1 files changed, 47 insertions, 0 deletions
diff --git a/src/stdio/freopen.c b/src/stdio/freopen.c
new file mode 100644
index 00000000..8d3af9fc
--- /dev/null
+++ b/src/stdio/freopen.c
@@ -0,0 +1,47 @@
+#include "stdio_impl.h"
+
+/* The basic idea of this implementation is to open a new FILE,
+ * hack the necessary parts of the new FILE into the old one, then
+ * close the new FILE. */
+
+/* Locking is not necessary because, in the event of failure, the stream
+ * passed to freopen is invalid as soon as freopen is called. */
+
+FILE *freopen(const char *filename, const char *mode, FILE *f)
+{
+	int fl;
+	FILE *f2;
+
+	fflush(f);
+
+	if (!filename) {
+		f2 = fopen("/dev/null", mode);
+		if (!f2) goto fail;
+		fl = __syscall_fcntl(f2->fd, F_GETFL, 0);
+		if (fl < 0 || __syscall_fcntl(f->fd, F_SETFL, fl) < 0)
+			goto fail2;
+	} else {
+		f2 = fopen(filename, mode);
+		if (!f2) goto fail;
+		if (__syscall_dup2(f2->fd, f->fd) < 0)
+			goto fail2;
+	}
+
+	f->flags = (f->flags & F_PERM) | f2->flags;
+	f->read = f2->read;
+	f->write = f2->write;
+	f->seek = f2->seek;
+	f->close = f2->close;
+	f->flush = f2->flush;
+
+	fclose(f2);
+	return f;
+
+fail2:
+	fclose(f2);
+fail:
+	fclose(f);
+	return NULL;
+}
+
+LFS64(freopen);