Use int64_t as offset to ext4_fseek.

This change makes it possible to fseek backwards in fseek.

Tested:
  make test_all

1 files changed, 6 insertions, 4 deletions

diff --git a/src/ext4.c b/src/ext4.c
index b27ae6b..a6d3e23 100644
--- a/src/ext4.c
+++ b/src/ext4.c
@@ -2016,23 +2016,25 @@ Finish:
 	return r;
 }
 
-int ext4_fseek(ext4_file *file, uint64_t offset, uint32_t origin)
+int ext4_fseek(ext4_file *file, int64_t offset, uint32_t origin)
 {
 	switch (origin) {
 	case SEEK_SET:
-		if (offset > file->fsize)
+		if (offset < 0 || (uint64_t)offset > file->fsize)
 			return EINVAL;
 
 		file->fpos = offset;
 		return EOK;
 	case SEEK_CUR:
-		if ((offset + file->fpos) > file->fsize)
+		if ((offset < 0 && (uint64_t)(-offset) > file->fpos) ||
+		    (offset > 0 &&
+		     (uint64_t)offset > (file->fsize - file->fpos)))
 			return EINVAL;
 
 		file->fpos += offset;
 		return EOK;
 	case SEEK_END:
-		if (offset > file->fsize)
+		if (offset < 0 || (uint64_t)offset > file->fsize)
 			return EINVAL;
 
 		file->fpos = file->fsize - offset;