methods/rred.cc

   1 // Copyright (c) 2014 Anthony Towns
   2 //
   3 // This program is free software; you can redistribute it and/or modify
   4 // it under the terms of the GNU General Public License as published by
   5 // the Free Software Foundation; either version 2 of the License, or
   6 // (at your option) any later version.
   7
   8 #include <config.h>
   9
  10 #include <apt-pkg/init.h>
  11 #include <apt-pkg/fileutl.h>
  12 #include <apt-pkg/error.h>
  13 #include <apt-pkg/strutl.h>
  14 #include <apt-pkg/hashes.h>
  15 #include <apt-pkg/configuration.h>
  16 #include "aptmethod.h"
  17
  18 #include <stddef.h>
  19 #include <iostream>
  20 #include <string>
  21 #include <list>
  22 #include <vector>
  23
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sys/stat.h>
  30 #include <sys/time.h>
  31
  32 #include <apti18n.h>
  33
  34 #define BLOCK_SIZE (512*1024)
  35
  36 class MemBlock {
  37    char *start;
  38    size_t size;
  39    char *free;
  40    MemBlock *next;
  41
  42    explicit MemBlock(size_t size) : size(size), next(NULL)
  43    {
  44       free = start = new char[size];
  45    }
  46
  47    size_t avail(void) { return size - (free - start); }
  48
  49    public:
  50
  51    MemBlock(void) {
  52       free = start = new char[BLOCK_SIZE];
  53       size = BLOCK_SIZE;
  54       next = NULL;
  55    }
  56
  57    ~MemBlock() {
  58       delete [] start;
  59       delete next;
  60    }
  61
  62    void clear(void) {
  63       free = start;
  64       if (next)
  65          next->clear();
  66    }
  67
  68    char *add_easy(char *src, size_t len, char *last)
  69    {
  70       if (last) {
  71          for (MemBlock *k = this; k; k = k->next) {
  72             if (k->free == last) {
  73                if (len <= k->avail()) {
  74                   char *n = k->add(src, len);
  75                   assert(last == n);
  76                   if (last == n)
  77                      return NULL;
  78                   return n;
  79                } else {
  80                   break;
  81                }
  82             } else if (last >= start && last < free) {
  83                break;
  84             }
  85          }
  86       }
  87       return add(src, len);
  88    }
  89
  90    char *add(char *src, size_t len) {
  91       if (len > avail()) {
  92          if (!next) {
  93             if (len > BLOCK_SIZE)  {
  94                next = new MemBlock(len);
  95             } else {
  96                next = new MemBlock;
  97             }
  98          }
  99          return next->add(src, len);
 100       }
 101       char *dst = free;
 102       free += len;
 103       memcpy(dst, src, len);
 104       return dst;
 105    }
 106 };
 107
 108 struct Change {
 109    /* Ordering:
 110     *
 111     *   1. write out <offset> lines unchanged
 112     *   2. skip <del_cnt> lines from source
 113     *   3. write out <add_cnt> lines (<add>/<add_len>)
 114     */
 115    size_t offset;
 116    size_t del_cnt;
 117    size_t add_cnt; /* lines */
 118    size_t add_len; /* bytes */
 119    char *add;
 120
 121    explicit Change(size_t off)
 122    {
 123       offset = off;
 124       del_cnt = add_cnt = add_len = 0;
 125       add = NULL;
 126    }
 127
 128    /* actually, don't write <lines> lines from <add> */
 129    void skip_lines(size_t lines)
 130    {
 131       while (lines > 0) {
 132          char *s = (char*) memchr(add, '\n', add_len);
 133          assert(s != NULL);
 134          s++;
 135          add_len -= (s - add);
 136          add_cnt--;
 137          lines--;
 138          if (add_len == 0) {
 139             add = NULL;
 140             assert(add_cnt == 0);
 141             assert(lines == 0);
 142          } else {
 143             add = s;
 144             assert(add_cnt > 0);
 145          }
 146       }
 147    }
 148 };
 149
 150 class FileChanges {
 151    std::list<struct Change> changes;
 152    std::list<struct Change>::iterator where;
 153    size_t pos; // line number is as far left of iterator as possible
 154
 155    bool pos_is_okay(void) const
 156    {
 157 #ifdef POSDEBUG
 158       size_t cpos = 0;
 159       std::list<struct Change>::const_iterator x;
 160       for (x = changes.begin(); x != where; ++x) {
 161          assert(x != changes.end());
 162          cpos += x->offset + x->add_cnt;
 163       }
 164       return cpos == pos;
 165 #else
 166       return true;
 167 #endif
 168    }
 169
 170    public:
 171    FileChanges() {
 172       where = changes.end();
 173       pos = 0;
 174    }
 175
 176    std::list<struct Change>::iterator begin(void) { return changes.begin(); }
 177    std::list<struct Change>::iterator end(void) { return changes.end(); }
 178
 179    std::list<struct Change>::reverse_iterator rbegin(void) { return changes.rbegin(); }
 180    std::list<struct Change>::reverse_iterator rend(void) { return changes.rend(); }
 181
 182    void add_change(Change c) {
 183       assert(pos_is_okay());
 184       go_to_change_for(c.offset);
 185       assert(pos + where->offset == c.offset);
 186       if (c.del_cnt > 0)
 187          delete_lines(c.del_cnt);
 188       assert(pos + where->offset == c.offset);
 189       if (c.add_len > 0) {
 190          assert(pos_is_okay());
 191          if (where->add_len > 0)
 192             new_change();
 193          assert(where->add_len == 0 && where->add_cnt == 0);
 194
 195          where->add_len = c.add_len;
 196          where->add_cnt = c.add_cnt;
 197          where->add = c.add;
 198       }
 199       assert(pos_is_okay());
 200       merge();
 201       assert(pos_is_okay());
 202    }
 203
 204    private:
 205    void merge(void)
 206    {
 207       while (where->offset == 0 && where != changes.begin()) {
 208          left();
 209       }
 210       std::list<struct Change>::iterator next = where;
 211       ++next;
 212
 213       while (next != changes.end() && next->offset == 0) {
 214          where->del_cnt += next->del_cnt;
 215          next->del_cnt = 0;
 216          if (next->add == NULL) {
 217             next = changes.erase(next);
 218          } else if (where->add == NULL) {
 219             where->add = next->add;
 220             where->add_len = next->add_len;
 221             where->add_cnt = next->add_cnt;
 222             next = changes.erase(next);
 223          } else {
 224             ++next;
 225          }
 226       }
 227    }
 228
 229    void go_to_change_for(size_t line)
 230    {
 231       while(where != changes.end()) {
 232          if (line < pos) {
 233             left();
 234             continue;
 235          }
 236          if (pos + where->offset + where->add_cnt <= line) {
 237             right();
 238             continue;
 239          }
 240          // line is somewhere in this slot
 241          if (line < pos + where->offset) {
 242             break;
 243          } else if (line == pos + where->offset) {
 244             return;
 245          } else {
 246             split(line - pos);
 247             right();
 248             return;
 249          }
 250       }
 251       /* it goes before this patch */
 252       insert(line-pos);
 253    }
 254
 255    void new_change(void) { insert(where->offset); }
 256
 257    void insert(size_t offset)
 258    {
 259       assert(pos_is_okay());
 260       assert(where == changes.end() || offset <= where->offset);
 261       if (where != changes.end())
 262          where->offset -= offset;
 263       changes.insert(where, Change(offset));
 264       --where;
 265       assert(pos_is_okay());
 266    }
 267
 268    void split(size_t offset)
 269    {
 270       assert(pos_is_okay());
 271
 272       assert(where->offset < offset);
 273       assert(offset < where->offset + where->add_cnt);
 274
 275       size_t keep_lines = offset - where->offset;
 276
 277       Change before(*where);
 278
 279       where->del_cnt = 0;
 280       where->offset = 0;
 281       where->skip_lines(keep_lines);
 282
 283       before.add_cnt = keep_lines;
 284       before.add_len -= where->add_len;
 285
 286       changes.insert(where, before);
 287       --where;
 288       assert(pos_is_okay());
 289    }
 290
 291    void delete_lines(size_t cnt)
 292    {
 293       std::list<struct Change>::iterator x = where;
 294       assert(pos_is_okay());
 295       while (cnt > 0)
 296       {
 297          size_t del;
 298          del = x->add_cnt;
 299          if (del > cnt)
 300             del = cnt;
 301          x->skip_lines(del);
 302          cnt -= del;
 303
 304          ++x;
 305          if (x == changes.end()) {
 306             del = cnt;
 307          } else {
 308             del = x->offset;
 309             if (del > cnt)
 310                del = cnt;
 311             x->offset -= del;
 312          }
 313          where->del_cnt += del;
 314          cnt -= del;
 315       }
 316       assert(pos_is_okay());
 317    }
 318
 319    void left(void) {
 320       assert(pos_is_okay());
 321       --where;
 322       pos -= where->offset + where->add_cnt;
 323       assert(pos_is_okay());
 324    }
 325
 326    void right(void) {
 327       assert(pos_is_okay());
 328       pos += where->offset + where->add_cnt;
 329       ++where;
 330       assert(pos_is_okay());
 331    }
 332 };
 333
 334 class Patch {
 335    FileChanges filechanges;
 336    MemBlock add_text;
 337
 338    static bool retry_fwrite(char *b, size_t l, FileFd &f, Hashes *hash)
 339    {
 340       if (f.Write(b, l) == false)
 341          return false;
 342       if (hash)
 343          hash->Add((unsigned char*)b, l);
 344       return true;
 345    }
 346
 347    static void dump_rest(FileFd &o, FileFd &i, Hashes *hash)
 348    {
 349       char buffer[BLOCK_SIZE];
 350       unsigned long long l = 0;
 351       while (i.Read(buffer, sizeof(buffer), &l)) {
 352          if (l ==0  || !retry_fwrite(buffer, l, o, hash))
 353             break;
 354       }
 355    }
 356
 357    static void dump_lines(FileFd &o, FileFd &i, size_t n, Hashes *hash)
 358    {
 359       char buffer[BLOCK_SIZE];
 360       while (n > 0) {
 361          if (i.ReadLine(buffer, sizeof(buffer)) == NULL)
 362             buffer[0] = '\0';
 363          size_t const l = strlen(buffer);
 364          if (l == 0 || buffer[l-1] == '\n')
 365             n--;
 366          retry_fwrite(buffer, l, o, hash);
 367       }
 368    }
 369
 370    static void skip_lines(FileFd &i, int n)
 371    {
 372       char buffer[BLOCK_SIZE];
 373       while (n > 0) {
 374          if (i.ReadLine(buffer, sizeof(buffer)) == NULL)
 375             buffer[0] = '\0';
 376          size_t const l = strlen(buffer);
 377          if (l == 0 || buffer[l-1] == '\n')
 378             n--;
 379       }
 380    }
 381
 382    static void dump_mem(FileFd &o, char *p, size_t s, Hashes *hash) {
 383       retry_fwrite(p, s, o, hash);
 384    }
 385
 386    public:
 387
 388    bool read_diff(FileFd &f, Hashes * const h)
 389    {
 390       char buffer[BLOCK_SIZE];
 391       bool cmdwanted = true;
 392
 393       Change ch(std::numeric_limits<size_t>::max());
 394       if (f.ReadLine(buffer, sizeof(buffer)) == NULL)
 395          return _error->Error("Reading first line of patchfile %s failed", f.Name().c_str());
 396       do {
 397          if (h != NULL)
 398             h->Add(buffer);
 399          if (cmdwanted) {
 400             char *m, *c;
 401             size_t s, e;
 402             errno = 0;
 403             s = strtoul(buffer, &m, 10);
 404             if (unlikely(m == buffer || s == std::numeric_limits<unsigned long>::max() || errno != 0))
 405                return _error->Error("Parsing patchfile %s failed: Expected an effected line start", f.Name().c_str());
 406             else if (*m == ',') {
 407                ++m;
 408                e = strtol(m, &c, 10);
 409                if (unlikely(m == c || e == std::numeric_limits<unsigned long>::max() || errno != 0))
 410                   return _error->Error("Parsing patchfile %s failed: Expected an effected line end", f.Name().c_str());
 411                if (unlikely(e < s))
 412                   return _error->Error("Parsing patchfile %s failed: Effected lines end %lu is before start %lu", f.Name().c_str(), e, s);
 413             } else {
 414                e = s;
 415                c = m;
 416             }
 417             if (s > ch.offset)
 418                return _error->Error("Parsing patchfile %s failed: Effected line is after previous effected line", f.Name().c_str());
 419             switch(*c) {
 420                case 'a':
 421                   cmdwanted = false;
 422                   ch.add = NULL;
 423                   ch.add_cnt = 0;
 424                   ch.add_len = 0;
 425                   ch.offset = s;
 426                   ch.del_cnt = 0;
 427                   break;
 428                case 'c':
 429                   if (unlikely(s == 0))
 430                      return _error->Error("Parsing patchfile %s failed: Change command can't effect line zero", f.Name().c_str());
 431                   cmdwanted = false;
 432                   ch.add = NULL;
 433                   ch.add_cnt = 0;
 434                   ch.add_len = 0;
 435                   ch.offset = s - 1;
 436                   ch.del_cnt = e - s + 1;
 437                   break;
 438                case 'd':
 439                   if (unlikely(s == 0))
 440                      return _error->Error("Parsing patchfile %s failed: Delete command can't effect line zero", f.Name().c_str());
 441                   ch.offset = s - 1;
 442                   ch.del_cnt = e - s + 1;
 443                   ch.add = NULL;
 444                   ch.add_cnt = 0;
 445                   ch.add_len = 0;
 446                   filechanges.add_change(ch);
 447                   break;
 448                default:
 449                   return _error->Error("Parsing patchfile %s failed: Unknown command", f.Name().c_str());
 450             }
 451          } else { /* !cmdwanted */
 452             if (strcmp(buffer, ".\n") == 0) {
 453                cmdwanted = true;
 454                filechanges.add_change(ch);
 455             } else {
 456                char *last = NULL;
 457                char *add;
 458                size_t l;
 459                if (ch.add)
 460                   last = ch.add + ch.add_len;
 461                l = strlen(buffer);
 462                add = add_text.add_easy(buffer, l, last);
 463                if (!add) {
 464                   ch.add_len += l;
 465                   ch.add_cnt++;
 466                } else {
 467                   if (ch.add) {
 468                      filechanges.add_change(ch);
 469                      ch.del_cnt = 0;
 470                   }
 471                   ch.offset += ch.add_cnt;
 472                   ch.add = add;
 473                   ch.add_len = l;
 474                   ch.add_cnt = 1;
 475                }
 476             }
 477          }
 478       } while(f.ReadLine(buffer, sizeof(buffer)));
 479       return true;
 480    }
 481
 482    void write_diff(FileFd &f)
 483    {
 484       unsigned long long line = 0;
 485       std::list<struct Change>::reverse_iterator ch;
 486       for (ch = filechanges.rbegin(); ch != filechanges.rend(); ++ch) {
 487          line += ch->offset + ch->del_cnt;
 488       }
 489
 490       for (ch = filechanges.rbegin(); ch != filechanges.rend(); ++ch) {
 491          std::list<struct Change>::reverse_iterator mg_i, mg_e = ch;
 492          while (ch->del_cnt == 0 && ch->offset == 0)
 493          {
 494             ++ch;
 495             if (unlikely(ch == filechanges.rend()))
 496                return;
 497          }
 498          line -= ch->del_cnt;
 499          std::string buf;
 500          if (ch->add_cnt > 0) {
 501             if (ch->del_cnt == 0) {
 502                strprintf(buf, "%llua\n", line);
 503             } else if (ch->del_cnt == 1) {
 504                strprintf(buf, "%lluc\n", line+1);
 505             } else {
 506                strprintf(buf, "%llu,%lluc\n", line+1, line+ch->del_cnt);
 507             }
 508             f.Write(buf.c_str(), buf.length());
 509
 510             mg_i = ch;
 511             do {
 512                dump_mem(f, mg_i->add, mg_i->add_len, NULL);
 513             } while (mg_i-- != mg_e);
 514
 515             buf = ".\n";
 516             f.Write(buf.c_str(), buf.length());
 517          } else if (ch->del_cnt == 1) {
 518             strprintf(buf, "%llud\n", line+1);
 519             f.Write(buf.c_str(), buf.length());
 520          } else if (ch->del_cnt > 1) {
 521             strprintf(buf, "%llu,%llud\n", line+1, line+ch->del_cnt);
 522             f.Write(buf.c_str(), buf.length());
 523          }
 524          line -= ch->offset;
 525       }
 526    }
 527
 528    void apply_against_file(FileFd &out, FileFd &in, Hashes *hash = NULL)
 529    {
 530       std::list<struct Change>::iterator ch;
 531       for (ch = filechanges.begin(); ch != filechanges.end(); ++ch) {
 532          dump_lines(out, in, ch->offset, hash);
 533          skip_lines(in, ch->del_cnt);
 534          dump_mem(out, ch->add, ch->add_len, hash);
 535       }
 536       dump_rest(out, in, hash);
 537       out.Flush();
 538    }
 539 };
 540
 541 class RredMethod : public aptMethod {
 542    private:
 543       bool Debug;
 544
 545       struct PDiffFile {
 546          std::string FileName;
 547          HashStringList ExpectedHashes;
 548          PDiffFile(std::string const &FileName, HashStringList const &ExpectedHashes) :
 549             FileName(FileName), ExpectedHashes(ExpectedHashes) {}
 550       };
 551
 552       HashStringList ReadExpectedHashesForPatch(unsigned int const patch, std::string const &Message)
 553       {
 554          HashStringList ExpectedHashes;
 555          for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
 556          {
 557             std::string tagname;
 558             strprintf(tagname, "Patch-%d-%s-Hash", patch, *type);
 559             std::string const hashsum = LookupTag(Message, tagname.c_str());
 560             if (hashsum.empty() == false)
 561                ExpectedHashes.push_back(HashString(*type, hashsum));
 562          }
 563          return ExpectedHashes;
 564       }
 565
 566    protected:
 567       virtual bool URIAcquire(std::string const &Message, FetchItem *Itm) APT_OVERRIDE {
 568          Debug = _config->FindB("Debug::pkgAcquire::RRed", false);
 569          URI Get = Itm->Uri;
 570          std::string Path = Get.Host + Get.Path; // rred:/path - no host
 571
 572          FetchResult Res;
 573          Res.Filename = Itm->DestFile;
 574          if (Itm->Uri.empty())
 575          {
 576             Path = Itm->DestFile;
 577             Itm->DestFile.append(".result");
 578          } else
 579             URIStart(Res);
 580
 581          std::vector<PDiffFile> patchfiles;
 582          Patch patch;
 583
 584          if (FileExists(Path + ".ed") == true)
 585          {
 586             HashStringList const ExpectedHashes = ReadExpectedHashesForPatch(0, Message);
 587             std::string const FileName = Path + ".ed";
 588             if (ExpectedHashes.usable() == false)
 589                return _error->Error("No hashes found for uncompressed patch: %s", FileName.c_str());
 590             patchfiles.push_back(PDiffFile(FileName, ExpectedHashes));
 591          }
 592          else
 593          {
 594             _error->PushToStack();
 595             std::vector<std::string> patches = GetListOfFilesInDir(flNotFile(Path), "gz", true, false);
 596             _error->RevertToStack();
 597
 598             std::string const baseName = Path + ".ed.";
 599             unsigned int seen_patches = 0;
 600             for (std::vector<std::string>::const_iterator p = patches.begin();
 601                   p != patches.end(); ++p)
 602             {
 603                if (p->compare(0, baseName.length(), baseName) == 0)
 604                {
 605                   HashStringList const ExpectedHashes = ReadExpectedHashesForPatch(seen_patches, Message);
 606                   if (ExpectedHashes.usable() == false)
 607                      return _error->Error("No hashes found for uncompressed patch %d: %s", seen_patches, p->c_str());
 608                   patchfiles.push_back(PDiffFile(*p, ExpectedHashes));
 609                   ++seen_patches;
 610                }
 611             }
 612          }
 613
 614          std::string patch_name;
 615          for (std::vector<PDiffFile>::iterator I = patchfiles.begin();
 616                I != patchfiles.end();
 617                ++I)
 618          {
 619             patch_name = I->FileName;
 620             if (Debug == true)
 621                std::clog << "Patching " << Path << " with " << patch_name
 622                   << std::endl;
 623
 624             FileFd p;
 625             Hashes patch_hash(I->ExpectedHashes);
 626             // all patches are compressed, even if the name doesn't reflect it
 627             if (p.Open(patch_name, FileFd::ReadOnly, FileFd::Gzip) == false ||
 628                   patch.read_diff(p, &patch_hash) == false)
 629             {
 630                _error->DumpErrors(std::cerr, GlobalError::DEBUG, false);
 631                return false;
 632             }
 633             p.Close();
 634             HashStringList const hsl = patch_hash.GetHashStringList();
 635             if (hsl != I->ExpectedHashes)
 636                return _error->Error("Hash Sum mismatch for uncompressed patch %s", patch_name.c_str());
 637          }
 638
 639          if (Debug == true)
 640             std::clog << "Applying patches against " << Path
 641                << " and writing results to " << Itm->DestFile
 642                << std::endl;
 643
 644          FileFd inp, out;
 645          if (inp.Open(Path, FileFd::ReadOnly, FileFd::Extension) == false)
 646          {
 647             std::cerr << "FAILED to open inp " << Path << std::endl;
 648             return _error->Error("Failed to open inp %s", Path.c_str());
 649          }
 650          if (out.Open(Itm->DestFile, FileFd::WriteOnly | FileFd::Create | FileFd::BufferedWrite, FileFd::Extension) == false)
 651          {
 652             std::cerr << "FAILED to open out " << Itm->DestFile << std::endl;
 653             return _error->Error("Failed to open out %s", Itm->DestFile.c_str());
 654          }
 655
 656          Hashes hash(Itm->ExpectedHashes);
 657          patch.apply_against_file(out, inp, &hash);
 658
 659          out.Close();
 660          inp.Close();
 661
 662          if (_error->PendingError() == true) {
 663             std::cerr << "FAILED to read or write files" << std::endl;
 664             return false;
 665          }
 666
 667          if (Debug == true) {
 668             std::clog << "rred: finished file patching of " << Path  << "." << std::endl;
 669          }
 670
 671          struct stat bufbase, bufpatch;
 672          if (stat(Path.c_str(), &bufbase) != 0 ||
 673                stat(patch_name.c_str(), &bufpatch) != 0)
 674             return _error->Errno("stat", _("Failed to stat %s"), Path.c_str());
 675
 676          struct timeval times[2];
 677          times[0].tv_sec = bufbase.st_atime;
 678          times[1].tv_sec = bufpatch.st_mtime;
 679          times[0].tv_usec = times[1].tv_usec = 0;
 680          if (utimes(Itm->DestFile.c_str(), times) != 0)
 681             return _error->Errno("utimes",_("Failed to set modification time"));
 682
 683          if (stat(Itm->DestFile.c_str(), &bufbase) != 0)
 684             return _error->Errno("stat", _("Failed to stat %s"), Itm->DestFile.c_str());
 685
 686          Res.LastModified = bufbase.st_mtime;
 687          Res.Size = bufbase.st_size;
 688          Res.TakeHashes(hash);
 689          URIDone(Res);
 690
 691          return true;
 692       }
 693
 694    public:
 695       RredMethod() : aptMethod("rred", "2.0", SendConfig), Debug(false) {}
 696 };
 697
 698 int main(int argc, char **argv)
 699 {
 700    int i;
 701    bool just_diff = true;
 702    bool test = false;
 703    Patch patch;
 704
 705    if (argc <= 1) {
 706       return RredMethod().Run();
 707    }
 708
 709    // Usage: rred -t input output diff ...
 710    if (argc > 1 && strcmp(argv[1], "-t") == 0) {
 711       // Read config files so we see compressors.
 712       pkgInitConfig(*_config);
 713       just_diff = false;
 714       test = true;
 715       i = 4;
 716    } else if (argc > 1 && strcmp(argv[1], "-f") == 0) {
 717       just_diff = false;
 718       i = 2;
 719    } else {
 720       i = 1;
 721    }
 722
 723    for (; i < argc; i++) {
 724       FileFd p;
 725       if (p.Open(argv[i], FileFd::ReadOnly) == false) {
 726          _error->DumpErrors(std::cerr);
 727          exit(1);
 728       }
 729       if (patch.read_diff(p, NULL) == false)
 730       {
 731          _error->DumpErrors(std::cerr);
 732          exit(2);
 733       }
 734    }
 735
 736    if (test) {
 737       FileFd out, inp;
 738       std::cerr << "Patching " << argv[2] << " into " << argv[3] << "\n";
 739       inp.Open(argv[2], FileFd::ReadOnly,FileFd::Extension);
 740       out.Open(argv[3], FileFd::WriteOnly | FileFd::Create | FileFd::BufferedWrite, FileFd::Extension);
 741       patch.apply_against_file(out, inp);
 742       out.Close();
 743    } else if (just_diff) {
 744       FileFd out;
 745       out.OpenDescriptor(STDOUT_FILENO, FileFd::WriteOnly | FileFd::Create);
 746       patch.write_diff(out);
 747       out.Close();
 748    } else {
 749       FileFd out, inp;
 750       out.OpenDescriptor(STDOUT_FILENO, FileFd::WriteOnly | FileFd::Create | FileFd::BufferedWrite);
 751       inp.OpenDescriptor(STDIN_FILENO, FileFd::ReadOnly);
 752       patch.apply_against_file(out, inp);
 753       out.Close();
 754    }
 755    return 0;
 756 }