Add vu-reverse

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 70 insertions, 0 deletions

diff --git a/src/vu-reverse.c b/src/vu-reverse.c
new file mode 100644
index 0000000..2a6b433
--- /dev/null
+++ b/src/vu-reverse.c
@@ -0,0 +1,70 @@
+/* See LICENSE file for copyright and license details. */
+#include "arg.h"
+#include "stream.h"
+#include "util.h"
+
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
+#include <unistd.h>
+
+static void
+usage(void)
+{
+	eprintf("usage: %s file\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct stream stream;
+	size_t frame_size, ptr, end, n, ptw;
+	ssize_t r;
+	char buf[BUFSIZ];
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 1)
+		usage();
+
+	stream.file = argv[1];
+	stream.fd = open(stream.file, O_RDONLY);
+	if (stream.fd < 0)
+		eprintf("open %s:", stream.file);
+	einit_stream(&stream);
+	fprint_stream_head(stdout, &stream);
+	fflush(stdout);
+	if (ferror(stdout))
+		eprintf("<stdout>:");
+	if (stream.width > SIZE_MAX / stream.height)
+		eprintf("%s: video is too large\n", stream.file);
+	frame_size = stream.width * stream.height;
+	if (stream.frames > SSIZE_MAX / frame_size)
+		eprintf("%s: video is too large\n", stream.file);
+
+	posix_fadvise(stream.fd, 0, 0, POSIX_FADV_RANDOM);
+	while (stream.frames--) {
+		ptr = stream.frames * frame_size;
+		end = ptr + frame_size;
+		while (ptr < end) {
+			r = pread(stream.fd, buf, sizeof(buf), ptr);
+			if (r < 0)
+				eprintf("pread %s:", stream.file);
+			else if (r == 0)
+				eprintf("%s: file is shorter than expected", stream.file);
+			ptr += n = (size_t)r;
+			for (ptw = 0; ptw < n;) {
+				r = write(STDOUT_FILENO, buf + ptw, n - ptw);
+				if (r < 0)
+					eprintf("write <stdout>:");
+				ptw += (size_t)r;
+			}
+		}
+	}
+
+	close(stream.fd);
+	return 0;
+}