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 #include <stdint.h>
  26
  27 #include <string>
  28 #include <vector>
  29 #include <list>
  30 #ifdef APT_PKG_EXPOSE_STRING_VIEW
  31 #include <apt-pkg/string_view.h>
  32 #endif
  33
  34 #ifndef APT_8_CLEANER_HEADERS
  35 #include <apt-pkg/fileutl.h>
  36 #endif
  37
  38 class FileFd;
  39 class pkgTagSectionPrivate;
  40 class pkgTagFilePrivate;
  41
  42 /** \class pkgTagSection parses a single deb822 stanza and provides various Find methods
  43  * to extract the included values. It can also be used to modify and write a
  44  * valid deb822 stanza optionally (re)ordering the fields inside the stanza.
  45  *
  46  * Beware: This class does \b NOT support (#-)comments in in- or output!
  47  * If the input contains comments they have to be stripped first like pkgTagFile
  48  * does with SUPPORT_COMMENTS flag set. */
  49 class pkgTagSection
  50 {
  51    const char *Section;
  52    unsigned int AlphaIndexes[128];
  53    unsigned int BetaIndexes[128];
  54
  55    pkgTagSectionPrivate * const d;
  56
  57    protected:
  58    const char *Stop;
  59
  60    public:
  61
  62    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  63    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  64
  65 #if !defined(APT_PKG_EXPOSE_STRING_VIEW) || defined(APT_COMPILING_TAGFILE_COMPAT_CC)
  66    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  67    bool Find(const char *Tag,unsigned int &Pos) const;
  68    signed int FindI(const char *Tag,signed long Default = 0) const;
  69    bool FindB(const char *Tag, bool const &Default = false) const;
  70    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  71    bool FindFlag(const char * const Tag,uint8_t &Flags,
  72                  uint8_t const Flag) const;
  73    bool FindFlag(const char *Tag,unsigned long &Flags,
  74                  unsigned long Flag) const;
  75    bool Exists(const char* const Tag) const;
  76 #endif
  77    // TODO: Remove internally
  78    std::string FindS(const char *Tag) const;
  79    std::string FindRawS(const char *Tag) const;
  80
  81 #ifdef APT_PKG_EXPOSE_STRING_VIEW
  82    APT_HIDDEN bool Find(APT::StringView Tag,const char *&Start, const char *&End) const;
  83    APT_HIDDEN bool Find(APT::StringView Tag,unsigned int &Pos) const;
  84    APT_HIDDEN APT::StringView Find(APT::StringView Tag) const;
  85    APT_HIDDEN APT::StringView FindRaw(APT::StringView Tag) const;
  86    APT_HIDDEN signed int FindI(APT::StringView Tag,signed long Default = 0) const;
  87    APT_HIDDEN bool FindB(APT::StringView, bool Default = false) const;
  88    APT_HIDDEN unsigned long long FindULL(APT::StringView Tag, unsigned long long const &Default = 0) const;
  89
  90    APT_HIDDEN bool FindFlag(APT::StringView Tag,uint8_t &Flags,
  91                  uint8_t const Flag) const;
  92    APT_HIDDEN bool FindFlag(APT::StringView Tag,unsigned long &Flags,
  93                  unsigned long Flag) const;
  94    APT_HIDDEN bool Exists(APT::StringView Tag) const;
  95 #endif
  96
  97    bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
  98                                 const char* const Start, const char* const Stop);
  99    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
 100                                 const char* Start, const char* Stop);
 101
 102    /** \brief searches the boundaries of the current section
 103     *
 104     * While parameter Start marks the beginning of the section, this method
 105     * will search for the first double newline in the data stream which marks
 106     * the end of the section. It also does a first pass over the content of
 107     * the section parsing it as encountered for processing later on by Find
 108     *
 109     * @param Start is the beginning of the section
 110     * @param MaxLength is the size of valid data in the stream pointed to by Start
 111     * @param Restart if enabled internal state will be cleared, otherwise it is
 112     *  assumed that now more data is available in the stream and the parsing will
 113     *  start were it encountered insufficent data the last time.
 114     *
 115     * @return \b true if section end was found, \b false otherwise.
 116     *  Beware that internal state will be inconsistent if \b false is returned!
 117     */
 118    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
 119
 120    inline unsigned long size() const {return Stop - Section;};
 121    void Trim();
 122    virtual void TrimRecord(bool BeforeRecord, const char* &End);
 123
 124    /** \brief amount of Tags in the current section
 125     *
 126     * Note: if a Tag is mentioned repeatly it will be counted multiple
 127     * times, but only the last occurrence is available via Find methods.
 128     */
 129    unsigned int Count() const;
 130
 131    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 132
 133    inline void GetSection(const char *&Start,const char *&Stop) const
 134    {
 135       Start = Section;
 136       Stop = this->Stop;
 137    };
 138
 139    pkgTagSection();
 140    virtual ~pkgTagSection();
 141
 142    struct Tag
 143    {
 144       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 145       std::string Name;
 146       std::string Data;
 147
 148       static Tag Remove(std::string const &Name);
 149       static Tag Rename(std::string const &OldName, std::string const &NewName);
 150       static Tag Rewrite(std::string const &Name, std::string const &Data);
 151       private:
 152       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 153          Action(Action), Name(Name), Data(Data) {}
 154    };
 155
 156    /** Write this section (with optional rewrites) to a file
 157     *
 158     * @param File to write the section to
 159     * @param Order in which tags should appear in the file
 160     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 161     * @return \b true if successful, otherwise \b false
 162     */
 163    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 164 };
 165
 166
 167 class APT_DEPRECATED_MSG("Use pkgTagFile with the SUPPORT_COMMENTS flag instead") pkgUserTagSection : public pkgTagSection
 168 {
 169    virtual void TrimRecord(bool BeforeRecord, const char* &End) APT_OVERRIDE;
 170 };
 171
 172 /** \class pkgTagFile reads and prepares a deb822 formatted file for parsing
 173  * via #pkgTagSection. The default mode tries to be as fast as possible and
 174  * assumes perfectly valid (machine generated) files like Packages. Support
 175  * for comments e.g. needs to be enabled explicitly. */
 176 class pkgTagFile
 177 {
 178    pkgTagFilePrivate * const d;
 179
 180    APT_HIDDEN bool Fill();
 181    APT_HIDDEN bool Resize();
 182    APT_HIDDEN bool Resize(unsigned long long const newSize);
 183
 184 public:
 185
 186    bool Step(pkgTagSection &Section);
 187    unsigned long Offset();
 188    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 189
 190    enum Flags
 191    {
 192       STRICT = 0,
 193       SUPPORT_COMMENTS = 1 << 0,
 194    };
 195
 196    void Init(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 197    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 198
 199    pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 200    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 201    virtual ~pkgTagFile();
 202 };
 203
 204 extern const char **TFRewritePackageOrder;
 205 extern const char **TFRewriteSourceOrder;
 206
 207 APT_IGNORE_DEPRECATED_PUSH
 208 struct APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") TFRewriteData
 209 {
 210    const char *Tag;
 211    const char *Rewrite;
 212    const char *NewTag;
 213 };
 214 APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 215                TFRewriteData *Rewrite);
 216 APT_IGNORE_DEPRECATED_POP
 217
 218 #endif