Simple example of stdin redirect problem, issue #12

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

examples/.gitignore

@@ -2,3 +2,4 @@ joystick
 signal
 cronrun
 test
+redirect

examples/Makefile.am

@@ -1,3 +1,3 @@
-noinst_PROGRAMS = joystick
+noinst_PROGRAMS = joystick redirect
 AM_CPPFLAGS     = -I$(top_srcdir)/src
 LDADD           = $(top_srcdir)/src/libuev.la

examples/redirect.c

@@ -0,0 +1,62 @@
+/* Example of how to handle stdin redirect
+ *
+ * The problem is non-trivial since Linux epoll, which libuEv uses, does
+ * not support I/O watchers for regular files or directories.
+ *
+ * This works:
+ *                  echo foo | redirect
+ * This doesn't:
+ *                  redirect < foo.txt
+ *
+ * However, with a little bit of hacking libuEv can be made to handle
+ * reading from stdin as a special case.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "src/uev.h"
+
+/*
+ * When stdin becomes ready to be read from, this callback is invoked by
+ * libuEv.  We just print out the data.
+ */
+void process_stdin(uev_t *w, void *arg, int events)
+{
+	char buf[256];
+	int len;
+
+	fprintf(stderr, "process_stdin() called with fd: %d, events: 0x%x\n", w->fd, events);
+
+	len = read(w->fd, buf, sizeof(buf));
+	if (len == -1) {
+		perror("Reading from stdin.");
+		return;
+	}
+
+	if (len == 0) {
+		fprintf(stderr, "Connection closed.\n");
+		exit(0);
+	}
+
+	fprintf(stdout, "--- read %d bytes\n", len);
+	if (write(STDOUT_FILENO, buf, len) != len)
+		fprintf(stdout, "--- failed writing\n");
+}
+
+int main(int argc, char **argv)
+{
+	int ret;
+	uev_t watcher;
+	uev_ctx_t ctx;
+
+	/* Initalize the event library */
+	uev_init(&ctx);
+
+	/* Bind an to a read-ready event on the new socket and activate. */
+	ret = uev_io_init(&ctx, &watcher, process_stdin, NULL, STDIN_FILENO, UEV_READ);
+	if (ret)
+		perror("Failed setting up STDIN watcher");
+
+	return uev_run(&ctx, 0);
+}