utils: add write from ELKS

diff --git a/Applications/util/Makefile b/Applications/util/Makefile
index 2614877..c71caf0 100644 (file)
--- a/Applications/util/Makefile
+++ b/Applications/util/Makefile
@@ -89,6 +89,7 @@ SRCS  = banner.c \
        wc.c \
        which.c \
        whoami.c \
+       write.c \
        xargs.c \
        yes.c
 

diff --git a/Applications/util/write.c b/Applications/util/write.c
new file mode 100644 (file)
index 0000000..672ec6a
--- /dev/null
+++ b/Applications/util/write.c
@@ -0,0 +1,104 @@
+/*
+ * write.c
+ *
+ * Copyright 2000 Alistair Riddoch
+ * ajr@ecs.soton.ac.uk
+ *
+ * This file may be distributed under the terms of the GNU General Public
+ * License v2, or at your option any later version.
+ */
+
+/*
+ * This is a small version of write for use in the ELKS project.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <utmp.h>
+#include <fcntl.h>
+#include <string.h>
+
+#define TTYPREFIX "/dev/"
+
+void usage(char ** argv)
+{
+       fprintf(stderr, "%s user [ttyname]\n", argv[0]);
+       exit(1);
+}
+
+int main(int argc, char ** argv)
+{
+       char ttyname[12];
+       struct passwd * pwdent;
+       int ofd = -1;
+       char buf[255];
+       int n;
+
+       if ((argc > 3) || (argc < 2)) {
+               usage(argv);
+       }
+       if ((pwdent = getpwnam(argv[1])) == NULL) {
+               fprintf(stderr, "%s: No such user %s\n", argv[0], argv[1]);
+               exit(1);
+       }
+       if (argc == 3) {
+               struct stat sbuf;
+
+               strncpy(ttyname, TTYPREFIX, 6);
+               strncat(ttyname, argv[2], 6);
+               ttyname[11] = '\0';
+               if (stat(ttyname, &sbuf) != 0) {
+                       fprintf(stderr, "%s: No such tty %s\n",
+                               argv[0], ttyname);
+                       exit(1);
+               }
+               if (pwdent->pw_uid != sbuf.st_uid) {
+                       fprintf(stderr, "%s: User %s is not logged onto %s\n",
+                               argv[0], argv[1], argv[2]);
+                       exit(1);
+               }
+               if ((ofd = open(ttyname, O_WRONLY)) < 0) {
+                       fprintf(stderr, "%s: %s has messages disabled on %s\n",
+                               argv[0], argv[1], argv[2]);
+                       exit(1);
+               }
+       } else { /* argc == 2 */
+               struct utmp * utmp;
+               setutent();
+               while ((utmp = getutent()) != NULL) {
+                       if ((strcmp(pwdent->pw_name, utmp->ut_user) == 0) &&
+                           (utmp->ut_type == USER_PROCESS)) {
+                               strncpy(ttyname, TTYPREFIX, 6);
+                               strncat(ttyname, utmp->ut_line, 6);
+                               ttyname[11] = '\0';
+                               if ((ofd = open(ttyname, O_WRONLY)) >= 0) {
+                                       break;
+                               }
+                       }
+               }
+               if (ofd < 0) {
+                       fprintf(stderr, "%s: User %s not logged in, or has messages disabled\n",
+                               argv[0], argv[1]);
+                       exit(1);
+               }
+       }
+       if ((pwdent = getpwnam(argv[1])) == NULL) {
+               fprintf(stderr, "%s: Who are you?\n", argv[0]);
+               exit(1);
+       }
+       write(ofd, "Message from ", 13);
+       write(ofd, pwdent->pw_name, strlen(pwdent->pw_name));
+       write(ofd, "\n", 1);
+       while ((n = read(STDIN_FILENO, buf, 254)) > 0) {
+               buf[254] = '\0';
+               write(ofd, buf, n);
+       }
+       write(ofd, "EOF\n", 4);
+       
+       exit(0);
+}