tagfile.h

// -*- mode: cpp; mode: fold -*-
// Description                                                          /*{{{*/
/* ######################################################################
 
   Fast scanner for RFC-822 type header information
 
   This parser handles Debian package files (and others). Their form is
   RFC-822 type header fields in groups separated by a blank line.
 
   The parser reads the file and provides methods to step linearly
   over it or to jump to a pre-recorded start point and read that record.
 
   A second class is used to perform pre-parsing of the record. It works
   by indexing the start of each header field and providing lookup
   functions for header fields.
 
   ##################################################################### */
                                                                        /*}}}*/
#ifndef PKGLIB_TAGFILE_H
#define PKGLIB_TAGFILE_H
 
#include <apt-pkg/macros.h>
 
#include <cstdint>
#include <cstdio>
 
#include <list>
#include <memory>
#include <string>
#include <string_view>
#include <vector>
 
 
class FileFd;
class pkgTagSectionPrivate;
class pkgTagFilePrivate;
 
class APT_PUBLIC pkgTagSection
{
   const char *Section;
   unsigned int AlphaIndexes[128];
   unsigned int BetaIndexes[128];
 
   std::unique_ptr<pkgTagSectionPrivate> const d;
 
   APT_HIDDEN bool FindInternal(unsigned int Pos,const char *&Start, const char *&End) const;
   APT_HIDDEN std::string_view FindInternal(unsigned int Pos) const;
   APT_HIDDEN std::string_view FindRawInternal(unsigned int Pos) const;
   APT_HIDDEN signed int FindIInternal(unsigned int Pos,signed long Default = 0) const;
   APT_HIDDEN bool FindBInternal(unsigned int Pos, bool Default = false) const;
   APT_HIDDEN unsigned long long FindULLInternal(unsigned int Pos, unsigned long long const &Default = 0) const;
   APT_HIDDEN bool FindFlagInternal(unsigned int Pos,uint8_t &Flags, uint8_t const Flag) const;
   APT_HIDDEN bool FindFlagInternal(unsigned int Pos,unsigned long &Flags, unsigned long Flag) const;
 
   protected:
   const char *Stop;
 
   public:
 
   inline bool operator ==(const pkgTagSection &rhs) {return Section == rhs.Section;};
   inline bool operator !=(const pkgTagSection &rhs) {return Section != rhs.Section;};
 
   // TODO: Remove internally
   std::string FindS(std::string_view sv) const { return std::string{Find(sv)}; }
   std::string FindRawS(std::string_view sv) const { return std::string{FindRaw(sv)}; };
 
   // Functions for lookup with a perfect hash function
   enum class Key;
#ifdef APT_COMPILING_APT
   bool Find(Key key,const char *&Start, const char *&End) const;
   bool Find(Key key,unsigned int &Pos) const;
   signed int FindI(Key key,signed long Default = 0) const;
   bool FindB(Key key, bool Default = false) const;
   unsigned long long FindULL(Key key, unsigned long long const &Default = 0) const;
   bool FindFlag(Key key,uint8_t &Flags, uint8_t const Flag) const;
   bool FindFlag(Key key,unsigned long &Flags, unsigned long Flag) const;
   bool Exists(Key key) const;
   std::string_view Find(Key key) const;
   std::string_view FindRaw(Key key) const;
#endif
 
   bool Find(std::string_view Tag,const char *&Start, const char *&End) const;
   bool Find(std::string_view Tag,unsigned int &Pos) const;
   std::string_view Find(std::string_view Tag) const;
   std::string_view FindRaw(std::string_view Tag) const;
   signed int FindI(std::string_view Tag,signed long Default = 0) const;
   bool FindB(std::string_view, bool Default = false) const;
   unsigned long long FindULL(std::string_view Tag, unsigned long long const &Default = 0) const;
 
   bool FindFlag(std::string_view Tag,uint8_t &Flags,
                 uint8_t const Flag) const;
   bool FindFlag(std::string_view Tag,unsigned long &Flags,
                 unsigned long Flag) const;
   bool Exists(std::string_view Tag) const;
 
   bool static FindFlag(uint8_t &Flags, uint8_t const Flag,
                                const char* const Start, const char* const Stop);
   bool static FindFlag(unsigned long &Flags, unsigned long Flag,
                                const char* Start, const char* Stop);
 
   [[nodiscard]] bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
 
   inline unsigned long size() const {return Stop - Section;};
   void Trim();
   virtual void TrimRecord(bool BeforeRecord, const char* &End);
 
   unsigned int Count() const;
 
   void Get(const char *&Start,const char *&Stop,unsigned int I) const;
 
   inline void GetSection(const char *&Start,const char *&Stop) const
   {
      Start = Section;
      Stop = this->Stop;
   };
 
   pkgTagSection();
   virtual ~pkgTagSection();
 
   struct Tag
   {
      enum ActionType { REMOVE, RENAME, REWRITE } Action;
      std::string Name;
      std::string Data;
 
      static Tag Remove(std::string_view Name);
      static Tag Rename(std::string_view OldName, std::string_view NewName);
      static Tag Rewrite(std::string_view Name, std::string_view Data);
      private:
      Tag(ActionType const Action, std::string_view Name, std::string_view Data) :
         Action(Action), Name(Name), Data(Data) {}
   };
 
   bool Write(FileFd &File, char const * const * const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
#ifdef APT_COMPILING_APT
   enum WriteFlags
   {
      WRITE_DEFAULT = 0,
      WRITE_HUMAN = (1 << 0), /* write human readable output, may include highlighting */
   };
   bool Write(FileFd &File, WriteFlags flags, char const *const *const Order = NULL, std::vector<Tag> const &Rewrite = std::vector<Tag>()) const;
#endif
};
 
 
class APT_PUBLIC pkgTagFile
{
   std::unique_ptr<pkgTagFilePrivate> const d;
 
   APT_HIDDEN bool Fill();
   APT_HIDDEN bool Resize();
   APT_HIDDEN bool Resize(unsigned long long const newSize);
 
public:
 
   bool Step(pkgTagSection &Section);
   unsigned long Offset();
   bool Jump(pkgTagSection &Tag,unsigned long long Offset);
 
   enum Flags
   {
      STRICT = 0,
      SUPPORT_COMMENTS = 1 << 0,
   };
 
   void Init(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = APT_BUFFER_SIZE);
   void Init(FileFd * const F,unsigned long long const Size = APT_BUFFER_SIZE);
 
   pkgTagFile(FileFd * const F, pkgTagFile::Flags const Flags, unsigned long long Size = APT_BUFFER_SIZE);
   pkgTagFile(FileFd * const F,unsigned long long Size = APT_BUFFER_SIZE);
   virtual ~pkgTagFile();
};
 
APT_PUBLIC extern const char **TFRewritePackageOrder;
APT_PUBLIC extern const char **TFRewriteSourceOrder;
 
#endif