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    // We have a limit of 256 tags per section with the old abi
  41 #if APT_PKG_ABI < 413
  42    APT_DEPRECATED unsigned int Indexes[256];
  43 #endif
  44    unsigned int AlphaIndexes[0x100];
  45 #if APT_PKG_ABI < 413
  46    APT_DEPRECATED unsigned int TagCount;
  47 #endif
  48
  49    pkgTagSectionPrivate * const d;
  50
  51    protected:
  52    const char *Stop;
  53
  54    public:
  55
  56    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  57    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  58
  59    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  60    bool Find(const char *Tag,unsigned int &Pos) const;
  61    std::string FindS(const char *Tag) const;
  62    std::string FindRawS(const char *Tag) const;
  63    signed int FindI(const char *Tag,signed long Default = 0) const;
  64    bool FindB(const char *Tag, bool const &Default = false) 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 FindFlag(unsigned long &Flags, unsigned long Flag,
  69                                 const char* Start, const char* Stop);
  70
  71    /** \brief searches the boundaries of the current section
  72     *
  73     * While parameter Start marks the beginning of the section, this method
  74     * will search for the first double newline in the data stream which marks
  75     * the end of the section. It also does a first pass over the content of
  76     * the section parsing it as encountered for processing later on by Find
  77     *
  78     * @param Start is the beginning of the section
  79     * @param MaxLength is the size of valid data in the stream pointed to by Start
  80     * @param Restart if enabled internal state will be cleared, otherwise it is
  81     *  assumed that now more data is available in the stream and the parsing will
  82     *  start were it encountered insufficent data the last time.
  83     *
  84     * @return \b true if section end was found, \b false otherwise.
  85     *  Beware that internal state will be inconsistent if \b false is returned!
  86     */
  87 #if APT_PKG_ABI >= 413
  88    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
  89 #else
  90    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart);
  91    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength);
  92 #endif
  93
  94    inline unsigned long size() const {return Stop - Section;};
  95    void Trim();
  96    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  97
  98    /** \brief amount of Tags in the current section
  99     *
 100     * Note: if a Tag is mentioned repeatly it will be counted multiple
 101     * times, but only the last occurrence is available via Find methods.
 102     */
 103    unsigned int Count() const;
 104 #if APT_PKG_ABI >= 413
 105    bool Exists(const char* const Tag) const;
 106 #else
 107    bool Exists(const char* const Tag);
 108 #endif
 109
 110    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 111
 112    inline void GetSection(const char *&Start,const char *&Stop) const
 113    {
 114       Start = Section;
 115       Stop = this->Stop;
 116    };
 117
 118    pkgTagSection();
 119    virtual ~pkgTagSection();
 120
 121    struct Tag
 122    {
 123       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 124       std::string Name;
 125       std::string Data;
 126
 127       static Tag Remove(std::string const &Name);
 128       static Tag Rename(std::string const &OldName, std::string const &NewName);
 129       static Tag Rewrite(std::string const &Name, std::string const &Data);
 130       private:
 131       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 132          Action(Action), Name(Name), Data(Data) {}
 133    };
 134
 135    /** Write this section (with optional rewrites) to a file
 136     *
 137     * @param File to write the section to
 138     * @param Order in which tags should appear in the file
 139     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 140     * @return \b true if successful, otherwise \b false
 141     */
 142    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 143 };
 144
 145
 146 /* For user generated file the parser should be a bit more relaxed in exchange
 147    for being a bit slower to allow comments and new lines all over the place */
 148 class pkgUserTagSection : public pkgTagSection
 149 {
 150    virtual void TrimRecord(bool BeforeRecord, const char* &End);
 151 };
 152
 153 class pkgTagFilePrivate;
 154 class pkgTagFile
 155 {
 156    pkgTagFilePrivate * const d;
 157
 158    APT_HIDDEN bool Fill();
 159    APT_HIDDEN bool Resize();
 160    APT_HIDDEN bool Resize(unsigned long long const newSize);
 161
 162    public:
 163
 164    bool Step(pkgTagSection &Section);
 165    unsigned long Offset();
 166    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 167
 168    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 169
 170    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 171    virtual ~pkgTagFile();
 172 };
 173
 174 extern const char **TFRewritePackageOrder;
 175 extern const char **TFRewriteSourceOrder;
 176
 177 // Use pkgTagSection::Tag and pkgTagSection::Write() instead
 178 APT_IGNORE_DEPRECATED_PUSH
 179 struct APT_DEPRECATED TFRewriteData
 180 {
 181    const char *Tag;
 182    const char *Rewrite;
 183    const char *NewTag;
 184 };
 185 APT_DEPRECATED bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 186                TFRewriteData *Rewrite);
 187 APT_IGNORE_DEPRECATED_POP
 188
 189 #endif