apt-pkg/tagfile.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: tagfile.h,v 1.20 2003/05/19 17:13:57 doogie Exp $
   4 /* ######################################################################
   5
   6    Fast scanner for RFC-822 type header information
   7
   8    This parser handles Debian package files (and others). Their form is
   9    RFC-822 type header fields in groups separated by a blank line.
  10
  11    The parser reads the file and provides methods to step linearly
  12    over it or to jump to a pre-recorded start point and read that record.
  13
  14    A second class is used to perform pre-parsing of the record. It works
  15    by indexing the start of each header field and providing lookup
  16    functions for header fields.
  17
  18    ##################################################################### */
  19                                                                         /*}}}*/
  20 #ifndef PKGLIB_TAGFILE_H
  21 #define PKGLIB_TAGFILE_H
  22
  23 #include <apt-pkg/macros.h>
  24
  25 #include <stdio.h>
  26
  27 #include <string>
  28
  29 #ifndef APT_8_CLEANER_HEADERS
  30 #include <apt-pkg/fileutl.h>
  31 #endif
  32
  33 class FileFd;
  34
  35 class pkgTagSection
  36 {
  37    const char *Section;
  38    // We have a limit of 256 tags per section.
  39    unsigned int Indexes[256];
  40    unsigned int AlphaIndexes[0x100];
  41    unsigned int TagCount;
  42    // dpointer placeholder (for later in case we need it)
  43    void *d;
  44
  45    /* This very simple hash function for the last 8 letters gives
  46       very good performance on the debian package files */
  47    inline static unsigned long AlphaHash(const char *Text, const char *End = 0)
  48    {
  49       unsigned long Res = 0;
  50       for (; Text != End && *Text != ':' && *Text != 0; Text++)
  51          Res = ((unsigned long)(*Text) & 0xDF) ^ (Res << 1);
  52       return Res & 0xFF;
  53    }
  54
  55    protected:
  56    const char *Stop;
  57
  58    public:
  59
  60    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  61    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  62
  63    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  64    bool Find(const char *Tag,unsigned int &Pos) const;
  65    std::string FindS(const char *Tag) const;
  66    signed int FindI(const char *Tag,signed long Default = 0) const ;
  67    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  68    bool FindFlag(const char *Tag,unsigned long &Flags,
  69                  unsigned long Flag) const;
  70    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
  71                                 const char* Start, const char* Stop);
  72    bool Scan(const char *Start,unsigned long MaxLength);
  73    inline unsigned long size() const {return Stop - Section;};
  74    void Trim();
  75    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  76
  77    inline unsigned int Count() const {return TagCount;};
  78    bool Exists(const char* const Tag);
  79
  80    inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
  81                    {Start = Section + Indexes[I]; Stop = Section + Indexes[I+1];}
  82
  83    inline void GetSection(const char *&Start,const char *&Stop) const
  84    {
  85       Start = Section;
  86       Stop = this->Stop;
  87    };
  88
  89    pkgTagSection();
  90    virtual ~pkgTagSection() {};
  91 };
  92
  93 class pkgTagFilePrivate;
  94 class pkgTagFile
  95 {
  96    pkgTagFilePrivate *d;
  97
  98    APT_HIDDEN bool Fill();
  99    APT_HIDDEN bool Resize();
 100    APT_HIDDEN bool Resize(unsigned long long const newSize);
 101
 102    public:
 103
 104    bool Step(pkgTagSection &Section);
 105    unsigned long Offset();
 106    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 107
 108    pkgTagFile(FileFd *F,unsigned long long Size = 32*1024);
 109    virtual ~pkgTagFile();
 110 };
 111
 112 /* This is the list of things to rewrite. The rewriter
 113    goes through and changes or adds each of these headers
 114    to suit. A zero forces the header to be erased, an empty string
 115    causes the old value to be used. (rewrite rule ignored) */
 116 struct TFRewriteData
 117 {
 118    const char *Tag;
 119    const char *Rewrite;
 120    const char *NewTag;
 121 };
 122 extern const char **TFRewritePackageOrder;
 123 extern const char **TFRewriteSourceOrder;
 124
 125 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 126                TFRewriteData *Rewrite);
 127
 128 #endif