sockread: add new package

sockread reads data from a Unix domain socket

Signed-off-by: Moritz Warning <moritzwarning@web.de>

utils/sockread/src/Makefile

@@ -0,0 +1,11 @@
+CC ?= gcc
+CFLAGS ?= -O2 -Wall -pedantic
+CFLAGS += -std=gnu99
+
+.PHONY: clean
+
+sockread:
+	$(CC) $(CFLAGS) main.c -o sockread
+
+clean:
+	rm -f sockread

utils/sockread/src/main.c

@@ -0,0 +1,55 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+
+int main(int argc, char *argv[]) {
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s <socket>\n", argv[0]);
+		return 1;
+	}
+
+	size_t addrlen = strlen(argv[1]);
+
+	/* Allocate enough space for arbitrary-length paths */
+	char addrbuf[offsetof(struct sockaddr_un, sun_path) + addrlen + 1];
+	memset(addrbuf, 0, sizeof(addrbuf));
+
+	struct sockaddr_un *addr = (struct sockaddr_un *)addrbuf;
+	addr->sun_family = AF_UNIX;
+	memcpy(addr->sun_path, argv[1], addrlen+1);
+
+	int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to create socket: %s\n", strerror(errno));
+		return 1;
+	}
+
+	if (connect(fd, (struct sockaddr*)addr, sizeof(addrbuf)) < 0) {
+		fprintf(stderr, "Can't connect to `%s': %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+
+	char buf[1024];
+	ssize_t r;
+	while (1) {
+		r = recv(fd, buf, sizeof(buf), 0);
+		if (r < 0) {
+			fprintf(stderr, "read: %s\n", strerror(errno));
+			return 1;
+		}
+
+		if (r == 0)
+			return 0;
+
+		fwrite(buf, r, 1, stdout);
+	}
+
+	return 0;
+}