Fixed positive seek bounds checking

This bug was a result of an annoying corner case around intermingling
signed and unsigned offsets. The boundary check that prevents seeking
a file to a position before the file was preventing valid seeks with
positive offsets.

This corner case is a bit more complicated than it looks because the
offset is signed, while the size of the file is unsigned. Simply
casting both to signed or unsigned offsets won't handle large files.

1 files changed, 2 insertions, 2 deletions

diff --git a/lfs.c b/lfs.c
index 2d0e331..4267d7c 100644
--- a/lfs.c
+++ b/lfs.c
@@ -1635,13 +1635,13 @@ lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
     if (whence == LFS_SEEK_SET) {
         file->pos = off;
     } else if (whence == LFS_SEEK_CUR) {
-        if ((lfs_off_t)-off > file->pos) {
+        if (off < 0 && (lfs_off_t)-off > file->pos) {
             return LFS_ERR_INVAL;
         }
 
         file->pos = file->pos + off;
     } else if (whence == LFS_SEEK_END) {
-        if ((lfs_off_t)-off > file->size) {
+        if (off < 0 && (lfs_off_t)-off > file->size) {
             return LFS_ERR_INVAL;
         }