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), 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    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  67    bool FindFlag(const char *Tag,unsigned long &Flags,
  68                  unsigned long Flag) const;
  69    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
  70                                 const char* Start, const char* Stop);
  71
  72    /** \brief searches the boundaries of the current section
  73     *
  74     * While parameter Start marks the beginning of the section, this method
  75     * will search for the first double newline in the data stream which marks
  76     * the end of the section. It also does a first pass over the content of
  77     * the section parsing it as encountered for processing later on by Find
  78     *
  79     * @param Start is the beginning of the section
  80     * @param MaxLength is the size of valid data in the stream pointed to by Start
  81     * @param Restart if enabled internal state will be cleared, otherwise it is
  82     *  assumed that now more data is available in the stream and the parsing will
  83     *  start were it encountered insufficent data the last time.
  84     *
  85     * @return \b true if section end was found, \b false otherwise.
  86     *  Beware that internal state will be inconsistent if \b false is returned!
  87     */
  88    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
  89    inline unsigned long size() const {return Stop - Section;};
  90    void Trim();
  91    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  92
  93    /** \brief amount of Tags in the current section
  94     *
  95     * Note: if a Tag is mentioned repeatly it will be counted multiple
  96     * times, but only the last occurance is available via Find methods.
  97     */
  98    unsigned int Count() const;
  99    bool Exists(const char* const Tag) const;
 100
 101    inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
 102                    {Start = Section + Tags[I].StartTag; Stop = Section + Tags[I+1].StartTag;}
 103
 104    inline void GetSection(const char *&Start,const char *&Stop) const
 105    {
 106       Start = Section;
 107       Stop = this->Stop;
 108    };
 109
 110    pkgTagSection();
 111    virtual ~pkgTagSection() {};
 112 };
 113
 114 class pkgTagFilePrivate;
 115 class pkgTagFile
 116 {
 117    pkgTagFilePrivate *d;
 118
 119    APT_HIDDEN bool Fill();
 120    APT_HIDDEN bool Resize();
 121    APT_HIDDEN bool Resize(unsigned long long const newSize);
 122
 123    public:
 124
 125    bool Step(pkgTagSection &Section);
 126    unsigned long Offset();
 127    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 128
 129    void Init(FileFd *F,unsigned long long Size = 32*1024);
 130
 131    pkgTagFile(FileFd *F,unsigned long long Size = 32*1024);
 132    virtual ~pkgTagFile();
 133 };
 134
 135 /* This is the list of things to rewrite. The rewriter
 136    goes through and changes or adds each of these headers
 137    to suit. A zero forces the header to be erased, an empty string
 138    causes the old value to be used. (rewrite rule ignored) */
 139 struct TFRewriteData
 140 {
 141    const char *Tag;
 142    const char *Rewrite;
 143    const char *NewTag;
 144 };
 145 extern const char **TFRewritePackageOrder;
 146 extern const char **TFRewriteSourceOrder;
 147
 148 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 149                TFRewriteData *Rewrite);
 150
 151 #endif