path: root/camel/providers/MH/camel-mh-folder.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* camel-mh-folder.c : Abstract class for an email folder */

/* 
 *
 * Copyright (C) 1999 Bertrand Guiheneuf <Bertrand.Guiheneuf@inria.fr> .
 *
 * 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 <config.h> 
#include <sys/stat.h> 
#include <sys/param.h> 
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdio.h>
#include <errno.h>
#include "camel-mh-folder.h"
#include "camel-mh-store.h"
#include "gstring-util.h"
#include "camel-log.h"
#include "camel-stream-fs.h"
#include "camel-stream-buffered-fs.h"


static CamelFolderClass *parent_class=NULL;

/* Returns the class for a CamelMhFolder */
#define CMHF_CLASS(so) CAMEL_MH_FOLDER_CLASS (GTK_OBJECT(so)->klass)
#define CF_CLASS(so) CAMEL_FOLDER_CLASS (GTK_OBJECT(so)->klass)
#define CMHS_CLASS(so) CAMEL_STORE_CLASS (GTK_OBJECT(so)->klass)

static int copy_reg (const char *src_path, const char *dst_path);
static void _set_name(CamelFolder *folder, const gchar *name);
static void _init_with_store (CamelFolder *folder, CamelStore *parent_store);
static gboolean _exists (CamelFolder *folder);
static gboolean _create(CamelFolder *folder);
static gboolean _delete (CamelFolder *folder, gboolean recurse);
static gboolean _delete_messages (CamelFolder *folder);
static GList *_list_subfolders (CamelFolder *folder);
static CamelMimeMessage *_get_message (CamelFolder *folder, gint number);
static gint _get_message_count (CamelFolder *folder);
static gint _append_message (CamelFolder *folder, CamelMimeMessage *message);
static void _expunge (CamelFolder *folder);
static void _copy_message_to (CamelFolder *folder, CamelMimeMessage *message, CamelFolder *dest_folder);

static gboolean _is_a_message_file (const gchar *file_name, const gchar *file_path);

static void
camel_mh_folder_class_init (CamelMhFolderClass *camel_mh_folder_class)
{
    CamelFolderClass *camel_folder_class = CAMEL_FOLDER_CLASS (camel_mh_folder_class);

    parent_class = gtk_type_class (camel_folder_get_type ());
        
    /* virtual method definition */
    /* virtual method overload */
    camel_folder_class->init_with_store = _init_with_store;
    camel_folder_class->set_name = _set_name;
    camel_folder_class->exists = _exists;
    camel_folder_class->delete = _delete;
    camel_folder_class->delete_messages = _delete_messages;
    camel_folder_class->list_subfolders = _list_subfolders;
    camel_folder_class->get_message = _get_message;
    camel_folder_class->get_message_count = _get_message_count;
    camel_folder_class->append_message = _append_message;
    camel_folder_class->expunge = _expunge;
    camel_folder_class->copy_message_to = _copy_message_to;
    
}







GtkType
camel_mh_folder_get_type (void)
{
    static GtkType camel_mh_folder_type = 0;
    
    if (!camel_mh_folder_type)  {
        GtkTypeInfo camel_mh_folder_info =  
        {
            "CamelMhFolder",
            sizeof (CamelMhFolder),
            sizeof (CamelMhFolderClass),
            (GtkClassInitFunc) camel_mh_folder_class_init,
            (GtkObjectInitFunc) NULL,
                /* reserved_1 */ NULL,
                /* reserved_2 */ NULL,
            (GtkClassInitFunc) NULL,
        };
        
        camel_mh_folder_type = gtk_type_unique (CAMEL_FOLDER_TYPE, &camel_mh_folder_info);
    }
    
    return camel_mh_folder_type;
}




static void 
_init_with_store (CamelFolder *folder, CamelStore *parent_store)
{
    /* call parent method */
    parent_class->init_with_store (folder, parent_store);
    
    folder->can_hold_messages = TRUE;
    folder->can_hold_folders = TRUE;
}



static gint
_message_name_compare (gconstpointer a, gconstpointer b)
{
    gchar *m1 = (gchar *)a;
    gchar *m2 = (gchar *)b;
    gint len_diff;

    return (atoi (m1) - atoi (m2));
}

/**
 * camel_mh_folder_set_name: set the name of an MH folder
 * @folder: the folder to set the name
 * @name: a string representing the (short) name
 * 
 * 
 * 
 **/
static void
_set_name (CamelFolder *folder, const gchar *name)
{
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER (folder);
    const gchar *root_dir_path;
    gchar *full_name;
    const gchar *parent_full_name;
    gchar separator;
    struct dirent *dir_entry;
    DIR *dir_handle;
    
    CAMEL_LOG_FULL_DEBUG ("Entering CamelMhFolder::set_name\n");
    g_assert(folder);
    g_assert(name);
    g_assert(folder->parent_store);

    /* call default implementation */
    parent_class->set_name (folder, name);
    
    if (mh_folder->directory_path) g_free (mh_folder->directory_path);
    
    separator = camel_store_get_separator (folder->parent_store);
    root_dir_path = camel_mh_store_get_toplevel_dir (CAMEL_MH_STORE(folder->parent_store));

    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::set_name full_name is %s\n", folder->full_name);
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::set_name root_dir_path is %s\n", root_dir_path);
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::separator is %c\n", separator);

    mh_folder->directory_path = g_strdup_printf ("%s%c%s", root_dir_path, separator, folder->full_name);
    
    if (!camel_folder_exists (folder)) return;
    
    /* create message list */
    /* read the whole folder and sort message names */
    dir_handle = opendir (mh_folder->directory_path);
    /* read first entry in the directory */
    dir_entry = readdir (dir_handle);
    while (dir_entry != NULL) {
        /* tests if the entry correspond to a message file */
        if (_is_a_message_file (dir_entry->d_name, mh_folder->directory_path)) 
            mh_folder->file_name_list = g_list_insert_sorted (mh_folder->file_name_list, g_strdup (dir_entry->d_name), 
                                 _message_name_compare);
        /* read next entry */
        dir_entry = readdir (dir_handle);
    }       

    closedir (dir_handle);
    
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::set_name mh_folder->directory_path is %s\n", 
                  mh_folder->directory_path);
    CAMEL_LOG_FULL_DEBUG ("Leaving CamelMhFolder::set_name\n");
}



static gboolean
_exists (CamelFolder *folder)
{
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    struct stat stat_buf;
    gint stat_error;
    gboolean exists;

    CAMEL_LOG_FULL_DEBUG ("Entering CamelMhFolder::exists\n");
    g_assert (folder);
    
    if (!mh_folder->directory_path)  return FALSE;
    
    stat_error = stat (mh_folder->directory_path, &stat_buf);
    if (stat_error == -1)  {
        CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::exists when executing stat on %s, stat_error = %d\n", 
                      mh_folder->directory_path, stat_error);
        CAMEL_LOG_FULL_DEBUG ("  Full error text is : %s\n", strerror(errno));
        return FALSE;
    }
    exists = S_ISDIR (stat_buf.st_mode);

    CAMEL_LOG_FULL_DEBUG ("Leaving CamelMhFolder::exists\n");
    return exists;
}


static gboolean
_create (CamelFolder *folder)
{
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    mode_t dir_mode = S_IRWXU;
    gint mkdir_error;

    g_assert(folder);

    /* call default implementation */
    parent_class->create (folder);

    directory_path = mh_folder->directory_path;
    if (!directory_path) return FALSE;
    
    if (camel_folder_exists (folder)) return TRUE;
    
    mkdir_error = mkdir (directory_path, dir_mode);
    return (mkdir_error == -1);
}



static gboolean
_delete (CamelFolder *folder, gboolean recurse)
{

    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    gint rmdir_error = 0;

    g_assert(folder);

    /* call default implementation */
    parent_class->delete (folder, recurse);
    /* the default implementation will care about deleting 
       messages first and recursing the operation if 
       necessary */
    
    directory_path = mh_folder->directory_path;
    if (!directory_path) return FALSE;
    
    if (!camel_folder_exists (folder)) return TRUE;
    
    /* physically delete the directory */
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::delete removing directory %s\n", directory_path);
    rmdir_error = rmdir (directory_path);
    if (rmdir_error == -1) {
        CAMEL_LOG_WARNING ("CamelMhFolder::delete Error when removing directory %s\n", directory_path);
        CAMEL_LOG_FULL_DEBUG ( "  Full error text is : %s\n", strerror(errno));
    }

    return (rmdir_error != -1);
}


static gboolean 
_delete_messages (CamelFolder *folder)
{
    
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    struct stat stat_buf;
    gint stat_error = 0;
    gchar *entry_name;
    struct dirent *dir_entry;
    gint unlink_error = 0;
    DIR *dir_handle;

    g_assert(folder);

    /* call default implementation */
    parent_class->delete_messages (folder);

    directory_path = mh_folder->directory_path;
    if (!directory_path) return FALSE;
    
    if (!camel_folder_exists (folder)) return TRUE;
    
    dir_handle = opendir (directory_path);
    
    /* read first entry in the directory */
    dir_entry = readdir (dir_handle);
    while ((stat_error != -1) && (unlink_error != -1) && (dir_entry != NULL)) {

        /* get the name of the next entry in the dir */
        entry_name = dir_entry->d_name;
        stat_error = stat (mh_folder->directory_path, &stat_buf);

        /* is it a regular file ? */
        if ((stat_error != -1) && S_ISREG(stat_buf.st_mode)) {
            /* yes, delete it */
            CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::delete_messages removing file %s\n", entry_name);
            unlink_error = unlink(entry_name);

            if (unlink_error == -1) {
                CAMEL_LOG_WARNING ("CamelMhFolder::delete_messages Error when deleting file %s\n", 
                           entry_name);
                CAMEL_LOG_FULL_DEBUG ( "  Full error text is : %s\n", strerror(errno));
            }
        }
        /* read next entry */
        dir_entry = readdir (dir_handle);
    }

    closedir (dir_handle);

    return ((stat_error != -1) && (unlink_error != -1));

}



static GList *
_list_subfolders (CamelFolder *folder)
{
    GList *subfolder_name_list = NULL;

    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    struct stat stat_buf;
    gint stat_error = 0;
    GList *file_list;
    gchar *entry_name;
    gchar *full_entry_name;
    struct dirent *dir_entry;
    DIR *dir_handle;

    g_assert(folder);

    /* call default implementation */
    parent_class->delete_messages (folder);

    directory_path = mh_folder->directory_path;
    if (!directory_path) return NULL;
    
    if (!camel_folder_exists (folder)) return NULL;
    
    dir_handle = opendir (directory_path);
    
    /* read first entry in the directory */
    dir_entry = readdir (dir_handle);
    while ((stat_error != -1) && (dir_entry != NULL)) {

        /* get the name of the next entry in the dir */
        entry_name = dir_entry->d_name;
        full_entry_name = g_strdup_printf ("%s/%s", mh_folder->directory_path, entry_name);
        stat_error = stat (full_entry_name, &stat_buf);
        g_free (full_entry_name);

        /* is it a directory ? */
        if ((stat_error != -1) && S_ISDIR (stat_buf.st_mode)) {
            /* yes, add it to the list */
            if (entry_name[0] != '.') {
                CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::list_subfolders adding  %s\n", entry_name);
                subfolder_name_list = g_list_append (subfolder_name_list, g_strdup (entry_name));
            }
        }
        /* read next entry */
        dir_entry = readdir (dir_handle);
    }

    closedir (dir_handle);

    return subfolder_name_list;
}




static gboolean
_is_a_message_file (const gchar *file_name, const gchar *file_path)
{
    struct stat stat_buf;
    gint stat_error = 0;
    gboolean ok;
    gchar *full_file_name;
    int i;
    
    /* test if the name is a number */
    i=0;
    while ((file_name[i] != '\0') && (file_name[i] >= '0') && (file_name[i] <= '9'))
        i++;
    if ((i==0) || (file_name[i] != '\0')) return FALSE;
    
    /* is it a regular file ? */
    full_file_name = g_strdup_printf ("%s/%s", file_path, file_name);
    stat_error = stat (full_file_name, &stat_buf);
    g_free (full_file_name);

    return  ((stat_error != -1) && S_ISREG (stat_buf.st_mode));
}


static void
_filename_free (gpointer data)
{
    g_free ((gchar *)data);
}


/* slow routine, may be optimixed, or we should use
   caches if users complain */
static CamelMimeMessage *
_get_message (CamelFolder *folder, gint number)
{
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    gchar *message_name;
    gchar *message_file_name;
    CamelStream *input_stream = NULL;
    CamelMimeMessage *message = NULL;
    GList *message_list = NULL;
    
    g_assert(folder);
    
    
    directory_path = mh_folder->directory_path;
    if (!directory_path) return NULL;   

        
    
    message_name = g_list_nth_data (mh_folder->file_name_list, number);
    
    if (message_name != NULL) {
        CAMEL_LOG_FULL_DEBUG  ("CanelMhFolder::get_message message number = %d, name = %s\n", 
                       number, message_name);
        message_file_name = g_strdup_printf ("%s/%s", directory_path, message_name);
        input_stream = camel_stream_buffered_fs_new_with_name (message_file_name, CAMEL_STREAM_BUFFERED_FS_READ);
        
        if (input_stream != NULL) {
#warning use session field here
            message = camel_mime_message_new_with_session ( (CamelSession *)NULL);
            camel_data_wrapper_construct_from_stream ( CAMEL_DATA_WRAPPER (message), input_stream);
            gtk_object_unref (GTK_OBJECT (input_stream));
            message->message_number = number;
            gtk_object_set_data_full (GTK_OBJECT (message), "fullpath", 
                          g_strdup (message_file_name), _filename_free);
            
#warning Set flags and all this stuff here
        }
        g_free (message_file_name);
    } else 
        CAMEL_LOG_FULL_DEBUG  ("CanelMhFolder::get_message message number = %d, not found\n", number);
    
    
    return message;   
}



static gint
_get_message_count (CamelFolder *folder)
{
    
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    struct dirent *dir_entry;
    DIR *dir_handle;
    guint message_count = 0;

    g_assert(folder);

    directory_path = mh_folder->directory_path;
    if (!directory_path) return -1;
    
    if (!camel_folder_exists (folder)) return 0;
    
    dir_handle = opendir (directory_path);
    
    /* read first entry in the directory */
    dir_entry = readdir (dir_handle);
    while (dir_entry != NULL) {
        /* tests if the entry correspond to a message file */
        if (_is_a_message_file (dir_entry->d_name, directory_path)) 
            message_count++;    
        /* read next entry */
        dir_entry = readdir (dir_handle);
    }

    closedir (dir_handle);
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::get_message_count found %d messages\n", message_count);
    return message_count;
}



static gboolean
_find_next_free_message_file (CamelFolder *folder, gint *new_msg_number, gchar **new_msg_filename)
{
    CamelMhFolder *mh_folder = CAMEL_MH_FOLDER(folder);
    const gchar *directory_path;
    struct dirent *dir_entry;
    DIR *dir_handle;
    gint last_max_message_number = 0;
    gint current_message_number;

    g_assert(folder);

    directory_path = mh_folder->directory_path;
    if (!directory_path) return FALSE;
    
    if (!camel_folder_exists (folder)) return FALSE;
    
    dir_handle = opendir (directory_path);
    
    /* read first entry in the directory */
    dir_entry = readdir (dir_handle);
    while (dir_entry != NULL) {
        /* tests if the entry correspond to a message file */
        if (_is_a_message_file (dir_entry->d_name, directory_path)) {
            /* see if the message number is the biggest found */
            current_message_number = atoi (dir_entry->d_name);
            if (current_message_number > last_max_message_number)
                last_max_message_number = current_message_number;
        }
        /* read next entry */
        dir_entry = readdir (dir_handle);
    }
    closedir (dir_handle);
    
    *new_msg_number = last_max_message_number + 1;
    *new_msg_filename = g_strdup_printf ("%s/%d", directory_path, *new_msg_number);
    CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::find_next_free_message_file new message path is %s\n", 
                  *new_msg_filename);
    return TRUE;
    
    
}
static gint
_append_message (CamelFolder *folder, CamelMimeMessage *message)
{
    guint new_msg_number;
    gchar *new_msg_filename;
    CamelStream *output_stream;
    gboolean error;

    CAMEL_LOG_FULL_DEBUG ("Entering CamelMhFolder::append_message\n");
    if (!_find_next_free_message_file (folder, &new_msg_number, &new_msg_filename))
        return -1;

    output_stream = camel_stream_fs_new_with_name (new_msg_filename, CAMEL_STREAM_FS_WRITE);
    if (output_stream != NULL) {
        camel_data_wrapper_write_to_stream (CAMEL_DATA_WRAPPER (message), output_stream);
        camel_stream_close (output_stream);
    } else {
        CAMEL_LOG_WARNING ("CamelMhFolder::append_message could not open %s for writing\n", 
                   new_msg_filename);
        CAMEL_LOG_FULL_DEBUG ("  Full error text is : %s\n", strerror(errno));
        error = TRUE;
    }

    g_free (new_msg_filename);
    CAMEL_LOG_FULL_DEBUG ("Leaving CamelMhFolder::append_message\n");
    if (error) return -1;
    else return new_msg_number;
}





static void
_expunge (CamelFolder *folder)
{
    /* For the moment, we look in the folder active message
     * list. I did not make my mind for the moment, should 
     * the gtk_object->destroy signal be used to expunge
     * freed messages objects marked DELETED ? 
     */
    CamelMimeMessage *message;
    GList *message_node;
    gchar *fullpath;
    gint unlink_error;

    CAMEL_LOG_FULL_DEBUG ("Entering CamelFolder::expunge\n");
    
    message_node = folder->message_list;

    /* look in folder message list which messages
     * need to be expunged  */
    while ( message_node) {
        message = CAMEL_MIME_MESSAGE (message_node->data);
        
        if (message && camel_mime_message_get_flag (message, "DELETED")) {
            CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::expunge, expunging  message %d\n", message->message_number);
            /* expunge the message */
            fullpath = gtk_object_get_data (GTK_OBJECT (message), "fullpath");
            CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::expunge, message fullpath is %s\n", 
                          fullpath);
            unlink_error = unlink(fullpath);
            if (unlink_error != -1) {
                message->expunged = TRUE;
            } else {
                CAMEL_LOG_WARNING ("CamelMhFolder:: could not unlink %s (message %d)\n", 
                           fullpath, message->message_number);
                CAMEL_LOG_FULL_DEBUG ("  Full error text is : %s\n", strerror(errno));
            }
        }
        message_node = message_node->next;
        CAMEL_LOG_FULL_DEBUG ("CamelFolder::expunge, examined message node %p\n", message_node);
    }
    
    CAMEL_LOG_FULL_DEBUG ("Leaving CamelFolder::expunge\n");
}


static void
_copy_message_to (CamelFolder *folder, CamelMimeMessage *message, CamelFolder *dest_folder)
{
    gchar *src_msg_filename;
    guint dest_msg_number;
    gchar *dest_msg_filename;

    if (IS_CAMEL_MH_FOLDER (dest_folder)) {
        /*g_return_if_fail (message->parent_folder == folder);*/
        
        if (!_find_next_free_message_file (dest_folder, &dest_msg_number, &dest_msg_filename))
            return;
        src_msg_filename = gtk_object_get_data (GTK_OBJECT (message), "fullpath");
        CAMEL_LOG_FULL_DEBUG ("CamelMhFolder::copy_to copy file %s to %s\n", src_msg_filename, dest_msg_filename);
        copy_reg (src_msg_filename, dest_msg_filename);
        
    } else 
        parent_class->copy_message_to (folder, message, dest_folder);
}




/************************************************************************/

/*** Took directly from GNU fileutils-4.0                             ***/
/* Copyright (C) 89, 90, 91, 95, 96, 97, 1998 Free Software Foundation. */
/* This may be rwritten soon. -Bertrand                                 */               

    
/* Write LEN bytes at PTR to descriptor DESC, retrying if interrupted.
   Return LEN upon success, write's (negative) error code otherwise.  */
int
full_write (int desc, const char *ptr, size_t len)
{
  int total_written;

  total_written = 0;
  while (len > 0)
    {
      int written = write (desc, ptr, len);
      if (written < 0)
    {
      if (errno == EINTR)
        continue;
      return written;
    }
      total_written += written;
      ptr += written;
      len -= written;
    }
  return total_written;
}




static int
copy_reg (const char *src_path, const char *dst_path)
{
  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;
  off_t n_read_total = 0;
  int last_write_made_hole = 0;
  int make_holes = TRUE;

  source_desc = open (src_path, O_RDONLY);
  if (source_desc < 0)
    {
      /* If SRC_PATH doesn't exist, then chances are good that the
     user did something like this `cp --backup foo foo': and foo
     existed to start with, but copy_internal renamed DST_PATH
     with the backup suffix, thus also renaming SRC_PATH.  */
      if (errno == ENOENT)
    error (0, 0, "`%s' and `%s' are the same file",
           src_path, dst_path);
      else
    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 = 8192;



  /* 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)
    {
      if (errno == EINTR)
        continue;
      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)
    {
#if 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;
}