git.distorted.org.uk Git - u/mdw/putty/blob - contrib/cygtermd/pty.c

   1 /*
   2  * pty.c - pseudo-terminal handling
   3  */
   4
   5 #define _XOPEN_SOURCE
   6 #include <features.h>
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <assert.h>
  12
  13 #include <unistd.h>
  14 #include <fcntl.h>
  15 #include <termios.h>
  16 #include <sys/ioctl.h>
  17 #include <sys/types.h>
  18 #include <pwd.h>
  19
  20 #include "pty.h"
  21 #include "malloc.h"
  22
  23 static char ptyname[FILENAME_MAX];
  24 int master = -1;
  25
  26 void pty_preinit(void)
  27 {
  28     /*
  29      * Allocate the pty.
  30      */
  31     master = open("/dev/ptmx", O_RDWR);
  32     if (master < 0) {
  33         perror("/dev/ptmx: open");
  34         exit(1);
  35     }
  36
  37     if (grantpt(master) < 0) {
  38         perror("grantpt");
  39         exit(1);
  40     }
  41
  42     if (unlockpt(master) < 0) {
  43         perror("unlockpt");
  44         exit(1);
  45     }
  46 }
  47
  48 void pty_resize(int w, int h)
  49 {
  50     struct winsize sz;
  51
  52     assert(master >= 0);
  53
  54     sz.ws_row = h;
  55     sz.ws_col = w;
  56     sz.ws_xpixel = sz.ws_ypixel = 0;
  57     ioctl(master, TIOCSWINSZ, &sz);
  58 }
  59
  60 int run_program_in_pty(const struct shell_data *shdata,
  61                        char *directory, char **program_args)
  62 {
  63     int slave, pid;
  64     char *fallback_args[2];
  65
  66     assert(master >= 0);
  67
  68     ptyname[FILENAME_MAX-1] = '\0';
  69     strncpy(ptyname, ptsname(master), FILENAME_MAX-1);
  70
  71 #if 0
  72     {
  73         struct winsize ws;
  74         struct termios ts;
  75
  76         /*
  77          * FIXME: think up some good defaults here
  78          */
  79
  80         if (!ioctl(0, TIOCGWINSZ, &ws))
  81             ioctl(master, TIOCSWINSZ, &ws);
  82         if (!tcgetattr(0, &ts))
  83             tcsetattr(master, TCSANOW, &ts);
  84     }
  85 #endif
  86
  87     slave = open(ptyname, O_RDWR | O_NOCTTY);
  88     if (slave < 0) {
  89         perror("slave pty: open");
  90         return 1;
  91     }
  92
  93     /*
  94      * Fork and execute the command.
  95      */
  96     pid = fork();
  97     if (pid < 0) {
  98         perror("fork");
  99         return 1;
 100     }
 101
 102     if (pid == 0) {
 103         int i, fd;
 104
 105         /*
 106          * We are the child.
 107          */
 108         close(master);
 109
 110         fcntl(slave, F_SETFD, 0);    /* don't close on exec */
 111         dup2(slave, 0);
 112         dup2(slave, 1);
 113         if (slave != 0 && slave != 1)
 114             close(slave);
 115         dup2(1, 2);
 116         setsid();
 117         setpgrp();
 118         i = 0;
 119 #ifdef TIOCNOTTY
 120         if ((fd = open("/dev/tty", O_RDWR)) >= 0) {
 121             ioctl(fd, TIOCNOTTY, &i);
 122             close(fd);
 123         }
 124 #endif
 125 #ifdef TIOCSCTTY
 126         ioctl(0, TIOCSCTTY, &i);
 127 #endif
 128         tcsetpgrp(0, getpgrp());
 129
 130         for (i = 0; i < shdata->nenvvars; i++)
 131             putenv(shdata->envvars[i]);
 132         if (shdata->termtype)
 133             putenv(shdata->termtype);
 134
 135         if (directory)
 136             chdir(directory);
 137
 138         /*
 139          * Use the provided shell program name, if the user gave
 140          * one. Failing that, use $SHELL; failing that, look up
 141          * the user's default shell in the password file; failing
 142          * _that_, revert to the bog-standard /bin/sh.
 143          */
 144         if (!program_args) {
 145             char *shell;
 146
 147             shell = getenv("SHELL");
 148             if (!shell) {
 149                 const char *login;
 150                 uid_t uid;
 151                 struct passwd *pwd;
 152
 153                 /*
 154                  * For maximum generality in the face of multiple
 155                  * /etc/passwd entries with different login names and
 156                  * shells but a shared uid, we start by using
 157                  * getpwnam(getlogin()) if it's available - but we
 158                  * insist that its uid must match our real one, or we
 159                  * give up and fall back to getpwuid(getuid()).
 160                  */
 161                 uid = getuid();
 162                 login = getlogin();
 163                 if (login && (pwd = getpwnam(login)) && pwd->pw_uid == uid)
 164                     shell = pwd->pw_shell;
 165                 else if ((pwd = getpwuid(uid)))
 166                     shell = pwd->pw_shell;
 167             }
 168             if (!shell)
 169                 shell = "/bin/sh";
 170
 171             fallback_args[0] = shell;
 172             fallback_args[1] = NULL;
 173             program_args = fallback_args;
 174         }
 175
 176         execv(program_args[0], program_args);
 177
 178         /*
 179          * If we're here, exec has gone badly foom.
 180          */
 181         perror("exec");
 182         exit(127);
 183     }
 184
 185     close(slave);
 186
 187     return master;
 188 }