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    // Functions for lookup with a perfect hash function
  93    enum class Key;
  94    APT_HIDDEN bool Find(Key key,const char *&Start, const char *&End) const;
  95    APT_HIDDEN bool Find(Key key,unsigned int &Pos) const;
  96    APT_HIDDEN signed int FindI(Key key,signed long Default = 0) const;
  97    APT_HIDDEN bool FindB(Key key, bool Default = false) const;
  98    APT_HIDDEN unsigned long long FindULL(Key key, unsigned long long const &Default = 0) const;
  99    APT_HIDDEN bool FindFlag(Key key,uint8_t &Flags, uint8_t const Flag) const;
 100    APT_HIDDEN bool FindFlag(Key key,unsigned long &Flags, unsigned long Flag) const;
 101    APT_HIDDEN bool Exists(Key key) const;
 102 #ifdef APT_PKG_EXPOSE_STRING_VIEW
 103    APT_HIDDEN APT::StringView Find(Key key) const;
 104    APT_HIDDEN APT::StringView FindRaw(Key key) const;
 105    APT_HIDDEN bool Find(APT::StringView Tag,const char *&Start, const char *&End) const;
 106    APT_HIDDEN bool Find(APT::StringView Tag,unsigned int &Pos) const;
 107    APT_HIDDEN APT::StringView Find(APT::StringView Tag) const;
 108    APT_HIDDEN APT::StringView FindRaw(APT::StringView Tag) const;
 109    APT_HIDDEN signed int FindI(APT::StringView Tag,signed long Default = 0) const;
 110    APT_HIDDEN bool FindB(APT::StringView, bool Default = false) const;
 111    APT_HIDDEN unsigned long long FindULL(APT::StringView Tag, unsigned long long const &Default = 0) const;
 112
 113    APT_HIDDEN bool FindFlag(APT::StringView Tag,uint8_t &Flags,
 114                  uint8_t const Flag) const;
 115    APT_HIDDEN bool FindFlag(APT::StringView Tag,unsigned long &Flags,
 116                  unsigned long Flag) const;
 117    APT_HIDDEN bool Exists(APT::StringView Tag) const;
 118 #endif
 119
 120    bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
 121                                 const char* const Start, const char* const Stop);
 122    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
 123                                 const char* Start, const char* Stop);
 124
 125    /** \brief searches the boundaries of the current section
 126     *
 127     * While parameter Start marks the beginning of the section, this method
 128     * will search for the first double newline in the data stream which marks
 129     * the end of the section. It also does a first pass over the content of
 130     * the section parsing it as encountered for processing later on by Find
 131     *
 132     * @param Start is the beginning of the section
 133     * @param MaxLength is the size of valid data in the stream pointed to by Start
 134     * @param Restart if enabled internal state will be cleared, otherwise it is
 135     *  assumed that now more data is available in the stream and the parsing will
 136     *  start were it encountered insufficent data the last time.
 137     *
 138     * @return \b true if section end was found, \b false otherwise.
 139     *  Beware that internal state will be inconsistent if \b false is returned!
 140     */
 141    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const SupportComments);
 142
 143    inline unsigned long size() const {return Stop - Section;};
 144    void TrimRecord(bool BeforeRecord, const char* &End, bool SupportComments);
 145
 146    /** \brief amount of Tags in the current section
 147     *
 148     * Note: if a Tag is mentioned repeatly it will be counted multiple
 149     * times, but only the last occurrence is available via Find methods.
 150     */
 151    unsigned int Count() const;
 152
 153    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 154
 155    inline void GetSection(const char *&Start,const char *&Stop) const
 156    {
 157       Start = Section;
 158       Stop = this->Stop;
 159    };
 160
 161    pkgTagSection();
 162    virtual ~pkgTagSection();
 163
 164    struct Tag
 165    {
 166       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 167       std::string Name;
 168       std::string Data;
 169
 170       static Tag Remove(std::string const &Name);
 171       static Tag Rename(std::string const &OldName, std::string const &NewName);
 172       static Tag Rewrite(std::string const &Name, std::string const &Data);
 173       private:
 174       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 175          Action(Action), Name(Name), Data(Data) {}
 176    };
 177
 178    /** Write this section (with optional rewrites) to a file
 179     *
 180     * @param File to write the section to
 181     * @param Order in which tags should appear in the file
 182     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 183     * @return \b true if successful, otherwise \b false
 184     */
 185    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 186 };
 187
 188
 189 /** \class pkgTagFile reads and prepares a deb822 formatted file for parsing
 190  * via #pkgTagSection. The default mode tries to be as fast as possible and
 191  * assumes perfectly valid (machine generated) files like Packages. Support
 192  * for comments e.g. needs to be enabled explicitly. */
 193 class pkgTagFile
 194 {
 195    pkgTagFilePrivate * const d;
 196
 197 public:
 198
 199    bool Step(pkgTagSection &Section);
 200    unsigned long Offset();
 201    bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 202
 203    enum Flags
 204    {
 205       STRICT = 0,
 206       SUPPORT_COMMENTS = 1 << 0,
 207    };
 208
 209    void Init(FileFd * const F, pkgTagFile::Flags const Flags);
 210    void Init(FileFd * const F);
 211
 212    pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags);
 213    pkgTagFile(FileFd * const F);
 214    virtual ~pkgTagFile();
 215 };
 216
 217 extern const char **TFRewritePackageOrder;
 218 extern const char **TFRewriteSourceOrder;
 219
 220 APT_IGNORE_DEPRECATED_PUSH
 221 struct APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") TFRewriteData
 222 {
 223    const char *Tag;
 224    const char *Rewrite;
 225    const char *NewTag;
 226 };
 227 APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 228                TFRewriteData *Rewrite);
 229 APT_IGNORE_DEPRECATED_POP
 230
 231 #endif