libguestfs/fish/fish.c

/* guestfish - the filesystem interactive shell
 * Copyright (C) 2009 Red Hat Inc. 
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <config.h>

#define _GNU_SOURCE // for strchrnul

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <getopt.h>
#include <assert.h>

#ifdef HAVE_LIBREADLINE
#include <readline/readline.h>
#include <readline/history.h>
#endif

#include <guestfs.h>

#include "fish.h"

struct mp {
  struct mp *next;
  char *device;
  char *mountpoint;
};

static void mount_mps (struct mp *mp);
static void interactive (void);
static void shell_script (void);
static void script (int prompt);
static void cmdline (char *argv[], int optind, int argc);
static int issue_command (const char *cmd, char *argv[]);
static void initialize_readline (void);
static void cleanup_readline (void);
static void add_history_line (const char *);

/* Currently open libguestfs handle. */
guestfs_h *g;
int g_launched = 0;

int read_only = 0;
int quit = 0;
int verbose = 0;

int
launch (guestfs_h *_g)
{
  assert (_g == g);

  if (!g_launched) {
    if (guestfs_launch (g) == -1)
      return -1;
    if (guestfs_wait_ready (g) == -1)
      return -1;
    g_launched = 1;
  }
  return 0;
}

static void
usage (void)
{
  fprintf (stderr,
	   "guestfish: guest filesystem shell\n"
	   "guestfish lets you edit virtual machine filesystems\n"
	   "Copyright (C) 2009 Red Hat Inc.\n"
	   "Usage:\n"
	   "  guestfish [--options] cmd [: cmd : cmd ...]\n"
	   "or for interactive use:\n"
	   "  guestfish\n"
	   "or from a shell script:\n"
	   "  guestfish <<EOF\n"
	   "  cmd\n"
	   "  ...\n"
	   "  EOF\n"
	   "Options:\n"
	   "  -h|--cmd-help        List available commands\n"
	   "  -h|--cmd-help cmd    Display detailed help on 'cmd'\n"
	   "  -a|--add image       Add image\n"
	   "  -m|--mount dev[:mnt] Mount dev on mnt (if omitted, /)\n"
	   "  -n|--no-sync         Don't autosync\n"
	   "  -r|--ro              Mount read-only\n"
	   "  -v|--verbose         Verbose messages\n"
	   "  -V|--version         Display version and exit\n"
	   "For more information,  see the manpage guestfish(1).\n");
}

int
main (int argc, char *argv[])
{
  static const char *options = "a:h::m:nrv?V";
  static struct option long_options[] = {
    { "add", 1, 0, 'a' },
    { "cmd-help", 2, 0, 'h' },
    { "help", 0, 0, '?' },
    { "mount", 1, 0, 'm' },
    { "no-sync", 0, 0, 'n' },
    { "ro", 0, 0, 'r' },
    { "verbose", 0, 0, 'v' },
    { "version", 0, 0, 'V' },
    { 0, 0, 0, 0 }
  };
  struct mp *mps = NULL;
  struct mp *mp;
  char *p;
  int c;

  initialize_readline ();

  /* guestfs_create is meant to be a lightweight operation, so
   * it's OK to do it early here.
   */
  g = guestfs_create ();
  if (g == NULL) {
    fprintf (stderr, "guestfs_create: failed to create handle\n");
    exit (1);
  }

  guestfs_set_autosync (g, 1);

  /* If developing, add . to the path.  Note that libtools interferes
   * with this because uninstalled guestfish is a shell script that runs
   * the real program with an absolute path.  Detect that too.
   *
   * BUT if LIBGUESTFS_PATH environment variable is already set by
   * the user, then don't override it.
   */
  if (getenv ("LIBGUESTFS_PATH") == NULL &&
      argv[0] &&
      (argv[0][0] != '/' || strstr (argv[0], "/.libs/lt-") != NULL))
    guestfs_set_path (g, ".:" GUESTFS_DEFAULT_PATH);

  for (;;) {
    c = getopt_long (argc, argv, options, long_options, NULL);
    if (c == -1) break;

    switch (c) {
    case 'a':
      if (access (optarg, R_OK) != 0) {
	perror (optarg);
	exit (1);
      }
      if (guestfs_add_drive (g, optarg) == -1)
	exit (1);
      break;

    case 'h':
      if (optarg)
	display_command (optarg);
      else if (argv[optind] && argv[optind][0] != '-')
	display_command (argv[optind++]);
      else
	list_commands ();
      exit (0);

    case 'm':
      mp = malloc (sizeof (struct mp));
      if (!mp) {
	perror ("malloc");
	exit (1);
      }
      p = strchr (optarg, ':');
      if (p) {
	*p = '\0';
	mp->mountpoint = p+1;
      } else
	mp->mountpoint = "/";
      mp->device = optarg;
      mp->next = mps;
      mps = mp;
      break;

    case 'n':
      guestfs_set_autosync (g, 0);
      break;

    case 'r':
      read_only = 1;
      break;

    case 'v':
      verbose++;
      guestfs_set_verbose (g, verbose);
      break;

    case 'V':
      printf ("guestfish %s\n", PACKAGE_VERSION);
      exit (0);

    case '?':
      usage ();
      exit (0);

    default:
      fprintf (stderr, "guestfish: unexpected command line option 0x%x\n", c);
      exit (1);
    }
  }

  /* If we've got mountpoints, we must launch the guest and mount them. */
  if (mps != NULL) {
    if (launch (g) == -1) exit (1);
    mount_mps (mps);
  }

  /* Interactive, shell script, or command(s) on the command line? */
  if (optind >= argc) {
    if (isatty (0))
      interactive ();
    else
      shell_script ();
  }
  else
    cmdline (argv, optind, argc);

  cleanup_readline ();

  exit (0);
}

void
pod2text (const char *heading, const char *str)
{
  FILE *fp;

  fp = popen ("pod2text", "w");
  if (fp == NULL) {
    /* pod2text failed, maybe not found, so let's just print the
     * source instead, since that's better than doing nothing.
     */
    printf ("%s\n\n%s\n", heading, str);
    return;
  }
  fputs ("=head1 ", fp);
  fputs (heading, fp);
  fputs ("\n\n", fp);
  fputs (str, fp);
  pclose (fp);
}

/* List is built in reverse order, so mount them in reverse order. */
static void
mount_mps (struct mp *mp)
{
  int r;

  if (mp) {
    mount_mps (mp->next);
    if (!read_only)
      r = guestfs_mount (g, mp->device, mp->mountpoint);
    else
      r = guestfs_mount_ro (g, mp->device, mp->mountpoint);
    if (r == -1)
      exit (1);
  }
}

static void
interactive (void)
{
  script (1);
}

static void
shell_script (void)
{
  script (0);
}

#define FISH "><fs> "

static char *line_read = NULL;

static char *
rl_gets (int prompt)
{
#ifdef HAVE_LIBREADLINE

  if (prompt) {
    if (line_read) {
      free (line_read);
      line_read = NULL;
    }

    line_read = readline (prompt ? FISH : "");

    if (line_read && *line_read)
      add_history_line (line_read);

    return line_read;
  }

#endif /* HAVE_LIBREADLINE */

  static char buf[8192];
  int len;

  if (prompt) printf (FISH);
  line_read = fgets (buf, sizeof buf, stdin);

  if (line_read) {
    len = strlen (line_read);
    if (len > 0 && buf[len-1] == '\n') buf[len-1] = '\0';
  }

  return line_read;
}

static void
script (int prompt)
{
  char *buf;
  char *cmd;
  char *p, *pend;
  char *argv[64];
  int i, len;

  if (prompt)
    printf ("\n"
	    "Welcome to guestfish, the libguestfs filesystem interactive shell for\n"
	    "editing virtual machine filesystems.\n"
	    "\n"
	    "Type: 'help' for help with commands\n"
	    "      'quit' to quit the shell\n"
	    "\n");

  while (!quit) {
    buf = rl_gets (prompt);
    if (!buf) {
      quit = 1;
      break;
    }

    /* Skip any initial whitespace before the command. */
    while (*buf && isspace (*buf))
      buf++;

    /* Get the command (cannot be quoted). */
    len = strcspn (buf, " \t");

    if (len == 0) continue;

    cmd = buf;
    i = 0;
    if (buf[len] == '\0') {
      argv[0] = NULL;
      goto got_command;
    }

    buf[len] = '\0';
    p = &buf[len+1];
    p += strspn (p, " \t");

    /* Get the parameters. */
    while (*p && i < sizeof argv / sizeof argv[0]) {
      /* Parameters which start with quotes or square brackets
       * are treated specially.  Bare parameters are delimited
       * by whitespace.
       */
      if (*p == '"') {
	p++;
	len = strcspn (p, "\"");
	if (p[len] == '\0') {
	  fprintf (stderr, "guestfish: unterminated double quote\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	if (p[len+1] && (p[len+1] != ' ' && p[len+1] != '\t')) {
	  fprintf (stderr, "guestfish: command arguments not separated by whitespace\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	p[len] = '\0';
	pend = p[len+1] ? &p[len+2] : &p[len+1];
      } else if (*p == '\'') {
	p++;
	len = strcspn (p, "'");
	if (p[len] == '\0') {
	  fprintf (stderr, "guestfish: unterminated single quote\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	if (p[len+1] && (p[len+1] != ' ' && p[len+1] != '\t')) {
	  fprintf (stderr, "guestfish: command arguments not separated by whitespace\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	p[len] = '\0';
	pend = p[len+1] ? &p[len+2] : &p[len+1];
	/*
      } else if (*p == '[') {
	int c = 1;
	p++;
	pend = p;
	while (*pend && c != 0) {
	  if (*pend == '[') c++;
	  else if (*pend == ']') c--;
	  pend++;
	}
	if (c != 0) {
	  fprintf (stderr, "guestfish: unterminated \"[...]\" sequence\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	if (*pend && (*pend != ' ' && *pend != '\t')) {
	  fprintf (stderr, "guestfish: command arguments not separated by whitespace\n");
	  if (!prompt) exit (1);
	  goto next_command;
	}
	*(pend-1) = '\0';
	*/
      } else if (*p != ' ' && *p != '\t') {
	len = strcspn (p, " \t");
	if (p[len]) {
	  p[len] = '\0';
	  pend = &p[len+1];
	} else
	  pend = &p[len];
      } else {
	fprintf (stderr, "guestfish: internal error parsing string at '%s'\n",
		 p);
	abort ();
      }

      argv[i++] = p;
      p = pend;

      if (*p)
	p += strspn (p, " \t");
    }

    if (i == sizeof argv / sizeof argv[0]) {
      fprintf (stderr, "guestfish: too many arguments\n");
      if (!prompt) exit (1);
      goto next_command;
    }

    argv[i] = NULL;

  got_command:
    if (issue_command (cmd, argv) == -1) {
      if (!prompt) exit (1);
    }

  next_command:;
  }
  if (prompt) printf ("\n");
}

static void
cmdline (char *argv[], int optind, int argc)
{
  const char *cmd;
  char **params;

  if (optind >= argc) return;

  cmd = argv[optind++];
  if (strcmp (cmd, ":") == 0) {
    fprintf (stderr, "guestfish: empty command on command line\n");
    exit (1);
  }
  params = &argv[optind];

  /* Search for end of command list or ":" ... */
  while (optind < argc && strcmp (argv[optind], ":") != 0)
    optind++;

  if (optind == argc) {
    if (issue_command (cmd, params) == -1) exit (1);
  } else {
    argv[optind] = NULL;
    if (issue_command (cmd, params) == -1) exit (1);
    cmdline (argv, optind+1, argc);
  }
}

static int
issue_command (const char *cmd, char *argv[])
{
  int argc;

  for (argc = 0; argv[argc] != NULL; ++argc)
    ;

  if (strcasecmp (cmd, "help") == 0) {
    if (argc == 0)
      list_commands ();
    else
      display_command (argv[0]);
    return 0;
  }
  else if (strcasecmp (cmd, "quit") == 0 ||
	   strcasecmp (cmd, "exit") == 0 ||
	   strcasecmp (cmd, "q") == 0) {
    quit = 1;
    return 0;
  }
  else if (strcasecmp (cmd, "alloc") == 0 ||
	   strcasecmp (cmd, "allocate") == 0)
    return do_alloc (cmd, argc, argv);
  else if (strcasecmp (cmd, "edit") == 0 ||
	   strcasecmp (cmd, "vi") == 0 ||
	   strcasecmp (cmd, "emacs") == 0)
    return do_edit (cmd, argc, argv);
  else
    return run_action (cmd, argc, argv);
}

void
list_builtin_commands (void)
{
  /* help and quit should appear at the top */
  printf ("%-20s %s\n",
	  "help", "display a list of commands or help on a command");
  printf ("%-20s %s\n",
	  "quit", "quit guestfish");

  printf ("%-20s %s\n",
	  "alloc", "allocate an image");
  printf ("%-20s %s\n",
	  "edit", "edit a file in the image");

  /* actions are printed after this (see list_commands) */
}

void
display_builtin_command (const char *cmd)
{
  /* help for actions is auto-generated, see display_command */

  if (strcasecmp (cmd, "alloc") == 0 ||
      strcasecmp (cmd, "allocate") == 0)
    printf ("alloc - allocate an image\n"
	    "     alloc <filename> <size>\n"
	    "\n"
	    "    This creates an empty (zeroed) file of the given size,\n"
	    "    and then adds so it can be further examined.\n"
	    "\n"
	    "    For more advanced image creation, see qemu-img utility.\n"
	    "\n"
	    "    Size can be specified (where <nn> means a number):\n"
	    "    <nn>             number of kilobytes\n"
	    "      eg: 1440       standard 3.5\" floppy\n"
	    "    <nn>K or <nn>KB  number of kilobytes\n"
	    "    <nn>M or <nn>MB  number of megabytes\n"
	    "    <nn>G or <nn>GB  number of gigabytes\n"
	    "    <nn>sects        number of 512 byte sectors\n");
  else if (strcasecmp (cmd, "edit") == 0 ||
	   strcasecmp (cmd, "vi") == 0 ||
	   strcasecmp (cmd, "emacs") == 0)
    printf ("edit - edit a file in the image\n"
	    "     edit <filename>\n"
	    "\n"
	    "    This is used to edit a file.\n"
	    "\n"
	    "    It is the equivalent of (and is implemented by)\n"
	    "    running \"cat\", editing locally, and then \"write-file\".\n"
	    "\n"
	    "    Normally it uses $EDITOR, but if you use the aliases\n"
	    "    \"vi\" or \"emacs\" you will get those editors.\n"
	    "\n"
	    "    NOTE: This will not work reliably for large files\n"
	    "    (> 2 MB) or binary files containing \\0 bytes.\n");
  else if (strcasecmp (cmd, "help") == 0)
    printf ("help - display a list of commands or help on a command\n"
	    "     help cmd\n"
	    "     help\n");
  else if (strcasecmp (cmd, "quit") == 0 ||
	   strcasecmp (cmd, "exit") == 0 ||
	   strcasecmp (cmd, "q") == 0)
    printf ("quit - quit guestfish\n"
	    "     quit\n");
  else
    fprintf (stderr, "%s: command not known, use -h to list all commands\n",
	     cmd);
}

void
free_strings (char **argv)
{
  int argc;

  for (argc = 0; argv[argc] != NULL; ++argc)
    free (argv[argc]);
  free (argv);
}

void
print_strings (char * const * const argv)
{
  int argc;

  for (argc = 0; argv[argc] != NULL; ++argc)
    printf ("%s\n", argv[argc]);
}

void
print_table (char * const * const argv)
{
  int i;

  for (i = 0; argv[i] != NULL; i += 2)
    printf ("%s: %s\n", argv[i], argv[i+1]);
}

int
is_true (const char *str)
{
  return
    strcasecmp (str, "0") != 0 &&
    strcasecmp (str, "f") != 0 &&
    strcasecmp (str, "false") != 0 &&
    strcasecmp (str, "n") != 0 &&
    strcasecmp (str, "no") != 0;
}

/* XXX We could improve list parsing. */
char **
parse_string_list (const char *str)
{
  char **argv;
  const char *p, *pend;
  int argc, i;

  argc = 1;
  for (i = 0; str[i]; ++i)
    if (str[i] == ' ') argc++;

  argv = malloc (sizeof (char *) * (argc+1));
  if (argv == NULL) { perror ("malloc"); exit (1); }

  p = str;
  i = 0;
  while (*p) {
    pend = strchrnul (p, ' ');
    argv[i] = strndup (p, pend-p);
    i++;
    p = *pend == ' ' ? pend+1 : pend;
  }
  argv[i] = NULL;

  return argv;
}

#ifdef HAVE_LIBREADLINE
static char histfile[1024];
static int nr_history_lines = 0;
#endif

static void
initialize_readline (void)
{
#ifdef HAVE_LIBREADLINE
  const char *home;

  home = getenv ("HOME");
  if (home) {
    snprintf (histfile, sizeof histfile, "%s/.guestfish", home);
    using_history ();
    (void) read_history (histfile);
  }

  rl_readline_name = "guestfish";
  rl_attempted_completion_function = do_completion;
#endif
}

static void
cleanup_readline (void)
{
#ifdef HAVE_LIBREADLINE
  int fd;

  if (histfile[0] != '\0') {
    fd = open (histfile, O_WRONLY|O_CREAT, 0644);
    if (fd == -1) {
      perror (histfile);
      return;
    }
    close (fd);

    (void) append_history (nr_history_lines, histfile);
  }
#endif
}

static void
add_history_line (const char *line)
{
#ifdef HAVE_LIBREADLINE
  add_history (line);
  nr_history_lines++;
#endif
}