
 }
 
 /* sync I/O */