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
  24 #include <apt-pkg/mmap.h>
  25 #include <apt-pkg/fileutl.h>
  26 #include <stdio.h>
  27
  28 class pkgTagSection
  29 {
  30    const char *Section;
  31
  32    protected:
  33    const char *Stop;
  34
  35    private:
  36    // We have a limit of 256 tags per section.
  37    unsigned int Indexes[256];
  38    unsigned int AlphaIndexes[0x100];
  39
  40    unsigned int TagCount;
  41
  42    public:
  43
  44    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  45    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  46
  47    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  48    bool Find(const char *Tag,unsigned &Pos) const;
  49    string FindS(const char *Tag) const;
  50    signed int FindI(const char *Tag,signed long Default = 0) const ;
  51    bool FindFlag(const char *Tag,unsigned long &Flags,
  52                  unsigned long Flag) const;
  53    bool Scan(const char *Start,unsigned long MaxLength);
  54    inline unsigned long size() const {return Stop - Section;};
  55    void Trim();
  56    void TrimRecord(bool BeforeRecord, const char* &End);
  57
  58    inline unsigned int Count() const {return TagCount;};
  59    inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
  60                    {Start = Section + Indexes[I]; Stop = Section + Indexes[I+1];}
  61
  62    inline void GetSection(const char *&Start,const char *&Stop) const
  63    {
  64       Start = Section;
  65       Stop = this->Stop;
  66    };
  67
  68    pkgTagSection() : Section(0), Stop(0) {};
  69 };
  70
  71 class pkgTagFile
  72 {
  73    FileFd &Fd;
  74    char *Buffer;
  75    char *Start;
  76    char *End;
  77    bool Done;
  78    unsigned long iOffset;
  79    MMap *Map;
  80
  81    bool Fill();
  82
  83    public:
  84
  85    bool Step(pkgTagSection &Section);
  86    inline unsigned long Offset() {return iOffset;};
  87    bool Jump(pkgTagSection &Tag,unsigned long Offset);
  88
  89    pkgTagFile(FileFd *F,unsigned long Size = 32*1024);
  90    ~pkgTagFile();
  91 };
  92
  93 /* This is the list of things to rewrite. The rewriter
  94    goes through and changes or adds each of these headers
  95    to suit. A zero forces the header to be erased, an empty string
  96    causes the old value to be used. (rewrite rule ignored) */
  97 struct TFRewriteData
  98 {
  99    const char *Tag;
 100    const char *Rewrite;
 101    const char *NewTag;
 102 };
 103 extern const char **TFRewritePackageOrder;
 104 extern const char **TFRewriteSourceOrder;
 105
 106 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 107                TFRewriteData *Rewrite);
 108
 109 #endif