First draft

sysklogd/syslogd.c

@@ -0,0 +1,86 @@
+/* userver.c - simple server for Unix domain sockets */
+
+/* Waits for a connection on the ./sample-socket Unix domain
+   socket. Once a connection has been established, copy data
+   from the socket to stdout until the other end closes the
+   connection, and then wait for another connection to the socket. */
+
+#include <stdio.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#define _PATH_LOG       "/dev/log"
+
+
+/* issue an error message via perror() and terminate the program */
+void die(char * message) {
+    perror(message);
+    exit(1);
+}
+
+/* Copies data from file descriptor 'from' to file descriptor 'to'
+   until nothing is left to be copied. Exits if an error occurs.   */
+void copyData(int from, int to) {
+    char buf[1024];
+    int amount;
+    
+    while ((amount = read(from, buf, sizeof(buf))) > 0) {
+        if (write(to, buf, amount) != amount) {
+            die("write");
+            return;
+        }
+    }
+    if (amount < 0)
+        die("read");
+}
+
+
+int main(void) {
+    struct sockaddr_un address;
+    int fd, conn;
+    size_t addrLength;
+
+    /* Remove any preexisting socket (or other file) */
+    unlink(_PATH_LOG);
+
+    memset(&address, 0, sizeof(address));
+    address.sun_family = AF_UNIX;	/* Unix domain socket */
+    strncpy(address.sun_path, _PATH_LOG, sizeof(address.sun_path));
+
+    if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+        die("socket");
+
+
+    /* The total length of the address includes the sun_family 
+       element */
+    addrLength = sizeof(address.sun_family) + 
+                 strlen(address.sun_path);
+
+    if (bind(fd, (struct sockaddr *) &address, addrLength))
+        die("bind");
+
+    if (chmod(_PATH_LOG, 0666) < 0)
+        die("chmod");
+
+    if (listen(fd, 5))
+        die("listen");
+
+
+    while ((conn = accept(fd, (struct sockaddr *) &address, 
+                          &addrLength)) >= 0) {
+        printf("---- getting data\n");
+        copyData(conn, fileno(stdout));
+        printf("---- done\n");
+        close(conn);
+    }
+
+    if (conn < 0) 
+        die("accept");
+    
+    close(fd);
+    return 0;
+}
+
+
+

syslogd.c

@@ -0,0 +1,86 @@
+/* userver.c - simple server for Unix domain sockets */
+
+/* Waits for a connection on the ./sample-socket Unix domain
+   socket. Once a connection has been established, copy data
+   from the socket to stdout until the other end closes the
+   connection, and then wait for another connection to the socket. */
+
+#include <stdio.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#define _PATH_LOG       "/dev/log"
+
+
+/* issue an error message via perror() and terminate the program */
+void die(char * message) {
+    perror(message);
+    exit(1);
+}
+
+/* Copies data from file descriptor 'from' to file descriptor 'to'
+   until nothing is left to be copied. Exits if an error occurs.   */
+void copyData(int from, int to) {
+    char buf[1024];
+    int amount;
+    
+    while ((amount = read(from, buf, sizeof(buf))) > 0) {
+        if (write(to, buf, amount) != amount) {
+            die("write");
+            return;
+        }
+    }
+    if (amount < 0)
+        die("read");
+}
+
+
+int main(void) {
+    struct sockaddr_un address;
+    int fd, conn;
+    size_t addrLength;
+
+    /* Remove any preexisting socket (or other file) */
+    unlink(_PATH_LOG);
+
+    memset(&address, 0, sizeof(address));
+    address.sun_family = AF_UNIX;	/* Unix domain socket */
+    strncpy(address.sun_path, _PATH_LOG, sizeof(address.sun_path));
+
+    if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+        die("socket");
+
+
+    /* The total length of the address includes the sun_family 
+       element */
+    addrLength = sizeof(address.sun_family) + 
+                 strlen(address.sun_path);
+
+    if (bind(fd, (struct sockaddr *) &address, addrLength))
+        die("bind");
+
+    if (chmod(_PATH_LOG, 0666) < 0)
+        die("chmod");
+
+    if (listen(fd, 5))
+        die("listen");
+
+
+    while ((conn = accept(fd, (struct sockaddr *) &address, 
+                          &addrLength)) >= 0) {
+        printf("---- getting data\n");
+        copyData(conn, fileno(stdout));
+        printf("---- done\n");
+        close(conn);
+    }
+
+    if (conn < 0) 
+        die("accept");
+    
+    close(fd);
+    return 0;
+}
+
+
+