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 #include <vector>
  29 #include <list>
  30
  31 #ifndef APT_8_CLEANER_HEADERS
  32 #include <apt-pkg/fileutl.h>
  33 #endif
  34
  35 class FileFd;
  36
  37 class pkgTagSection
  38 {
  39    const char *Section;
  40    struct TagData {
  41       unsigned int StartTag;
  42       unsigned int EndTag;
  43       unsigned int StartValue;
  44       unsigned int NextInBucket;
  45
  46       TagData(unsigned int const StartTag) : StartTag(StartTag), EndTag(0), StartValue(0), NextInBucket(0) {}
  47    };
  48    std::vector<TagData> Tags;
  49    unsigned int LookupTable[0x100];
  50
  51    // dpointer placeholder (for later in case we need it)
  52    void *d;
  53
  54    protected:
  55    const char *Stop;
  56
  57    public:
  58
  59    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  60    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  61
  62    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  63    bool Find(const char *Tag,unsigned int &Pos) const;
  64    std::string FindS(const char *Tag) const;
  65    signed int FindI(const char *Tag,signed long Default = 0) const;
  66    bool FindB(const char *Tag, bool const &Default = false) 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
  73    /** \brief searches the boundaries of the current section
  74     *
  75     * While parameter Start marks the beginning of the section, this method
  76     * will search for the first double newline in the data stream which marks
  77     * the end of the section. It also does a first pass over the content of
  78     * the section parsing it as encountered for processing later on by Find
  79     *
  80     * @param Start is the beginning of the section
  81     * @param MaxLength is the size of valid data in the stream pointed to by Start
  82     * @param Restart if enabled internal state will be cleared, otherwise it is
  83     *  assumed that now more data is available in the stream and the parsing will
  84     *  start were it encountered insufficent data the last time.
  85     *
  86     * @return \b true if section end was found, \b false otherwise.
  87     *  Beware that internal state will be inconsistent if \b false is returned!
  88     */
  89    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
  90    inline unsigned long size() const {return Stop - Section;};
  91    void Trim();
  92    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  93
  94    /** \brief amount of Tags in the current section
  95     *
  96     * Note: if a Tag is mentioned repeatly it will be counted multiple
  97     * times, but only the last occurrence is available via Find methods.
  98     */
  99    unsigned int Count() const;
 100    bool Exists(const char* const Tag) const;
 101
 102    inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
 103                    {Start = Section + Tags[I].StartTag; Stop = Section + Tags[I+1].StartTag;}
 104
 105    inline void GetSection(const char *&Start,const char *&Stop) const
 106    {
 107       Start = Section;
 108       Stop = this->Stop;
 109    };
 110
 111    pkgTagSection();
 112    virtual ~pkgTagSection();
 113 };
 114
 115 class pkgTagFilePrivate;
 116 class pkgTagFile
 117 {
 118    pkgTagFilePrivate *d;
 119
 120    APT_HIDDEN bool Fill();
 121    APT_HIDDEN bool Resize();
 122    APT_HIDDEN bool Resize(unsigned long long const newSize);
 123
 124    public:
 125
 126    bool Step(pkgTagSection &Section);
 127    unsigned long Offset();
 128    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 129
 130    void Init(FileFd *F,unsigned long long Size = 32*1024);
 131
 132    pkgTagFile(FileFd *F,unsigned long long Size = 32*1024);
 133    virtual ~pkgTagFile();
 134 };
 135
 136 /* This is the list of things to rewrite. The rewriter
 137    goes through and changes or adds each of these headers
 138    to suit. A zero forces the header to be erased, an empty string
 139    causes the old value to be used. (rewrite rule ignored) */
 140 struct TFRewriteData
 141 {
 142    const char *Tag;
 143    const char *Rewrite;
 144    const char *NewTag;
 145 };
 146 extern const char **TFRewritePackageOrder;
 147 extern const char **TFRewriteSourceOrder;
 148
 149 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 150                TFRewriteData *Rewrite);
 151
 152 #endif