Add tty line support

Not always is desirable to create a pseudo terminal, and some times
we want to open a terminal emulator over a tty line. With this new
patch is possible to do someting like:

	$ st -l /dev/ttyS0 115200

Without this option was needed to launch another terminal emulator
over st (for example minicom, picocom, cu, ...).

3 files changed, 91 insertions, 13 deletions

diff --git a/config.def.h b/config.def.h
index 5e7caaf..bb5596e 100644
--- a/config.def.h
+++ b/config.def.h
@@ -9,6 +9,7 @@ static char font[] = "Liberation Mono:pixelsize=12:antialias=false:autohint=fals
 static int borderpx = 2;
 static char shell[] = "/bin/sh";
 static char *utmp = NULL;
+static char stty_args[] = "stty raw -echo -iexten echonl";
 
 /* identification sequence returned in DA and DECID */
 static char vtiden[] = "\033[?6c";
diff --git a/st.1 b/st.1
index a9fec15..9548c1a 100644
--- a/st.1
+++ b/st.1
@@ -15,11 +15,36 @@ st \- simple terminal
 .IR file ]
 .RB [ \-t 
 .IR title ]
+.RB [ \-l
+.IR line ]
 .RB [ \-w 
 .IR windowid ]
 .RB [ \-v ]
 .RB [ \-e
 .IR command ...]
+.RI [ commands ...]
+.PP
+.B st
+.RB [ \-a ]
+.RB [ \-c
+.IR class ]
+.RB [ \-f
+.IR font ]
+.RB [ \-g
+.IR geometry ]
+.RB [ \-i ]
+.RB [ \-o
+.IR file ]
+.RB [ \-t
+.IR title ]
+.RB [ \-l
+.IR line ]
+.RB [ \-w
+.IR windowid ]
+.RB [ \-v ]
+.RB [ \-l
+.IR line ]
+.RI [ stty_args ...]
 .SH DESCRIPTION
 .B st
 is a simple terminal emulator.
@@ -58,6 +83,11 @@ defines the window title (default 'st').
 embeds st within the window identified by 
 .I windowid
 .TP
+.BI \-l " line"
+use a tty line instead of a pseudo terminal.
+When this flag is used
+remaining arguments are used as flags for stty.
+.TP
 .B \-v
 prints version information to stderr, then exits.
 .TP
@@ -67,6 +97,9 @@ st executes
 instead of the shell.  If this is used it
 .B must be the last option
 on the command line, as in xterm / rxvt.
+This option is only intended for compability,
+and all the remaining arguments are used as a command
+even without it.
 .SH SHORTCUTS
 .TP
 .B Ctrl-Print Screen
@@ -110,7 +143,9 @@ See the LICENSE file for the authors.
 .SH LICENSE
 See the LICENSE file for the terms of redistribution.
 .SH SEE ALSO
-.BR tabbed (1)
+.BR tabbed (1),
+.BR utmp (1),
+.BR stty (1)
 .SH BUGS
 See the TODO file in the distribution.
 
diff --git a/st.c b/st.c
index bb8c365..d22c605 100644
--- a/st.c
+++ b/st.c
@@ -352,6 +352,7 @@ static void draw(void);
 static void redraw(void);
 static void drawregion(int, int, int, int);
 static void execsh(void);
+static void stty(void);
 static void sigchld(int);
 static void run(void);
 
@@ -508,6 +509,7 @@ static char *opt_title = NULL;
 static char *opt_embed = NULL;
 static char *opt_class = NULL;
 static char *opt_font = NULL;
+static char *opt_line = NULL;
 static int oldbutton = 3; /* button event on startup: 3 = release */
 
 static char *usedfont = NULL;
@@ -1253,11 +1255,55 @@ sigchld(int a) {
         exit(EXIT_SUCCESS);
 }
 
+
+void
+stty(void)
+{
+        char cmd[_POSIX_ARG_MAX], **p, *q, *s;
+        size_t n, siz;
+
+        if((n = strlen(stty_args)) > sizeof(cmd)-1)
+                die("incorrect stty parameters\n");
+        memcpy(cmd, stty_args, n);
+        q = cmd + n;
+        siz = sizeof(cmd) - n;
+        for(p = opt_cmd; p && (s = *p); ++p) {
+                if((n = strlen(s)) > siz-1)
+                        die("stty parameter length too long\n");
+                *q++ = ' ';
+                q = memcpy(q, s, n);
+                q += n;
+                siz-= n + 1;
+        }
+        *q = '\0';
+        system(cmd);
+}
+
 void
 ttynew(void) {
         int m, s;
         struct winsize w = {term.row, term.col, 0, 0};
 
+        if(opt_io) {
+                term.mode |= MODE_PRINT;
+                iofd = (!strcmp(opt_io, "-")) ?
+                          STDOUT_FILENO :
+                          open(opt_io, O_WRONLY | O_CREAT, 0666);
+                if(iofd < 0) {
+                        fprintf(stderr, "Error opening %s:%s\n",
+                                opt_io, strerror(errno));
+                }
+        }
+
+        if (opt_line) {
+                if((cmdfd = open(opt_line, O_RDWR)) < 0)
+                        die("open line failed: %s\n", strerror(errno));
+                close(STDIN_FILENO);
+                dup(cmdfd);
+                stty();
+                return;
+        }
+
         /* seems to work fine on linux, openbsd and freebsd */
         if(openpty(&m, &s, NULL, NULL, &w) < 0)
                 die("openpty failed: %s\n", strerror(errno));
@@ -1267,6 +1313,7 @@ ttynew(void) {
                 die("fork failed\n");
                 break;
         case 0:
+                close(iofd);
                 setsid(); /* create a new process group */
                 dup2(s, STDIN_FILENO);
                 dup2(s, STDOUT_FILENO);
@@ -1281,16 +1328,6 @@ ttynew(void) {
                 close(s);
                 cmdfd = m;
                 signal(SIGCHLD, sigchld);
-                if(opt_io) {
-                        term.mode |= MODE_PRINT;
-                        iofd = (!strcmp(opt_io, "-")) ?
-                                  STDOUT_FILENO :
-                                  open(opt_io, O_WRONLY | O_CREAT, 0666);
-                        if(iofd < 0) {
-                                fprintf(stderr, "Error opening %s:%s\n",
-                                        opt_io, strerror(errno));
-                        }
-                }
                 break;
         }
 }
@@ -4009,9 +4046,11 @@ run(void) {
 
 void
 usage(void) {
-        die("%s " VERSION " (c) 2010-2015 st engineers\n" \
+        die("%s " VERSION " (c) 2010-2015 st engineers\n"
         "usage: st [-a] [-v] [-c class] [-f font] [-g geometry] [-o file]\n"
-        "          [-i] [-t title] [-w windowid] [-e command ...] [command ...]\n",
+        "          [-i] [-t title] [-w windowid] [-e command ...] [command ...]\n"
+        "       st [-a] [-v] [-c class] [-f font] [-g geometry] [-o file]\n"
+        "          [-i] [-t title] [-w windowid] [-l line] [stty_args ...]\n",
         argv0);
 }
 
@@ -4047,6 +4086,9 @@ main(int argc, char *argv[]) {
         case 'o':
                 opt_io = EARGF(usage());
                 break;
+        case 'l':
+                opt_line = EARGF(usage());
+                break;
         case 't':
                 opt_title = EARGF(usage());
                 break;