1 files changed, 78 insertions, 0 deletions
diff --git a/src/vu-read-head.c b/src/vu-read-head.c
new file mode 100644
index 0000000..5ad3085
--- /dev/null
+++ b/src/vu-read-head.c
@@ -0,0 +1,78 @@
+/* See LICENSE file for copyright and license details. */
+#include "arg.h"
+#include "stream.h"
+#include "util.h"
+
+#include <ctype.h>
+#include <unistd.h>
+
+static void
+usage(void)
+{
+	eprintf("usage: %s\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	char buf[2 + 3 * sizeof(size_t) + sizeof(((struct stream *)0)->pixfmt)];
+	char magic[] = {'\0', 'u', 'i', 'v', 'f'};
+	char b;
+	char *p, *end;
+	size_t i, ptr;
+	ssize_t r;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc)
+		usage();
+
+	for (ptr = 0; ptr < sizeof(buf);) {
+		r = read(STDIN_FILENO, buf + ptr, 1);
+		if (r < 0)
+			eprintf("read <stdin>:");
+		if (r == 0)
+			goto bad_format;
+		if (buf[ptr++] == '\n')
+			break;
+	}
+	if (ptr == sizeof(buf))
+		goto bad_format;
+
+	for (i = 0; i < 5; i++) {
+		r = read(STDIN_FILENO, &b, 1);
+		if (r < 0)
+			eprintf("read <stdin>:");
+		if (!r || b != magic[i])
+			goto bad_format;
+	}
+
+	end = (p = buf) + ptr;
+	for (i = 0; i < 2; i++) {
+		if (!isdigit(*p))
+			goto bad_format;
+		while (isdigit(*p)) p++;
+		if (*p++ != ' ')
+			goto bad_format;
+	}
+	while (isalnum(*p) || *p == ' ') {
+		if (p[0] == ' ' && p[-1] == ' ')
+			goto bad_format;
+		p++;
+	}
+	if (p[-1] == ' ' || p[0] != '\n')
+		goto bad_format;
+
+	for (i = 0; i < ptr; i += (size_t)r) {
+		r = write(STDOUT_FILENO, buf + i, ptr - i);
+		if (r < 0)
+			eprintf("write <stdout>:");
+	}
+
+	return 0;
+bad_format:
+	eprintf("<stdin>: file format not supported\n");
+}