apt-pkg/tagfile.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 /* ######################################################################
   4
   5    Fast scanner for RFC-822 type header information
   6
   7    This parser handles Debian package files (and others). Their form is
   8    RFC-822 type header fields in groups separated by a blank line.
   9
  10    The parser reads the file and provides methods to step linearly
  11    over it or to jump to a pre-recorded start point and read that record.
  12
  13    A second class is used to perform pre-parsing of the record. It works
  14    by indexing the start of each header field and providing lookup
  15    functions for header fields.
  16
  17    ##################################################################### */
  18                                                                         /*}}}*/
  19 #ifndef PKGLIB_TAGFILE_H
  20 #define PKGLIB_TAGFILE_H
  21
  22 #include <apt-pkg/macros.h>
  23
  24 #include <stdio.h>
  25
  26 #include <string>
  27 #include <vector>
  28 #include <list>
  29
  30 #ifndef APT_8_CLEANER_HEADERS
  31 #include <apt-pkg/fileutl.h>
  32 #endif
  33
  34 class FileFd;
  35 class pkgTagSectionPrivate;
  36
  37 class pkgTagSection
  38 {
  39    const char *Section;
  40    unsigned int AlphaIndexes[0x100];
  41
  42    pkgTagSectionPrivate * const d;
  43
  44    protected:
  45    const char *Stop;
  46
  47    public:
  48
  49    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  50    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  51
  52    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  53    bool Find(const char *Tag,unsigned int &Pos) const;
  54    std::string FindS(const char *Tag) const;
  55    std::string FindRawS(const char *Tag) const;
  56    signed int FindI(const char *Tag,signed long Default = 0) const;
  57    bool FindB(const char *Tag, bool const &Default = false) const;
  58    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  59    bool FindFlag(const char *Tag,unsigned long &Flags,
  60                  unsigned long Flag) const;
  61    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
  62                                 const char* Start, const char* Stop);
  63
  64    /** \brief searches the boundaries of the current section
  65     *
  66     * While parameter Start marks the beginning of the section, this method
  67     * will search for the first double newline in the data stream which marks
  68     * the end of the section. It also does a first pass over the content of
  69     * the section parsing it as encountered for processing later on by Find
  70     *
  71     * @param Start is the beginning of the section
  72     * @param MaxLength is the size of valid data in the stream pointed to by Start
  73     * @param Restart if enabled internal state will be cleared, otherwise it is
  74     *  assumed that now more data is available in the stream and the parsing will
  75     *  start were it encountered insufficent data the last time.
  76     *
  77     * @return \b true if section end was found, \b false otherwise.
  78     *  Beware that internal state will be inconsistent if \b false is returned!
  79     */
  80    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
  81
  82    inline unsigned long size() const {return Stop - Section;};
  83    void Trim();
  84    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  85
  86    /** \brief amount of Tags in the current section
  87     *
  88     * Note: if a Tag is mentioned repeatly it will be counted multiple
  89     * times, but only the last occurrence is available via Find methods.
  90     */
  91    unsigned int Count() const;
  92    bool Exists(const char* const Tag) const;
  93
  94    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
  95
  96    inline void GetSection(const char *&Start,const char *&Stop) const
  97    {
  98       Start = Section;
  99       Stop = this->Stop;
 100    };
 101
 102    pkgTagSection();
 103    virtual ~pkgTagSection();
 104
 105    struct Tag
 106    {
 107       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 108       std::string Name;
 109       std::string Data;
 110
 111       static Tag Remove(std::string const &Name);
 112       static Tag Rename(std::string const &OldName, std::string const &NewName);
 113       static Tag Rewrite(std::string const &Name, std::string const &Data);
 114       private:
 115       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 116          Action(Action), Name(Name), Data(Data) {}
 117    };
 118
 119    /** Write this section (with optional rewrites) to a file
 120     *
 121     * @param File to write the section to
 122     * @param Order in which tags should appear in the file
 123     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 124     * @return \b true if successful, otherwise \b false
 125     */
 126    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 127 };
 128
 129
 130 /* For user generated file the parser should be a bit more relaxed in exchange
 131    for being a bit slower to allow comments and new lines all over the place */
 132 class pkgUserTagSection : public pkgTagSection
 133 {
 134    virtual void TrimRecord(bool BeforeRecord, const char* &End) APT_OVERRIDE;
 135 };
 136
 137 class pkgTagFilePrivate;
 138 class pkgTagFile
 139 {
 140    pkgTagFilePrivate * const d;
 141
 142    APT_HIDDEN bool Fill();
 143    APT_HIDDEN bool Resize();
 144    APT_HIDDEN bool Resize(unsigned long long const newSize);
 145
 146    public:
 147
 148    bool Step(pkgTagSection &Section);
 149    unsigned long Offset();
 150    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 151
 152    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 153
 154    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 155    virtual ~pkgTagFile();
 156 };
 157
 158 extern const char **TFRewritePackageOrder;
 159 extern const char **TFRewriteSourceOrder;
 160
 161 // Use pkgTagSection::Tag and pkgTagSection::Write() instead
 162 APT_IGNORE_DEPRECATED_PUSH
 163 struct APT_DEPRECATED TFRewriteData
 164 {
 165    const char *Tag;
 166    const char *Rewrite;
 167    const char *NewTag;
 168 };
 169 APT_DEPRECATED bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 170                TFRewriteData *Rewrite);
 171 APT_IGNORE_DEPRECATED_POP
 172
 173 #endif