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mswshell.c

/* Copyright (c) 1992, 1998, 2000, 2002 John E. Davis
 * This file is part of JED editor library source.
 *
 * You may distribute this file under the terms the GNU General Public
 * License.  See the file COPYING for more information.
 */
#include "config.h"
#include "jed-feat.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <io.h>
#include <fcntl.h>
#include <process.h>
#include <errno.h>
#include <sys\stat.h>

/* FIXME!!!
 * This file basically parses a command line looking for redirections, 
 * and dups stdout and stderr when appropriate, then it spawns the suprocess.
 * For Win32, we should use CreateProcess instead of spawnvp because spawnvp
 * appears to be broken when using MINGW32.
 */
static char Error_Buffer[1024];

static void msg_error(char *msg)
{
   unsigned int len = strlen (Error_Buffer);
   if (len + strlen (msg) + 2 < sizeof (Error_Buffer))
     sprintf (Error_Buffer, ":%s", msg);
}

static char *shell = NULL, *shell_switch = NULL;
static void discover_shell(void)
{
#ifdef SH_SHELL                      /* maybe some day ... */
   shell_switch = "-c";
   if ( (shell = getenv("SHELL")) != NULL )  return;
#endif
   shell_switch = "/c";
   if ( (shell = getenv("COMSPEC")) != NULL ) return;
   shell = "command.com";                             /* absolute last resort! */
}

/* ///////////////////////////////////////////////////////////////////
//  Function:   static int parse_command_line( int *argc, char ***argv,
//                                   char **fname,
//                                   char *command_line );
//  Descript:     parse command_line
//
//  Returns:      the handles to redirect
//
//  Caveat: requires spaces to separate each argument
//          ie., args>filename      will NOT work
///////////////////////////////////////////////////////////////////// */
#define DIRECT_SPAWN 0x1000          /* some arbitrary number */
static int
parse_command_line( int *argc, char ***argv, char **fname, char *command_line )
{
   int count, handles = 0;
   char *pt;

   discover_shell();                 /* find which shell to use */
   while ( (*command_line != '\0') && (*command_line == ' '))
     command_line++;                 /* start on 1st non-space */

   if ( *command_line == '!' )
     {
      handles = DIRECT_SPAWN;
      command_line++;                /* advance past '!' */
      while ((*command_line != '\0') && (*command_line == ' '))
        command_line++;              /* start on next non-space */
     }

   pt = command_line;
   count = 0;
   while ( *pt != '\0' )
     {
      count++;                       /* this is an argument */
      while ((*pt != '\0') && (*pt != ' '))
        {
           if ( *pt == '|' )         /* cannot spawn directly */
             handles = 0;                  /* need shell for pipes */
           pt++;                     /* advance until a space */
        }
      while ( *pt == ' '  )
        pt++;                        /* advance until a non-space */
     }

   *argv = (char **) malloc( (count+3) * sizeof(char *) );
   if ( *argv == NULL )
     return 0;                       /* malloc error */

   *argc = 0;
   if ( !(handles & DIRECT_SPAWN) )
     {
      (*argv)[ *argc ] = shell;
      (*argc)++;
      if ( count > 0 )
        {
           (*argv)[ *argc ] = shell_switch;
           (*argc)++;
        }
      count += (*argc);
     }

   pt = command_line;
   while ((*argc < count) && (*pt != '\0'))
     {
      (*argv)[ *argc ] = pt;
      (*argc)++;
      while ( *pt != '\0' && *pt != ' ' )
        pt++;                 /* advance until a space */
      if ( *pt != '\0' )
        *(pt++) = '\0';       /* parse argument here */
      while ( *pt == ' ')
        pt++;                   /* advance until a non-space */
     }
   (*argv) [ *argc ] = (char *) NULL;     /* NULL terminated list */

/*  now examine the arguments for '>' redirect */

   for ( count = 0; count < *argc; count++ )
     {
      /* find '>' char */
      for ( pt = (*argv)[count]; *pt && (*pt != '>'); pt++ )
        ;

      if ( *pt == '>' )
        {
           if ( pt == (*argv)[count] )
             {
              handles |= 0x01;
             }
           else
             {
              pt--;
              switch ( *pt )
                {
                 case '1':
                   handles |= 0x01;
                   break;
                 case '2':
                   handles |= 0x02;
                   break;
                 case '&':
                   handles |= 0x03;
                   break;
                }
             }
           (*argv)[count] = NULL;         /* remove from the list */
           count++;                 /* file name follows '>' */
           if ( (*argv)[count] != NULL )
             *fname = (*argv)[count];
        }
     }
   if ((*fname == NULL) || (**fname == '\0' ))
     handles = 0x00;          /* don't redirect if there is no name */

   return handles;
}

/* ///////////////////////////////////////////////////////////////////
 //  Function:   int sys_System(char *command_line);
 //
 //  Descript:    shell wrapper that understands some common redirection syntax
 //         command args  > filename            ; stdout
 //         command args 1> filename            ; stdout
 //         command args 2> filename            ; stderr
 //         command args &> filename            ; stdout+stderr
 //         command args  > filename 2>&1       ; stdout+stderr
 //
 // additionally, if command is prefixed by a '!', then the command is
 // spawned directly without invoking the shell
 //
 //  Returns:     returns error codes as per spawn*()
 //
 //  Caveat:      requires spaces to separate each argument
 //         ie., command args>filename    will NOT work
 ///////////////////////////////////////////////////////////////////// */

static int execute_the_command (char **, int, char *);

static int sys_System(char *command_line)
{
   int ret = -1, handles, argc = 0;
   char *fname = NULL, **argv = NULL;

   handles = parse_command_line( &argc, &argv, &fname, command_line );

   if (argc)
     {
      ret = execute_the_command (argv, handles, fname);
     }

   return ret;
}

static int execute_the_command (char **argv, int handles, char *file)
{
   int ret = 0;
   int fd1 = -1, fd2 = -1;
   int fd_err = -1, fd_out = -1;

   if (handles & 1)
     {
       /* save stdout file handle */
      fd1 = dup (fileno (stdout));

      if (fd1 == -1)
        {
           msg_error ("Unable to dup stdout");
           return -1;
        }

      fd_out = open (file,
                   O_CREAT | O_TRUNC | O_TEXT | O_WRONLY | O_APPEND,
                   S_IREAD | S_IWRITE);

      if ((fd_out == -1) || (-1 == dup2 (fd_out, fileno (stdout))))
        {
           msg_error ("Unable to redirect stdout!");
           ret = -1;
        }
     }

   if (handles & 0x2)                /* stderr */
     {
       /* save stderr file handle */
      fd2 = dup (fileno (stderr));

      if (fd2 == -1)
        {
           msg_error ("Unable to dup stderr");
           return -1;
        }

      if (fd_out == -1)
        {
           fd_err = open (file,
                      O_CREAT | O_TRUNC | O_TEXT | O_RDWR | O_APPEND,
                      S_IREAD | S_IWRITE);
        }
      else fd_err = fd_out;

      if ((fd_err == -1) || (-1 == dup2 (fd_err, fileno (stderr))))
        {
           msg_error ("Unable to redirect stderr!");
           ret = -1;
        }
     }

   if (fd_out != -1) close (fd_out);
   if ((fd_err != -1) && (fd_err != fd_out)) close (fd_err);

   if (ret == 0)
     {
      ret = spawnvp(P_WAIT, argv[0], (void *) argv);

      if (-1 == ret )
        {
           switch(errno)
             {
            case ENOENT:
              if (handles & DIRECT_SPAWN ) msg_error("Command not found.");
              else msg_error("Shell not found.");
              break;
            case ENOMEM:
              msg_error("Insufficient Memory.");
              break;
            default:
              msg_error("Unknown Error.");
             }
        }
     }

   if (fd1 != -1)
     {
      if (-1 == dup2 (fd1, fileno (stdout)))
        {
           msg_error ("Unable to reattach stdout");
        }
      close (fd1);
     }

   if (fd2 != -1)
     {
      if (-1 == dup2 (fd2, fileno (stderr)))
        {
           msg_error ("Unable to reattach stderr");
        }
      close (fd2);
     }

   return ret;
}

int main(int argc, char **argv)
{
   char *command_line, *p;
   int   i, j;
   FILE *fp;
   int ret;

   Error_Buffer[0] = 0;
   
   ret = 1;

   if (argc == 1)
     msg_error ("mswshell: no arguments");
   else
     {
      j = 1;
      for(i = 1; i < argc; i++)
        j += strlen(argv[i]) + 1;

      if (NULL == (p = command_line = malloc(j + 1)))
        msg_error("mswshell: Malloc Error");
      else
        {
           for(i = 1; i < argc; i++)
             {
              strcpy(p, argv[i]);
              p += strlen(argv[i]);
              *p++ = ' ';
             }
           *p = 0;
           ret = sys_System(command_line);
           free(command_line);
        }
     }

   fp = fopen("jedshell.tmp", "w");
   if (fp == NULL)
     {
      /* I realize that this does nothing... */
      msg_error ("Unable to open tmp file.");
      return 1;
     }

   fprintf(fp, "%d\n%s", ret, Error_Buffer);
   fclose(fp);
   return ret;
}

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