feat(iso): add seek function

k/iso.c

@@ -102,6 +102,31 @@ s64 read(int fd, void *buf, size_t count)
     return i;
 }
 
+s64 seek(int fd, u32 offset, int whence)
+{
+    if (fd > MAX_FD)
+        return -1;
+
+    struct file_entry *f = &fd_table[fd];
+    if (!f->open)
+        return -1;
+
+    switch (whence)
+    {
+        case SEEK_SET:
+            f->file_offset = offset;
+            break;
+        case SEEK_CUR:
+            f->file_offset += offset;
+            break;
+        case SEEK_END:
+            f->file_offset = f->file_size + offset;
+            break;
+    }
+
+    return f->file_offset;
+}
+
 int close(int fd)
 {
     return destroy_fd(fd);

k/iso.h

@@ -3,10 +3,18 @@
 
 #include <k/types.h>
 
+/* open flags */
 #define O_RDONLY    0
 
+/* seek flags */
+#define SEEK_SET    0
+#define SEEK_CUR    1
+#define SEEK_END    2
+
+/* functions */
 int open(const char *path, int flags);
 s64 read(int fd, void *buf, size_t count);
+s64 seek(int fd, u32 offset, int whence);
 int close(int fd);
 
 #endif /* !ISO_H */