write: add control structure to clarify what is going on

This is done purely an improve readability of the source code.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

diff --git a/term-utils/write.c b/term-utils/write.c
index 568892d7946da18cdab84c016af9a625c1237003..2557f3361ecc3d37fb7f1d03e5e6c95a41686906 100644 (file)
--- a/term-utils/write.c
+++ b/term-utils/write.c
@@ -68,6 +68,14 @@
 
 static sig_atomic_t signal_received = 0;
 
+struct write_control {
+       uid_t src_uid;
+       const char *src_login;
+       char *src_tty;
+       const char *dst_login;
+       char dst_tty[PATH_MAX];
+};
+
 static void __attribute__ ((__noreturn__)) usage(FILE * out)
 {
        fputs(USAGE_HEADER, out);
@@ -116,7 +124,7 @@ static int term_chk(char *tty, int *msgsokP, time_t * atimeP, int showerror)
  * utmp_chk - checks that the given user is actually logged in on
  *     the given tty
  */
-static int utmp_chk(char *user, char *tty)
+static int utmp_chk(const struct write_control *ctl)
 {
        struct utmp u;
        struct utmp *uptr;
@@ -127,8 +135,8 @@ static int utmp_chk(char *user, char *tty)
 
        while ((uptr = getutent())) {
                memcpy(&u, uptr, sizeof(u));
-               if (strncmp(user, u.ut_user, sizeof(u.ut_user)) == 0 &&
-                   strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) {
+               if (strncmp(ctl->dst_login, u.ut_user, sizeof(u.ut_user)) == 0 &&
+                   strncmp(ctl->dst_tty, u.ut_line, sizeof(u.ut_line)) == 0) {
                        res = 0;
                        break;
                }
@@ -149,7 +157,7 @@ static int utmp_chk(char *user, char *tty)
  * Special case for writing to yourself - ignore the terminal you're
  * writing from, unless that's the only terminal with messages enabled.
  */
-static void search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
+static void search_utmp(struct write_control *ctl)
 {
        struct utmp u;
        struct utmp *uptr;
@@ -165,16 +173,16 @@ static void search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
        user_is_me = 0;
        while ((uptr = getutent())) {
                memcpy(&u, uptr, sizeof(u));
-               if (strncmp(user, u.ut_user, sizeof(u.ut_user)) == 0) {
+               if (strncmp(ctl->dst_login, u.ut_user, sizeof(u.ut_user)) == 0) {
                        ++nloggedttys;
                        xstrncpy(atty, u.ut_line, sizeof(atty));
                        if (term_chk(atty, &msgsok, &atime, 0))
                                /* bad term? skip */
                                continue;
-                       if (myuid && !msgsok)
+                       if (ctl->src_uid && !msgsok)
                                /* skip ttys with msgs off */
                                continue;
-                       if (strcmp(atty, mytty) == 0) {
+                       if (strcmp(atty, ctl->src_tty) == 0) {
                                user_is_me = 1;
                                /* don't write to yourself */
                                continue;
@@ -185,25 +193,26 @@ static void search_utmp(char *user, char *tty, char *mytty, uid_t myuid)
                        ++nttys;
                        if (atime > bestatime) {
                                bestatime = atime;
-                               strcpy(tty, atty);
+                               xstrncpy(ctl->dst_tty, atty, sizeof(ctl->dst_tty));
                        }
                }
        }
 
        endutent();
        if (nloggedttys == 0)
-               errx(EXIT_FAILURE, _("%s is not logged in"), user);
+               errx(EXIT_FAILURE, _("%s is not logged in"), ctl->dst_login);
        if (nttys == 0) {
                if (user_is_me) {
                        /* ok, so write to yourself! */
-                       strcpy(tty, mytty);
+                       xstrncpy(ctl->dst_tty, ctl->src_tty, sizeof(ctl->dst_tty));
                        return;
                }
-               errx(EXIT_FAILURE, _("%s has messages disabled"), user);
+               errx(EXIT_FAILURE, _("%s has messages disabled"), ctl->dst_login);
        } else if (nttys > 1) {
                warnx(_("%s is logged in more than once; writing to %s"),
-                     user, tty);
+                     ctl->dst_login, ctl->dst_tty);
        }
+
 }
 
 /*
@@ -237,7 +246,7 @@ static void wr_fputs(char *s)
 /*
  * do_write - actually make the connection
  */
-static void do_write(char *tty, char *mytty, uid_t myuid)
+static void do_write(const struct write_control *ctl)
 {
        char *login, *pwuid, *nows;
        struct passwd *pwd;
@@ -246,16 +255,16 @@ static void do_write(char *tty, char *mytty, uid_t myuid)
        struct sigaction sigact;
 
        /* Determine our login name(s) before the we reopen() stdout */
-       if ((pwd = getpwuid(myuid)) != NULL)
+       if ((pwd = getpwuid(ctl->src_uid)) != NULL)
                pwuid = pwd->pw_name;
        else
                pwuid = "???";
        if ((login = getlogin()) == NULL)
                login = pwuid;
 
-       if (strlen(tty) + 6 > sizeof(path))
-               errx(EXIT_FAILURE, _("tty path %s too long"), tty);
-       snprintf(path, sizeof(path), "/dev/%s", tty);
+       if (strlen(ctl->dst_tty) + 6 > sizeof(path))
+               errx(EXIT_FAILURE, _("tty path %s too long"), ctl->dst_tty);
+       snprintf(path, sizeof(path), "/dev/%s", ctl->dst_tty);
        if ((freopen(path, "w", stdout)) == NULL)
                err(EXIT_FAILURE, "%s", path);
 
@@ -276,10 +285,10 @@ static void do_write(char *tty, char *mytty, uid_t myuid)
        printf("\r\n\007\007\007");
        if (strcmp(login, pwuid))
                printf(_("Message from %s@%s (as %s) on %s at %s ..."),
-                      login, host, pwuid, mytty, nows + 11);
+                      login, host, pwuid, ctl->src_tty, nows + 11);
        else
                printf(_("Message from %s@%s on %s at %s ..."),
-                      login, host, mytty, nows + 11);
+                      login, host, ctl->src_tty, nows + 11);
        free(host);
        printf("\r\n");
 
@@ -293,9 +302,8 @@ static void do_write(char *tty, char *mytty, uid_t myuid)
 
 int main(int argc, char **argv)
 {
-       uid_t myuid;
-       int msgsok = 0, myttyfd, c;
-       char tty[PATH_MAX], *mytty;
+       int msgsok = 0, src_fd, c;
+       struct write_control ctl = { 0 };
 
        static const struct option longopts[] = {
                {"version", no_argument, NULL, 'V'},
@@ -321,16 +329,16 @@ int main(int argc, char **argv)
 
        /* check that sender has write enabled */
        if (isatty(STDIN_FILENO))
-               myttyfd = STDIN_FILENO;
+               src_fd = STDIN_FILENO;
        else if (isatty(STDOUT_FILENO))
-               myttyfd = STDOUT_FILENO;
+               src_fd = STDOUT_FILENO;
        else if (isatty(STDERR_FILENO))
-               myttyfd = STDERR_FILENO;
+               src_fd = STDERR_FILENO;
        else
-               myttyfd = -1;
+               src_fd = -1;
 
-       if (myttyfd != -1) {
-               if (!(mytty = ttyname(myttyfd)))
+       if (src_fd != -1) {
+               if (!(ctl.src_tty = ttyname(src_fd)))
                        errx(EXIT_FAILURE,
                             _("can't find your tty's name"));
 
@@ -339,39 +347,43 @@ int main(int argc, char **argv)
                 * term_chk() will put "/dev/" in front, so remove that
                 * part.
                 */
-               if (!strncmp(mytty, "/dev/", 5))
-                       mytty += 5;
-               if (term_chk(mytty, &msgsok, NULL, 1))
+               if (!strncmp(ctl.src_tty, "/dev/", 5))
+                       ctl.src_tty += 5;
+               if (term_chk(ctl.src_tty, &msgsok, NULL, 1))
                        exit(EXIT_FAILURE);
                if (!msgsok)
                        errx(EXIT_FAILURE,
                             _("you have write permission turned off"));
                msgsok = 0;
        } else
-               mytty = "<no tty>";
+               ctl.src_tty = "<no tty>";
 
-       myuid = getuid();
+       ctl.src_uid = getuid();
 
        /* check args */
        switch (argc) {
        case 2:
-               search_utmp(argv[1], tty, mytty, myuid);
-               do_write(tty, mytty, myuid);
+               ctl.dst_login = argv[1];
+               search_utmp(&ctl);
+               do_write(&ctl);
                break;
        case 3:
+               ctl.dst_login = argv[1];
                if (!strncmp(argv[2], "/dev/", 5))
-                       argv[2] += 5;
-               if (utmp_chk(argv[1], argv[2]))
+                       xstrncpy(ctl.dst_tty, argv[2] + 5, sizeof(ctl.dst_tty));
+               else
+                       xstrncpy(ctl.dst_tty, argv[2], sizeof(ctl.dst_tty));
+               if (utmp_chk(&ctl))
                        errx(EXIT_FAILURE,
                             _("%s is not logged in on %s"),
-                            argv[1], argv[2]);
-               if (term_chk(argv[2], &msgsok, NULL, 1))
+                            ctl.dst_login, ctl.dst_tty);
+               if (term_chk(ctl.dst_tty, &msgsok, NULL, 1))
                        exit(EXIT_FAILURE);
-               if (myuid && !msgsok)
+               if (ctl.src_uid && !msgsok)
                        errx(EXIT_FAILURE,
                             _("%s has messages disabled on %s"),
-                            argv[1], argv[2]);
-               do_write(argv[2], mytty, myuid);
+                            ctl.dst_login, ctl.dst_tty);
+               do_write(&ctl);
                break;
        default:
                usage(stderr);