agetty: resolve tty name even if stdin is specified

[kzak@redhat.com: - use "const" for options->tty (and friends)
                    as expected by get_terminal_name()]

Addresses: https://github.com/util-linux/util-linux/issues/1546
Signed-off-by: tamz <totemz@protonmail.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/term-utils/agetty.c b/term-utils/agetty.c
index 55d3734613912dcc8f070343a38c20793bc2b8fe..22850786da0646f1aaa852f075962995570c01fc 100644 (file)
--- a/term-utils/agetty.c
+++ b/term-utils/agetty.c
@@ -190,8 +190,8 @@ struct options {
        char *chroot;                   /* Chroot before the login */
        char *login;                    /* login program */
        char *logopt;                   /* options for login program */
-       char *tty;                      /* name of tty */
-       char *vcline;                   /* line of virtual console */
+       const char *tty;                /* name of tty */
+       const char *vcline;             /* line of virtual console */
        char *term;                     /* terminal type */
        char *initstring;               /* modem init string */
        char *issue;                    /* alternative issue file or directory */
@@ -203,6 +203,7 @@ struct options {
        int numspeed;                   /* number of baud rates to try */
        int clocal;                     /* CLOCAL_MODE_* */
        int kbmode;                     /* Keyboard mode if virtual console */
+       int tty_is_stdin;               /* is the tty the standard input stream */
        speed_t speeds[MAX_SPEED];      /* baud rates to be tried */
 };
 
@@ -319,7 +320,7 @@ static void init_special_char(char* arg, struct options *op);
 static void parse_args(int argc, char **argv, struct options *op);
 static void parse_speeds(struct options *op, char *arg);
 static void update_utmp(struct options *op);
-static void open_tty(char *tty, struct termios *tp, struct options *op);
+static void open_tty(const char *tty, struct termios *tp, struct options *op);
 static void termio_init(struct options *op, struct termios *tp);
 static void reset_vc(const struct options *op, struct termios *tp, int canon);
 static void auto_baud(struct termios *tp);
@@ -922,6 +923,15 @@ static void parse_args(int argc, char **argv, struct options *op)
                }
        }
 
+       /* resolve the tty path in case it was provided as stdin */
+       if (strcmp(op->tty, "-") == 0) {
+               op->tty_is_stdin = 1;
+               int fd = get_terminal_name(NULL, &op->tty, NULL);
+               if (fd < 0) {
+                       log_warn(_("could not get terminal name: %d"), fd);
+               }
+       }
+
        /* On virtual console remember the line which is used for */
        if (strncmp(op->tty, "tty", 3) == 0 &&
            strspn(op->tty + 3, "0123456789") == strlen(op->tty+3))
@@ -962,8 +972,8 @@ static void update_utmp(struct options *op)
        time_t t;
        pid_t pid = getpid();
        pid_t sid = getsid(0);
-       char *vcline = op->vcline;
-       char *line   = op->tty;
+       const char *vcline = op->vcline;
+       const char *line = op->tty;
        struct utmpx *utp;
 
        /*
@@ -1002,7 +1012,7 @@ static void update_utmp(struct options *op)
                        str2memcpy(ut.ut_id, vcline, sizeof(ut.ut_id));
                else {
                        size_t len = strlen(line);
-                       char * ptr;
+                       const char * ptr;
                        if (len >= sizeof(ut.ut_id))
                                ptr = line + len - sizeof(ut.ut_id);
                        else
@@ -1030,7 +1040,7 @@ static void update_utmp(struct options *op)
 #endif                         /* SYSV_STYLE */
 
 /* Set up tty as stdin, stdout & stderr. */
-static void open_tty(char *tty, struct termios *tp, struct options *op)
+static void open_tty(const char *tty, struct termios *tp, struct options *op)
 {
        const pid_t pid = getpid();
        int closed = 0;
@@ -1040,7 +1050,7 @@ static void open_tty(char *tty, struct termios *tp, struct options *op)
 
        /* Set up new standard input, unless we are given an already opened port. */
 
-       if (strcmp(tty, "-") != 0) {
+       if (!op->tty_is_stdin) {
                char buf[PATH_MAX+1];
                struct group *gr = NULL;
                struct stat st;