apt-pkg/tagfile.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: tagfile.cc,v 1.35 2002/11/06 06:43:14 jgg 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 #ifdef __GNUG__
  15 #pragma implementation "apt-pkg/tagfile.h"
  16 #endif
  17
  18 #include <apt-pkg/tagfile.h>
  19 #include <apt-pkg/error.h>
  20 #include <apt-pkg/strutl.h>
  21
  22 #include <apti18n.h>
  23
  24 #include <string>
  25 #include <stdio.h>
  26 #include <ctype.h>
  27                                                                         /*}}}*/
  28
  29 using std::string;
  30
  31 // TagFile::pkgTagFile - Constructor                                    /*{{{*/
  32 // ---------------------------------------------------------------------
  33 /* */
  34 pkgTagFile::pkgTagFile(FileFd *pFd,unsigned long Size) : Fd(*pFd), Size(Size)
  35 {
  36    if (Fd.IsOpen() == false)
  37    {
  38       Buffer = 0;
  39       Start = End = Buffer = 0;
  40       Done = true;
  41       iOffset = 0;
  42       return;
  43    }
  44
  45    Buffer = new char[Size];
  46    Start = End = Buffer;
  47    Done = false;
  48    iOffset = 0;
  49    Fill();
  50 }
  51                                                                         /*}}}*/
  52 // TagFile::~pkgTagFile - Destructor                                    /*{{{*/
  53 // ---------------------------------------------------------------------
  54 /* */
  55 pkgTagFile::~pkgTagFile()
  56 {
  57    delete [] Buffer;
  58 }
  59                                                                         /*}}}*/
  60 // TagFile::Step - Advance to the next section                          /*{{{*/
  61 // ---------------------------------------------------------------------
  62 /* If the Section Scanner fails we refill the buffer and try again. */
  63 bool pkgTagFile::Step(pkgTagSection &Tag)
  64 {
  65    if (Tag.Scan(Start,End - Start) == false)
  66    {
  67       if (Fill() == false)
  68          return false;
  69
  70       if (Tag.Scan(Start,End - Start) == false)
  71          return _error->Error(_("Unable to parse package file %s (1)"),
  72                               Fd.Name().c_str());
  73    }
  74    Start += Tag.size();
  75    iOffset += Tag.size();
  76
  77    Tag.Trim();
  78    return true;
  79 }
  80                                                                         /*}}}*/
  81 // TagFile::Fill - Top up the buffer                                    /*{{{*/
  82 // ---------------------------------------------------------------------
  83 /* This takes the bit at the end of the buffer and puts it at the start
  84    then fills the rest from the file */
  85 bool pkgTagFile::Fill()
  86 {
  87    unsigned long EndSize = End - Start;
  88    unsigned long Actual = 0;
  89
  90    memmove(Buffer,Start,EndSize);
  91    Start = Buffer;
  92    End = Buffer + EndSize;
  93
  94    if (Done == false)
  95    {
  96       // See if only a bit of the file is left
  97       if (Fd.Read(End,Size - (End - Buffer),&Actual) == false)
  98          return false;
  99       if (Actual != Size - (End - Buffer))
 100          Done = true;
 101       End += Actual;
 102    }
 103
 104    if (Done == true)
 105    {
 106       if (EndSize <= 3 && Actual == 0)
 107          return false;
 108       if (Size - (End - Buffer) < 4)
 109          return true;
 110
 111       // Append a double new line if one does not exist
 112       unsigned int LineCount = 0;
 113       for (const char *E = End - 1; E - End < 6 && (*E == '\n' || *E == '\r'); E--)
 114          if (*E == '\n')
 115             LineCount++;
 116       for (; LineCount < 2; LineCount++)
 117          *End++ = '\n';
 118
 119       return true;
 120    }
 121
 122    return true;
 123 }
 124                                                                         /*}}}*/
 125 // TagFile::Jump - Jump to a pre-recorded location in the file          /*{{{*/
 126 // ---------------------------------------------------------------------
 127 /* This jumps to a pre-recorded file location and reads the record
 128    that is there */
 129 bool pkgTagFile::Jump(pkgTagSection &Tag,unsigned long Offset)
 130 {
 131    // We are within a buffer space of the next hit..
 132    if (Offset >= iOffset && iOffset + (End - Start) > Offset)
 133    {
 134       unsigned long Dist = Offset - iOffset;
 135       Start += Dist;
 136       iOffset += Dist;
 137       return Step(Tag);
 138    }
 139
 140    // Reposition and reload..
 141    iOffset = Offset;
 142    Done = false;
 143    if (Fd.Seek(Offset) == false)
 144       return false;
 145    End = Start = Buffer;
 146
 147    if (Fill() == false)
 148       return false;
 149
 150    if (Tag.Scan(Start,End - Start) == true)
 151       return true;
 152
 153    // This appends a double new line (for the real eof handling)
 154    if (Fill() == false)
 155       return false;
 156
 157    if (Tag.Scan(Start,End - Start) == false)
 158       return _error->Error(_("Unable to parse package file %s (2)"),Fd.Name().c_str());
 159
 160    return true;
 161 }
 162                                                                         /*}}}*/
 163 // TagSection::Scan - Scan for the end of the header information        /*{{{*/
 164 // ---------------------------------------------------------------------
 165 /* This looks for the first double new line in the data stream. It also
 166    indexes the tags in the section. This very simple hash function for the
 167    first 3 letters gives very good performance on the debian package files */
 168 inline static unsigned long AlphaHash(const char *Text, const char *End = 0)
 169 {
 170    unsigned long Res = 0;
 171    for (; Text != End && *Text != ':' && *Text != 0; Text++)
 172       Res = (unsigned long)(*Text) ^ (Res << 2);
 173    return Res & 0xFF;
 174 }
 175
 176 bool pkgTagSection::Scan(const char *Start,unsigned long MaxLength)
 177 {
 178    const char *End = Start + MaxLength;
 179    Stop = Section = Start;
 180    memset(AlphaIndexes,0,sizeof(AlphaIndexes));
 181
 182    if (Stop == 0)
 183       return false;
 184
 185    TagCount = 0;
 186    while (TagCount+1 < sizeof(Indexes)/sizeof(Indexes[0]) && Stop < End)
 187    {
 188       // Start a new index and add it to the hash
 189       if (isspace(Stop[0]) == 0)
 190       {
 191          Indexes[TagCount++] = Stop - Section;
 192          AlphaIndexes[AlphaHash(Stop,End)] = TagCount;
 193       }
 194
 195       Stop = (const char *)memchr(Stop,'\n',End - Stop);
 196
 197       if (Stop == 0)
 198          return false;
 199
 200       for (; Stop+1 < End && Stop[1] == '\r'; Stop++);
 201
 202       // Double newline marks the end of the record
 203       if (Stop+1 < End && Stop[1] == '\n')
 204       {
 205          Indexes[TagCount] = Stop - Section;
 206          for (; Stop < End && (Stop[0] == '\n' || Stop[0] == '\r'); Stop++);
 207          return true;
 208       }
 209
 210       Stop++;
 211    }
 212
 213    return false;
 214 }
 215                                                                         /*}}}*/
 216 // TagSection::Trim - Trim off any trailing garbage                     /*{{{*/
 217 // ---------------------------------------------------------------------
 218 /* There should be exactly 1 newline at the end of the buffer, no more. */
 219 void pkgTagSection::Trim()
 220 {
 221    for (; Stop > Section + 2 && (Stop[-2] == '\n' || Stop[-2] == '\r'); Stop--);
 222 }
 223                                                                         /*}}}*/
 224 // TagSection::Find - Locate a tag                                      /*{{{*/
 225 // ---------------------------------------------------------------------
 226 /* This searches the section for a tag that matches the given string. */
 227 bool pkgTagSection::Find(const char *Tag,unsigned &Pos) const
 228 {
 229    unsigned int Length = strlen(Tag);
 230    unsigned int I = AlphaIndexes[AlphaHash(Tag)];
 231    if (I == 0)
 232       return false;
 233    I--;
 234
 235    for (unsigned int Counter = 0; Counter != TagCount; Counter++,
 236         I = (I+1)%TagCount)
 237    {
 238       const char *St;
 239       St = Section + Indexes[I];
 240       if (strncasecmp(Tag,St,Length) != 0)
 241          continue;
 242
 243       // Make sure the colon is in the right place
 244       const char *C = St + Length;
 245       for (; isspace(*C) != 0; C++);
 246       if (*C != ':')
 247          continue;
 248       Pos = I;
 249       return true;
 250    }
 251
 252    Pos = 0;
 253    return false;
 254 }
 255                                                                         /*}}}*/
 256 // TagSection::Find - Locate a tag                                      /*{{{*/
 257 // ---------------------------------------------------------------------
 258 /* This searches the section for a tag that matches the given string. */
 259 bool pkgTagSection::Find(const char *Tag,const char *&Start,
 260                          const char *&End) const
 261 {
 262    unsigned int Length = strlen(Tag);
 263    unsigned int I = AlphaIndexes[AlphaHash(Tag)];
 264    if (I == 0)
 265       return false;
 266    I--;
 267
 268    for (unsigned int Counter = 0; Counter != TagCount; Counter++,
 269         I = (I+1)%TagCount)
 270    {
 271       const char *St;
 272       St = Section + Indexes[I];
 273       if (strncasecmp(Tag,St,Length) != 0)
 274          continue;
 275
 276       // Make sure the colon is in the right place
 277       const char *C = St + Length;
 278       for (; isspace(*C) != 0; C++);
 279       if (*C != ':')
 280          continue;
 281
 282       // Strip off the gunk from the start end
 283       Start = C;
 284       End = Section + Indexes[I+1];
 285       if (Start >= End)
 286          return _error->Error("Internal parsing error");
 287
 288       for (; (isspace(*Start) != 0 || *Start == ':') && Start < End; Start++);
 289       for (; isspace(End[-1]) != 0 && End > Start; End--);
 290
 291       return true;
 292    }
 293
 294    Start = End = 0;
 295    return false;
 296 }
 297                                                                         /*}}}*/
 298 // TagSection::FindS - Find a string                                    /*{{{*/
 299 // ---------------------------------------------------------------------
 300 /* */
 301 string pkgTagSection::FindS(const char *Tag) const
 302 {
 303    const char *Start;
 304    const char *End;
 305    if (Find(Tag,Start,End) == false)
 306       return string();
 307    return string(Start,End);
 308 }
 309                                                                         /*}}}*/
 310 // TagSection::FindI - Find an integer                                  /*{{{*/
 311 // ---------------------------------------------------------------------
 312 /* */
 313 signed int pkgTagSection::FindI(const char *Tag,signed long Default) const
 314 {
 315    const char *Start;
 316    const char *Stop;
 317    if (Find(Tag,Start,Stop) == false)
 318       return Default;
 319
 320    // Copy it into a temp buffer so we can use strtol
 321    char S[300];
 322    if ((unsigned)(Stop - Start) >= sizeof(S))
 323       return Default;
 324    strncpy(S,Start,Stop-Start);
 325    S[Stop - Start] = 0;
 326
 327    char *End;
 328    signed long Result = strtol(S,&End,10);
 329    if (S == End)
 330       return Default;
 331    return Result;
 332 }
 333                                                                         /*}}}*/
 334 // TagSection::FindFlag - Locate a yes/no type flag                     /*{{{*/
 335 // ---------------------------------------------------------------------
 336 /* The bits marked in Flag are masked on/off in Flags */
 337 bool pkgTagSection::FindFlag(const char *Tag,unsigned long &Flags,
 338                              unsigned long Flag) const
 339 {
 340    const char *Start;
 341    const char *Stop;
 342    if (Find(Tag,Start,Stop) == false)
 343       return true;
 344
 345    switch (StringToBool(string(Start,Stop)))
 346    {
 347       case 0:
 348       Flags &= ~Flag;
 349       return true;
 350
 351       case 1:
 352       Flags |= Flag;
 353       return true;
 354
 355       default:
 356       _error->Warning("Unknown flag value: %s",string(Start,Stop).c_str());
 357       return true;
 358    }
 359    return true;
 360 }
 361                                                                         /*}}}*/
 362
 363 // TFRewrite - Rewrite a control record                                 /*{{{*/
 364 // ---------------------------------------------------------------------
 365 /* This writes the control record to stdout rewriting it as necessary. The
 366    override map item specificies the rewriting rules to follow. This also
 367    takes the time to sort the feild list. */
 368
 369 /* The order of this list is taken from dpkg source lib/parse.c the fieldinfos
 370    array. */
 371 static const char *iTFRewritePackageOrder[] = {
 372                           "Package",
 373                           "Essential",
 374                           "Status",
 375                           "Priority",
 376                           "Section",
 377                           "Installed-Size",
 378                           "Maintainer",
 379                           "Architecture",
 380                           "Source",
 381                           "Version",
 382                            "Revision",         // Obsolete
 383                            "Config-Version",   // Obsolete
 384                           "Replaces",
 385                           "Provides",
 386                           "Depends",
 387                           "Pre-Depends",
 388                           "Recommends",
 389                           "Suggests",
 390                           "Conflicts",
 391                           "Conffiles",
 392                           "Filename",
 393                           "Size",
 394                           "MD5Sum",
 395                           "SHA1Sum",
 396                            "MSDOS-Filename",   // Obsolete
 397                           "Description",
 398                           0};
 399 static const char *iTFRewriteSourceOrder[] = {"Package",
 400                                       "Source",
 401                                       "Binary",
 402                                       "Version",
 403                                       "Priority",
 404                                       "Section",
 405                                       "Maintainer",
 406                                       "Build-Depends",
 407                                       "Build-Depends-Indep",
 408                                       "Build-Conflicts",
 409                                       "Build-Conflicts-Indep",
 410                                       "Architecture",
 411                                       "Standards-Version",
 412                                       "Format",
 413                                       "Directory",
 414                                       "Files",
 415                                       0};
 416
 417 /* Two levels of initialization are used because gcc will set the symbol
 418    size of an array to the length of the array, causing dynamic relinking
 419    errors. Doing this makes the symbol size constant */
 420 const char **TFRewritePackageOrder = iTFRewritePackageOrder;
 421 const char **TFRewriteSourceOrder = iTFRewriteSourceOrder;
 422
 423 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 424                TFRewriteData *Rewrite)
 425 {
 426    unsigned char Visited[256];   // Bit 1 is Order, Bit 2 is Rewrite
 427    for (unsigned I = 0; I != 256; I++)
 428       Visited[I] = 0;
 429
 430    // Set new tag up as necessary.
 431    for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 432    {
 433       if (Rewrite[J].NewTag == 0)
 434          Rewrite[J].NewTag = Rewrite[J].Tag;
 435    }
 436
 437    // Write all all of the tags, in order.
 438    for (unsigned int I = 0; Order[I] != 0; I++)
 439    {
 440       bool Rewritten = false;
 441
 442       // See if this is a field that needs to be rewritten
 443       for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 444       {
 445          if (strcasecmp(Rewrite[J].Tag,Order[I]) == 0)
 446          {
 447             Visited[J] |= 2;
 448             if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 449             {
 450                if (isspace(Rewrite[J].Rewrite[0]))
 451                   fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 452                else
 453                   fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 454             }
 455
 456             Rewritten = true;
 457             break;
 458          }
 459       }
 460
 461       // See if it is in the fragment
 462       unsigned Pos;
 463       if (Tags.Find(Order[I],Pos) == false)
 464          continue;
 465       Visited[Pos] |= 1;
 466
 467       if (Rewritten == true)
 468          continue;
 469
 470       /* Write out this element, taking a moment to rewrite the tag
 471          in case of changes of case. */
 472       const char *Start;
 473       const char *Stop;
 474       Tags.Get(Start,Stop,Pos);
 475
 476       if (fputs(Order[I],Output) < 0)
 477          return _error->Errno("fputs","IO Error to output");
 478       Start += strlen(Order[I]);
 479       if (fwrite(Start,Stop - Start,1,Output) != 1)
 480          return _error->Errno("fwrite","IO Error to output");
 481       if (Stop[-1] != '\n')
 482          fprintf(Output,"\n");
 483    }
 484
 485    // Now write all the old tags that were missed.
 486    for (unsigned int I = 0; I != Tags.Count(); I++)
 487    {
 488       if ((Visited[I] & 1) == 1)
 489          continue;
 490
 491       const char *Start;
 492       const char *Stop;
 493       Tags.Get(Start,Stop,I);
 494       const char *End = Start;
 495       for (; End < Stop && *End != ':'; End++);
 496
 497       // See if this is a field that needs to be rewritten
 498       bool Rewritten = false;
 499       for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 500       {
 501          if (stringcasecmp(Start,End,Rewrite[J].Tag) == 0)
 502          {
 503             Visited[J] |= 2;
 504             if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 505             {
 506                if (isspace(Rewrite[J].Rewrite[0]))
 507                   fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 508                else
 509                   fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 510             }
 511
 512             Rewritten = true;
 513             break;
 514          }
 515       }
 516
 517       if (Rewritten == true)
 518          continue;
 519
 520       // Write out this element
 521       if (fwrite(Start,Stop - Start,1,Output) != 1)
 522          return _error->Errno("fwrite","IO Error to output");
 523       if (Stop[-1] != '\n')
 524          fprintf(Output,"\n");
 525    }
 526
 527    // Now write all the rewrites that were missed
 528    for (unsigned int J = 0; Rewrite != 0 && Rewrite[J].Tag != 0; J++)
 529    {
 530       if ((Visited[J] & 2) == 2)
 531          continue;
 532
 533       if (Rewrite[J].Rewrite != 0 && Rewrite[J].Rewrite[0] != 0)
 534       {
 535          if (isspace(Rewrite[J].Rewrite[0]))
 536             fprintf(Output,"%s:%s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 537          else
 538             fprintf(Output,"%s: %s\n",Rewrite[J].NewTag,Rewrite[J].Rewrite);
 539       }
 540    }
 541
 542    return true;
 543 }
 544                                                                         /*}}}*/