Imported Upstream version 1.1.4upstream/1.1.4

1 files changed, 1941 insertions, 0 deletions

diff --git a/xdmain.c b/xdmain.c
new file mode 100755
index 0000000..b1abc74
--- /dev/null
+++ b/xdmain.c
@@ -0,0 +1,1941 @@
+/* -*- Mode: C;-*-
+ *
+ * This file is part of XDelta - A binary delta generator.
+ *
+ * Copyright (C) 1997, 1998, 1999, 2001  Josh MacDonald
+ *
+ * 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.
+ *
+ * Author: Josh MacDonald <jmacd@CS.Berkeley.EDU>
+ *
+ * $Id: xdmain.c 1.22.1.7.1.1 Sat, 27 Jan 2007 17:53:47 -0800 jmacd $
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#if defined(_WIN32) || defined(__DJGPP__)
+#define WINHACK
+#endif
+
+#ifndef WINHACK
+#include <unistd.h>
+#include <sys/mman.h>
+#define O_BINARY 0
+
+#else /* WINHACK */
+
+#include <io.h>
+#include <process.h>
+#ifdef __DJGPP__
+#include <unistd.h>
+#include <dpmi.h>
+#endif
+
+#define STDOUT_FILENO 1
+#define lstat stat
+
+#ifndef __DJGPP__
+#define S_IFMT _S_IFMT
+#define S_IFREG _S_IFREG
+#endif /* !__DJGPP__ */
+
+#endif /* !WINHACK_ */
+
+#include <zlib.h>
+
+#include "xdelta.h"
+
+static HandleFuncTable xd_handle_table;
+
+#define XD_PAGE_SIZE (1<<20)
+
+#define XDELTA_110_PREFIX "%XDZ004%"
+#define XDELTA_104_PREFIX "%XDZ003%"
+#define XDELTA_100_PREFIX "%XDZ002%"
+#define XDELTA_020_PREFIX "%XDZ001%"
+#define XDELTA_018_PREFIX "%XDZ000%"
+#define XDELTA_014_PREFIX "%XDELTA%"
+#define XDELTA_PREFIX     XDELTA_110_PREFIX
+#define XDELTA_PREFIX_LEN 8
+
+#define HEADER_WORDS (6)
+#define HEADER_SPACE (HEADER_WORDS*4)
+/* The header is composed of 4-byte words (network byte order) as follows:
+ * word 1: flags
+ * word 2: (from name length) << 16 | (to name length)
+ * word 3: (reserved)
+ * word 4: (reserved)
+ * word 5: (reserved)
+ * word 6: (reserved)
+ * flags are:
+ */
+#define FLAG_NO_VERIFY 1
+#define FLAG_FROM_COMPRESSED 2
+#define FLAG_TO_COMPRESSED 4
+#define FLAG_PATCH_COMPRESSED 8
+/* and, the header is follwed by the from file name, then the to file
+ * name, then the data. */
+
+#ifdef WINHACK
+#define FOPEN_READ_ARG "rb"
+#define FOPEN_WRITE_ARG "wb"
+#define FILE_SEPARATOR '\\'
+#else
+#define FOPEN_READ_ARG "r"
+#define FOPEN_WRITE_ARG "w"
+#define FILE_SEPARATOR '/'
+#endif /* WINHACK */
+
+#include "getopt.h"
+
+typedef struct _LRU LRU;
+
+struct _LRU
+{
+  LRU *next;
+  LRU *prev;
+
+  gint refs;
+  guint page;
+  guint8* buffer;
+};
+
+typedef struct _XdFileHandle XdFileHandle;
+
+typedef struct {
+  gboolean       patch_is_compressed;
+  const gchar*   patch_name;
+  guint          patch_flags;
+  const gchar*   patch_version;
+  gboolean       has_trailer;
+
+  XdeltaSourceInfo* data_source;
+  XdeltaSourceInfo* from_source;
+
+  gchar         *from_name;
+  gchar         *to_name;
+
+  guint          control_offset;
+  guint          header_offset;
+
+  gint16         from_name_len;
+  gint16         to_name_len;
+
+  guint32        header_space[HEADER_WORDS];
+  guint8         magic_buf[XDELTA_PREFIX_LEN];
+
+  XdFileHandle      *patch_in;
+
+  XdeltaControl   *cont;
+} XdeltaPatch;
+
+struct _XdFileHandle
+{
+  FileHandle fh;
+
+  guint    length;
+  guint    real_length;
+  gint     type;
+  const char* name;
+  const char* cleanup;
+
+  guint8 md5[16];
+  EdsioMD5Ctx ctx;
+
+  /* for write */
+  int out_fd;
+  void* out;
+  gboolean (* out_write) (XdFileHandle* handle, const void* buf, gint nbyte);
+  gboolean (* out_close) (XdFileHandle* handle);
+
+  /* for read */
+  GPtrArray *lru_table;
+  LRU       *lru_head;  /* most recently used. */
+  LRU       *lru_tail;  /* least recently used. */
+  GMemChunk *lru_chunk;
+  guint      lru_count;
+  guint      lru_outstanding_refs;
+
+  guint    narrow_low;
+  guint    narrow_high;
+  guint    current_pos;
+  FILE*    in;
+  gboolean (* in_read) (XdFileHandle* handle, void* buf, gint nbyte);
+  gboolean (* in_close) (XdFileHandle* handle);
+  gboolean in_compressed;
+
+  const guint8* copy_page;
+  guint  copy_pgno;
+  gboolean md5_good;
+  gboolean reset_length_next_write;
+
+  gint md5_page;
+  gint fd;
+};
+
+/* $Format: "static const char xdelta_version[] = \"$ReleaseVersion$\"; " $ */
+static const char xdelta_version[] = "1.1.4"; 
+
+typedef struct _Command Command;
+
+struct _Command {
+  gchar* name;
+  gint (* func) (gint argc, gchar** argv);
+  gint nargs;
+};
+
+static gint    delta_command    (gint argc, gchar** argv);
+static gint    patch_command    (gint argc, gchar** argv);
+static gint    info_command     (gint argc, gchar** argv);
+
+static const Command commands[] =
+{
+  { "delta",    delta_command,    -1 },
+  { "patch",    patch_command,    -1 },
+  { "info",     info_command,     1 },
+  { NULL, NULL, 0 }
+};
+
+static struct option const long_options[] =
+{
+  {"help",                no_argument, 0, 'h'},
+  {"version",             no_argument, 0, 'v'},
+  {"verbose",             no_argument, 0, 'V'},
+  {"noverify",            no_argument, 0, 'n'},
+  {"pristine",            no_argument, 0, 'p'},
+  {"quiet",               no_argument, 0, 'q'},
+  {"maxmem",              required_argument, 0, 'm'},
+  {"blocksize",           required_argument, 0, 's'},
+  {0,0,0,0}
+};
+
+static const gchar* program_name;
+static gint         compress_level = Z_DEFAULT_COMPRESSION;
+static gint         no_verify = FALSE;
+static gint         pristine = FALSE;
+static gint         verbose = FALSE;
+static gint         max_mapped_pages = G_MAXINT;
+static gint         quiet = FALSE;
+
+#define xd_error g_warning
+
+static void
+usage ()
+{
+  xd_error ("usage: %s COMMAND [OPTIONS] [ARG1 ...]\n", program_name);
+  xd_error ("use --help for more help\n");
+  exit (2);
+}
+
+static void
+help ()
+{
+  xd_error ("usage: %s COMMAND [OPTIONS] [ARG1 ...]\n", program_name);
+  xd_error ("COMMAND is one of:\n");
+  xd_error ("  delta     Produce a delta from ARG1 to ARG2 producing ARG3\n");
+  xd_error ("  info      List details about delta ARG1\n");
+  xd_error ("  patch     Apply patch ARG1 using file ARG2 producing ARG3\n");
+  xd_error ("OPTIONS are:\n");
+  xd_error ("  -v, --version      Print version information\n");
+  xd_error ("  -V, --verbose      Print verbose error messages\n");
+  xd_error ("  -h, --help         Print this summary\n");
+  xd_error ("  -n, --noverify     Disable automatic MD5 verification\n");
+  xd_error ("  -p, --pristine     Disable automatic GZIP decompression\n");
+  xd_error ("  -m, --maxmem=SIZE  Set the buffer size limit, e.g. 640K, 16M\n");
+  xd_error ("  -[0-9]             ZLIB compress level: 0=none, 1=fast, 6=default, 9=best\n");
+  xd_error ("  -s=BLOCK_SIZE      Sets block size (power of 2), minimum match length\n");
+  xd_error ("                     In-core memory requirement is (FROM_LEN * 8) / BLOCK_SIZE\n");
+  exit (2);
+}
+
+static void
+version ()
+{
+  xd_error ("version %s\n", xdelta_version);
+  exit (2);
+}
+
+static FILE* xd_error_file = NULL;
+
+static void
+xd_error_func (const gchar   *log_domain,
+	       GLogLevelFlags	log_level,
+	       const gchar   *message,
+	       gpointer	user_data)
+{
+  if (! xd_error_file)
+    xd_error_file = stderr;
+
+  fprintf (xd_error_file, "%s: %s", program_name, message);
+}
+
+static gboolean
+event_devel (void)
+{
+  static gboolean once = FALSE;
+  static gboolean devel = FALSE;
+
+  if (! once)
+    {
+      devel = g_getenv ("EDSIO_DEVEL") != NULL;
+      once = TRUE;
+    }
+
+  return devel;
+}
+
+static gboolean
+event_watch (GenericEvent* ev, GenericEventDef* def, const char* message)
+{
+  if (quiet && def->level <= EL_Warning)
+    return TRUE;
+
+  if (event_devel ())
+    fprintf (stderr, "%s:%d: %s\n", ev->srcfile, ev->srcline, message);
+  else
+    fprintf (stderr, "%s: %s\n", program_name, message);
+
+  return TRUE;
+}
+
+gint
+main (gint argc, gchar** argv)
+{
+  const Command *cmd = NULL;
+  gint c;
+  gint longind;
+
+  eventdelivery_event_watch_all (event_watch);
+
+  if (! xd_edsio_init ())
+    return 2;
+
+#ifdef __DJGPP__
+  /*
+   * (richdawe@bigfoot.com): Limit maximum memory usage to 87.5% of available
+   * physical memory for DJGPP. Otherwise the replacement for mmap() will
+   * exhaust memory and XDelta will fail.
+   */
+  {
+    unsigned long phys_free = _go32_dpmi_remaining_physical_memory();
+
+    max_mapped_pages  = phys_free / XD_PAGE_SIZE;
+    max_mapped_pages %= 8;
+    max_mapped_pages *= 7;
+  }
+
+  /*
+   * (richdawe@bigfoot.com): Strip off the file extension 'exe' from
+   * program_name, since it makes the help messages look ugly.
+   */
+  {
+    char strip_ext[PATH_MAX + 1];
+    char *p;
+
+    strcpy (strip_ext, argv[0]);
+    p = strrchr (strip_ext, '.');
+    if ((p != NULL) && (strncasecmp (p + 1, "exe", 3) == 0))
+      *p = '\0';
+    program_name = g_basename (strip_ext);
+  }
+#else /* !__DJGPP__ */
+  program_name = g_basename (argv[0]);
+#endif /* __DJGPP__ */  
+
+  g_log_set_handler (G_LOG_DOMAIN,
+		     G_LOG_LEVEL_WARNING,
+		     xd_error_func,
+		     NULL);
+
+  if (argc < 2)
+    usage ();
+
+  for (cmd = commands; cmd->name; cmd += 1)
+    if (strcmp (cmd->name, argv[1]) == 0)
+      break;
+
+  if (strcmp (argv[1], "-h") == 0 ||
+      strcmp (argv[1], "--help") == 0)
+    help ();
+
+  if (strcmp (argv[1], "-v") == 0 ||
+      strcmp (argv[1], "--version") == 0)
+    version ();
+
+  if (!cmd->name)
+    {
+      xd_error ("unrecognized command\n");
+      help ();
+    }
+
+  argc -= 1;
+  argv += 1;
+
+  while ((c = getopt_long(argc,
+			  argv,
+			  "+nqphvVs:m:0123456789",
+			  long_options,
+			  &longind)) != EOF)
+    {
+      switch (c)
+	{
+	case 'q': quiet = TRUE; break;
+	case 'n': no_verify = TRUE; break;
+	case 'p': pristine = TRUE; break;
+	case 'V': verbose = TRUE; break;
+	case 's':
+	  {
+	    int ret;
+	    int s = atoi (optarg);
+
+	    if ((ret = xdp_set_query_size_pow (s)) && ! quiet)
+	      {
+		xd_error ("illegal query size: %s\n", xdp_errno (ret));
+	      }
+	  }
+	  break;
+	case 'm':
+	  {
+	    gchar* end = NULL;
+	    glong l = strtol (optarg, &end, 0);
+
+	    if (end && g_strcasecmp (end, "M") == 0)
+	      l <<= 20;
+	    else if (end && g_strcasecmp (end, "K") == 0)
+	      l <<= 10;
+	    else if (end || l < 0)
+	      {
+		xd_error ("illegal maxmem argument %s\n", optarg);
+		return 2;
+	      }
+
+#ifdef __DJGPP__
+	    /*
+	     * (richdawe@bigfoot.com): Old MS-DOS systems may have a maximum
+	     * of 8MB memory == XD_PAGE_SIZE * 8. Therefore, do what the user
+	     * asks for on MS-DOS.
+	     */
+#else /* !__DJGPP__ */
+	    l = MAX (l, XD_PAGE_SIZE * 8);
+#endif /* __DJGPP__ */
+
+	    max_mapped_pages = l / XD_PAGE_SIZE;
+	  }
+	  break;
+	case 'h': help (); break;
+	case 'v': version (); break;
+	case '0': case '1': case '2': case '3': case '4':
+	case '5': case '6': case '7': case '8': case '9':
+	  compress_level = c - '0';
+	  break;
+	case '?':
+	default:
+	  xd_error ("illegal argument, use --help for help\n");
+	  return 2;
+	}
+    }
+
+  if (verbose && max_mapped_pages < G_MAXINT)
+    xd_error ("using %d kilobytes of buffer space\n", (max_mapped_pages * XD_PAGE_SIZE) >> 10);
+
+  argc -= optind;
+  argv += optind;
+
+  if (cmd->nargs >= 0 && argc != cmd->nargs)
+    {
+      xd_error ("wrong number of arguments\n");
+      help ();
+      return 2;
+    }
+
+  return (* cmd->func) (argc, argv);
+}
+
+/* Commands */
+
+#define READ_TYPE 1
+#define READ_NOSEEK_TYPE 1
+#define READ_SEEK_TYPE   3
+#define WRITE_TYPE 4
+
+/* Note to the casual reader: the filehandle implemented here is
+ * highly aware of the calling patterns of the Xdelta library.  It
+ * also plays games with narrowing to implement several files in the
+ * same handle.  So, if you try to modify or use this code, BEWARE.
+ * See the repository package for a complete implementation.
+ * In fact, its really quite a hack. */
+
+static gssize xd_handle_map_page (XdFileHandle *fh, guint pgno, const guint8** mem);
+static gboolean xd_handle_unmap_page (XdFileHandle *fh, guint pgno, const guint8** mem);
+
+static gboolean
+xd_fwrite (XdFileHandle* fh, const void* buf, gint nbyte)
+{
+  return fwrite (buf, nbyte, 1, fh->out) == 1;
+}
+
+static gboolean
+xd_fread (XdFileHandle* fh, void* buf, gint nbyte)
+{
+  return fread (buf, nbyte, 1, fh->in) == 1;
+}
+
+static gboolean
+xd_fclose (XdFileHandle* fh)
+{
+  return fclose (fh->out) == 0;
+}
+
+static gboolean
+xd_frclose (XdFileHandle* fh)
+{
+  return fclose (fh->in) == 0;
+}
+
+static gboolean
+xd_gzwrite (XdFileHandle* fh, const void* buf, gint nbyte)
+{
+  return gzwrite (fh->out, (void*) buf, nbyte) == nbyte;
+}
+
+static gboolean
+xd_gzread (XdFileHandle* fh, void* buf, gint nbyte)
+{
+  return gzread (fh->in, buf, nbyte) == nbyte;
+}
+
+static gboolean
+xd_gzclose (XdFileHandle* fh)
+{
+  return gzclose (fh->out) == Z_OK;
+}
+
+static gboolean
+xd_gzrclose (XdFileHandle* fh)
+{
+  return gzclose (fh->in) == Z_OK;
+}
+
+static void
+init_table (XdFileHandle* fh)
+{
+  fh->lru_table = g_ptr_array_new ();
+  fh->lru_chunk = g_mem_chunk_create(LRU, 1<<9, G_ALLOC_ONLY);
+  fh->lru_head = NULL;
+  fh->lru_tail = NULL;
+}
+
+static XdFileHandle*
+open_common (const char* name, const char* real_name)
+{
+  XdFileHandle* fh;
+
+  gint fd;
+  struct stat buf;
+
+  if ((fd = open (name, O_RDONLY | O_BINARY, 0)) < 0)
+    {
+      xd_error ("open %s failed: %s\n", name, g_strerror (errno));
+      return NULL;
+    }
+
+  if (stat (name, &buf) < 0)
+    {
+      xd_error ("stat %s failed: %s\n", name, g_strerror (errno));
+      return NULL;
+    }
+
+  /* S_ISREG() is not on Windows */
+  if ((buf.st_mode & S_IFMT) != S_IFREG)
+    {
+      xd_error ("%s is not a regular file\n", name);
+      return NULL;
+    }
+
+  fh = g_new0 (XdFileHandle, 1);
+
+  fh->fh.table = & xd_handle_table;
+  fh->name = real_name;
+  fh->fd = fd;
+  fh->length = buf.st_size;
+  fh->narrow_high = buf.st_size;
+
+  return fh;
+}
+
+static gboolean
+file_gzipped (const char* name, gboolean *is_compressed)
+{
+  FILE* f = fopen (name, FOPEN_READ_ARG);
+  guint8 buf[2];
+
+  (*is_compressed) = FALSE;
+
+  if (! f)
+    {
+      xd_error ("open %s failed: %s\n", name, g_strerror (errno));
+      return FALSE;
+    }
+
+  if (fread (buf, 2, 1, f) != 1)
+    return TRUE;
+
+#define GZIP_MAGIC1 037
+#define GZIP_MAGIC2 0213
+
+  if (buf[0] == GZIP_MAGIC1 && buf[1] == GZIP_MAGIC2)
+    (* is_compressed) = TRUE;
+
+  return TRUE;
+}
+
+static const char*
+xd_tmpname (void)
+{
+  const char* tmpdir = g_get_tmp_dir ();
+  GString* s;
+  gint x = getpid ();
+  static gint seq = 0;
+  struct stat buf;
+
+  s = g_string_new (NULL);
+
+  do
+    {
+      /*
+       * (richdawe@bigfoot.com): Limit temporary filenames to
+       * the MS-DOS 8+3 convention for DJGPP.
+       */
+      g_string_sprintf (s, "%s/xd-%05d.%03d", tmpdir, x, seq++);
+    }
+  while (lstat (s->str, &buf) == 0);
+
+  return s->str;
+}
+
+static const char*
+file_gunzip (const char* name)
+{
+  const char* new_name = xd_tmpname ();
+  FILE* out = fopen (new_name, FOPEN_WRITE_ARG);
+  gzFile in = gzopen (name, "rb");
+  guint8 buf[1024];
+  int nread;
+
+  while ((nread = gzread (in, buf, 1024)) > 0)
+    {
+      if (fwrite (buf, nread, 1, out) != 1)
+	{
+	  xd_error ("write %s failed (during uncompression): %s\n", new_name, g_strerror (errno));
+	  return NULL;
+	}
+    }
+
+  if (nread < 0)
+    {
+      xd_error ("gzread %s failed\n", name);
+      return NULL;
+    }
+
+  gzclose (in);
+
+  if (fclose (out))
+    {
+      xd_error ("close %s failed (during uncompression): %s\n", new_name, g_strerror (errno));
+      return NULL;
+    }
+
+  return new_name;
+}
+
+static XdFileHandle*
+open_read_noseek_handle (const char* name, gboolean* is_compressed, gboolean will_read, gboolean honor_pristine)
+{
+  XdFileHandle* fh;
+  const char* name0 = name;
+
+  /* we _could_ stream-read this file if compressed, but it adds a
+   * lot of complexity.  the library can handle it, just set the
+   * length to (XDELTA_MAX_FILE_LEN-1) and make sure that the end
+   * of file condition is set when on the last page.  However, I
+   * don't feel like it. */
+  if (honor_pristine && pristine)
+    *is_compressed = FALSE;
+  else
+    {
+      if (! file_gzipped (name, is_compressed))
+        return NULL;
+    }
+
+  if ((* is_compressed) && ! (name = file_gunzip (name)))
+    return NULL;
+
+  if (! (fh = open_common (name, name0)))
+    return NULL;
+
+  fh->type = READ_NOSEEK_TYPE;
+
+  edsio_md5_init (&fh->ctx);
+
+  if (*is_compressed)
+    fh->cleanup = name;
+
+  if (will_read)
+    {
+      g_assert (fh->fd >= 0);
+      if (! (fh->in = fdopen (dup (fh->fd), FOPEN_READ_ARG)))
+	{
+	  xd_error ("fdopen: %s\n", g_strerror (errno));
+	  return NULL;
+	}
+      fh->in_read = &xd_fread;
+      fh->in_close = &xd_frclose;
+    }
+  else
+    {
+      init_table (fh);
+    }
+
+  return fh;
+}
+
+static void
+xd_read_close (XdFileHandle* fh)
+{
+  /*
+   * (richdawe@bigfoot.com): On Unix you can unlink a file while it is
+   * still open. On MS-DOS this can lead to filesystem corruption. Close
+   * the file before unlinking it.
+   */
+  close (fh->fd);
+
+  if (fh->cleanup)
+    unlink (fh->cleanup);
+
+  if (fh->in)
+    (*fh->in_close) (fh);
+}
+
+static XdFileHandle*
+open_read_seek_handle (const char* name, gboolean* is_compressed, gboolean honor_pristine)
+{
+  XdFileHandle* fh;
+  const char* name0 = name;
+
+  if (honor_pristine && pristine)
+    *is_compressed = FALSE;
+  else
+    {
+      if (! file_gzipped (name, is_compressed))
+	return NULL;
+    }
+
+  if ((* is_compressed) && ! (name = file_gunzip (name)))
+    return NULL;
+
+  if (! (fh = open_common (name, name0)))
+    return NULL;
+
+  fh->type = READ_SEEK_TYPE;
+
+  if (*is_compressed)
+    fh->cleanup = name;
+
+  init_table (fh);
+
+  edsio_md5_init (&fh->ctx);
+
+  return fh;
+}
+
+static XdFileHandle*
+open_write_handle (int fd, const char* name)
+{
+  XdFileHandle* fh = g_new0 (XdFileHandle, 1);
+  int nfd;
+
+  fh->fh.table = & xd_handle_table;
+  fh->out_fd = fd;
+  fh->out_write = &xd_fwrite;
+  fh->out_close = &xd_fclose;
+
+  g_assert (fh->out_fd >= 0);
+
+  nfd = dup (fh->out_fd);
+
+  if (! (fh->out = fdopen (nfd, FOPEN_WRITE_ARG)))
+    {
+      xd_error ("fdopen %s failed: %s\n", name, g_strerror (errno));
+      return NULL;
+    }
+
+  fh->type = WRITE_TYPE;
+  fh->name = name;
+
+  edsio_md5_init (&fh->ctx);
+
+  return fh;
+}
+
+static gint
+xd_begin_compression (XdFileHandle* fh)
+{
+  gint filepos, nfd;
+
+  if (compress_level == 0)
+    return fh->real_length;
+
+  if (! (fh->out_close) (fh))
+    {
+      xd_error ("fclose failed: %s\n", g_strerror (errno));
+      return -1;
+    }
+
+  filepos = lseek (fh->out_fd, 0, SEEK_END);
+
+  if (filepos < 0)
+    {
+      xd_error ("lseek failed: %s\n", g_strerror (errno));
+      return -1;
+    }
+
+  g_assert (fh->out_fd >= 0);
+
+  nfd = dup (fh->out_fd);
+
+  fh->out = gzdopen (nfd, "wb");
+  fh->out_write = &xd_gzwrite;
+  fh->out_close = &xd_gzclose;
+
+  if (! fh->out)
+    {
+      xd_error ("gzdopen failed: %s\n", g_strerror (errno));
+      return -1;
+    }
+
+  if (gzsetparams(fh->out, compress_level, Z_DEFAULT_STRATEGY) != Z_OK)
+    {
+      int foo;
+      xd_error ("gzsetparams failed: %s\n", gzerror (fh->out, &foo));
+      return -1;
+    }
+
+  return filepos;
+}
+
+static gboolean
+xd_end_compression (XdFileHandle* fh)
+{
+  if (compress_level == 0)
+    return TRUE;
+
+  if (! (fh->out_close) (fh))
+    {
+      xd_error ("fdclose failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  if (lseek (fh->out_fd, 0, SEEK_END) < 0)
+    {
+      xd_error ("lseek failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  g_assert (fh->out_fd >= 0);
+  fh->out = fdopen (dup (fh->out_fd), FOPEN_WRITE_ARG);
+  fh->out_write = &xd_fwrite;
+  fh->out_close = &xd_fclose;
+
+  if (! fh->out)
+    {
+      xd_error ("fdopen failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gssize
+xd_handle_length (XdFileHandle *fh)
+{
+  if (fh->in_compressed)
+    return fh->current_pos;
+  else
+    return fh->narrow_high - fh->narrow_low;
+}
+
+static gssize
+xd_handle_pages (XdFileHandle *fh)
+{
+  g_assert (fh->type & READ_TYPE);
+  return xd_handle_length (fh) / XD_PAGE_SIZE;
+}
+
+static gssize
+xd_handle_pagesize (XdFileHandle *fh)
+{
+  g_assert (fh->type & READ_TYPE);
+  return XD_PAGE_SIZE;
+}
+
+static gint
+on_page (XdFileHandle* fh, guint pgno)
+{
+  if (pgno > xd_handle_pages (fh))
+    return -1;
+
+  if (pgno == xd_handle_pages (fh))
+    return xd_handle_length (fh) % XD_PAGE_SIZE;
+
+  return XD_PAGE_SIZE;
+}
+
+static gboolean
+xd_handle_close (XdFileHandle *fh, gint ignore)
+{
+  /* this is really a reset for writable files */
+
+  if (fh->type == WRITE_TYPE)
+    {
+      if (fh->reset_length_next_write)
+	{
+	  fh->reset_length_next_write = FALSE;
+	  fh->length = 0;
+	  fh->narrow_high = 0;
+	}
+
+      fh->reset_length_next_write = TRUE;
+      edsio_md5_final (fh->md5, &fh->ctx);
+      edsio_md5_init (&fh->ctx);
+    }
+  else if (fh->in)
+    {
+      edsio_md5_final (fh->md5, &fh->ctx);
+      edsio_md5_init (&fh->ctx);
+      fh->md5_good = FALSE;
+    }
+
+  return TRUE;
+}
+
+static const guint8*
+xd_handle_checksum_md5 (XdFileHandle *fh)
+{
+  if (fh->in && ! fh->md5_good)
+    {
+      edsio_md5_final (fh->md5, &fh->ctx);
+      fh->md5_good = TRUE;
+    }
+  else if (fh->type != WRITE_TYPE && !fh->in)
+    {
+      const guint8* page;
+
+      while (fh->md5_page <= xd_handle_pages (fh))
+	{
+	  gint pgno = fh->md5_page;
+	  gint onpage;
+
+	  if ((onpage = xd_handle_map_page (fh, pgno, &page)) < 0)
+	    return NULL;
+
+	  if (pgno == fh->md5_page)
+	    {
+	      fh->md5_page += 1;
+	      edsio_md5_update (&fh->ctx, page, onpage);
+
+	      if (fh->md5_page > xd_handle_pages (fh))
+		edsio_md5_final (fh->md5, &fh->ctx);
+	    }
+
+	  if (! xd_handle_unmap_page (fh, pgno, &page))
+	    return NULL;
+	}
+    }
+
+  return g_memdup (fh->md5, 16);
+}
+
+static gboolean
+xd_handle_set_pos (XdFileHandle *fh, guint pos)
+{
+  if (fh->current_pos == pos + fh->narrow_low)
+    return TRUE;
+
+  if (pos + fh->narrow_low > fh->narrow_high)
+    {
+      xd_error ("unexpected EOF in %s\n", fh->name);
+      return FALSE;
+    }
+
+  fh->current_pos = pos + fh->narrow_low;
+
+  if (fseek (fh->in, fh->current_pos, SEEK_SET))
+    {
+      xd_error ("fseek failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+xd_handle_narrow (XdFileHandle* fh, guint low, guint high, gboolean compressed)
+{
+  if (high > fh->length)
+    {
+      xd_error ("%s: corrupt or truncated delta\n", fh->name);
+      return FALSE;
+    }
+
+  fh->narrow_low = low;
+  fh->narrow_high = high;
+
+  edsio_md5_init (&fh->ctx);
+
+  if (compressed)
+    {
+      (* fh->in_close) (fh);
+
+      if (lseek (fh->fd, low, SEEK_SET) < 0)
+	{
+	  xd_error ("%s: corrupt or truncated delta: cannot seek to %d: %s\n", fh->name, low, g_strerror (errno));
+	  return FALSE;
+	}
+
+      g_assert (fh->fd >= 0);
+      fh->in = gzdopen (dup (fh->fd), "rb");
+      fh->in_read =  &xd_gzread;
+      fh->in_close = &xd_gzrclose;
+      fh->in_compressed = TRUE;
+      fh->current_pos = 0;
+
+      if (! fh->in)
+	{
+	  xd_error ("gzdopen failed: %s\n", g_strerror (errno));
+	  return -1;
+	}
+    }
+  else
+    {
+      if (! xd_handle_set_pos (fh, 0))
+	return FALSE;
+    }
+
+  return TRUE;
+}
+
+static guint
+xd_handle_get_pos (XdFileHandle* fh)
+{
+  return fh->current_pos - fh->narrow_low;
+}
+
+static const gchar*
+xd_handle_name (XdFileHandle *fh)
+{
+  return g_strdup (fh->name);
+}
+
+static gssize
+xd_handle_read (XdFileHandle *fh, guint8 *buf, gsize nbyte)
+{
+  if (nbyte == 0)
+    return 0;
+
+  if (! (fh->in_read) (fh, buf, nbyte)) /* This is suspicious */
+    {
+      xd_error ("read failed: %s\n", g_strerror (errno));
+      return -1;
+    }
+
+  if (!no_verify)
+    edsio_md5_update (&fh->ctx, buf, nbyte);
+
+  fh->current_pos += nbyte;
+
+  return nbyte;
+}
+
+static gboolean
+xd_handle_write (XdFileHandle *fh, const guint8 *buf, gsize nbyte)
+{
+  g_assert (fh->type == WRITE_TYPE);
+
+  if (fh->reset_length_next_write)
+    {
+      fh->reset_length_next_write = FALSE;
+      fh->length = 0;
+      fh->narrow_high = 0;
+    }
+
+  if (! no_verify)
+    edsio_md5_update (&fh->ctx, buf, nbyte);
+
+  if (! (*fh->out_write) (fh, buf, nbyte))
+    {
+      xd_error ("write failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  fh->length += nbyte;
+  fh->real_length += nbyte;
+  fh->narrow_high += nbyte;
+
+  return TRUE;
+}
+
+static gboolean
+xd_handle_really_close (XdFileHandle *fh)
+{
+  g_assert (fh->type == WRITE_TYPE);
+
+  if (! (* fh->out_close) (fh) || close (fh->out_fd) < 0)
+    {
+      xd_error ("write failed: %s\n", g_strerror (errno));
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static LRU*
+pull_lru (XdFileHandle* fh, LRU* lru)
+{
+  if (lru->next && lru->prev)
+    {
+      lru->next->prev = lru->prev;
+      lru->prev->next = lru->next;
+    }
+  else if (lru->next)
+    {
+      fh->lru_tail = lru->next;
+      lru->next->prev = NULL;
+    }
+  else if (lru->prev)
+    {
+      fh->lru_head = lru->prev;
+      lru->prev->next = NULL;
+    }
+  else
+    {
+      fh->lru_head = NULL;
+      fh->lru_tail = NULL;
+    }
+
+  lru->next = NULL;
+  lru->prev = NULL;
+
+  return lru;
+}
+
+static gboolean
+really_free_one_page (XdFileHandle* fh)
+{
+  LRU *lru = fh->lru_tail;
+
+  for (; lru; lru = lru->prev)
+    {
+      gint to_unmap;
+      LRU *lru_dead;
+
+      if (lru->refs > 0)
+	continue;
+
+      lru_dead = pull_lru (fh, lru);
+
+      g_assert (lru_dead->buffer);
+
+      to_unmap = on_page (fh, lru_dead->page);
+
+      fh->lru_count -= 1;
+
+      if (to_unmap > 0)
+	{
+#ifdef WINHACK
+	  g_free (lru_dead->buffer);
+#else
+	  if (munmap (lru_dead->buffer, to_unmap))
+	    {
+	      xd_error ("munmap failed: %s\n", g_strerror (errno));
+	      return FALSE;
+	    }
+#endif /* WINHACK */
+	}
+
+      lru_dead->buffer = NULL;
+
+      return TRUE;
+    }
+
+  return TRUE;
+}
+
+#if 0
+static void
+print_lru (XdFileHandle* fh)
+{
+  LRU* lru = fh->lru_head;
+
+  for (; lru; lru = lru->prev)
+    {
+      g_print ("page %d buffer %p\n", lru->page, lru->buffer);
+
+      if (! lru->prev && lru != fh->lru_tail)
+	g_print ("incorrect lru_tail\n");
+    }
+}
+#endif
+
+static gboolean
+make_lru_room (XdFileHandle* fh)
+{
+  if (fh->lru_count == max_mapped_pages)
+    {
+      if (! really_free_one_page (fh))
+	return FALSE;
+    }
+
+  g_assert (fh->lru_count < max_mapped_pages);
+
+  return TRUE;
+}
+
+/*#define DEBUG_MAP*/
+
+static gssize
+xd_handle_map_page (XdFileHandle *fh, guint pgno, const guint8** mem)
+{
+  LRU* lru;
+  guint to_map;
+
+#ifdef DEBUG_MAP
+  g_print ("map %p:%d\n", fh, pgno);
+#endif
+
+  g_assert (fh->type & READ_TYPE);
+
+  if (fh->lru_table->len < (pgno + 1))
+    {
+      gint olen = fh->lru_table->len;
+
+      g_ptr_array_set_size (fh->lru_table, pgno + 1);
+
+      while (olen <= pgno)
+	fh->lru_table->pdata[olen++] = NULL;
+    }
+
+  lru = fh->lru_table->pdata[pgno];
+
+  if (! lru)
+    {
+      lru = g_chunk_new0 (LRU, fh->lru_chunk);
+      fh->lru_table->pdata[pgno] = lru;
+      lru->page = pgno;
+    }
+  else if (lru->buffer)
+    {
+      pull_lru (fh, lru);
+    }
+
+  lru->prev = fh->lru_head;
+  lru->next = NULL;
+
+  fh->lru_head = lru;
+
+  if (lru->prev)
+    lru->prev->next = lru;
+
+  if (! fh->lru_tail)
+    fh->lru_tail = lru;
+
+  to_map = on_page (fh, pgno);
+
+  if (to_map < 0)
+    {
+      xd_error ("unexpected EOF in %s\n", fh->name);
+      return -1;
+    }
+
+  if (! lru->buffer)
+    {
+      if (! make_lru_room (fh))
+	return -1;
+
+      fh->lru_count += 1;
+
+      if (to_map > 0)
+	{
+#ifdef WINHACK
+	  lru->buffer = g_malloc (to_map);
+
+	  if (lseek (fh->fd, pgno * XD_PAGE_SIZE, SEEK_SET) < 0)
+	    {
+	      xd_error ("lseek failed: %s\n", g_strerror (errno));
+	      return -1;
+	    }
+
+	  if (read (fh->fd, lru->buffer, to_map) != to_map)
+	    {
+	      xd_error ("read failed: %s\n", g_strerror (errno));
+	      return -1;
+	    }
+#else
+	  if (! (lru->buffer = mmap (NULL, to_map, PROT_READ, MAP_PRIVATE, fh->fd, pgno * XD_PAGE_SIZE)))
+	    {
+	      xd_error ("mmap failed: %s\n", g_strerror (errno));
+	      return -1;
+	    }
+#endif
+	}
+      else
+	{
+	  lru->buffer = (void*) -1;
+	}
+
+      if (pgno == fh->md5_page)
+	{
+	  if (! no_verify)
+	    edsio_md5_update (&fh->ctx, lru->buffer, to_map);
+	  fh->md5_page += 1;
+
+	  if (fh->md5_page > xd_handle_pages (fh))
+	    edsio_md5_final (fh->md5, &fh->ctx);
+	}
+    }
+
+  (*mem) = lru->buffer;
+
+  lru->refs += 1;
+  fh->lru_outstanding_refs += 1;
+
+  return to_map;
+}
+
+static gboolean
+xd_handle_unmap_page (XdFileHandle *fh, guint pgno, const guint8** mem)
+{
+  LRU* lru;
+
+#ifdef DEBUG_MAP
+  g_print ("unmap %p:%d\n", fh, pgno);
+#endif
+
+  g_assert (fh->type & READ_TYPE);
+
+  g_assert (pgno < fh->lru_table->len);
+
+  lru = fh->lru_table->pdata[pgno];
+
+  g_assert (lru && lru->refs > 0);
+
+  g_assert (lru->buffer == (*mem));
+
+  (*mem) = NULL;
+
+  lru->refs -= 1;
+  fh->lru_outstanding_refs += 1;
+
+  if (lru->refs == 0 && fh->type == READ_NOSEEK_TYPE)
+    {
+      pull_lru (fh, lru);
+
+      lru->next = fh->lru_tail;
+      if (lru->next) lru->next->prev = lru;
+      lru->prev = NULL;
+      fh->lru_tail = lru;
+
+      if (! really_free_one_page (fh))
+	return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
+xd_handle_copy (XdFileHandle *from, XdFileHandle *to, guint off, guint len)
+{
+  if (from->in)
+    {
+      guint8 buf[1024];
+
+      /*if (! xd_handle_set_pos (from, off))
+	return FALSE;*/
+
+      while (len > 0)
+	{
+	  guint r = MIN (1024, len);
+
+	  if (xd_handle_read (from, buf, r) != r)
+	    return FALSE;
+
+	  if (! xd_handle_write (to, buf, r))
+	    return FALSE;
+
+	  len -= r;
+	}
+    }
+  else
+    {
+      while (len > 0)
+	{
+	  guint off_page = off / XD_PAGE_SIZE;
+	  guint off_off = off % XD_PAGE_SIZE;
+
+	  gint on = on_page (from, off_page);
+	  guint rem;
+	  guint copy;
+
+	  if (on <= 0)
+	    {
+	      xd_error ("unexpected EOF in %s\n", from->name);
+	      return FALSE;
+	    }
+
+	  rem = on - off_off;
+	  copy = MIN (len, rem);
+
+	  if (from->copy_pgno != off_page &&
+	      from->copy_page &&
+	      ! xd_handle_unmap_page (from, from->copy_pgno, &from->copy_page))
+	    return FALSE;
+
+	  from->copy_pgno = off_page;
+
+	  if (xd_handle_map_page (from, off_page, &from->copy_page) < 0)
+	    return FALSE;
+
+	  if (! xd_handle_write (to, from->copy_page + off_off, copy))
+	    return FALSE;
+
+	  if (! xd_handle_unmap_page (from, off_page, &from->copy_page))
+	    return FALSE;
+
+	  len -= copy;
+	  off += copy;
+	}
+    }
+
+  return TRUE;
+}
+
+static gboolean
+xd_handle_putui (XdFileHandle *fh, guint32 i)
+{
+  guint32 hi = g_htonl (i);
+
+  return xd_handle_write (fh, (guint8*)&hi, 4);
+}
+
+static gboolean
+xd_handle_getui (XdFileHandle *fh, guint32* i)
+{
+  if (xd_handle_read (fh, (guint8*)i, 4) != 4)
+    return FALSE;
+
+  *i = g_ntohl (*i);
+
+  return TRUE;
+}
+
+static HandleFuncTable xd_handle_table =
+{
+  (gssize (*) (FileHandle *fh)) xd_handle_length,
+  (gssize (*) (FileHandle *fh)) xd_handle_pages,
+  (gssize (*) (FileHandle *fh)) xd_handle_pagesize,
+  (gssize (*) (FileHandle *fh, guint pgno, const guint8** mem)) xd_handle_map_page,
+  (gboolean (*) (FileHandle *fh, guint pgno, const guint8** mem)) xd_handle_unmap_page,
+  (const guint8* (*) (FileHandle *fh)) xd_handle_checksum_md5,
+
+  (gboolean (*) (FileHandle *fh, gint flags)) xd_handle_close,
+
+  (gboolean (*) (FileHandle *fh, const guint8 *buf, gsize nbyte)) xd_handle_write,
+  (gboolean (*) (FileHandle *from, FileHandle *to, guint off, guint len)) xd_handle_copy,
+
+  (gboolean (*) (FileHandle *fh, guint32* i)) xd_handle_getui,
+  (gboolean (*) (FileHandle *fh, guint32 i)) xd_handle_putui,
+  (gssize   (*) (FileHandle *fh, guint8 *buf, gsize nbyte)) xd_handle_read,
+  (const gchar* (*) (FileHandle *fh)) xd_handle_name,
+};
+
+static void
+htonl_array (guint32* array, gint len)
+{
+  gint i;
+
+  for (i = 0; i < len; i += 1)
+    array[i] = g_htonl(array[i]);
+}
+
+static void
+ntohl_array (guint32* array, gint len)
+{
+  gint i;
+
+  for (i = 0; i < len; i += 1)
+    array[i] = g_ntohl(array[i]);
+}
+
+static gint
+delta_command (gint argc, gchar** argv)
+{
+  gint patch_out_fd;
+  const char* patch_out_name;
+  XdFileHandle *from, *to, *out;
+  XdeltaGenerator* gen;
+  XdeltaSource* src;
+  XdeltaControl* cont;
+  gboolean from_is_compressed = FALSE, to_is_compressed = FALSE;
+  guint32 control_offset, header_offset;
+  const char* from_name, *to_name;
+  guint32 header_space[HEADER_WORDS];
+  int fd;
+
+  memset (header_space, 0, sizeof (header_space));
+
+  if (argc != 3)
+    {
+      xd_error ("usage: %s delta fromfile tofile patchfile\n", program_name);
+      return 2;
+    }
+
+  if (verbose)
+    {
+      xd_error ("using block size: %d bytes\n", xdp_blocksize ());
+    }
+
+
+  if (! (from = open_read_seek_handle (argv[0], &from_is_compressed, TRUE)))
+    return 2;
+
+  if (! (to = open_read_noseek_handle (argv[1], &to_is_compressed, FALSE, TRUE)))
+    return 2;
+
+  // Note: I tried support to patches to stdout, but it broke when
+  // compression was added.  Sigh
+  fd = open (argv[2], O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0666);
+
+  if (fd < 0)
+    {
+      xd_error ("open %s failed: %s\n", argv[2], g_strerror (errno));
+      return 2;
+    }
+
+  patch_out_fd = fd;
+  patch_out_name = argv[2];
+
+  from_name = g_basename (argv[0]);
+  to_name = g_basename (argv[1]);
+
+  if (! (out = open_write_handle (patch_out_fd, patch_out_name)))
+    return 2;
+
+  if (! (gen = xdp_generator_new ()))
+    return 2;
+
+  if (! (src = xdp_source_new (from_name, (FileHandle*) from, NULL, NULL)))
+    return 2;
+
+  xdp_source_add (gen, src);
+
+  if (! xd_handle_write (out, XDELTA_PREFIX, XDELTA_PREFIX_LEN))
+    return 2;
+
+  /* compute the header */
+  header_space[0] = 0;
+
+  if (no_verify) header_space[0]           |= FLAG_NO_VERIFY;
+  if (from_is_compressed) header_space[0]  |= FLAG_FROM_COMPRESSED;
+  if (to_is_compressed) header_space[0]    |= FLAG_TO_COMPRESSED;
+  if (compress_level != 0) header_space[0] |= FLAG_PATCH_COMPRESSED;
+
+  header_space[1] = strlen (from_name) << 16 | strlen (to_name);
+  /* end compute the header */
+
+  htonl_array (header_space, HEADER_WORDS);
+
+  if (! xd_handle_write (out, (guint8*) header_space, HEADER_SPACE))
+    return 2;
+
+  if (! xd_handle_write (out, from_name, strlen (from_name)))
+    return 2;
+
+  if (! xd_handle_write (out, to_name, strlen (to_name)))
+    return 2;
+
+  if (! xd_handle_close (out, 0))
+    return 2;
+
+  if ((header_offset = xd_begin_compression (out)) < 0)
+    return 2;
+
+  if (! (cont = xdp_generate_delta (gen, (FileHandle*) to, NULL, (FileHandle*) out)))
+    return 2;
+
+#if 0
+  serializeio_print_xdeltacontrol_obj (cont, 0);
+#endif
+
+  if (cont->has_data && cont->has_data == cont->source_info_len)
+    {
+      if (! quiet)
+	xd_error ("warning: no matches found in from file, patch will apply without it\n");
+    }
+
+  if (! xd_handle_close (out, 0))
+    return 2;
+
+  if ((control_offset = xd_begin_compression (out)) < 0)
+    return 2;
+
+  if (! xdp_control_write (cont, (FileHandle*) out))
+    return 2;
+
+  if (! xd_end_compression (out))
+    return 2;
+
+  if (! xd_handle_putui (out, control_offset))
+    return 2;
+
+  if (! xd_handle_write (out, XDELTA_PREFIX, XDELTA_PREFIX_LEN))
+    return 2;
+
+  xd_read_close (from);
+  xd_read_close (to);
+
+  if (! xd_handle_really_close (out))
+    return 2;
+
+  xdp_generator_free (gen);
+
+  return control_offset != header_offset;
+}
+
+static XdeltaPatch*
+process_patch (const char* name)
+{
+  XdeltaPatch* patch;
+  guint total_trailer;
+
+  patch = g_new0 (XdeltaPatch, 1);
+
+  patch->patch_name = name;
+
+  /* Strictly speaking, I'm violating the intended semantics of noseek here.
+   * It will seek the file, which is not in fact checked in the map/unmap
+   * logic above.  This only means that it will not cache pages of this file
+   * since it will be read piecewise sequentially. */
+  if (! (patch->patch_in = open_read_noseek_handle (name, &patch->patch_is_compressed, TRUE, TRUE)))
+    return NULL;
+
+  if (xd_handle_read (patch->patch_in, patch->magic_buf, XDELTA_PREFIX_LEN) != XDELTA_PREFIX_LEN)
+    return NULL;
+
+  if (xd_handle_read (patch->patch_in, (guint8*) patch->header_space, HEADER_SPACE) != HEADER_SPACE)
+    return NULL;
+
+  ntohl_array (patch->header_space, HEADER_WORDS);
+
+  if (strncmp (patch->magic_buf, XDELTA_110_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    {
+      patch->has_trailer = TRUE;
+      patch->patch_version = "1.1";
+    }
+  else if (strncmp (patch->magic_buf, XDELTA_104_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    {
+      patch->has_trailer = TRUE;
+      patch->patch_version = "1.0.4";
+    }
+  else if (strncmp (patch->magic_buf, XDELTA_100_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    {
+      patch->patch_version = "1.0";
+    }
+  else if (strncmp (patch->magic_buf, XDELTA_020_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    goto nosupport;
+  else if (strncmp (patch->magic_buf, XDELTA_018_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    goto nosupport;
+  else if (strncmp (patch->magic_buf, XDELTA_014_PREFIX, XDELTA_PREFIX_LEN) == 0)
+    goto nosupport;
+  else
+    {
+      xd_error ("%s: bad magic number: not a valid delta\n", name);
+      return NULL;
+    }
+
+  patch->patch_flags = patch->header_space[0];
+
+  if (no_verify)
+    xd_error ("--noverify is only accepted when creating a delta\n");
+
+  if (patch->patch_flags & FLAG_NO_VERIFY)
+    no_verify = TRUE;
+  else
+    no_verify = FALSE;
+
+  patch->from_name_len = patch->header_space[1] >> 16;
+  patch->to_name_len = patch->header_space[1] & 0xffff;
+
+  patch->from_name = g_malloc (patch->from_name_len+1);
+  patch->to_name = g_malloc (patch->to_name_len+1);
+
+  patch->from_name[patch->from_name_len] = 0;
+  patch->to_name[patch->to_name_len] = 0;
+
+  if (xd_handle_read (patch->patch_in, patch->from_name, patch->from_name_len) != patch->from_name_len)
+    return NULL;
+
+  if (xd_handle_read (patch->patch_in, patch->to_name, patch->to_name_len) != patch->to_name_len)
+    return NULL;
+
+  patch->header_offset = xd_handle_get_pos (patch->patch_in);
+
+  total_trailer = 4 + (patch->has_trailer ? XDELTA_PREFIX_LEN : 0);
+
+  if (! xd_handle_set_pos (patch->patch_in, xd_handle_length (patch->patch_in) - total_trailer))
+    return NULL;
+
+  if (! xd_handle_getui (patch->patch_in, &patch->control_offset))
+    return NULL;
+
+  if (patch->has_trailer)
+    {
+      guint8 trailer_buf[XDELTA_PREFIX_LEN];
+
+      if (xd_handle_read (patch->patch_in, trailer_buf, XDELTA_PREFIX_LEN) != XDELTA_PREFIX_LEN)
+	return NULL;
+
+      if (strncmp (trailer_buf, patch->magic_buf, XDELTA_PREFIX_LEN) != 0)
+	{
+	  xd_error ("%s: bad trailing magic number, delta is corrupt\n", name);
+	  return NULL;
+	}
+    }
+
+  if (! xd_handle_narrow (patch->patch_in, patch->control_offset,
+			  xd_handle_length (patch->patch_in) - total_trailer,
+			  patch->patch_flags & FLAG_PATCH_COMPRESSED))
+    return NULL;
+
+  if (! (patch->cont = xdp_control_read ((FileHandle*) patch->patch_in)))
+    return NULL;
+
+  if (patch->cont->source_info_len > 0)
+    {
+      XdeltaSourceInfo* info = patch->cont->source_info[0];
+
+      if (info->isdata)
+	patch->data_source = info;
+      else
+	{
+	  patch->from_source = info;
+
+	  if (patch->cont->source_info_len > 1)
+	    {
+	      xd_generate_void_event (EC_XdIncompatibleDelta);
+	      return NULL;
+	    }
+	}
+    }
+
+  if (patch->cont->source_info_len > 1)
+    {
+      patch->from_source = patch->cont->source_info[1];
+    }
+
+  if (patch->cont->source_info_len > 2)
+    {
+      xd_generate_void_event (EC_XdIncompatibleDelta);
+      return NULL;
+    }
+
+  if (! xd_handle_narrow (patch->patch_in,
+			  patch->header_offset,
+			  patch->control_offset,
+			  patch->patch_flags & FLAG_PATCH_COMPRESSED))
+    return NULL;
+
+  return patch;
+
+ nosupport:
+
+  xd_error ("delta format is unsupported (too old)\n");
+  return NULL;
+}
+
+static gint
+info_command (gint argc, gchar** argv)
+{
+  XdeltaPatch* patch;
+  char buf[33];
+  int i;
+  XdeltaSourceInfo* si;
+
+  if (! (patch = process_patch (argv[0])))
+    return 2;
+
+  xd_error_file = stdout;
+
+  xd_error ("version %s found patch version %s in %s%s\n",
+	    xdelta_version,
+	    patch->patch_version,
+	    patch->patch_name,
+	    patch->patch_flags & FLAG_PATCH_COMPRESSED ? " (compressed)" : "");
+
+  if (patch->patch_flags & FLAG_NO_VERIFY)
+    xd_error ("generated with --noverify\n");
+
+  if (patch->patch_flags & FLAG_FROM_COMPRESSED)
+    xd_error ("generated with a gzipped FROM file\n");
+
+  if (patch->patch_flags & FLAG_TO_COMPRESSED)
+    xd_error ("generated with a gzipped TO file\n");
+
+  edsio_md5_to_string (patch->cont->to_md5, buf);
+
+  xd_error ("output name:   %s\n", patch->to_name);
+  xd_error ("output length: %d\n", patch->cont->to_len);
+  xd_error ("output md5:    %s\n", buf);
+
+  xd_error ("patch from segments: %d\n", patch->cont->source_info_len);
+
+  xd_error ("MD5\t\t\t\t\tLength\tCopies\tUsed\tSeq?\tName\n");
+
+  for (i = 0; i < patch->cont->source_info_len; i += 1)
+    {
+      si = patch->cont->source_info[i];
+
+      edsio_md5_to_string (si->md5, buf);
+
+      xd_error ("%s\t%d\t%d\t%d\t%s\t%s\n",
+		buf,
+		si->len,
+		si->copies,
+		si->copy_length,
+		si->sequential ? "yes" : "no",
+		si->name);
+    }
+
+  return 0;
+}
+
+static gint
+patch_command (gint argc, gchar** argv)
+{
+  XdFileHandle* to_out;
+  XdeltaPatch* patch;
+  gint to_out_fd;
+  int count = 1;
+  int ret;
+
+  if (argc < 1 || argc > 3)
+    {
+      xd_error ("usage: %s patch patchfile [fromfile [tofile]]\n", program_name);
+      return 2;
+    }
+
+  if (! (patch = process_patch (argv[0])))
+    return 2;
+
+  if (argc > 1)
+    patch->from_name = argv[1];
+  else if (verbose)
+    xd_error ("using from file name: %s\n", patch->from_name);
+
+  if (argc > 2)
+    patch->to_name = argv[2];
+  else
+    {
+      struct stat sbuf;
+      gchar *defname = g_strdup (patch->to_name);
+
+      while ((ret = stat (patch->to_name, & sbuf)) == 0)
+	{
+	  if (verbose)
+	    xd_error ("to file exists: %s\n", patch->to_name);
+	  patch->to_name = g_strdup_printf ("%s.xdp%d", defname, count++);
+	}
+
+      if (verbose || strcmp (defname, patch->to_name) != 0)
+	xd_error ("using to file name: %s\n", patch->to_name);
+    }
+
+  if (strcmp (patch->to_name, "-") == 0)
+    {
+      to_out_fd = STDOUT_FILENO;
+      patch->to_name = "standard output";
+    }
+  else
+    {
+      to_out_fd = open (patch->to_name, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0666);
+
+      if (to_out_fd < 0)
+	{
+	  xd_error ("open %s failed: %s\n", patch->to_name, g_strerror (errno));
+	  return 2;
+	}
+    }
+
+  to_out = open_write_handle (to_out_fd, patch->to_name);
+
+  if ((patch->patch_flags & FLAG_TO_COMPRESSED) && (xd_begin_compression (to_out) < 0))
+    return 2;
+
+  if (patch->from_source)
+    {
+      XdFileHandle* from_in;
+      gboolean from_is_compressed = FALSE;
+
+      if (! (from_in = open_read_seek_handle (patch->from_name, &from_is_compressed, TRUE)))
+	return 2;
+
+      if (from_is_compressed != ((patch->patch_flags & FLAG_FROM_COMPRESSED) && 1))
+	xd_error ("warning: expected %scompressed from file (%s)\n",
+		  (patch->patch_flags & FLAG_FROM_COMPRESSED) ? "" : "un",
+		  patch->from_name);
+
+      if (xd_handle_length (from_in) != patch->from_source->len)
+	{
+	  xd_error ("expected from file (%s) of %slength %d bytes\n",
+		    patch->from_name,
+		    from_is_compressed ? "uncompressed " : "",
+		    patch->from_source->len);
+	  return 2;
+	}
+
+      patch->from_source->in = (XdeltaStream*) from_in;
+    }
+
+  if (patch->data_source)
+    patch->data_source->in = (XdeltaStream*) patch->patch_in;
+
+  if (! xdp_apply_delta (patch->cont, (FileHandle*) to_out))
+    return 2;
+
+  if (patch->from_source)
+    xd_read_close ((XdFileHandle*) patch->from_source->in);
+
+  xd_read_close (patch->patch_in);
+
+  if (! xd_handle_really_close (to_out))
+    return 2;
+
+  return 0;
+}