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lsystem.c

/*
 * Copyright (C) 1984-2002  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * Routines to execute other programs.
 * Necessarily very OS dependent.
 */

#include "less.h"
#include <signal.h>
#include "position.h"

#if MSDOS_COMPILER
#include <dos.h>
#ifdef _MSC_VER
#include <direct.h>
#define setdisk(n) _chdrive((n)+1)
#else
#include <dir.h>
#endif
#endif

extern int screen_trashed;
extern IFILE curr_ifile;


#if HAVE_SYSTEM

/*
 * Pass the specified command to a shell to be executed.
 * Like plain "system()", but handles resetting terminal modes, etc.
 */
      public void
lsystem(cmd, donemsg)
      char *cmd;
      char *donemsg;
{
      register int inp;
#if HAVE_SHELL
      register char *shell;
      register char *p;
#endif
      IFILE save_ifile;
#if MSDOS_COMPILER
      char cwd[FILENAME_MAX+1];
#endif

      /*
       * Print the command which is to be executed,
       * unless the command starts with a "-".
       */
      if (cmd[0] == '-')
            cmd++;
      else
      {
            clear_bot();
            putstr("!");
            putstr(cmd);
            putstr("\n");
      }

#if MSDOS_COMPILER
      /*
       * Working directory is global on MSDOS.
       * The child might change the working directory, so we
       * must save and restore CWD across calls to "system",
       * or else we won't find our file when we return and
       * try to "reedit_ifile" it.
       */
      getcwd(cwd, FILENAME_MAX);
#endif

      /*
       * Close the current input file.
       */
      save_ifile = save_curr_ifile();
      (void) edit_ifile(NULL_IFILE);

      /*
       * De-initialize the terminal and take out of raw mode.
       */
      deinit();
      flush();    /* Make sure the deinit chars get out */
      raw_mode(0);
#if MSDOS_COMPILER==WIN32C
      close_getchr();
#endif

      /*
       * Restore signals to their defaults.
       */
      init_signals(0);

#if HAVE_DUP
      /*
       * Force standard input to be the user's terminal
       * (the normal standard input), even if less's standard input 
       * is coming from a pipe.
       */
      inp = dup(0);
      close(0);
#if OS2
      /* The __open() system call translates "/dev/tty" to "con". */
      if (__open("/dev/tty", OPEN_READ) < 0)
#else
      if (open("/dev/tty", OPEN_READ) < 0)
#endif
            dup(inp);
#endif

      /*
       * Pass the command to the system to be executed.
       * If we have a SHELL environment variable, use
       * <$SHELL -c "command"> instead of just <command>.
       * If the command is empty, just invoke a shell.
       */
#if HAVE_SHELL
      p = NULL;
      if ((shell = lgetenv("SHELL")) != NULL && *shell != '\0')
      {
            if (*cmd == '\0')
                  p = save(shell);
            else
            {
                  char *esccmd = shell_quote(cmd);
                  if (esccmd != NULL)
                  {
                        p = (char *) ecalloc(strlen(shell) +
                              strlen(esccmd) + 5, sizeof(char));
                        sprintf(p, "%s %s %s", shell, shell_coption(), esccmd);
                        free(esccmd);
                  }
            }
      }
      if (p == NULL)
      {
            if (*cmd == '\0')
                  p = save("sh");
            else
                  p = save(cmd);
      }
      system(p);
      free(p);
#else
#if MSDOS_COMPILER==DJGPPC
      /*
       * Make stdin of the child be in cooked mode.
       */
      setmode(0, O_TEXT);
      /*
       * We don't need to catch signals of the child (it
       * also makes trouble with some DPMI servers).
       */
      __djgpp_exception_toggle();
      system(cmd);
      __djgpp_exception_toggle();
#else
      system(cmd);
#endif
#endif

#if HAVE_DUP
      /*
       * Restore standard input, reset signals, raw mode, etc.
       */
      close(0);
      dup(inp);
      close(inp);
#endif

#if MSDOS_COMPILER==WIN32C
      open_getchr();
#endif
      init_signals(1);
      raw_mode(1);
      if (donemsg != NULL)
      {
            putstr(donemsg);
            putstr("  (press RETURN)");
            get_return();
            putchr('\n');
            flush();
      }
      init();
      screen_trashed = 1;

#if MSDOS_COMPILER
      /*
       * Restore the previous directory (possibly
       * changed by the child program we just ran).
       */
      chdir(cwd);
#if MSDOS_COMPILER != DJGPPC
      /*
       * Some versions of chdir() don't change to the drive
       * which is part of CWD.  (DJGPP does this in chdir.)
       */
      if (cwd[1] == ':')
      {
            if (cwd[0] >= 'a' && cwd[0] <= 'z')
                  setdisk(cwd[0] - 'a');
            else if (cwd[0] >= 'A' && cwd[0] <= 'Z')
                  setdisk(cwd[0] - 'A');
      }
#endif
#endif

      /*
       * Reopen the current input file.
       */
      reedit_ifile(save_ifile);

#if defined(SIGWINCH) || defined(SIGWIND)
      /*
       * Since we were ignoring window change signals while we executed
       * the system command, we must assume the window changed.
       * Warning: this leaves a signal pending (in "sigs"),
       * so psignals() should be called soon after lsystem().
       */
      winch(0);
#endif
}

#endif

#if PIPEC

/*
 * Pipe a section of the input file into the given shell command.
 * The section to be piped is the section "between" the current
 * position and the position marked by the given letter.
 *
 * If the mark is after the current screen, the section between
 * the top line displayed and the mark is piped.
 * If the mark is before the current screen, the section between
 * the mark and the bottom line displayed is piped.
 * If the mark is on the current screen, or if the mark is ".",
 * the whole current screen is piped.
 */
      public int
pipe_mark(c, cmd)
      int c;
      char *cmd;
{
      POSITION mpos, tpos, bpos;

      /*
       * mpos = the marked position.
       * tpos = top of screen.
       * bpos = bottom of screen.
       */
      mpos = markpos(c);
      if (mpos == NULL_POSITION)
            return (-1);
      tpos = position(TOP);
      if (tpos == NULL_POSITION)
            tpos = ch_zero();
      bpos = position(BOTTOM);

      if (c == '.') 
            return (pipe_data(cmd, tpos, bpos));
      else if (mpos <= tpos)
            return (pipe_data(cmd, mpos, bpos));
      else if (bpos == NULL_POSITION)
            return (pipe_data(cmd, tpos, bpos));
      else
            return (pipe_data(cmd, tpos, mpos));
}

/*
 * Create a pipe to the given shell command.
 * Feed it the file contents between the positions spos and epos.
 */
      public int
pipe_data(cmd, spos, epos)
      char *cmd;
      POSITION spos;
      POSITION epos;
{
      register FILE *f;
      register int c;
      extern FILE *popen();

      /*
       * This is structured much like lsystem().
       * Since we're running a shell program, we must be careful
       * to perform the necessary deinitialization before running
       * the command, and reinitialization after it.
       */
      if (ch_seek(spos) != 0)
      {
            error("Cannot seek to start position", NULL_PARG);
            return (-1);
      }

      if ((f = popen(cmd, "w")) == NULL)
      {
            error("Cannot create pipe", NULL_PARG);
            return (-1);
      }
      clear_bot();
      putstr("!");
      putstr(cmd);
      putstr("\n");

      deinit();
      flush();
      raw_mode(0);
      init_signals(0);
#if MSDOS_COMPILER==WIN32C
      close_getchr();
#endif
#ifdef SIGPIPE
      LSIGNAL(SIGPIPE, SIG_IGN);
#endif

      c = EOI;
      while (epos == NULL_POSITION || spos++ <= epos)
      {
            /*
             * Read a character from the file and give it to the pipe.
             */
            c = ch_forw_get();
            if (c == EOI)
                  break;
            if (putc(c, f) == EOF)
                  break;
      }

      /*
       * Finish up the last line.
       */
      while (c != '\n' && c != EOI ) 
      {
            c = ch_forw_get();
            if (c == EOI)
                  break;
            if (putc(c, f) == EOF)
                  break;
      }

      pclose(f);

#ifdef SIGPIPE
      LSIGNAL(SIGPIPE, SIG_DFL);
#endif
#if MSDOS_COMPILER==WIN32C
      open_getchr();
#endif
      init_signals(1);
      raw_mode(1);
      init();
      screen_trashed = 1;
#if defined(SIGWINCH) || defined(SIGWIND)
      /* {{ Probably don't need this here. }} */
      winch(0);
#endif
      return (0);
}

#endif

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