apt  0.9.7.5ubuntu5
tagfile.h
1 // -*- mode: cpp; mode: fold -*-
2 // Description /*{{{*/
3 // $Id: tagfile.h,v 1.20 2003/05/19 17:13:57 doogie Exp $
4 /* ######################################################################
5 
6  Fast scanner for RFC-822 type header information
7 
8  This parser handles Debian package files (and others). Their form is
9  RFC-822 type header fields in groups separated by a blank line.
10 
11  The parser reads the file and provides methods to step linearly
12  over it or to jump to a pre-recorded start point and read that record.
13 
14  A second class is used to perform pre-parsing of the record. It works
15  by indexing the start of each header field and providing lookup
16  functions for header fields.
17 
18  ##################################################################### */
19  /*}}}*/
20 #ifndef PKGLIB_TAGFILE_H
21 #define PKGLIB_TAGFILE_H
22 
23 #include <stdio.h>
24 
25 #include <string>
26 
27 #ifndef APT_8_CLEANER_HEADERS
28 #include <apt-pkg/fileutl.h>
29 #endif
30 
31 class FileFd;
32 
34 {
35  const char *Section;
36  // We have a limit of 256 tags per section.
37  unsigned int Indexes[256];
38  unsigned int AlphaIndexes[0x100];
39  unsigned int TagCount;
40  // dpointer placeholder (for later in case we need it)
41  void *d;
42 
43  /* This very simple hash function for the last 8 letters gives
44  very good performance on the debian package files */
45  inline static unsigned long AlphaHash(const char *Text, const char *End = 0)
46  {
47  unsigned long Res = 0;
48  for (; Text != End && *Text != ':' && *Text != 0; Text++)
49  Res = ((unsigned long)(*Text) & 0xDF) ^ (Res << 1);
50  return Res & 0xFF;
51  }
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 &Pos) const;
63  std::string FindS(const char *Tag) const;
64  signed int FindI(const char *Tag,signed long Default = 0) const ;
65  unsigned long long FindULL(const char *Tag, unsigned long long const &Default = 0) const;
66  bool FindFlag(const char *Tag,unsigned long &Flags,
67  unsigned long Flag) const;
68  bool static const FindFlag(unsigned long &Flags, unsigned long Flag,
69  const char* Start, const char* Stop);
70  bool Scan(const char *Start,unsigned long MaxLength);
71  inline unsigned long size() const {return Stop - Section;};
72  void Trim();
73  virtual void TrimRecord(bool BeforeRecord, const char* &End);
74 
75  inline unsigned int Count() const {return TagCount;};
76  inline bool Exists(const char* const Tag) {return AlphaIndexes[AlphaHash(Tag)] != 0;}
77 
78  inline void Get(const char *&Start,const char *&Stop,unsigned int I) const
79  {Start = Section + Indexes[I]; Stop = Section + Indexes[I+1];}
80 
81  inline void GetSection(const char *&Start,const char *&Stop) const
82  {
83  Start = Section;
84  Stop = this->Stop;
85  };
86 
87  pkgTagSection() : Section(0), TagCount(0), Stop(0) {};
88  virtual ~pkgTagSection() {};
89 };
90 
91 class pkgTagFilePrivate;
93 {
95 
96  bool Fill();
97  bool Resize();
98 
99  public:
100 
101  bool Step(pkgTagSection &Section);
102  unsigned long Offset();
103  bool Jump(pkgTagSection &Tag,unsigned long long Offset);
104 
105  pkgTagFile(FileFd *F,unsigned long long Size = 32*1024);
106  virtual ~pkgTagFile();
107 };
108 
109 /* This is the list of things to rewrite. The rewriter
110  goes through and changes or adds each of these headers
111  to suit. A zero forces the header to be erased, an empty string
112  causes the old value to be used. (rewrite rule ignored) */
114 {
115  const char *Tag;
116  const char *Rewrite;
117  const char *NewTag;
118 };
119 extern const char **TFRewritePackageOrder;
120 extern const char **TFRewriteSourceOrder;
121 
122 bool TFRewrite(FILE *Output,pkgTagSection const &Tags,const char *Order[],
123  TFRewriteData *Rewrite);
124 
125 #endif