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 <stdio.h>
  24
  25 #include <string>
  26
  27 #ifndef APT_8_CLEANER_HEADERS
  28 #include <apt-pkg/fileutl.h>
  29 #endif
  30
  31 class FileFd;
  32
  33 class pkgTagSection
  34 {
  35    const char *Section;
  36    // We have a limit of 256 tags per section.
  37    unsigned int Indexes[256];
  38    unsigned int AlphaIndexes[0x100];
  39    unsigned int TagCount;
  40    // dpointer placeholder (for later in case we need it)
  41    void *d;
  42
  43    /* This very simple hash function for the last 8 letters gives
  44       very good performance on the debian package files */
  45    inline static unsigned long AlphaHash(const char *Text, const char *End = 0)
  46    {
  47       unsigned long Res = 0;
  48       for (; Text != End && *Text != ':' && *Text != 0; Text++)
  49          Res = ((unsigned long)(*Text) & 0xDF) ^ (Res << 1);
  50       return Res & 0xFF;
  51    }
  52
  53    protected:
  54    const char *Stop;
  55
  56    public:
  57
  58    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  59    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  60
  61    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  62    bool Find(const char *Tag,unsigned &Pos) const;
  63    std::string FindS(const char *Tag) const;
  64    signed int FindI(const char *Tag,signed long Default = 0) const ;
  65    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  66    bool FindFlag(const char *Tag,unsigned long &Flags,
  67                  unsigned long Flag) const;
  68    bool static const FindFlag(unsigned long &Flags, unsigned long Flag,
  69                                 const char* Start, const char* Stop);
  70    bool Scan(const char *Start,unsigned long MaxLength);
  71    inline unsigned long size() const {return Stop - Section;};
  72    void Trim();
  73    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  74
  75    inline unsigned int Count() const {return TagCount;};
  76    inline bool Exists(const char* const Tag) {return AlphaIndexes[AlphaHash(Tag)] != 0;}
  77
  78    inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
  79                    {Start = Section + Indexes[I]; Stop = Section + Indexes[I+1];}
  80
  81    inline void GetSection(const char *&Start,const char *&Stop) const
  82    {
  83       Start = Section;
  84       Stop = this->Stop;
  85    };
  86
  87    pkgTagSection() : Section(0), TagCount(0), Stop(0) {};
  88    virtual ~pkgTagSection() {};
  89 };
  90
  91 class pkgTagFilePrivate;
  92 class pkgTagFile
  93 {
  94    pkgTagFilePrivate *d;
  95
  96    bool Fill();
  97    bool Resize();
  98
  99    public:
 100
 101    bool Step(pkgTagSection &Section);
 102    unsigned long Offset();
 103    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 104
 105    pkgTagFile(FileFd *F,unsigned long long Size = 32*1024);
 106    virtual ~pkgTagFile();
 107 };
 108
 109 /* This is the list of things to rewrite. The rewriter
 110    goes through and changes or adds each of these headers
 111    to suit. A zero forces the header to be erased, an empty string
 112    causes the old value to be used. (rewrite rule ignored) */
 113 struct TFRewriteData
 114 {
 115    const char *Tag;
 116    const char *Rewrite;
 117    const char *NewTag;
 118 };
 119 extern const char **TFRewritePackageOrder;
 120 extern const char **TFRewriteSourceOrder;
 121
 122 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 123                TFRewriteData *Rewrite);
 124
 125 #endif