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[0x100];
  53
  54    pkgTagSectionPrivate * const d;
  55
  56    protected:
  57    const char *Stop;
  58
  59    public:
  60
  61    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  62    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  63
  64 #if !defined(APT_PKG_EXPOSE_STRING_VIEW) || defined(APT_COMPILING_TAGFILE_COMPAT_CC)
  65    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  66    bool Find(const char *Tag,unsigned int &Pos) const;
  67    signed int FindI(const char *Tag,signed long Default = 0) const;
  68    bool FindB(const char *Tag, bool const &Default = false) const;
  69    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  70    bool FindFlag(const char * const Tag,uint8_t &Flags,
  71                  uint8_t const Flag) const;
  72    bool FindFlag(const char *Tag,unsigned long &Flags,
  73                  unsigned long Flag) const;
  74    bool Exists(const char* const Tag) const;
  75 #endif
  76    // TODO: Remove internally
  77    std::string FindS(const char *Tag) const;
  78    std::string FindRawS(const char *Tag) const;
  79
  80 #ifdef APT_PKG_EXPOSE_STRING_VIEW
  81    APT_HIDDEN bool Find(APT::StringView Tag,const char *&Start, const char *&End) const;
  82    APT_HIDDEN bool Find(APT::StringView Tag,unsigned int &Pos) const;
  83    APT_HIDDEN APT::StringView Find(APT::StringView Tag) const;
  84    APT_HIDDEN APT::StringView FindRaw(APT::StringView Tag) const;
  85    APT_HIDDEN signed int FindI(APT::StringView Tag,signed long Default = 0) const;
  86    APT_HIDDEN bool FindB(APT::StringView, bool Default = false) const;
  87    APT_HIDDEN unsigned long long FindULL(APT::StringView Tag, unsigned long long const &Default = 0) const;
  88
  89    APT_HIDDEN bool FindFlag(APT::StringView Tag,uint8_t &Flags,
  90                  uint8_t const Flag) const;
  91    APT_HIDDEN bool FindFlag(APT::StringView Tag,unsigned long &Flags,
  92                  unsigned long Flag) const;
  93    APT_HIDDEN bool Exists(APT::StringView Tag) const;
  94 #endif
  95
  96    bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
  97                                 const char* const Start, const char* const Stop);
  98    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
  99                                 const char* Start, const char* Stop);
 100
 101    /** \brief searches the boundaries of the current section
 102     *
 103     * While parameter Start marks the beginning of the section, this method
 104     * will search for the first double newline in the data stream which marks
 105     * the end of the section. It also does a first pass over the content of
 106     * the section parsing it as encountered for processing later on by Find
 107     *
 108     * @param Start is the beginning of the section
 109     * @param MaxLength is the size of valid data in the stream pointed to by Start
 110     * @param Restart if enabled internal state will be cleared, otherwise it is
 111     *  assumed that now more data is available in the stream and the parsing will
 112     *  start were it encountered insufficent data the last time.
 113     *
 114     * @return \b true if section end was found, \b false otherwise.
 115     *  Beware that internal state will be inconsistent if \b false is returned!
 116     */
 117    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
 118
 119    inline unsigned long size() const {return Stop - Section;};
 120    void Trim();
 121    virtual void TrimRecord(bool BeforeRecord, const char* &End);
 122
 123    /** \brief amount of Tags in the current section
 124     *
 125     * Note: if a Tag is mentioned repeatly it will be counted multiple
 126     * times, but only the last occurrence is available via Find methods.
 127     */
 128    unsigned int Count() const;
 129
 130    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 131
 132    inline void GetSection(const char *&Start,const char *&Stop) const
 133    {
 134       Start = Section;
 135       Stop = this->Stop;
 136    };
 137
 138    pkgTagSection();
 139    virtual ~pkgTagSection();
 140
 141    struct Tag
 142    {
 143       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 144       std::string Name;
 145       std::string Data;
 146
 147       static Tag Remove(std::string const &Name);
 148       static Tag Rename(std::string const &OldName, std::string const &NewName);
 149       static Tag Rewrite(std::string const &Name, std::string const &Data);
 150       private:
 151       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 152          Action(Action), Name(Name), Data(Data) {}
 153    };
 154
 155    /** Write this section (with optional rewrites) to a file
 156     *
 157     * @param File to write the section to
 158     * @param Order in which tags should appear in the file
 159     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 160     * @return \b true if successful, otherwise \b false
 161     */
 162    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 163 };
 164
 165
 166 class APT_DEPRECATED_MSG("Use pkgTagFile with the SUPPORT_COMMENTS flag instead") pkgUserTagSection : public pkgTagSection
 167 {
 168    virtual void TrimRecord(bool BeforeRecord, const char* &End) APT_OVERRIDE;
 169 };
 170
 171 /** \class pkgTagFile reads and prepares a deb822 formatted file for parsing
 172  * via #pkgTagSection. The default mode tries to be as fast as possible and
 173  * assumes perfectly valid (machine generated) files like Packages. Support
 174  * for comments e.g. needs to be enabled explicitly. */
 175 class pkgTagFile
 176 {
 177    pkgTagFilePrivate * const d;
 178
 179    APT_HIDDEN bool Fill();
 180    APT_HIDDEN bool Resize();
 181    APT_HIDDEN bool Resize(unsigned long long const newSize);
 182
 183 public:
 184
 185    bool Step(pkgTagSection &Section);
 186    unsigned long Offset();
 187    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 188
 189    enum Flags
 190    {
 191       STRICT = 0,
 192       SUPPORT_COMMENTS = 1 << 0,
 193    };
 194
 195    void Init(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 196    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 197
 198    pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 199    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 200    virtual ~pkgTagFile();
 201 };
 202
 203 extern const char **TFRewritePackageOrder;
 204 extern const char **TFRewriteSourceOrder;
 205
 206 APT_IGNORE_DEPRECATED_PUSH
 207 struct APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") TFRewriteData
 208 {
 209    const char *Tag;
 210    const char *Rewrite;
 211    const char *NewTag;
 212 };
 213 APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 214                TFRewriteData *Rewrite);
 215 APT_IGNORE_DEPRECATED_POP
 216
 217 #endif