1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/syscalls/lseek.c b/kernel/syscalls/lseek.c
new file mode 100644
index 0000000..3e38822
--- /dev/null
+++ b/kernel/syscalls/lseek.c
@@ -0,0 +1,34 @@
+#include <assert.h>
+#include <errno.h>
+#include <fs/vfs.h>
+
+// FIXME: These should be in a shared header file with libc
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
+
+off_t syscall_lseek(int fd, off_t offset, int whence) {
+  vfs_fd_t *fd_ptr = get_vfs_fd(fd, NULL);
+  if (!fd_ptr) {
+    return -EBADF;
+  }
+
+  off_t ret_offset = fd_ptr->offset;
+  switch (whence) {
+  case SEEK_SET:
+    ret_offset = offset;
+    break;
+  case SEEK_CUR:
+    ret_offset += offset;
+    break;
+  case SEEK_END:
+    assert(fd_ptr->inode);
+    ret_offset = fd_ptr->inode->file_size + offset;
+    break;
+  default:
+    return -EINVAL;
+    break;
+  }
+  fd_ptr->offset = ret_offset;
+  return ret_offset;
+}