coreutils/src/copy.c

#ifdef _AIX
 #pragma alloca
#endif

#include <config.h>
#include <stdio.h>

#include "cp.h"
#include "copy.h"
#include "backupfile.h"

/* On Linux (from slackware-1.2.13 to 2.0.2?) there is no lchown function.
   To change ownership of symlinks, you must run chown with an effective
   UID of 0.  */
#ifdef __linux__
# define ROOT_CHOWN_AFFECTS_SYMLINKS
#endif

#define DO_CHOWN(Chown, File, New_uid, New_gid)				\
  (Chown ((File), (x->myeuid == 0 ? (New_uid) : x->myeuid), (New_gid))	\
   /* If non-root uses -p, it's ok if we can't preserve ownership.	\
      But root probably wants to know, e.g. if NFS disallows it.  */	\
   && (errno != EPERM || x->myeuid == 0))

/* Control creation of sparse files (files with holes).  */
enum Sparse_type
{
  /* Never create holes in DEST.  */
  SPARSE_NEVER,

  /* This is the default.  Use a crude (and sometimes inaccurate)
     heuristic to determine if SOURCE has holes.  If so, try to create
     holes in DEST.  */
  SPARSE_AUTO,

  /* For every sufficiently long sequence of bytes in SOURCE, try to
     create a corresponding hole in DEST.  There is a performance penalty
     here because CP has to search for holes in SRC.  But if the holes are
     big enough, that penalty can be offset by the decrease in the amount
     of data written to disk.   */
  SPARSE_ALWAYS
};

struct flag
{
  /* If nonzero, copy all files except (directories and, if not dereferencing
     them, symbolic links,) as if they were regular files. */
  int copy_as_regular;

  /* If nonzero, dereference symbolic links (copy the files they point to). */
  int dereference;

  /* If nonzero, remove existing destination nondirectories. */
  int force;

  /* If nonzero, create hard links instead of copying files.
     Create destination directories as usual. */
  int hard_link;

  /* If nonzero, query before overwriting existing destinations
     with regular files. */
  int interactive;

  /* If nonzero, when copying recursively, skip any subdirectories that are
     on different filesystems from the one we started on. */
  int one_file_system;

  /* If nonzero, give the copies the original files' permissions,
     ownership, and timestamps. */
  int preserve;

  /* If nonzero, copy directories recursively and copy special files
     as themselves rather than copying their contents. */
  int recursive;

  /* Control creation of sparse files.  */
  enum Sparse_type sparse_mode;

  /* If nonzero, create symbolic links instead of copying files.
     Create destination directories as usual. */
  int symbolic_link;

  /* The bits to preserve in created files' modes. */
  int umask_kill;

  /* If nonzero, do not copy a nondirectory that has an existing destination
     with the same or newer modification time. */
  int update;

  /* If nonzero, display the names of the files before copying them. */
  int verbose;

  /* This process's effective user ID.  */
  uid_t myeuid;

  /* A pointer to either lstat or stat, depending on
     whether dereferencing of symlinks is done.  */
  int (*xstat) ();
};

struct dir_list
{
  struct dir_list *parent;
  ino_t ino;
  dev_t dev;
};

int full_write ();
int euidaccess ();

/* The invocation name of this program.  */
extern char *program_name;

static int
is_ancestor (const struct stat *sb, const struct dir_list *ancestors)
{
  while (ancestors != 0)
    {
      if (ancestors->ino == sb->st_ino && ancestors->dev == sb->st_dev)
	return 1;
      ancestors = ancestors->parent;
    }
  return 0;
}

/* Read the contents of the directory SRC_PATH_IN, and recursively
   copy the contents to DST_PATH_IN.  NEW_DST is nonzero if
   DST_PATH_IN is a directory that was created previously in the
   recursion.   SRC_SB and ANCESTORS describe SRC_PATH_IN.
   Return 0 if successful, -1 if an error occurs. */

static int
copy_dir (const char *src_path_in, const char *dst_path_in, int new_dst,
	  const struct stat *src_sb, struct dir_list *ancestors,
	  const struct flag *x)
{
  char *name_space;
  char *namep;
  char *src_path;
  char *dst_path;
  int ret = 0;

  errno = 0;
  name_space = savedir (src_path_in, src_sb->st_size);
  if (name_space == 0)
    {
      if (errno)
	{
	  error (0, errno, "%s", src_path_in);
	  return -1;
	}
      else
	error (1, 0, _("virtual memory exhausted"));
    }

  namep = name_space;
  while (*namep != '\0')
    {
      int fn_length = strlen (namep) + 1;

      dst_path = xmalloc (strlen (dst_path_in) + fn_length + 1);
      src_path = xmalloc (strlen (src_path_in) + fn_length + 1);

      stpcpy (stpcpy (stpcpy (src_path, src_path_in), "/"), namep);
      stpcpy (stpcpy (stpcpy (dst_path, dst_path_in), "/"), namep);

      ret |= copy (src_path, dst_path, new_dst, src_sb->st_dev, ancestors, x);

      /* Free the memory for `src_path'.  The memory for `dst_path'
	 cannot be deallocated, since it is used to create multiple
	 hard links.  */

      free (src_path);

      namep += fn_length;
    }
  free (name_space);
  return -ret;
}

/* Copy a regular file from SRC_PATH to DST_PATH.
   If the source file contains holes, copies holes and blocks of zeros
   in the source file as holes in the destination file.
   (Holes are read as zeroes by the `read' system call.)
   Return 0 if successful, -1 if an error occurred.
   FIXME: describe sparse_mode.  */

static int
copy_reg (const char *src_path, const char *dst_path,
	  enum Sparse_type sparse_mode)
{
  char *buf;
  int buf_size;
  int dest_desc;
  int source_desc;
  int n_read;
  struct stat sb;
  char *cp;
  int *ip;
  int return_val = 0;
  long n_read_total = 0;
  int last_write_made_hole = 0;
  int make_holes = (sparse_mode == SPARSE_ALWAYS);

  source_desc = open (src_path, O_RDONLY);
  if (source_desc < 0)
    {
      error (0, errno, "%s", src_path);
      return -1;
    }

  /* Create the new regular file with small permissions initially,
     to not create a security hole.  */

  dest_desc = open (dst_path, O_WRONLY | O_CREAT | O_TRUNC, 0600);
  if (dest_desc < 0)
    {
      error (0, errno, _("cannot create regular file `%s'"), dst_path);
      return_val = -1;
      goto ret2;
    }

  /* Find out the optimal buffer size.  */

  if (fstat (dest_desc, &sb))
    {
      error (0, errno, "%s", dst_path);
      return_val = -1;
      goto ret;
    }

  buf_size = ST_BLKSIZE (sb);

#ifdef HAVE_ST_BLOCKS
  if (sparse_mode == SPARSE_AUTO && S_ISREG (sb.st_mode))
    {
      /* Use a heuristic to determine whether SRC_PATH contains any
	 sparse blocks. */

      if (fstat (source_desc, &sb))
	{
	  error (0, errno, "%s", src_path);
	  return_val = -1;
	  goto ret;
	}

      /* If the file has fewer blocks than would normally
	 be needed for a file of its size, then
	 at least one of the blocks in the file is a hole. */
      if (S_ISREG (sb.st_mode)
	  && (size_t) (sb.st_size / 512) > (size_t) ST_NBLOCKS (sb))
	make_holes = 1;
    }
#endif

  /* Make a buffer with space for a sentinel at the end.  */

  buf = (char *) alloca (buf_size + sizeof (int));

  for (;;)
    {
      n_read = read (source_desc, buf, buf_size);
      if (n_read < 0)
	{
#ifdef EINTR
	  if (errno == EINTR)
	    continue;
#endif
	  error (0, errno, "%s", src_path);
	  return_val = -1;
	  goto ret;
	}
      if (n_read == 0)
	break;

      n_read_total += n_read;

      ip = 0;
      if (make_holes)
	{
	  buf[n_read] = 1;	/* Sentinel to stop loop.  */

	  /* Find first nonzero *word*, or the word with the sentinel.  */

	  ip = (int *) buf;
	  while (*ip++ == 0)
	    ;

	  /* Find the first nonzero *byte*, or the sentinel.  */

	  cp = (char *) (ip - 1);
	  while (*cp++ == 0)
	    ;

	  /* If we found the sentinel, the whole input block was zero,
	     and we can make a hole.  */

	  if (cp > buf + n_read)
	    {
	      /* Make a hole.  */
	      if (lseek (dest_desc, (off_t) n_read, SEEK_CUR) < 0L)
		{
		  error (0, errno, "%s", dst_path);
		  return_val = -1;
		  goto ret;
		}
	      last_write_made_hole = 1;
	    }
	  else
	    /* Clear to indicate that a normal write is needed. */
	    ip = 0;
	}
      if (ip == 0)
	{
	  if (full_write (dest_desc, buf, n_read) < 0)
	    {
	      error (0, errno, "%s", dst_path);
	      return_val = -1;
	      goto ret;
	    }
	  last_write_made_hole = 0;
	}
    }

  /* If the file ends with a `hole', something needs to be written at
     the end.  Otherwise the kernel would truncate the file at the end
     of the last write operation.  */

  if (last_write_made_hole)
    {
#ifdef HAVE_FTRUNCATE
      /* Write a null character and truncate it again.  */
      if (full_write (dest_desc, "", 1) < 0
	  || ftruncate (dest_desc, n_read_total) < 0)
#else
      /* Seek backwards one character and write a null.  */
      if (lseek (dest_desc, (off_t) -1, SEEK_CUR) < 0L
	  || full_write (dest_desc, "", 1) < 0)
#endif
	{
	  error (0, errno, "%s", dst_path);
	  return_val = -1;
	}
    }

ret:
  if (close (dest_desc) < 0)
    {
      error (0, errno, "%s", dst_path);
      return_val = -1;
    }
ret2:
  if (close (source_desc) < 0)
    {
      error (0, errno, "%s", src_path);
      return_val = -1;
    }

  return return_val;
}

/* Copy the file SRC_PATH to the file DST_PATH.  The files may be of
   any type.  NEW_DST should be nonzero if the file DST_PATH cannot
   exist because its parent directory was just created; NEW_DST should
   be zero if DST_PATH might already exist.  DEVICE is the device
   number of the parent directory, or 0 if the parent of this file is
   not known.  ANCESTORS points to a linked, null terminated list of
   devices and inodes of parent directories of SRC_PATH.
   Return 0 if successful, 1 if an error occurs. */

static int
copy_internal (const char *src_path, const char *dst_path,
	       int new_dst, dev_t device, struct dir_list *ancestors,
	       const struct flag *x)
{
  struct stat src_sb;
  struct stat dst_sb;
  int src_mode;
  int src_type;
  char *earlier_file;
  char *dst_backup = NULL;
  int fix_mode = 0;

  if ((*(x->xstat)) (src_path, &src_sb))
    {
      error (0, errno, "%s", src_path);
      return 1;
    }

  /* Are we crossing a file system boundary?  */
  if (x->one_file_system && device != 0 && device != src_sb.st_dev)
    return 0;

  /* We wouldn't insert a node unless nlink > 1, except that we need to
     find created files so as to not copy infinitely if a directory is
     copied into itself.  */

  earlier_file = remember_copied (dst_path, src_sb.st_ino, src_sb.st_dev);

  /* Did we just create this file?  */

  if (earlier_file == &new_file)
    return 0;

  src_mode = src_sb.st_mode;
  src_type = src_sb.st_mode;

  if (S_ISDIR (src_type) && !x->recursive)
    {
      error (0, 0, _("%s: omitting directory"), src_path);
      return 1;
    }

  if (!new_dst)
    {
      if ((*(x->xstat)) (dst_path, &dst_sb))
	{
	  if (errno != ENOENT)
	    {
	      error (0, errno, "%s", dst_path);
	      return 1;
	    }
	  else
	    new_dst = 1;
	}
      else
	{
	  /* The file exists already.  */

	  if (src_sb.st_ino == dst_sb.st_ino && src_sb.st_dev == dst_sb.st_dev)
	    {
	      if (x->hard_link)
		return 0;

	      error (0, 0, _("`%s' and `%s' are the same file"),
		     src_path, dst_path);
	      return 1;
	    }

	  if (!S_ISDIR (src_type))
	    {
	      if (S_ISDIR (dst_sb.st_mode))
		{
		  error (0, 0,
		       _("%s: cannot overwrite directory with non-directory"),
			 dst_path);
		  return 1;
		}

	      if (x->update && src_sb.st_mtime <= dst_sb.st_mtime)
		return 0;
	    }

	  if (!S_ISDIR (src_type) && !x->force && x->interactive)
	    {
	      if (euidaccess (dst_path, W_OK) != 0)
		{
		  fprintf (stderr,
			   _("%s: overwrite `%s', overriding mode %04o? "),
			   program_name, dst_path,
			   (unsigned int) (dst_sb.st_mode & 07777));
		}
	      else
		{
		  fprintf (stderr, _("%s: overwrite `%s'? "),
			   program_name, dst_path);
		}
	      if (!yesno ())
		return 0;
	    }

	  if (backup_type != none && !S_ISDIR (dst_sb.st_mode))
	    {
	      char *tmp_backup = find_backup_file_name (dst_path);
	      if (tmp_backup == NULL)
		error (1, 0, _("virtual memory exhausted"));

	      /* Detect (and fail) when creating the backup file would
		 destroy the source file.  Before, running the commands
		 cd /tmp; rm -f a a~; : > a; echo A > a~; cp -b -V simple a~ a
		 would leave two zero-length files: a and a~.  */
	      if (STREQ (tmp_backup, src_path))
		{
		  error (0, 0,
		   _("backing up `%s' would destroy source;  `%s' not copied"),
			 dst_path, src_path);
		  return 1;

		}
	      dst_backup = (char *) alloca (strlen (tmp_backup) + 1);
	      strcpy (dst_backup, tmp_backup);
	      free (tmp_backup);
	      if (rename (dst_path, dst_backup))
		{
		  if (errno != ENOENT)
		    {
		      error (0, errno, _("cannot backup `%s'"), dst_path);
		      return 1;
		    }
		  else
		    dst_backup = NULL;
		}
	      new_dst = 1;
	    }
	  else if (x->force)
	    {
	      if (S_ISDIR (dst_sb.st_mode))
		{
		  /* Temporarily change mode to allow overwriting. */
		  if (euidaccess (dst_path, W_OK | X_OK) != 0)
		    {
		      if (chmod (dst_path, 0700))
			{
			  error (0, errno, "%s", dst_path);
			  return 1;
			}
		      else
			fix_mode = 1;
		    }
		}
	      else
		{
		  if (unlink (dst_path) && errno != ENOENT)
		    {
		      error (0, errno, _("cannot remove old link to `%s'"),
			     dst_path);
		      return 1;
		    }
		  new_dst = 1;
		}
	    }
	}
    }

  /* If the source is a directory, we don't always create the destination
     directory.  So --verbose should not announce anything until we're
     sure we'll create a directory. */
  if (x->verbose && !S_ISDIR (src_type))
    printf ("%s -> %s\n", src_path, dst_path);

  /* Did we copy this inode somewhere else (in this command line argument)
     and therefore this is a second hard link to the inode?  */

  if (!x->dereference && src_sb.st_nlink > 1 && earlier_file)
    {
      if (link (earlier_file, dst_path))
	{
	  error (0, errno, "%s", dst_path);
	  goto un_backup;
	}
      return 0;
    }

  if (S_ISDIR (src_type))
    {
      struct dir_list *dir;

      /* If this directory has been copied before during the
         recursion, there is a symbolic link to an ancestor
         directory of the symbolic link.  It is impossible to
         continue to copy this, unless we've got an infinite disk.  */

      if (is_ancestor (&src_sb, ancestors))
	{
	  error (0, 0, _("%s: cannot copy cyclic symbolic link"), src_path);
	  goto un_backup;
	}

      /* Insert the current directory in the list of parents.  */

      dir = (struct dir_list *) alloca (sizeof (struct dir_list));
      dir->parent = ancestors;
      dir->ino = src_sb.st_ino;
      dir->dev = src_sb.st_dev;

      if (new_dst || !S_ISDIR (dst_sb.st_mode))
	{
	  /* Create the new directory writable and searchable, so
             we can create new entries in it.  */

	  if (mkdir (dst_path, (src_mode & x->umask_kill) | 0700))
	    {
	      error (0, errno, _("cannot create directory `%s'"), dst_path);
	      goto un_backup;
	    }

	  /* Insert the created directory's inode and device
             numbers into the search structure, so that we can
             avoid copying it again.  */

	  if (remember_created (dst_path))
	    goto un_backup;

	  if (x->verbose)
	    printf ("%s -> %s\n", src_path, dst_path);
	}

      /* Copy the contents of the directory.  */

      if (copy_dir (src_path, dst_path, new_dst, &src_sb, dir, x))
	return 1;
    }
#ifdef S_ISLNK
  else if (x->symbolic_link)
    {
      if (*src_path == '/'
	  || (!strncmp (dst_path, "./", 2) && strchr (dst_path + 2, '/') == 0)
	  || strchr (dst_path, '/') == 0)
	{
	  if (symlink (src_path, dst_path))
	    {
	      error (0, errno, "%s", dst_path);
	      goto un_backup;
	    }

	  return 0;
	}
      else
	{
	  error (0, 0,
	   _("%s: can make relative symbolic links only in current directory"),
		 dst_path);
	  goto un_backup;
	}
    }
#endif
  else if (x->hard_link)
    {
      if (link (src_path, dst_path))
	{
	  error (0, errno, _("cannot create link `%s'"), dst_path);
	  goto un_backup;
	}
      return 0;
    }
  else if (S_ISREG (src_type)
	   || (x->copy_as_regular && !S_ISDIR (src_type)
#ifdef S_ISLNK
	       && !S_ISLNK (src_type)
#endif
	       ))
    {
      if (copy_reg (src_path, dst_path, x->sparse_mode))
	goto un_backup;
    }
  else
#ifdef S_ISFIFO
  if (S_ISFIFO (src_type))
    {
      if (mkfifo (dst_path, src_mode & x->umask_kill))
	{
	  error (0, errno, _("cannot create fifo `%s'"), dst_path);
	  goto un_backup;
	}
    }
  else
#endif
    if (S_ISBLK (src_type) || S_ISCHR (src_type)
#ifdef S_ISSOCK
	|| S_ISSOCK (src_type)
#endif
	)
    {
      if (mknod (dst_path, src_mode & x->umask_kill, src_sb.st_rdev))
	{
	  error (0, errno, _("cannot create special file `%s'"), dst_path);
	  goto un_backup;
	}
    }
  else
#ifdef S_ISLNK
  if (S_ISLNK (src_type))
    {
      char *link_val;
      int link_size;

      link_val = (char *) alloca (PATH_MAX + 2);
      link_size = readlink (src_path, link_val, PATH_MAX + 1);
      if (link_size < 0)
	{
	  error (0, errno, _("cannot read symbolic link `%s'"), src_path);
	  goto un_backup;
	}
      link_val[link_size] = '\0';

      if (symlink (link_val, dst_path))
	{
	  error (0, errno, _("cannot create symbolic link `%s'"), dst_path);
	  goto un_backup;
	}

      if (x->preserve)
	{
	  /* Preserve the owner and group of the just-`copied'
	     symbolic link, if possible.  */
#ifdef HAVE_LCHOWN
	  if (DO_CHOWN (lchown, dst_path, src_sb.st_uid, src_sb.st_gid))
	    {
	      error (0, errno, "%s", dst_path);
	      goto un_backup;
	    }
#else
# ifdef ROOT_CHOWN_AFFECTS_SYMLINKS
	  if (x->myeuid == 0)
	    {
	      if (DO_CHOWN (chown, dst_path, src_sb.st_uid, src_sb.st_gid))
		{
		  error (0, errno, "%s", dst_path);
		  goto un_backup;
		}
	    }
	  else
	    {
	      /* FIXME: maybe give a diagnostic: you must be root
		 to preserve ownership and group of symlinks.  */
	    }
# else
	  /* Can't preserve ownership of symlinks.
	     FIXME: maybe give a warning or even error for symlinks
	     in directories with the sticky bit set -- there, not
	     preserving owner/group is a potential security problem.  */
# endif
#endif
	}

      return 0;
    }
  else
#endif
    {
      error (0, 0, _("%s: unknown file type"), src_path);
      goto un_backup;
    }

  /* Adjust the times (and if possible, ownership) for the copy.
     chown turns off set[ug]id bits for non-root,
     so do the chmod last.  */

  if (x->preserve)
    {
      struct utimbuf utb;

      utb.actime = src_sb.st_atime;
      utb.modtime = src_sb.st_mtime;

      if (utime (dst_path, &utb))
	{
	  error (0, errno, "%s", dst_path);
	  return 1;
	}

      if (DO_CHOWN (chown, dst_path, src_sb.st_uid, src_sb.st_gid))
	{
	  error (0, errno, "%s", dst_path);
	  return 1;
	}
    }

  if ((x->preserve || new_dst)
      && (x->copy_as_regular || S_ISREG (src_type) || S_ISDIR (src_type)))
    {
      if (chmod (dst_path, src_mode & x->umask_kill))
	{
	  error (0, errno, "%s", dst_path);
	  return 1;
	}
    }
  else if (fix_mode)
    {
      /* Reset the temporarily changed mode.  */
      if (chmod (dst_path, dst_sb.st_mode))
	{
	  error (0, errno, "%s", dst_path);
	  return 1;
	}
    }

  return 0;

un_backup:
  if (dst_backup)
    {
      if (rename (dst_backup, dst_path))
	error (0, errno, _("cannot un-backup `%s'"), dst_path);
    }
  return 1;
}

/* Copy the file SRC_PATH to the file DST_PATH.  The files may be of
   any type.  NONEXISTENT_DST should be nonzero if the file DST_PATH is
   not to exist (e.g., because its parent directory was just created);
   NONEXISTENT_DST should be zero if DST_PATH might already exist.
   DEVICE is the device number of the parent directory, or 0 if the
   parent of this file is not known.  ANCESTORS points to a linked, null
   terminated list of devices and inodes of parent directories of SRC_PATH.
   Return 0 if successful, 1 if an error occurs. */

int
copy (const char *src_path, const char *dst_path, int nonexistent_dst,
      const struct flag *x)
{
  copy_internal (src_path, dst_path, ... , x);
}