sos-code-article10/userland/shell.c

/* Copyright (C) 2005 Thomas Petazzoni, David Decotigny

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA. 
*/

#include <crt.h>
#include <libc.h>
#include <stdarg.h>
#include <string.h>
#include <debug.h>
#include <drivers/devices.h>

#include "fstest_utils.h"

/**
 * @file shell.c
 *
 * Small shell.
 */

static int shell_uname (int argc, char *argv[])
{
  printf ("SOS article 10\n");
  return 0;
}

static void shell_ls_internal(int detailed, int recursive, int reclevel)
{
  char tab[256], *c;
  int i;
  struct dirent * dirent;
  DIR * here;

  here = opendir(".");
  if (! here)
    return;

  /* Build initial tabulation */
  if (recursive)
    {
      for (c = tab, i = 0 ; (i < reclevel) && (i < sizeof(tab)/2) ; i++)
	{
	  *c++ = ' ';
	  *c++ = ' ';
	}
      *c++ = '\0';
    }
  else
    *tab = '\0';

  while ((dirent = readdir(here)) != NULL)
    {
      char entrychar;
      char * entrysuffix;

      switch(dirent->type)
	{
	case S_IFREG: entrychar='-'; entrysuffix=""; break;
	case S_IFDIR: entrychar='d'; entrysuffix="/"; break;
	case S_IFLNK: entrychar='l'; entrysuffix="@"; break;
	case S_IFCHR: entrychar='c'; entrysuffix=NULL; break;
	case S_IFBLK: entrychar='b'; entrysuffix=NULL; break;
	default: entrychar='?'; entrysuffix="?!?"; break;
	}

      if (detailed)
	{
	  struct stat stat;
	  char target_name[SOS_FS_DIRENT_NAME_MAXLEN];
	  char majorminor[24];

	  if (lstat(dirent->name, & stat))
	    continue;

	  *target_name = '\0';
	  if (stat.st_type == S_IFLNK)
	    {
	      int fd = open(dirent->name, O_RDONLY | O_NOFOLLOW);
	      if (fd >= 0)
		{
		  int len = read(fd, target_name, sizeof(target_name) - 1);
		  if (len < 0)
		    *target_name='\0';
		  else
		    target_name[len] = '\0';
		  close(fd);
		}
	    }
	  else if ( (stat.st_type == S_IFCHR) || (stat.st_type == S_IFBLK) )
	    {
	      snprintf(majorminor, sizeof(majorminor), " %d,%d",
		       stat.st_rdev_major, stat.st_rdev_minor);
	      entrysuffix = majorminor;
	    }

	  printf("%s%c%c%c%c %lld %s%s%s%s (location=0x%llx)\n",
		 tab, entrychar,
		 (stat.st_access_rights&S_IRUSR)?'r':'-',
		 (stat.st_access_rights&S_IWUSR)?'w':'-',
		 (stat.st_access_rights&S_IXUSR)?'x':'-',
		 stat.st_size,
		 dirent->name,
		 entrysuffix,
		 (stat.st_type==S_IFLNK)?" -> ":"",
		 target_name,
		 stat.st_storage_location);
	}
      else
	  printf("%s%s%s\n",
		 tab, dirent->name, entrysuffix);

      /* Next iteration */
      if (recursive)
	{
	  int fd_here = dirfd(here);
	  if (chdir(dirent->name))
	    continue;
	  shell_ls_internal(detailed, recursive, reclevel+1);
	  if(fchdir(fd_here))
            {
		closedir(here);
	        return;
            }
	}
    }
  closedir(here);
}

static void shell_ls(const char * path, int detailed, int recursive)
{
  int fd_here = open(".", O_RDONLY | O_DIRECTORY);
  if (fd_here < 0)
    return;

  if (chdir(path))
    {
      close(fd_here);
      return;
    }

  shell_ls_internal(detailed, recursive, 1);

  fchdir(fd_here);
  close(fd_here);
}

static int shell_chdir(int argc, char *argv[])
{
  int ret;

  ret = chdir(argv[1]);

  if (ret < 0)
    printf("Cannot chdir '%s': %d\n", argv[1], ret);

  return 0;
}

static int shell_touch (int argc, char *argv[])
{
  return creat (argv[1], S_IRUSR | S_IWUSR);
}

static int shell_mkdir (int argc, char *argv[])
{
  int retval;

  retval = mkdir (argv[1], S_IRUSR | S_IWUSR | S_IXUSR);

  if (retval != 0)
    printf("Cannot mkdir %s (%d)\n", argv[1], retval);
  return retval;
}

static int shell_rmdir (int argc, char *argv[])
{
  int ret;

  ret = rmdir (argv[1]);

  if (ret < 0)
    printf("Cannot rmdir '%s': %d\n", argv[1], ret);

  return 0;
}

static int shell_cat (int argc, char *argv[])
{
  int fd;
  char buf[4096];
  int len;

  fd = open (argv[1], O_RDONLY);
  if (fd < 0) {
    printf ("Cannot open '%s'\n", argv[1]);
    return -1;
  }

  while (1)
    {
      len = read (fd, buf, sizeof(buf)-1);
      if (len <= 0)
	break;
      buf[len] = '\0';

      printf ("%s", buf);
    }

  close (fd);
  return 0;
}

static int shell_edit (int argc, char *argv[])
{
  int fd;
  char buf[16];
  int len;

  fd = open (argv[1], O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
  if (fd < 0) {
    printf ("Cannot create '%s': %d\n", argv[1], fd);
    return -1;
  }

  /* Activate echo and activate again canonical mode */
  ioctl (0, SOS_IOCTL_TTY_SETPARAM, SOS_IOCTLPARAM_TTY_ECHO);
  ioctl (0, SOS_IOCTL_TTY_SETPARAM, SOS_IOCTLPARAM_TTY_CANON);

  while (1)
    {
      len = read (0, buf, sizeof(buf));
      if (len <= 1)
	break;

      bochs_printf ("Writing %d bytes\n", len);
      len = write (fd, buf, len);
      if (len <= 0) {
	printf ("Cannot write to '%s': %d\n", argv[1], len);
	break;
      }
    }

  /* Desactivate echo and remove canonical mode */
  ioctl (0, SOS_IOCTL_TTY_RESETPARAM, SOS_IOCTLPARAM_TTY_ECHO);
  ioctl (0, SOS_IOCTL_TTY_RESETPARAM, SOS_IOCTLPARAM_TTY_CANON);

  close (fd);
  return 0;
}

static int shell_hexdump (int argc, char *argv[])
{
  int fd;
  char buf[16];
  int count = 0;
  int len;

  fd = open (argv[1], O_RDONLY);
  if (fd < 0) {
    printf ("Cannot open '%s': %d\n", argv[1], fd);
    return -1;
  }

  while (1)
    {
      int i;

      len = read (fd, buf, sizeof(buf));
      if (len <= 0)
	break;

      if (count < 0x10)
	printf ("00%x ", count);
      else if (count < 0x100)
	printf ("0%x ", count);
      else if (count < 0x1000)
	printf ("%x ", count);

      for (i = 0; i < len; i++)
	{
	  if (buf[i] < 0x10)
	    printf ("0%x ", buf[i]);
	  else
	    printf ("%x ", buf[i]);
	}

      printf ("\n");

      count += len;
    }

  close (fd);
  return 0;
}

static int shell_test (int argc, char *argv[])
{
  int i;
  for (i = 0; i < argc; i++)
    {
      printf ("argv[%d] = %s\n", i, argv[i]);
    }
  return 0;
}


static int shell_spawn (int argc, char *argv[])
{
  int retval;
  if (argc < 2)
    {
      printf("Usage: spawn prog_name\n");
      return -1;
    }
  retval = fork();
  if (retval > 0)
    return 0; /* father returns */
  if (retval < 0)
    {
      printf("Could not fork (%d)\n", retval);
      return -1;
    }
  printf("Created new process %d\n", getpid());
  retval = execv(argv[1], & argv[1]);
  printf("Could not exec %s: error %d\n", argv[1], retval);
  exit(0);
  return 0;
}


static int shell_rm (int argc, char *argv[])
{
  int i;

  for (i = 1; i < argc; i++)
    {
      int ret;

      ret = unlink (argv[i]);
      if (ret < 0)
	printf ("Cannot remove '%s', %d\n", argv[i], ret);
    }

  return 0;
}


static int shell_dd (int argc, char *argv[])
{
  char *infile = NULL;
  char *outfile = NULL;
  long bs = 1;
  long count = -1;
  int i;
  int infd, outfd;
  char *buffer;
  int ret;

  for (i = 1; i < argc; i++)
    {
      if (strncmp (argv[i], "if=", 3) == 0)
	infile = argv[i] + 3;
      else if (strncmp (argv[i], "of=", 3) == 0)
	outfile = argv[i] + 3;
      else if (strncmp (argv[i], "bs=", 3) == 0)
	{
	  char *tmp = argv[i] + 3;
	  char *multiplier_char;
	  int multiplier = 1;
	  int j;

	  multiplier_char = & tmp[strlen(tmp)-1];
	  if (*multiplier_char == 'k' ||
	      *multiplier_char == 'K')
	    {
	      multiplier = 1024;
	      *multiplier_char = '\0';
	    }
	  else if (*multiplier_char == 'm' ||
		   *multiplier_char == 'M')
	    {
	      multiplier = 1024 * 1024;
	      *multiplier_char = '\0';
	    }

	  for (j = 0; j < strlen(tmp); j++)
	    if (! isdigit(tmp[j]))
	      {
		printf ("Syntax error in block size\n");
		return -1;
	      }

	  bs = atol(tmp) * multiplier;
	}
      else if (strncmp (argv[i], "count=", 6) == 0)
	{
	  char *tmp = argv[i] + 6;
	  int j;

	  for (j = 0; j < strlen(tmp); j++)
	    if (! isdigit(tmp[j]))
	      {
		printf ("Syntax error in block count\n");
		return -1;
	      }

	  count = atol(tmp);
	}
      else
	{
	  printf ("Syntax error\n");
	  return -1;
	}
    }

  infd = open(infile, O_RDONLY);
  if (infd < 0)
    {
      printf ("Cannot open '%s', %d\n", infile, infd);
      return infd;
    }

  outfd = open(outfile, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
  if (outfd < 0)
    {
      printf ("Cannot open '%s', %d\n", outfile, outfd);
      return outfd;
    }

  buffer = malloc (bs);
  if (! buffer)
    return -1;

  for (i = 0; (count < 0) || (i < count) ; i++)
    {
      int len;

      ret = read (infd, buffer, bs);
      if (ret < 0)
	{
	  printf ("Input error from '%s' at %d\n", infile, i);
	  return -1;
	}
      if (ret == 0)
	break;

      len = ret;

      ret = write (outfd, buffer, len);
      if (ret != len)
	{
	  printf ("Output error to '%s' at %d (%d)\n", outfile, i, ret);
	  return -1;
	}
    }

  return 0;
}


static int shell_partdump (int argc, char *argv[])
{
  /**
   * This structure defines the structure of a partition entry
   * (determined by the PC architecture)
   */
  struct partition_entry
  {
    unsigned char  active;
    unsigned char  start_dl;
    unsigned short start_cylinder;
    unsigned char  type;
    unsigned char  end_dl;
    unsigned short end_cylinder;
    unsigned long  lba;
    unsigned long  size;
  };

  /**
   * Offset of the partition table inside the 512-byte sector.
   */
#define PART_TABLE_OFFSET 446

  /**
   * The most common partition types. For a complete list, you can for
   * example refer to
   * http://www.win.tue.nl/~aeb/partitions/partition_types-1.html
   */
#define PART_TYPE_EXTENDED   0x5
#define PART_TYPE_FAT16_1    0xe
#define PART_TYPE_FAT16_2    0x6
#define PART_TYPE_FAT32_1    0xb
#define PART_TYPE_FAT32_2    0xc
#define PART_TYPE_LINUX_SWAP 0x82
#define PART_TYPE_LINUX      0x83

  /**
   * Converts a partition type to a string
   */
  const char *
    sos_part_type_str (unsigned int type)
    {
      switch (type)
	{
	case PART_TYPE_EXTENDED:
	  return "Extended";
	case PART_TYPE_FAT16_1:
	case PART_TYPE_FAT16_2:
	  return "FAT16";
	case PART_TYPE_FAT32_1:
	case PART_TYPE_FAT32_2:
	  return "FAT32";
	case PART_TYPE_LINUX_SWAP:
	  return "Linux Swap";
	case PART_TYPE_LINUX:
	  return "Linux";
	default:
	  return "Unknown";
	}
    }

  int fd;
  /* We assume the block size is 512 bytes. The clean way would be to
     have a BLKGETSIZE ioctl() on block devices */
#define BLKSIZE 512
  char buffer[BLKSIZE];
  int ret;
  struct partition_entry *part_entry;
  int partnum;
  unsigned int extstart = 0, extsup = 0;

  if (argc != 2)
    {
      printf ("Usage: partdump /dev/device\n");
      return -1;
    }

  fd = open (argv[1], O_RDONLY);
  if (fd < 0)
    {
      printf ("Cannot open '%s', %d\n", argv[1], fd);
      return -1;
    }

  ret = read (fd, buffer, sizeof(buffer));
  if (ret != sizeof(buffer))
    {
      printf ("Read error in '%s', %d\n", argv[1], fd);
      return -1;
    }

  part_entry = (struct partition_entry *) (buffer + PART_TABLE_OFFSET);

  printf ("Partitions in %s:\n", argv[1]);

  /* Handle primary partitions */
  for (partnum = 0; partnum < 4; partnum++)
    {
      if (part_entry [partnum].size == 0)
	continue;

      if (part_entry [partnum].type == PART_TYPE_EXTENDED)
	{
	  if (extstart != 0)
	    printf ("Warning: two extended partitions detected\n");
	  extstart = part_entry [partnum].lba;
	  continue;
	}

      /* When size is >= 1 Mb, display size in Mb, otherwise display
	 size in Kb */
      if (part_entry[partnum].size * BLKSIZE >= (1024*1024))
	printf (" - %s%d (primary, %lu Mb, %s)\n", argv[1], partnum+1,
		(part_entry[partnum].size * BLKSIZE >> 20),
		sos_part_type_str(part_entry[partnum].type));
      else
	printf (" - %s%d (primary, %lu Kb, %s)\n", argv[1], partnum+1,
		(part_entry[partnum].size * BLKSIZE >> 10),
		sos_part_type_str(part_entry[partnum].type));
    }

  while (extstart != 0)
    {
      ret = lseek (fd, (extstart + extsup) * BLKSIZE, SEEK_SET);
      if (ret != (extstart + extsup) * BLKSIZE)
	{
	  printf ("Cannot seek at position %d in '%s', %d\n",
		  (extstart + extsup) * BLKSIZE, argv[1], ret);
	  return -1;
	}

      ret = read (fd, buffer, BLKSIZE);
      if (ret != BLKSIZE)
	{
	  printf ("Read error in '%s', %d\n", argv[1], ret);
	  break;
	}

      /* When size is >= 1 Mb, display size in Mb, otherwise display
	 size in Kb */
      if (part_entry[0].size * BLKSIZE >= (1024*1024))
	printf (" - %s%d (logical volume, %lu Mb, %s)\n", argv[1], partnum+1,
		(part_entry[0].size * BLKSIZE >> 20),
		sos_part_type_str(part_entry[0].type));
      else
	printf (" - %s%d (logical volume, %lu Kb, %s)\n", argv[1], partnum+1,
		(part_entry[0].size * BLKSIZE >> 10),
		sos_part_type_str(part_entry[0].type));

      extsup = part_entry[1].lba;
      partnum ++;
      if (extsup == 0)
	break;
    }

  return 0;
}

static int shell_mount (int argc, char *argv[])
{
  /*char * end = NULL;*/
  int retval = 0;
  int flags = 0;

  if (strncmp(argv[1], "-t", 2)) {
    /*flags = strtol(argv[1], &end, 10);*/
    if (argc == 8) {
	retval = mount(argv[4], argv[5], argv[3], flags, argv[7]);
    } else {
	if (argc == 6) {
	    retval = mount(argv[4], argv[5], argv[3], flags, NULL);
	} else {
	    printf("mount [FLAGS] -t TYPE DEVICE MOUNT_DIR [-o ARGS]\n");
	}
    }
  } else {
    if (argc == 7) {
	retval = mount(argv[3], argv[4], argv[2], 0, argv[6]);
    } else {
	if (argc == 5) {
	    retval = mount(argv[3], argv[4], argv[2], 0, NULL);
	} else {
	    printf("mount [FLAGS] -t TYPE DEVICE MOUNT_DIR [-o ARGS]\n");
	}
    }
  }

  if (retval != 0)
    printf("Cannot mount %s (%d)\n", argv[2], retval);
  return retval;
}

static int shell_umount (int argc, char *argv[])
{
  int retval = 0;

  if (argc == 2)
    retval = umount(argv[1]);
  else
    printf("umount DIR\n");

  if (retval != 0)
    printf("Cannot umount %s (%d)\n", argv[1], retval);
  return retval;
}

static int shell_mmap (int argc, char *argv[])
{
  /*
   * test mmap
   */
  int fd, ret;

  /* Common use: shared file suppressed as soon as possible */
  fd = open("mmap.txt", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);

  if (fork() == 0)
    {
      char *shrd;
      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd children error\n");

      nanosleep(1, 0);
      strzcpy(shrd, "Hello1 from the child (shared mapping) !", 4096);
      exit(0);
    }
  else
    {
      char *shrd;
      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd father error\n");

      strzcpy(shrd, "Garbage garbage garbage", 256);
      nanosleep(2, 0);
      bochs_printf("Father woken up\n");
      bochs_printf("Read string from child: '%s'\n", shrd);
      if (strcmp(shrd, "Hello1 from the child (shared mapping) !") == 0)
	bochs_printf("TEST1 OK\n");
      munmap(shrd, 8192);
    }
  ret = close(fd);
  if (ret == 0)
    bochs_printf("close OK\n");
  ret = unlink("mmap.txt");
  if (ret == 0)
    bochs_printf("delete mmap.txt OK\n");

  shell_ls_internal(1, 0, 1);

  /* Common use: shared file suppressed as soon as possible */
  fd = open("mmap.txt", O_RDWR | O_CREAT,
				  S_IRUSR | S_IWUSR);
  ret = unlink("mmap.txt");
  if (ret == 0)
    bochs_printf("delete mmap.txt OK 2\n");
  if (fork() == 0)
    {
      char *shrd;
      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
					MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd children error\n");

      nanosleep(1, 0);
      strzcpy(shrd, "Hello2 from the child (shared mapping) !", 4096);
      exit(0);
    }
  else
    {
      char *shrd;
      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
					MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd father error\n");

      strzcpy(shrd, "Garbage garbage garbage", 256);
      nanosleep(2, 0);
      bochs_printf("Father woken up\n");
      bochs_printf("Read string from child: '%s'\n", shrd);
      if (strcmp(shrd, "Hello2 from the child (shared mapping) !") == 0)
	bochs_printf("Test 2 OK\n");
      /*msync(shrd, 4096, MAP_SHARED);*/
      munmap(shrd, 8192);
    }
  ret = close(fd);
  if (ret == 0)
    bochs_printf("close OK\n");

  shell_ls_internal(1, 0, 1);

  /* Basic use */
  ret = creat("mmap.txt", S_IRUSR | S_IWUSR);
  if (ret == 0)
    bochs_printf("creat OK\n");
  if (fork() == 0)
    {
      char *shrd;
      fd = open("mmap.txt", O_RDWR | O_CREAT,
				      S_IRUSR | S_IWUSR);

      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
					MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd children error\n");
      nanosleep(1, 0);
      strzcpy(shrd, "Hello3 from the child (shared mapping) !", 4096);
      exit(0);
    }
  else
    {
      char *shrd;
      fd = open("mmap.txt", O_RDWR | O_CREAT,
				      S_IRUSR | S_IWUSR);

      shrd = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
					MAP_SHARED, fd, 4096);
      if (shrd == NULL)
	bochs_printf("shrd father error\n");

      strzcpy(shrd, "Garbage garbage garbage", 256);
      nanosleep(2, 0);
      bochs_printf("Father woken up\n");
      bochs_printf("Read string from child: '%s'\n", shrd);
      if (strcmp(shrd, "Hello3 from the child (shared mapping) !") == 0)
	bochs_printf("TEST3 OK\n");
	
      munmap(shrd, 8192);
      ret = close(fd);
      if (ret == 0)
        bochs_printf("close OK\n");
    }
  shell_ls_internal(1, 0, 1);

    return 0;
}

void command_exec (char * cmd)
{
  char *c;
  int argc = 1, i;
  char **argv;

  for (c = cmd; *c != '\0'; c++)
    {
      if (*c == ' ')
	{
	  /* Skip all spaces */
	  while (*c && *c == ' ')
	    c++;

	  /* Reached the end of the command line ? */
	  if (! *c)
	    break;

	  argc++;
	}
    }

  argv = malloc ((argc+1) * sizeof(char*));
  argv[argc] = NULL; /* To be compatible with execv(e) */
  if (argv == NULL)
    return;

  for (i = 0, c = cmd; i < argc; i++)
    {
      argv[i] = c;
      while (*c != ' ' && *c != '\0')
	c++;
      *c = '\0';
      c++;
      /* Skip spaces */
      while (*c && *c == ' ')
	c++;
    }

  if (! strcmp (argv[0], "uname"))
    shell_uname(argc, argv);

  else if (! strcmp (argv[0], "ls"))
    {
      if (argv[1])
	shell_ls (argv[1], 1, 0);
      else
	shell_ls (".", 1, 0);
    }

  else if (! strcmp (argv[0], "cd"))
    {
      shell_chdir(argc, argv);
    }

  else if (! strcmp (argv[0], "touch"))
    {
      shell_touch (argc, argv);
    }

  else if (! strcmp (argv[0], "mkdir"))
    {
      shell_mkdir (argc, argv);
    }

  else if (! strcmp (argv[0], "rmdir"))
    {
      shell_rmdir (argc, argv);
    }

  else if (! strcmp (argv[0], "cat"))
    {
      shell_cat (argc, argv);
    }

  else if (! strcmp (argv[0], "edit"))
    {
      shell_edit (argc, argv);
    }

  else if (! strcmp (argv[0], "hexdump"))
    {
      shell_hexdump (argc, argv);
    }
  else if (! strcmp (argv[0], "test"))
    {
      shell_test (argc, argv);
    }
  else if (! strcmp (argv[0], "spawn"))
    {
      shell_spawn (argc, argv);
    }
  else if (! strcmp (argv[0], "dd"))
    {
      shell_dd (argc, argv);
    }
  else if (! strcmp (argv[0], "rm"))
    {
      shell_rm (argc, argv);
    }
  else if (! strcmp (argv[0], "partdump"))
    {
      shell_partdump (argc, argv);
    }
  else if (! strcmp (argv[0], "mount"))
    {
      shell_mount (argc, argv);
    }
  else if (! strcmp (argv[0], "umount"))
    {
      shell_umount (argc, argv);
    }
  else if (! strcmp (argv[0], "mmap"))
    {
      shell_mmap (argc, argv);
    }
  else if (! strcmp(argv[0], "getenv"))
    {
      if (argc > 1)
	printf("%s\n", getenv(argv[1]));
      else
	printf("Variable name missing\n");
    }
  else if (! strcmp(argv[0], "setenv"))
    {
      if (argc > 2)
	printf("retval=%d\n",
	       setenv(argv[1], argv[2], TRUE));
      else
	printf("Variable name/value missing\n");
    }
  else if (! strcmp(argv[0], "unsetenv"))
    {
      if (argc > 1)
	unsetenv(argv[1]);
      else
	printf("Variable name missing\n");
    }
  else
    printf ("Command not found\n");

  free (argv);
}

int main(void)
{
  char buffer[256];
  int i;
  char chr;

  ioctl (0, SOS_IOCTL_TTY_RESETPARAM, SOS_IOCTLPARAM_TTY_CANON);

  while (1)
    {
      memset (buffer, 0, sizeof(buffer));
      i = 0;
      printf ("$ ");

      while (1)
	{
	  read (0, & chr, 1);
	  if (chr == '\n')
	    {
	      buffer[i] = '\0';
	      printf ("\n");
	      if (i != 0)
		command_exec (buffer);
	      break;
	    }
	  else if (chr == '\b')
	    {
	      if (i > 0)
		{
		  i--;
		  printf ("\b");
		}
	    }

	  else if (i < 256)
	    {
	      buffer[i++] = chr;
	      printf ("%c", chr);
	    }
	  else
	    printf ("%c", chr);
	}
    }

  return 0;
}