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    APT_HIDDEN bool FindInternal(unsigned int Pos,const char *&Start, const char *&End) const;
  58 #if defined(APT_PKG_EXPOSE_STRING_VIEW)
  59    APT_HIDDEN APT::StringView FindInternal(unsigned int Pos) const;
  60    APT_HIDDEN APT::StringView FindRawInternal(unsigned int Pos) const;
  61 #endif
  62    APT_HIDDEN signed int FindIInternal(unsigned int Pos,signed long Default = 0) const;
  63    APT_HIDDEN bool FindBInternal(unsigned int Pos, bool Default = false) const;
  64    APT_HIDDEN unsigned long long FindULLInternal(unsigned int Pos, unsigned long long const &Default = 0) const;
  65    APT_HIDDEN bool FindFlagInternal(unsigned int Pos,uint8_t &Flags, uint8_t const Flag) const;
  66    APT_HIDDEN bool FindFlagInternal(unsigned int Pos,unsigned long &Flags, unsigned long Flag) const;
  67
  68    protected:
  69    const char *Stop;
  70
  71    public:
  72
  73    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  74    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  75
  76 #if !defined(APT_PKG_EXPOSE_STRING_VIEW) || defined(APT_COMPILING_TAGFILE_COMPAT_CC)
  77    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  78    bool Find(const char *Tag,unsigned int &Pos) const;
  79    signed int FindI(const char *Tag,signed long Default = 0) const;
  80    bool FindB(const char *Tag, bool const &Default = false) const;
  81    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  82    bool FindFlag(const char * const Tag,uint8_t &Flags,
  83                  uint8_t const Flag) const;
  84    bool FindFlag(const char *Tag,unsigned long &Flags,
  85                  unsigned long Flag) const;
  86    bool Exists(const char* const Tag) const;
  87 #endif
  88    // TODO: Remove internally
  89    std::string FindS(const char *Tag) const;
  90    std::string FindRawS(const char *Tag) const;
  91
  92 #ifdef APT_PKG_EXPOSE_STRING_VIEW
  93    APT_HIDDEN bool Find(APT::StringView Tag,const char *&Start, const char *&End) const;
  94    APT_HIDDEN bool Find(APT::StringView Tag,unsigned int &Pos) const;
  95    APT_HIDDEN APT::StringView Find(APT::StringView Tag) const;
  96    APT_HIDDEN APT::StringView FindRaw(APT::StringView Tag) const;
  97    APT_HIDDEN signed int FindI(APT::StringView Tag,signed long Default = 0) const;
  98    APT_HIDDEN bool FindB(APT::StringView, bool Default = false) const;
  99    APT_HIDDEN unsigned long long FindULL(APT::StringView Tag, unsigned long long const &Default = 0) const;
 100
 101    APT_HIDDEN bool FindFlag(APT::StringView Tag,uint8_t &Flags,
 102                  uint8_t const Flag) const;
 103    APT_HIDDEN bool FindFlag(APT::StringView Tag,unsigned long &Flags,
 104                  unsigned long Flag) const;
 105    APT_HIDDEN bool Exists(APT::StringView Tag) const;
 106 #endif
 107
 108    bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
 109                                 const char* const Start, const char* const Stop);
 110    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
 111                                 const char* Start, const char* Stop);
 112
 113    /** \brief searches the boundaries of the current section
 114     *
 115     * While parameter Start marks the beginning of the section, this method
 116     * will search for the first double newline in the data stream which marks
 117     * the end of the section. It also does a first pass over the content of
 118     * the section parsing it as encountered for processing later on by Find
 119     *
 120     * @param Start is the beginning of the section
 121     * @param MaxLength is the size of valid data in the stream pointed to by Start
 122     * @param Restart if enabled internal state will be cleared, otherwise it is
 123     *  assumed that now more data is available in the stream and the parsing will
 124     *  start were it encountered insufficent data the last time.
 125     *
 126     * @return \b true if section end was found, \b false otherwise.
 127     *  Beware that internal state will be inconsistent if \b false is returned!
 128     */
 129    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
 130
 131    inline unsigned long size() const {return Stop - Section;};
 132    void Trim();
 133    virtual void TrimRecord(bool BeforeRecord, const char* &End);
 134
 135    /** \brief amount of Tags in the current section
 136     *
 137     * Note: if a Tag is mentioned repeatly it will be counted multiple
 138     * times, but only the last occurrence is available via Find methods.
 139     */
 140    unsigned int Count() const;
 141
 142    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 143
 144    inline void GetSection(const char *&Start,const char *&Stop) const
 145    {
 146       Start = Section;
 147       Stop = this->Stop;
 148    };
 149
 150    pkgTagSection();
 151    virtual ~pkgTagSection();
 152
 153    struct Tag
 154    {
 155       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 156       std::string Name;
 157       std::string Data;
 158
 159       static Tag Remove(std::string const &Name);
 160       static Tag Rename(std::string const &OldName, std::string const &NewName);
 161       static Tag Rewrite(std::string const &Name, std::string const &Data);
 162       private:
 163       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 164          Action(Action), Name(Name), Data(Data) {}
 165    };
 166
 167    /** Write this section (with optional rewrites) to a file
 168     *
 169     * @param File to write the section to
 170     * @param Order in which tags should appear in the file
 171     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 172     * @return \b true if successful, otherwise \b false
 173     */
 174    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 175 };
 176
 177
 178 class APT_DEPRECATED_MSG("Use pkgTagFile with the SUPPORT_COMMENTS flag instead") pkgUserTagSection : public pkgTagSection
 179 {
 180    virtual void TrimRecord(bool BeforeRecord, const char* &End) APT_OVERRIDE;
 181 };
 182
 183 /** \class pkgTagFile reads and prepares a deb822 formatted file for parsing
 184  * via #pkgTagSection. The default mode tries to be as fast as possible and
 185  * assumes perfectly valid (machine generated) files like Packages. Support
 186  * for comments e.g. needs to be enabled explicitly. */
 187 class pkgTagFile
 188 {
 189    pkgTagFilePrivate * const d;
 190
 191    APT_HIDDEN bool Fill();
 192    APT_HIDDEN bool Resize();
 193    APT_HIDDEN bool Resize(unsigned long long const newSize);
 194
 195 public:
 196
 197    bool Step(pkgTagSection &Section);
 198    unsigned long Offset();
 199    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 200
 201    enum Flags
 202    {
 203       STRICT = 0,
 204       SUPPORT_COMMENTS = 1 << 0,
 205    };
 206
 207    void Init(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 208    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 209
 210    pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 211    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 212    virtual ~pkgTagFile();
 213 };
 214
 215 extern const char **TFRewritePackageOrder;
 216 extern const char **TFRewriteSourceOrder;
 217
 218 APT_IGNORE_DEPRECATED_PUSH
 219 struct APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") TFRewriteData
 220 {
 221    const char *Tag;
 222    const char *Rewrite;
 223    const char *NewTag;
 224 };
 225 APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 226                TFRewriteData *Rewrite);
 227 APT_IGNORE_DEPRECATED_POP
 228
 229 #endif