apt-pkg/tagfile.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: tagfile.cc,v 1.37.2.2 2003/12/31 16:02:30 mdz Exp $
   4 /* ######################################################################
   5
   6    Fast scanner for RFC-822 type header information
   7
   8    This uses a rotating buffer to load the package information into.
   9    The scanner runs over it and isolates and indexes a single section.
  10
  11    ##################################################################### */
  12                                                                         /*}}}*/
  13 // Include Files                                                        /*{{{*/
  14 #include <apt-pkg/tagfile.h>
  15 #include <apt-pkg/error.h>
  16 #include <apt-pkg/strutl.h>
  17
  18 #include <apti18n.h>
  19
  20 #include <string>
  21 #include <stdio.h>
  22 #include <ctype.h>
  23                                                                         /*}}}*/
  24
  25 using std::string;
  26
  27 // TagFile::pkgTagFile - Constructor                                    /*{{{*/
  28 // ---------------------------------------------------------------------
  29 /* */
  30 pkgTagFile::pkgTagFile(FileFd *pFd,unsigned long Size) :
  31      Fd(*pFd),
  32      Size(Size)
  33 {
  34    if (Fd.IsOpen() == false)
  35    {
  36       Buffer = 0;
  37       Start = End = Buffer = 0;
  38       Done = true;
  39       iOffset = 0;
  40       return;
  41    }
  42
  43    Buffer = new char[Size];
  44    Start = End = Buffer;
  45    Done = false;
  46    iOffset = 0;
  47    Fill();
  48 }
  49                                                                         /*}}}*/
  50 // TagFile::~pkgTagFile - Destructor                                    /*{{{*/
  51 // ---------------------------------------------------------------------
  52 /* */
  53 pkgTagFile::~pkgTagFile()
  54 {
  55    delete [] Buffer;
  56 }
  57                                                                         /*}}}*/
  58 // TagFile::Resize - Resize the internal buffer                         /*{{{*/
  59 // ---------------------------------------------------------------------
  60 /* Resize the internal buffer (double it in size). Fail if a maximum size
  61  * size is reached.
  62  */
  63 bool pkgTagFile::Resize()
  64 {
  65    char *tmp;
  66    unsigned long EndSize = End - Start;
  67
  68    // fail is the buffer grows too big
  69    if(Size > 1024*1024+1)
  70       return false;
  71
  72    // get new buffer and use it
  73    tmp = new char[2*Size];
  74    memcpy(tmp, Buffer, Size);
  75    Size = Size*2;
  76    delete [] Buffer;
  77    Buffer = tmp;
  78
  79    // update the start/end pointers to the new buffer
  80    Start = Buffer;
  81    End = Start + EndSize;
  82    return true;
  83 }
  84                                                                         /*}}}*/
  85 // TagFile::Step - Advance to the next section                          /*{{{*/
  86 // ---------------------------------------------------------------------
  87 /* If the Section Scanner fails we refill the buffer and try again.
  88  * If that fails too, double the buffer size and try again until a
  89  * maximum buffer is reached.
  90  */
  91 bool pkgTagFile::Step(pkgTagSection &Tag)
  92 {
  93    while (Tag.Scan(Start,End - Start) == false)
  94    {
  95       if (Fill() == false)
  96          return false;
  97
  98       if(Tag.Scan(Start,End - Start))
  99          break;
 100
 101       if (Resize() == false)
 102          return _error->Error(_("Unable to parse package file %s (1)"),
 103                                  Fd.Name().c_str());
 104    }
 105    Start += Tag.size();
 106    iOffset += Tag.size();
 107
 108    Tag.Trim();
 109    return true;
 110 }
 111                                                                         /*}}}*/
 112 // TagFile::Fill - Top up the buffer                                    /*{{{*/
 113 // ---------------------------------------------------------------------
 114 /* This takes the bit at the end of the buffer and puts it at the start
 115    then fills the rest from the file */
 116 bool pkgTagFile::Fill()
 117 {
 118    unsigned long EndSize = End - Start;
 119    unsigned long Actual = 0;
 120
 121    memmove(Buffer,Start,EndSize);
 122    Start = Buffer;
 123    End = Buffer + EndSize;
 124
 125    if (Done == false)
 126    {
 127       // See if only a bit of the file is left
 128       if (Fd.Read(End,Size - (End - Buffer),&Actual) == false)
 129          return false;
 130       if (Actual != Size - (End - Buffer))
 131          Done = true;
 132       End += Actual;
 133    }
 134
 135    if (Done == true)
 136    {
 137       if (EndSize <= 3 && Actual == 0)
 138          return false;
 139       if (Size - (End - Buffer) < 4)
 140          return true;
 141
 142       // Append a double new line if one does not exist
 143       unsigned int LineCount = 0;
 144       for (const char *E = End - 1; E - End < 6 && (*E == '\n' || *E == '\r'); E--)
 145          if (*E == '\n')
 146             LineCount++;
 147       for (; LineCount < 2; LineCount++)
 148          *End++ = '\n';
 149
 150       return true;
 151    }
 152
 153    return true;
 154 }
 155                                                                         /*}}}*/
 156 // TagFile::Jump - Jump to a pre-recorded location in the file          /*{{{*/
 157 // ---------------------------------------------------------------------
 158 /* This jumps to a pre-recorded file location and reads the record
 159    that is there */
 160 bool pkgTagFile::Jump(pkgTagSection &Tag,unsigned long Offset)
 161 {
 162    // We are within a buffer space of the next hit..
 163    if (Offset >= iOffset && iOffset + (End - Start) > Offset)
 164    {
 165       unsigned long Dist = Offset - iOffset;
 166       Start += Dist;
 167       iOffset += Dist;
 168       return Step(Tag);
 169    }
 170
 171    // Reposition and reload..
 172    iOffset = Offset;
 173    Done = false;
 174    if (Fd.Seek(Offset) == false)
 175       return false;
 176    End = Start = Buffer;
 177
 178    if (Fill() == false)
 179       return false;
 180
 181    if (Tag.Scan(Start,End - Start) == true)
 182       return true;
 183
 184    // This appends a double new line (for the real eof handling)
 185    if (Fill() == false)
 186       return false;
 187
 188    if (Tag.Scan(Start,End - Start) == false)
 189       return _error->Error(_("Unable to parse package file %s (2)"),Fd.Name().c_str());
 190
 191    return true;
 192 }
 193                                                                         /*}}}*/
 194 // TagSection::Scan - Scan for the end of the header information        /*{{{*/
 195 // ---------------------------------------------------------------------
 196 /* This looks for the first double new line in the data stream. It also
 197    indexes the tags in the section. This very simple hash function for the
 198    last 8 letters gives very good performance on the debian package files */
 199 inline static unsigned long AlphaHash(const char *Text, const char *End = 0)
 200 {
 201    unsigned long Res = 0;
 202    for (; Text != End && *Text != ':' && *Text != 0; Text++)
 203       Res = ((unsigned long)(*Text) & 0xDF) ^ (Res << 1);
 204    return Res & 0xFF;
 205 }
 206
 207 bool pkgTagSection::Scan(const char *Start,unsigned long MaxLength)
 208 {
 209    const char *End = Start + MaxLength;
 210    Stop = Section = Start;
 211    memset(AlphaIndexes,0,sizeof(AlphaIndexes));
 212
 213    if (Stop == 0)
 214       return false;
 215
 216    TagCount = 0;
 217    while (TagCount+1 < sizeof(Indexes)/sizeof(Indexes[0]) && Stop < End)
 218    {
 219        TrimRecord(true,End);
 220
 221       // Start a new index and add it to the hash
 222       if (isspace(Stop[0]) == 0)
 223       {
 224          Indexes[TagCount++] = Stop - Section;
 225          AlphaIndexes[AlphaHash(Stop,End)] = TagCount;
 226       }
 227
 228       Stop = (const char *)memchr(Stop,'\n',End - Stop);
 229
 230       if (Stop == 0)
 231          return false;
 232
 233       for (; Stop+1 < End && Stop[1] == '\r'; Stop++);
 234
 235       // Double newline marks the end of the record
 236       if (Stop+1 < End && Stop[1] == '\n')
 237       {
 238          Indexes[TagCount] = Stop - Section;
 239          TrimRecord(false,End);
 240          return true;
 241       }
 242
 243       Stop++;
 244    }
 245
 246    return false;
 247 }
 248                                                                         /*}}}*/
 249 // TagSection::TrimRecord - Trim off any garbage before/after a record  /*{{{*/
 250 // ---------------------------------------------------------------------
 251 /* There should be exactly 2 newline at the end of the record, no more. */
 252 void pkgTagSection::TrimRecord(bool BeforeRecord, const char*& End)
 253 {
 254    if (BeforeRecord == true)
 255       return;
 256    for (; Stop < End && (Stop[0] == '\n' || Stop[0] == '\r'); Stop++);
 257 }
 258                                                                         /*}}}*/
 259 // TagSection::Trim - Trim off any trailing garbage                     /*{{{*/
 260 // ---------------------------------------------------------------------
 261 /* There should be exactly 1 newline at the end of the buffer, no more. */
 262 void pkgTagSection::Trim()
 263 {
 264    for (; Stop > Section + 2 && (Stop[-2] == '\n' || Stop[-2] == '\r'); Stop--);
 265 }
 266                                                                         /*}}}*/
 267 // TagSection::Find - Locate a tag                                      /*{{{*/
 268 // ---------------------------------------------------------------------
 269 /* This searches the section for a tag that matches the given string. */
 270 bool pkgTagSection::Find(const char *Tag,unsigned &Pos) const
 271 {
 272    unsigned int Length = strlen(Tag);
 273    unsigned int I = AlphaIndexes[AlphaHash(Tag)];
 274    if (I == 0)
 275       return false;
 276    I--;
 277
 278    for (unsigned int Counter = 0; Counter != TagCount; Counter++,
 279         I = (I+1)%TagCount)
 280    {
 281       const char *St;
 282       St = Section + Indexes[I];
 283       if (strncasecmp(Tag,St,Length) != 0)
 284          continue;
 285
 286       // Make sure the colon is in the right place
 287       const char *C = St + Length;
 288       for (; isspace(*C) != 0; C++);
 289       if (*C != ':')
 290          continue;
 291       Pos = I;
 292       return true;
 293    }
 294
 295    Pos = 0;
 296    return false;
 297 }
 298                                                                         /*}}}*/
 299 // TagSection::Find - Locate a tag                                      /*{{{*/
 300 // ---------------------------------------------------------------------
 301 /* This searches the section for a tag that matches the given string. */
 302 bool pkgTagSection::Find(const char *Tag,const char *&Start,
 303                          const char *&End) const
 304 {
 305    unsigned int Length = strlen(Tag);
 306    unsigned int I = AlphaIndexes[AlphaHash(Tag)];
 307    if (I == 0)
 308       return false;
 309    I--;
 310
 311    for (unsigned int Counter = 0; Counter != TagCount; Counter++,
 312         I = (I+1)%TagCount)
 313    {
 314       const char *St;
 315       St = Section + Indexes[I];
 316       if (strncasecmp(Tag,St,Length) != 0)
 317          continue;
 318
 319       // Make sure the colon is in the right place
 320       const char *C = St + Length;
 321       for (; isspace(*C) != 0; C++);
 322       if (*C != ':')
 323          continue;
 324
 325       // Strip off the gunk from the start end
 326       Start = C;
 327       End = Section + Indexes[I+1];
 328       if (Start >= End)
 329          return _error->Error("Internal parsing error");
 330
 331       for (; (isspace(*Start) != 0 || *Start == ':') && Start < End; Start++);
 332       for (; isspace(End[-1]) != 0 && End > Start; End--);
 333
 334       return true;
 335    }
 336
 337    Start = End = 0;
 338    return false;
 339 }
 340                                                                         /*}}}*/
 341 // TagSection::FindS - Find a string                                    /*{{{*/
 342 // ---------------------------------------------------------------------
 343 /* */
 344 string pkgTagSection::FindS(const char *Tag) const
 345 {
 346    const char *Start;
 347    const char *End;
 348    if (Find(Tag,Start,End) == false)
 349       return string();
 350    return string(Start,End);
 351 }
 352                                                                         /*}}}*/
 353 // TagSection::FindI - Find an integer                                  /*{{{*/
 354 // ---------------------------------------------------------------------
 355 /* */
 356 signed int pkgTagSection::FindI(const char *Tag,signed long Default) const
 357 {
 358    const char *Start;
 359    const char *Stop;
 360    if (Find(Tag,Start,Stop) == false)
 361       return Default;
 362
 363    // Copy it into a temp buffer so we can use strtol
 364    char S[300];
 365    if ((unsigned)(Stop - Start) >= sizeof(S))
 366       return Default;
 367    strncpy(S,Start,Stop-Start);
 368    S[Stop - Start] = 0;
 369
 370    char *End;
 371    signed long Result = strtol(S,&End,10);
 372    if (S == End)
 373       return Default;
 374    return Result;
 375 }
 376                                                                         /*}}}*/
 377 // TagSection::FindFlag - Locate a yes/no type flag                     /*{{{*/
 378 // ---------------------------------------------------------------------
 379 /* The bits marked in Flag are masked on/off in Flags */
 380 bool pkgTagSection::FindFlag(const char *Tag,unsigned long &Flags,
 381                              unsigned long Flag) const
 382 {
 383    const char *Start;
 384    const char *Stop;
 385    if (Find(Tag,Start,Stop) == false)
 386       return true;
 387
 388    switch (StringToBool(string(Start,Stop)))
 389    {
 390       case 0:
 391       Flags &= ~Flag;
 392       return true;
 393
 394       case 1:
 395       Flags |= Flag;
 396       return true;
 397
 398       default:
 399       _error->Warning("Unknown flag value: %s",string(Start,Stop).c_str());
 400       return true;
 401    }
 402    return true;
 403 }
 404                                                                         /*}}}*/
 405 // TFRewrite - Rewrite a control record                                 /*{{{*/
 406 // ---------------------------------------------------------------------
 407 /* This writes the control record to stdout rewriting it as necessary. The
 408    override map item specificies the rewriting rules to follow. This also
 409    takes the time to sort the feild list. */
 410
 411 /* The order of this list is taken from dpkg source lib/parse.c the fieldinfos
 412    array. */
 413 static const char *iTFRewritePackageOrder[] = {
 414                           "Package",
 415                           "Essential",
 416                           "Status",
 417                           "Priority",
 418                           "Section",
 419                           "Installed-Size",
 420                           "Maintainer",
 421                           "Architecture",
 422                           "Source",
 423                           "Version",
 424                            "Revision",         // Obsolete
 425                            "Config-Version",   // Obsolete
 426                           "Replaces",
 427                           "Provides",
 428                           "Depends",
 429                           "Pre-Depends",
 430                           "Recommends",
 431                           "Suggests",
 432                           "Conflicts",
 433                           "Breaks",
 434                           "Conffiles",
 435                           "Filename",
 436                           "Size",
 437                           "MD5Sum",
 438                           "SHA1",
 439                           "SHA256",
 440                            "MSDOS-Filename",   // Obsolete
 441                           "Description",
 442                           0};
 443 static const char *iTFRewriteSourceOrder[] = {"Package",
 444                                       "Source",
 445                                       "Binary",
 446                                       "Version",
 447                                       "Priority",
 448                                       "Section",
 449                                       "Maintainer",
 450                                       "Build-Depends",
 451                                       "Build-Depends-Indep",
 452                                       "Build-Conflicts",
 453                                       "Build-Conflicts-Indep",
 454                                       "Architecture",
 455                                       "Standards-Version",
 456                                       "Format",
 457                                       "Directory",
 458                                       "Files",
 459                                       0};
 460
 461 /* Two levels of initialization are used because gcc will set the symbol
 462    size of an array to the length of the array, causing dynamic relinking
 463    errors. Doing this makes the symbol size constant */
 464 const char **TFRewritePackageOrder = iTFRewritePackageOrder;
 465 const char **TFRewriteSourceOrder = iTFRewriteSourceOrder;
 466
 467 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 468                TFRewriteData *Rewrite)
 469 {
 470    unsigned char Visited[256];   // Bit 1 is Order, Bit 2 is Rewrite
 471    for (unsigned I = 0; I != 256; I++)
 472       Visited[I] = 0;
 473
 474    // Set new tag up as necessary.
 475    for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 476    {
 477       if (Rewrite[J].NewTag == 0)
 478          Rewrite[J].NewTag = Rewrite[J].Tag;
 479    }
 480
 481    // Write all all of the tags, in order.
 482    for (unsigned int I = 0; Order[I] != 0; I++)
 483    {
 484       bool Rewritten = false;
 485
 486       // See if this is a field that needs to be rewritten
 487       for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 488       {
 489          if (strcasecmp(Rewrite[J].Tag,Order[I]) == 0)
 490          {
 491             Visited[J] |= 2;
 492             if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 493             {
 494                if (isspace(Rewrite[J].Rewrite[0]))
 495                   fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 496                else
 497                   fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 498             }
 499
 500             Rewritten = true;
 501             break;
 502          }
 503       }
 504
 505       // See if it is in the fragment
 506       unsigned Pos;
 507       if (Tags.Find(Order[I],Pos) == false)
 508          continue;
 509       Visited[Pos] |= 1;
 510
 511       if (Rewritten == true)
 512          continue;
 513
 514       /* Write out this element, taking a moment to rewrite the tag
 515          in case of changes of case. */
 516       const char *Start;
 517       const char *Stop;
 518       Tags.Get(Start,Stop,Pos);
 519
 520       if (fputs(Order[I],Output) < 0)
 521          return _error->Errno("fputs","IO Error to output");
 522       Start += strlen(Order[I]);
 523       if (fwrite(Start,Stop - Start,1,Output) != 1)
 524          return _error->Errno("fwrite","IO Error to output");
 525       if (Stop[-1] != '\n')
 526          fprintf(Output,"\n");
 527    }
 528
 529    // Now write all the old tags that were missed.
 530    for (unsigned int I = 0; I != Tags.Count(); I++)
 531    {
 532       if ((Visited[I] & 1) == 1)
 533          continue;
 534
 535       const char *Start;
 536       const char *Stop;
 537       Tags.Get(Start,Stop,I);
 538       const char *End = Start;
 539       for (; End < Stop && *End != ':'; End++);
 540
 541       // See if this is a field that needs to be rewritten
 542       bool Rewritten = false;
 543       for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 544       {
 545          if (stringcasecmp(Start,End,Rewrite[J].Tag) == 0)
 546          {
 547             Visited[J] |= 2;
 548             if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 549             {
 550                if (isspace(Rewrite[J].Rewrite[0]))
 551                   fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 552                else
 553                   fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 554             }
 555
 556             Rewritten = true;
 557             break;
 558          }
 559       }
 560
 561       if (Rewritten == true)
 562          continue;
 563
 564       // Write out this element
 565       if (fwrite(Start,Stop - Start,1,Output) != 1)
 566          return _error->Errno("fwrite","IO Error to output");
 567       if (Stop[-1] != '\n')
 568          fprintf(Output,"\n");
 569    }
 570
 571    // Now write all the rewrites that were missed
 572    for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 573    {
 574       if ((Visited[J] & 2) == 2)
 575          continue;
 576
 577       if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 578       {
 579          if (isspace(Rewrite[J].Rewrite[0]))
 580             fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 581          else
 582             fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 583       }
 584    }
 585
 586    return true;
 587 }
 588                                                                         /*}}}*/