additional info to a comment about pty mangling

1 files changed, 1 insertions, 1 deletions

diff --git a/core/apps/embeddedkonsole/MyPty.cpp b/core/apps/embeddedkonsole/MyPty.cpp
index 4b1ae59..c11889e 100644
--- a/core/apps/embeddedkonsole/MyPty.cpp
+++ b/core/apps/embeddedkonsole/MyPty.cpp
@@ -36,255 +36,255 @@
 
     One can create many instances of this class within a program.
     As a side effect of using this class, a signal(2) handler is
     installed on SIGCHLD.
 
     \par FIXME
 
     [NOTE: much of the technical stuff below will be replaced by forkpty.]
 
     publish the SIGCHLD signal if not related to an instance.
 
     clearify TEPty::done vs. TEPty::~TEPty semantics.
     check if pty is restartable via run after done.
 
     \par Pseudo terminals
 
     Pseudo terminals are a unique feature of UNIX, and always come in form of
     pairs of devices (/dev/ptyXX and /dev/ttyXX), which are connected to each
     other by the operating system. One may think of them as two serial devices
     linked by a null-modem cable. Being based on devices the number of
     simultanous instances of this class is (globally) limited by the number of
     those device pairs, which is 256.
 
     Another technic are UNIX 98 PTY's. These are supported also, and prefered
     over the (obsolete) predecessor.
 
     There's a sinister ioctl(2), signal(2) and job control stuff
     nessesary to make everything work as it should.
 */
 
 
 #include <qfileinfo.h>
 #include <qapplication.h>
 #include <qsocketnotifier.h>
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <termios.h>
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/wait.h>
 
 #ifdef HAVE_OPENPTY
 #include <pty.h>
 #endif
 
 #include "MyPty.h"
 
 
 #undef VERBOSE_DEBUG
 
 
 /* -------------------------------------------------------------------------- */
 
 /*!
    Informs the client program about the
    actual size of the window.
 */
 
 void MyPty::setSize(int lines, int columns)
 {
   struct winsize wsize;
   wsize.ws_row = (unsigned short)lines;
   wsize.ws_col = (unsigned short)columns;
   if(fd < 0) return;
   ioctl(fd,TIOCSWINSZ,(char *)&wsize);
 }
 
 
 void MyPty::donePty()
 {
     // This is code from the Qt DumbTerminal example
     int status = 0;
 
     ::close(fd);
 
     if (cpid) {
   kill(cpid, SIGHUP);
   waitpid(cpid, &status, 0);
     }
 
     emit done(status);
 }
 
 
 const char* MyPty::deviceName()
 {
     return ttynam;
 }
 
 
 void MyPty::error()
 {
     // This is code from the Qt DumbTerminal example
     donePty();
 }
 
 
 /*!
     start the client program.
 */
 int MyPty::run(const char* cmd, QStrList &, const char*, int)
 {
       // This is code from the Qt DumbTerminal example
     cpid = fork();
 
     if ( !cpid ) {
   // child - exec shell on tty
   for (int sig = 1; sig < NSIG; sig++) signal(sig,SIG_DFL);
 
   // attempt to keep apm driver from killing us on power on/off
   signal(SIGSTOP, SIG_IGN);
   signal(SIGCONT, SIG_IGN);
   signal(SIGTSTP, SIG_IGN);
 
   int ttyfd = open(ttynam, O_RDWR);
   dup2(ttyfd, STDIN_FILENO);
   dup2(ttyfd, STDOUT_FILENO);
   dup2(ttyfd, STDERR_FILENO);
   // should be done with tty, so close it
   close(ttyfd);
   static struct termios ttmode;
   if ( setsid() < 0 )
       perror( "failed to set process group" );
 #if defined (TIOCSCTTY)
-  // grabbed from APUE by Stevens
+  // grabbed from APUE by Stevens (see section 9.6, should be page 246)
   ioctl(STDIN_FILENO, TIOCSCTTY, 0);
 #endif
   tcgetattr( STDIN_FILENO, &ttmode );
   ttmode.c_cc[VINTR] = 3;
   ttmode.c_cc[VERASE] = 8;
   tcsetattr( STDIN_FILENO, TCSANOW, &ttmode );
 
 	if(strlen(getenv("TERM"))<=0)
 			setenv("TERM","vt100",1);
   setenv("COLORTERM","0",1);
 
   if (getuid() == 0) {
       char msg[] = "WARNING: You are running this shell as root!\n";
       write(ttyfd, msg, sizeof(msg));
   }
 
   QString ccmd = "-"+QFileInfo(cmd).fileName(); //creates a login shell
 
   execl(cmd, ccmd.latin1(), 0);
 
   donePty();
   exit(-1);
     }
 
     // parent - continue as a widget
     QSocketNotifier* sn_r = new QSocketNotifier(fd,QSocketNotifier::Read,this);
     QSocketNotifier* sn_e = new QSocketNotifier(fd,QSocketNotifier::Exception,this);
     connect(sn_r,SIGNAL(activated(int)),this,SLOT(readPty()));
     connect(sn_e,SIGNAL(activated(int)),this,SLOT(error()));
 
     return 0;
 }
 
 int MyPty::openPty()
 {
     // This is code from the Qt DumbTerminal example
     int ptyfd = -1;
 
 #ifdef HAVE_OPENPTY
     int ttyfd;
     if ( openpty(&ptyfd,&ttyfd,ttynam,0,0) )
   ptyfd = -1;
     else
   close(ttyfd); // we open the ttynam ourselves.
 #else
     for (const char* c0 = "pqrstuvwxyzabcde"; ptyfd < 0 && *c0 != 0; c0++) {
   for (const char* c1 = "0123456789abcdef"; ptyfd < 0 && *c1 != 0; c1++) {
       sprintf(ptynam,"/dev/pty%c%c",*c0,*c1);
       sprintf(ttynam,"/dev/tty%c%c",*c0,*c1);
       if ((ptyfd = ::open(ptynam,O_RDWR)) >= 0) {
     if (geteuid() != 0 && !access(ttynam,R_OK|W_OK) == 0) {
         ::close(ptyfd);
         ptyfd = -1;
     }
       }
   }
     }
 #endif
 
     if ( ptyfd < 0 ) {
   qApp->exit(1);
   return -1;
     }
 
     return ptyfd;
 }
 
 /*!
     Create an instance.
 */
 MyPty::MyPty() : cpid(0)
 {
   fd = openPty();
 }
 
 /*!
     Destructor.
     Note that the related client program is not killed
     (yet) when a instance is deleted.
 */
 MyPty::~MyPty()
 {
     donePty();
 }
 
 
 /*! sends len bytes through the line */
 void MyPty::send_bytes(const char* s, int len)
 {
 
 #ifdef VERBOSE_DEBUG
   // verbose debug
   printf("sending bytes:\n");
   for (int i = 0; i < len; i++)
     printf("%c", s[i]);
   printf("\n");
 #endif
 
   ::write(fd, s, len);
 }
 
 /*! indicates that a block of data is received */
 void MyPty::readPty()
 {
   char buf[4096];
 
   int len = ::read( fd, buf, 4096 );
 
   if (len == -1)
      donePty();
 
   if (len < 0)
      return;
 
   emit block_in(buf,len);
 
 #ifdef VERBOSE_DEBUG
   // verbose debug
   printf("read bytes:\n");
   for (int i = 0; i < len; i++)
     printf("%c", buf[i]);
   printf("\n");
 #endif
 
 }