improvement on the earlier patch with usbi_reallocf

Prevent-memory-leaks-on-realloc-failures.patch

From c85a751dfd6519d126772bab7796e96c4c63351f Mon Sep 17 00:00:00 2001
From: Pete Batard <pete@akeo.ie>
Date: Thu, 7 Jun 2012 19:27:43 +0100
Subject: [PATCH] All: Prevent memory leaks on realloc failures

* p = realloc(p, new_size) does not free the original buffer in case of
  a realloc failure.
* reallocf() can be used to do so, but is not available on all platforms.
* This patch introduces usbi_reallocf() in libusbi.h and use that instead of realloc
* Issue and original patch submitted by Moritz Lipp (trac #27)
---
 libusb/core.c           |    2 +-
 libusb/descriptor.c     |    2 +-
 libusb/libusbi.h        |    8 ++++++++
 libusb/os/windows_usb.c |    2 +-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/libusb/core.c b/libusb/core.c
index a286da0..b0fa1c0 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -472,7 +472,7 @@ struct discovered_devs *discovered_devs_append(
 	/* exceeded capacity, need to grow */
 	usbi_dbg("need to increase capacity");
 	capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
-	discdevs = realloc(discdevs,
+	discdevs = usbi_reallocf(discdevs,
 		sizeof(*discdevs) + (sizeof(void *) * capacity));
 	if (discdevs) {
 		discdevs->capacity = capacity;
diff --git a/libusb/descriptor.c b/libusb/descriptor.c
index 590d1dc..763f93c 100644
--- a/libusb/descriptor.c
+++ b/libusb/descriptor.c
@@ -198,7 +198,7 @@ static int parse_interface(libusb_context *ctx,
 	while (size >= INTERFACE_DESC_LENGTH) {
 		struct libusb_interface_descriptor *altsetting =
 			(struct libusb_interface_descriptor *) usb_interface->altsetting;
-		altsetting = realloc(altsetting,
+		altsetting = usbi_reallocf(altsetting,
 			sizeof(struct libusb_interface_descriptor) *
 			(usb_interface->num_altsetting + 1));
 		if (!altsetting) {
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index 9de56a1..41a6bf0 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -110,6 +110,14 @@ static inline void list_del(struct list_head *entry)
 	entry->prev->next = entry->next;
 }
 
+static inline void *usbi_reallocf(void *ptr, size_t size)
+{
+	void *ret = realloc(ptr, size);
+	if (!ret)
+		free(ptr);
+	return ret;
+}
+
 #define container_of(ptr, type, member) ({                      \
         const typeof( ((type *)0)->member ) *mptr = (ptr);    \
         (type *)( (char *)mptr - offsetof(type,member) );})
diff --git a/libusb/os/windows_usb.c b/libusb/os/windows_usb.c
index dbebfaf..98b26eb 100644
--- a/libusb/os/windows_usb.c
+++ b/libusb/os/windows_usb.c
@@ -1471,7 +1471,7 @@ static int windows_get_device_list(struct libusb_context *ctx, struct discovered
 					unref_list[unref_cur++] = dev;
 					if (unref_cur >= unref_size) {
 						unref_size += 64;
-						unref_list = realloc(unref_list, unref_size*sizeof(libusb_device*));
+						unref_list = usbi_reallocf(unref_list, unref_size*sizeof(libusb_device*));
 						if (unref_list == NULL) {
 							usbi_err(ctx, "could not realloc list for unref - aborting.");
 							LOOP_BREAK(LIBUSB_ERROR_NO_MEM);
-- 
1.7.10.msysgit.1