lib: c: io: implement lseek()

lib/libc/include/unistd.h

@@ -2,6 +2,7 @@
 #define UNISTD_H_
 
 #include <stddef.h>
+#include <sys/types.h>
 
 extern int open(const char *path, int flags);
 extern int close(int fd);
@@ -9,4 +10,6 @@ extern int close(int fd);
 extern int read(int fd, void *buf, size_t count);
 extern int write(int fd, const void *buf, size_t count);
 
+extern off_t lseek(int fd, off_t offset, int whence);
+
 #endif

lib/libc/io/unistd/lseek.c

@@ -0,0 +1,22 @@
+#include <errno.h>
+#include <mango/handle.h>
+#include <mango/msg.h>
+#include <rosetta/fs.h>
+#include <sys/remote.h>
+
+off_t lseek(int fd, off_t offset, int whence)
+{
+	int err;
+	off_t new_offset;
+
+	kern_status_t status = fs_seek(fd, offset, whence, &err, &new_offset);
+	if (status != KERN_OK) {
+		return __set_errno(__errno_from_kern_status(status));
+	}
+
+	if (err != SUCCESS) {
+		return __set_errno(err);
+	}
+
+	return new_offset;
+}