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
  31 #ifndef APT_8_CLEANER_HEADERS
  32 #include <apt-pkg/fileutl.h>
  33 #endif
  34
  35 class FileFd;
  36 class pkgTagSectionPrivate;
  37 class pkgTagFilePrivate;
  38
  39 /** \class pkgTagSection parses a single deb822 stanza and provides various Find methods
  40  * to extract the included values. It can also be used to modify and write a
  41  * valid deb822 stanza optionally (re)ordering the fields inside the stanza.
  42  *
  43  * Beware: This class does \b NOT support (#-)comments in in- or output!
  44  * If the input contains comments they have to be stripped first like pkgTagFile
  45  * does with SUPPORT_COMMENTS flag set. */
  46 class pkgTagSection
  47 {
  48    const char *Section;
  49    unsigned int AlphaIndexes[0x100];
  50
  51    pkgTagSectionPrivate * const d;
  52
  53    protected:
  54    const char *Stop;
  55
  56    public:
  57
  58    inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
  59    inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
  60
  61    bool Find(const char *Tag,const char *&Start, const char *&End) const;
  62    bool Find(const char *Tag,unsigned int &Pos) const;
  63    std::string FindS(const char *Tag) const;
  64    std::string FindRawS(const char *Tag) const;
  65    signed int FindI(const char *Tag,signed long Default = 0) const;
  66    bool FindB(const char *Tag, bool const &Default = false) const;
  67    unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
  68    bool FindFlag(const char * const Tag,uint8_t &Flags,
  69                  uint8_t const Flag) const;
  70    bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
  71                                 const char* const Start, const char* const Stop);
  72    bool FindFlag(const char *Tag,unsigned long &Flags,
  73                  unsigned long Flag) const;
  74    bool static FindFlag(unsigned long &Flags, unsigned long Flag,
  75                                 const char* Start, const char* Stop);
  76
  77    /** \brief searches the boundaries of the current section
  78     *
  79     * While parameter Start marks the beginning of the section, this method
  80     * will search for the first double newline in the data stream which marks
  81     * the end of the section. It also does a first pass over the content of
  82     * the section parsing it as encountered for processing later on by Find
  83     *
  84     * @param Start is the beginning of the section
  85     * @param MaxLength is the size of valid data in the stream pointed to by Start
  86     * @param Restart if enabled internal state will be cleared, otherwise it is
  87     *  assumed that now more data is available in the stream and the parsing will
  88     *  start were it encountered insufficent data the last time.
  89     *
  90     * @return \b true if section end was found, \b false otherwise.
  91     *  Beware that internal state will be inconsistent if \b false is returned!
  92     */
  93    APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
  94
  95    inline unsigned long size() const {return Stop - Section;};
  96    void Trim();
  97    virtual void TrimRecord(bool BeforeRecord, const char* &End);
  98
  99    /** \brief amount of Tags in the current section
 100     *
 101     * Note: if a Tag is mentioned repeatly it will be counted multiple
 102     * times, but only the last occurrence is available via Find methods.
 103     */
 104    unsigned int Count() const;
 105    bool Exists(const char* const Tag) const;
 106
 107    void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 108
 109    inline void GetSection(const char *&Start,const char *&Stop) const
 110    {
 111       Start = Section;
 112       Stop = this->Stop;
 113    };
 114
 115    pkgTagSection();
 116    virtual ~pkgTagSection();
 117
 118    struct Tag
 119    {
 120       enum ActionType { REMOVE, RENAME, REWRITE } Action;
 121       std::string Name;
 122       std::string Data;
 123
 124       static Tag Remove(std::string const &Name);
 125       static Tag Rename(std::string const &OldName, std::string const &NewName);
 126       static Tag Rewrite(std::string const &Name, std::string const &Data);
 127       private:
 128       Tag(ActionType const Action, std::string const &Name, std::string const &Data) :
 129          Action(Action), Name(Name), Data(Data) {}
 130    };
 131
 132    /** Write this section (with optional rewrites) to a file
 133     *
 134     * @param File to write the section to
 135     * @param Order in which tags should appear in the file
 136     * @param Rewrite is a set of tags to be renamed, rewritten and/or removed
 137     * @return \b true if successful, otherwise \b false
 138     */
 139    bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
 140 };
 141
 142
 143 /* For user generated file the parser should be a bit more relaxed in exchange
 144    for being a bit slower to allow comments and new lines all over the place */
 145 class pkgUserTagSection : public pkgTagSection
 146 {
 147    virtual void TrimRecord(bool BeforeRecord, const char* &End) APT_OVERRIDE;
 148 };
 149
 150 /** \class pkgTagFile reads and prepares a deb822 formatted file for parsing
 151  * via #pkgTagSection. The default mode tries to be as fast as possible and
 152  * assumes perfectly valid (machine generated) files like Packages. Support
 153  * for comments e.g. needs to be enabled explicitly. */
 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    enum Flags
 169    {
 170       STRICT = 0,
 171       SUPPORT_COMMENTS = 1 << 0,
 172    };
 173
 174    void Init(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 175    void Init(FileFd * const F,unsigned long long const Size = 32*1024);
 176
 177    pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = 32*1024);
 178    pkgTagFile(FileFd * const F,unsigned long long Size = 32*1024);
 179    virtual ~pkgTagFile();
 180 };
 181
 182 extern const char **TFRewritePackageOrder;
 183 extern const char **TFRewriteSourceOrder;
 184
 185 APT_IGNORE_DEPRECATED_PUSH
 186 struct APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") TFRewriteData
 187 {
 188    const char *Tag;
 189    const char *Rewrite;
 190    const char *NewTag;
 191 };
 192 APT_DEPRECATED_MSG("Use pkgTagSection::Tag and pkgTagSection::Write() instead") bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
 193                TFRewriteData *Rewrite);
 194 APT_IGNORE_DEPRECATED_POP
 195
 196 #endif