sockets/us_abstract_bind.c

+/* us_abstract_bind.c
+
+   Demonstrate how to bind a UNIX domain socket to a name in the
+   Linux-specific abstract namespace.
+
+   This program is Linux-specific.
+
+   The first printing of the book used slightly different code. The code was
+   correct, but could have been better (to understand why, see the errata
+   for page 1176 of the book).  The old code is shown in comments below.
+*/
 #include <sys/un.h>
 #include <sys/socket.h>
 #include "tlpi_hdr.h"
 
 int
 main(int argc, char *argv[])
 {
     int sockfd;
     struct sockaddr_un addr;
     char *str;
 
     memset(&addr, 0, sizeof(struct sockaddr_un));  /* Clear address structure */
     addr.sun_family = AF_UNIX;                     /* UNIX domain address */
 
     /* addr.sun_path[0] has already been set to 0 by memset() */
 
     str = "xyz";        /* Abstract name is "\0xyz" */
     strncpy(&addr.sun_path[1], str, strlen(str));
 
+    // In early printings of the book, the above two lines were instead:
+    //
+    // strncpy(&addr.sun_path[1], "xyz", sizeof(addr.sun_path) - 2);
+    //            /* Abstract name is "xyz" followed by null bytes */
+
     sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (sockfd == -1)
         errExit("socket");
 
     if (bind(sockfd, (struct sockaddr *) &addr,
             sizeof(sa_family_t) + strlen(str) + 1) == -1)
         errExit("bind");
 
+    // In early printings of the book, the final part of the bind() call
+    // above was instead:
+    //        sizeof(struct sockaddr_un)) == -1)
+
     sleep(60);
 
     exit(EXIT_SUCCESS);
 }