Fix dealing with large files

In C, the result of an operation has always the size of the largest
operand, in this case both operands are unsigned longs, which was
causing the operation to overflow on 32bit machines.

The solution is to force an operand to be of a size that would not
overflow and to store the result somewhere with a safe size.

1 files changed, 3 insertions, 1 deletions

diff --git a/plugins/filesystem.c b/plugins/filesystem.c
index 633036b..2844329 100644
--- a/plugins/filesystem.c
+++ b/plugins/filesystem.c
@@ -138,6 +138,7 @@ static void *filesystem_open(const char *name, int oflag, mode_t mode,
 	char *folder;
 	gboolean root;
 	int fd = open(name, oflag, mode);
+	uint64_t avail;
 
 	if (fd < 0) {
 		if (err)
@@ -181,7 +182,8 @@ static void *filesystem_open(const char *name, int oflag, mode_t mode,
 	if (size == NULL)
 		goto done;
 
-	if (buf.f_bsize * buf.f_bavail < *size) {
+	avail = (uint64_t) buf.f_bsize * buf.f_bavail;
+	if (avail < *size) {
 		if (err)
 			*err = -ENOSPC;
 		goto failed;