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-rw-r--r--src/stdio/fseek.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/src/stdio/fseek.c b/src/stdio/fseek.c
new file mode 100644
index 00000000..bfaad375
--- /dev/null
+++ b/src/stdio/fseek.c
@@ -0,0 +1,38 @@
+#include "stdio_impl.h"
+
+int __fseeko_unlocked(FILE *f, off_t off, int whence)
+{
+ /* Adjust relative offset for unread data in buffer, if any. */
+ if (whence == SEEK_CUR) off -= f->rend - f->rpos;
+
+ /* If writing, flush output. */
+ if (f->wpos > f->buf && __oflow(f)) return -1;
+
+ /* Perform the underlying seek operation. */
+ if (f->seek(f, off, whence) < 0) return -1;
+
+ /* If seek succeeded, file is seekable and we discard read buffer. */
+ f->rpos = f->rend = f->rstop = 0;
+ f->flags &= ~F_EOF;
+
+ FUNLOCK(f);
+ return 0;
+}
+
+int __fseeko(FILE *f, off_t off, int whence)
+{
+ int result;
+ FLOCK(f);
+ result = __fseeko_unlocked(f, off, whence);
+ FUNLOCK(f);
+ return result;
+}
+
+int fseek(FILE *f, long off, int whence)
+{
+ return __fseeko(f, off, whence);
+}
+
+weak_alias(__fseeko, fseeko);
+
+LFS64(fseeko);