/* Copyright 1999 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

/* This program checks a list of files against stat information
 * as produced by the os-statfiles program, and recreates regular
 * files, symlinks, and directories whose stat information does
 * not match the given data.  Files are recreated by copying from
 * a given root directory, presumably an Athena /os hierarchy.
 */

static const char rcsid[] = "$Id: os-checkfiles.c,v 1.6 2004/04/20 15:26:18 rbasch Exp $";

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <utime.h>
#include <dirent.h>
#include <limits.h>
#include <fcntl.h>
#include <errno.h>
#include "array.h"

#define MAXLINE ((PATH_MAX * 2) + 256)

/* Bit mask for chmod() */
#define MODEMASK (S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO)

char *progname;

char *osroot = "/os";
Array *exceptlist = NULL;
int noop = 0;
int verbose = 0;

void usage();

void do_file(const char *path, const struct stat *statp, mode_t mode,
	     off_t size, uid_t uid, gid_t gid, time_t mtime);

void do_symlink(const char *from, const struct stat *statp, const char *to);

void do_hardlink(const char *path, const struct stat *statp, const char *to);

void do_directory(const char *path, const struct stat *statp, mode_t mode,
		  uid_t uid, gid_t gid);

void nuke(const char *path, const struct stat *statp);

void nukedir(const char *path);

void copyfile(const char *from, const char *to, const struct stat *to_statp,
	      off_t size);

void make_parent(const char *path);

void set_stat(const char *path, mode_t mode, uid_t uid, gid_t gid);

Array *make_list(const char *file);

int in_list(const Array *list, const char *what);

int compare_string(const void *p1, const void *p2);

char *estrdup(const char *s);


void usage()
{
  fprintf(stderr, "Usage: %s [<options>] <statfile>\n", progname);
  fprintf(stderr, "Options:\n");
  fprintf(stderr, "        -n               No-op mode\n");
  fprintf(stderr, "        -o <osroot>      OS root, default is /os\n");
  fprintf(stderr, "        -r <target>      Target root, default is /\n");
  fprintf(stderr, "        -v               Verbose output mode\n");
  fprintf(stderr, "        -x <file>        File containing exception list\n");
  exit(1);
}

int main(int argc, char **argv)
{
  const char *statfile = NULL;
  const char *exceptfile = NULL;
  const char *target = "/";
  FILE *statfp;
  char inbuf[MAXLINE];
  char *path;
  char linkpath[PATH_MAX+1];
  struct stat sb, *statp;
  unsigned long long mode, uid, gid, size;
  int c, len;
  time_t mtime;

  progname = argv[0];

  while ((c = getopt(argc, argv, "no:r:vx:")) != EOF)
    {
      switch(c)
	{
	case 'n':
	  noop = 1;
	  break;
	case 'o':
	  osroot = optarg;
	  break;
	case 'r':
	  target = optarg;
	  break;
	case 'v':
	  verbose = 1;
	  break;
	case 'x':
	  exceptfile = optarg;
	  break;
	case '?':
	  usage();
	  break;
	}
    }

  if (optind + 1 != argc)
    usage();

  statfile = argv[optind++];
  statfp = fopen(statfile, "r");
  if (statfp == NULL)
    {
      fprintf(stderr, "%s: Cannot open %s: %s\n", progname, statfile,
	      strerror(errno));
      exit(1);
    }

  if (stat(osroot, &sb) != 0 || !S_ISDIR(sb.st_mode))
    {
      fprintf(stderr, "%s: Invalid operating system root %s\n",
	      progname, osroot);
      exit(1);
    }

  if (exceptfile != NULL)
    exceptlist = make_list(exceptfile);

  /* Chdir to the target root. */
  if (chdir(target) != 0)
    {
      fprintf(stderr, "%s: Cannot chdir to %s: %s\n",
	      progname, target, strerror(errno));
      exit(1);
    }

  /* Main loop -- read entries from the stat file. */
  while (fgets(inbuf, sizeof(inbuf), statfp) != NULL)
    {
      len = strlen(inbuf);
      if (inbuf[len-1] != '\n')
	{
	  fprintf(stderr, "%s: Invalid entry '%s', aborting\n",
		  progname, inbuf);
	  exit(1);
	}
      inbuf[--len] = '\0';

      /* Get the entry path, always the last field in the line.
       * Skip it if it is in the exception list.
       * Note now whether we can stat it.
       */
      for (path = &inbuf[len-1]; path > &inbuf[0] && *path != ' '; --path);
      if (path <= &inbuf[0])
	{
	  fprintf(stderr, "%s: Invalid entry '%s', aborting\n",
		  progname, inbuf);
	  exit(1);
	}
      ++path;

      if (in_list(exceptlist, path))
	{
	  if (verbose)
	    printf("Skipping exception %s\n", path);
	  continue;
	}

      statp = (lstat(path, &sb) == 0 ? &sb : NULL);

      switch (inbuf[0])
	{
	case 'l':
	  if (sscanf(&inbuf[2], "%s", linkpath) != 1)
	    {
	      fprintf(stderr,
		      "%s: Invalid symlink entry '%s', aborting\n",
		      progname, inbuf);
	      exit(1);
	    }
	  do_symlink(path, statp, linkpath);
	  break;
	case 'f':
	  if (sscanf(&inbuf[2], "%llo %llu %llu %llu %lu", &mode, &size,
		     &uid, &gid, &mtime) != 5)
	    {
	      fprintf(stderr,
		      "%s: Invalid file entry '%s', aborting\n",
		      progname, inbuf);
	      exit(1);
	    }
	  do_file(path, statp, mode & MODEMASK, size, uid, gid, mtime);
	  break;
	case 'h':
	  if (sscanf(&inbuf[2], "%s", linkpath) != 1)
	    {
	      fprintf(stderr,
		      "%s: Invalid hard link entry '%s', aborting\n",
		      progname, inbuf);
	      exit(1);
	    }
	  do_hardlink(path, statp, linkpath);
	  break;
	case 'd':
	  if (sscanf(&inbuf[2], "%llo %llu %llu", &mode, &uid, &gid) != 3)
	    {
	      fprintf(stderr,
		      "%s: Invalid directory entry '%s', aborting\n",
		      progname, inbuf);
	      exit(1);
	    }
	  do_directory(path, statp, mode & MODEMASK, uid, gid);
	  break;
	default:
	  fprintf(stderr, "%s: Unrecognized type '%c', aborting.\n",
		  progname, inbuf[0]);
	  exit(1);
	}
    }
  exit(0);
}

void do_file(const char *path, const struct stat *statp, mode_t mode,
	     off_t size, uid_t uid, gid_t gid, time_t mtime)
{
  struct stat sb;
  char ospath[PATH_MAX+1];
  struct utimbuf utbuf;

  if (statp == NULL
      || !S_ISREG(statp->st_mode)
      || statp->st_mtime != mtime
      || statp->st_size != size)
    {
      printf("Replace regular file %s\n", path);
      if (!noop)
	{
	  /* Copy the file into place. */
	  sprintf(ospath, "%s/%s", osroot, path);
	  copyfile(ospath, path, statp, size);

	  /* Make sure new copy has expected size. */
	  if (lstat(path, &sb) != 0)
	    {
	      fprintf(stderr, "%s: Cannot stat %s after copy: %s\n",
		      progname, path, strerror(errno));
	      exit(1);
	    }
	  if (sb.st_size != size)
	    {
	      fprintf(stderr,
		      "%s: Size mismatch after copy of %s (%llu, %llu)\n",
		      progname, path, (unsigned long long) size,
		      (unsigned long long) sb.st_size);
	      exit(1);
	    }

	  set_stat(path, mode, uid, gid);

	  /* Set the restored file's modification time to the expected
	   * value.  The file access time gets the same value, since it
	   * is handy.
	   */
	  utbuf.actime = mtime;
	  utbuf.modtime = mtime;
	  if (utime(path, &utbuf) != 0)
	    {
	      fprintf(stderr,
		      "%s: Cannot set modification time of %s: %s\n",
		      progname, path, strerror(errno));
	      exit(1);
	    }
	}
    }

  else if ((statp->st_mode & MODEMASK) != mode
	   || statp->st_uid != uid
	   || statp->st_gid != gid)
    {
      /* Here to fix file permissions and ownership. */
      printf("Set permission/ownership of regular file %s\n", path);
      if (!noop)
	set_stat(path, mode, uid, gid);
    }

  return;
}

void do_symlink(const char *from, const struct stat *statp, const char *to)
{
  char linkbuf[PATH_MAX+1];
  int len, status;
  int result = 0;

  if (statp != NULL && S_ISLNK(statp->st_mode))
    {
      len = readlink(from, linkbuf, sizeof(linkbuf));
      if (len > 0)
	{
	  linkbuf[len] = '\0';
	  if (strcmp(linkbuf, to) == 0)
	    result = 1;
	}
    }
  if (!result)
    {
      printf("Relink (symbolic) %s to %s\n", from, to);
      if (!noop)
	{
	  nuke(from, statp);
	  status = symlink(to, from);
	  if (status != 0 && (errno == ENOENT || errno == ENOTDIR))
	    {
	      /* The parent directory does not exist.  Create it and retry. */
	      make_parent(from);
	      status = symlink(to, from);
	    }
	  if (status != 0)
	    {
	      fprintf(stderr, "%s: Cannot create symlink %s: %s\n",
		      progname, from, strerror(errno));
	      exit(1);
	    }
	}
    }
}

/* Handle a hard link. */
void do_hardlink(const char *path, const struct stat *statp, const char *to)
{
  struct stat to_stat;
  int status;

  if (lstat(to, &to_stat) != 0)
    {
      fprintf(stderr,
	      "%s: Warning: %s (link to %s) does not exist\n",
	      progname, to, path);
      return;
    }
  if (S_ISDIR(to_stat.st_mode))
    {
      fprintf(stderr,
	      "%s: Warning: %s (link to %s) is a directory\n",
	      progname, to, path);
      return;
    }

  if (statp == NULL
      || statp->st_ino != to_stat.st_ino
      || statp->st_dev != to_stat.st_dev)
    {
      printf("Relink (hard) %s to %s\n", path, to);
      if (!noop)
	{
	  if (statp != NULL)
	    nuke(path, statp);
	  status = link(to, path);
	  if (status != 0 && (errno == ENOENT || errno == ENOTDIR))
	    {
	      /* The parent directory does not exist.  Create it and retry. */
	      make_parent(path);
	      status = link(to, path);
	    }
	  if (status != 0)
	    {
	      fprintf(stderr, "%s: Cannot create hard link %s to %s: %s\n",
		      progname, path, to, strerror(errno));
	      exit(1);
	    }
	}
    }
}

void do_directory(const char *path, const struct stat *statp, mode_t mode,
		  uid_t uid, gid_t gid)
{
  int status;

  if (statp == NULL || !S_ISDIR(statp->st_mode))
    {
      /* Path doesn't exist, or is not a directory. Recreate it. */
      printf("Recreate directory %s\n", path);
      if (!noop)
	{
	  if (statp != NULL)
	    nuke(path, statp);
	  status = mkdir(path, S_IRWXU);
	  if (status != 0 && (errno == ENOENT || errno == ENOTDIR))
	    {
	      /* The parent directory does not exist.  Create it and retry. */
	      make_parent(path);
	      status = mkdir(path, S_IRWXU);
	    }
	  if (status != 0)
	    {
	      fprintf(stderr, "%s: Cannot mkdir %s: %s\n",
		      progname, path, strerror(errno));
	      exit(1);
	    }
	}
    }
  else if ((statp->st_mode & MODEMASK) == mode
	   && statp->st_uid == uid
	   && statp->st_gid == gid)
    return;

  /* Here when path is a directory, but needs permissions and ownership
   * to be set.
   */
  printf("Set permission/ownership of directory %s\n", path);
  if (!noop)
    set_stat(path, mode, uid, gid);
  return;
}

void nuke(const char *path, const struct stat *statp)
{
  if (statp == NULL)
    return;
  if (S_ISDIR(statp->st_mode))
    nukedir(path);
  else if (unlink(path) != 0)
    {
      fprintf(stderr, "%s: Cannot unlink %s: %s\n",
	      progname, path, strerror(errno));
      exit(1);
    }
  return;
}


void nukedir(const char *path)
{
  DIR *dirp;
  struct dirent *dp;
  char pathbuf[PATH_MAX+1];
  struct stat sb;

  dirp = opendir(path);
  if (dirp == NULL)
    {
      fprintf(stderr, "%s: Cannot open directory %s: %s\n",
	      progname, path, strerror(errno));
      exit(1);
    }
  while ((dp = readdir(dirp)) != NULL)
    {
      if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)
	continue;
      sprintf(pathbuf, "%s/%s", path, dp->d_name);
      if (lstat(pathbuf, &sb) != 0)
	{
	  fprintf(stderr, "%s: Cannot stat %s: %s\n",
		  progname, pathbuf, strerror(errno));
	  continue;
	}
      /* Recurse if we encounter a subdirectory. */
      if (S_ISDIR(sb.st_mode))
	nukedir(pathbuf);
      else if (unlink(pathbuf) != 0)
	{
	  fprintf(stderr, "%s: Cannot unlink %s: %s\n",
		  progname, pathbuf, strerror(errno));
	  exit(1);
	}
    }
  closedir(dirp);
  if (rmdir(path) != 0)
    {
      fprintf(stderr, "%s: Cannot rmdir %s: %s\n",
	      progname, path, strerror(errno));
      exit(1);
    }
  return;
}

/* Copy a file.  If the target exists, it will be nuked before copying
 * the file into place.
 */
void copyfile(const char *from, const char *to, const struct stat *to_statp,
	      off_t size)
{
  char buf[4096];
  FILE *infp, *outfp;
  int n, fd, status;
  struct stat from_stat;

  /* Open and check the input file. */
  infp = fopen(from, "r");
  if (infp == NULL)
    {
      fprintf(stderr, "%s: Cannot open %s: %s\n",
	      progname, from, strerror(errno));
      exit(1);
    }
  if (fstat(fileno(infp), &from_stat) == -1)
    {
      fprintf(stderr, "%s: Cannot stat %s: %s\n",
	      progname, from, strerror(errno));
      fclose(infp);
      exit(1);
    }
  if (from_stat.st_size != size)
    {
      fprintf(stderr, "%s: Size mismatch for %s (%llu, %llu)\n",
	      progname, from, (unsigned long long) size,
	      (unsigned long long) from_stat.st_size);
      fclose(infp);
      exit(1);
    }

  /* Remove the existing path, if any. */
  nuke(to, to_statp);

  fd = open(to, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
  if (fd < 0 && (errno == ENOENT || errno == ENOTDIR))
    {
      /* The parent directory does not exist.  Create it and retry. */
      make_parent(to);
      fd = open(to, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
    }
  if (fd < 0)
    {
      fprintf(stderr, "%s: Cannot create %s: %s\n",
	      progname, to, strerror(errno));
      fclose(infp);
      exit(1);
    }
  outfp = fdopen(fd, "w");
  if (outfp == NULL)
    {
      fprintf(stderr, "%s: fdopen failed for %s: %s\n",
	      progname, to, strerror(errno));
      fclose(infp);
      close(fd);
      exit(1);
    }

  while ((n = fread(buf, 1, sizeof(buf), infp)) > 0)
    {
      if (fwrite(buf, 1, n, outfp) != n)
	{
	  fprintf(stderr, "%s: Write failed for %s: %s\n",
		  progname, to, strerror(errno));
	  fclose(infp);
	  fclose(outfp);
	  exit(1);
	}
    }
  status = ferror(infp);
  if ((fclose(infp) != 0) || (status != 0))
    {
      fprintf(stderr, "%s: Error reading %s: %s\n",
	      progname, from, strerror(errno));
      fclose(outfp);
      exit(1);
    }
  status = ferror(outfp);
  if ((fclose(outfp) != 0) || (status != 0))
    {
      fprintf(stderr, "%s: Error writing %s: %s\n",
	      progname, to, strerror(errno));
      exit(1);
    }
  return;
}

/* Ensure that the parent directory of the given path exists, by
 * creating all components of the path prefix, as necessary.
 * If any path component exists but is not a directory, it is
 * removed.
 * Directories are created mode 755, owned by the current user.
 */
void make_parent(const char *path)
{
  char *p, *path_buf;
  struct stat sb;
  mode_t saved_umask;

  /* Make a copy of the path string so we can modify it. */
  path_buf = estrdup(path);

  saved_umask = umask(0);

  p = path_buf;
  while (*p == '/')
    p++;

  /* Find the first component in the path prefix that does not exist. */
  while ((p = strchr(p, '/')) != NULL)
    {
      *p = '\0';
      if (stat(path_buf, &sb) != 0)
	break;
      if (!S_ISDIR(sb.st_mode))
	{
	  /* Component exists, but is not a directory.  Nuke it. */
	  printf("Remove non-directory path prefix %s\n", path_buf);
	  unlink(path_buf);
	  break;
	}
      *p++ = '/';
    }

  /* The remaining path components do not exist -- create them. */
  for ( ; p != NULL; p = strchr(p, '/'))
    {
      *p = '\0';
      printf("Create path prefix %s\n", path_buf);
      if (mkdir(path_buf, 0755) != 0)
	{
	  fprintf(stderr, "%s: Cannot mkdir %s: %s\n",
		  progname, path_buf, strerror(errno));
	  exit(1);
	}
      *p++ = '/';
    }

  free(path_buf);
  umask(saved_umask);
  return;
}

void set_stat(const char *path, mode_t mode, uid_t uid, gid_t gid)
{
  if (chmod(path, mode & MODEMASK) != 0)
    {
      fprintf(stderr, "%s: Cannot chmod %s: %s\n",
	      progname, path, strerror(errno));
      exit(1);
    }
  if (chown(path, uid, gid) != 0)
    {
      fprintf(stderr, "%s: Cannot chown %s: %s\n",
	      progname, path, strerror(errno));
      exit(1);
    }
}

/* Read a file into an array, one element per line. */
Array *make_list(const char *file)
{
  FILE *f;
  Array *list;
  char buffer[MAXLINE];

  f = fopen(file, "r");
  if (f == NULL)
    return NULL;

  list = array_new();
  while (fgets(buffer, sizeof(buffer), f))
    {
      buffer[strlen(buffer) - 1] = '\0';
      array_add(list, estrdup(buffer));
    }

  fclose(f);
  array_sort(list, compare_string);
  return list;
}

/* Check if the given string is an element in the given array.
 * Returns 1 if found in the array, 0 otherwise.
 */
int in_list(const Array *list, const char *what)
{
  if (list == NULL)
    return 0;

  return (array_search(list, what) != NULL);
}

int compare_string(const void *p1, const void *p2)
{
  return strcmp(*((char **)p1), *((char **)p2));
}

char *estrdup(const char *s)
{
  char *s2;

  s2 = strdup(s);
  if (s2 == NULL)
    {
      fprintf(stderr, "%s: Out of memory\n", progname);
      exit(1);
    }
  return s2;
}