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// -*- mode: cpp; mode: fold -*-
// Description /*{{{*/
// $Id: tagfile.cc,v 1.17 1998/12/07 07:26:22 jgg Exp $
/* ######################################################################
Fast scanner for RFC-822 type header information
This uses a rotating buffer to load the package information into.
The scanner runs over it and isolates and indexes a single section.
##################################################################### */
/*}}}*/
// Include Files /*{{{*/
#ifdef __GNUG__
#pragma implementation "apt-pkg/tagfile.h"
#endif
#include <apt-pkg/tagfile.h>
#include <apt-pkg/error.h>
#include <string>
#include <stdio.h>
/*}}}*/
// TagFile::pkgTagFile - Constructor /*{{{*/
// ---------------------------------------------------------------------
/* */
pkgTagFile::pkgTagFile(FileFd &Fd,unsigned long Size) : Fd(Fd), Size(Size)
{
Buffer = new char[Size];
Start = End = Buffer;
Left = Fd.Size();
iOffset = 0;
Fill();
}
/*}}}*/
// TagFile::Step - Advance to the next section /*{{{*/
// ---------------------------------------------------------------------
/* If the Section Scanner fails we refill the buffer and try again. */
bool pkgTagFile::Step(pkgTagSection &Tag)
{
if (Tag.Scan(Start,End - Start) == false)
{
if (Fill() == false)
return false;
if (Tag.Scan(Start,End - Start) == false)
return _error->Error("Unable to parse package file");
}
Start += Tag.size();
iOffset += Tag.size();
return true;
}
/*}}}*/
// TagFile::Fill - Top up the buffer /*{{{*/
// ---------------------------------------------------------------------
/* This takes the bit at the end of the buffer and puts it at the start
then fills the rest from the file */
bool pkgTagFile::Fill()
{
unsigned long EndSize = End - Start;
if (Left == 0)
{
if (EndSize <= 1)
return false;
return true;
}
memmove(Buffer,Start,EndSize);
Start = Buffer;
End = Buffer + EndSize;
// See if only a bit of the file is left
if (Left < Size - (End - Buffer))
{
if (Fd.Read(End,Left) == false)
return false;
End += Left;
Left = 0;
}
else
{
if (Fd.Read(End,Size - (End - Buffer)) == false)
return false;
Left -= Size - (End - Buffer);
End = Buffer + Size;
}
return true;
}
/*}}}*/
// TagFile::Jump - Jump to a pre-recorded location in the file /*{{{*/
// ---------------------------------------------------------------------
/* This jumps to a pre-recorded file location and reads the record
that is there */
bool pkgTagFile::Jump(pkgTagSection &Tag,unsigned long Offset)
{
iOffset = Offset;
Left = Fd.Size() - Offset;
if (Fd.Seek(Offset) == false)
return false;
End = Start = Buffer;
if (Fill() == false)
return false;
if (Tag.Scan(Start,End - Start) == false)
return _error->Error("Unable to parse package file");
return true;
}
/*}}}*/
// TagSection::Scan - Scan for the end of the header information /*{{{*/
// ---------------------------------------------------------------------
/* This looks for the first double new line in the data stream. It also
indexes the tags in the section. This very simple hash function for the
first 3 letters gives very good performance on the debian package files */
bool pkgTagSection::Scan(const char *Start,unsigned long MaxLength)
{
const char *End = Start + MaxLength;
Stop = Section = Start;
memset(AlphaIndexes,0,sizeof(AlphaIndexes));
TagCount = 0;
while (TagCount < sizeof(Indexes)/sizeof(Indexes[0]))
{
if (isspace(Stop[0]) == 0)
{
Indexes[TagCount++] = Stop - Section;
unsigned char A = tolower(Stop[0]) - 'a';
unsigned char B = tolower(Stop[1]) - 'a';
unsigned char C = tolower(Stop[3]) - 'a';
AlphaIndexes[((A + C/3)%26) + 26*((B + C/2)%26)] = TagCount;
}
Stop = (const char *)memchr(Stop,'\n',End - Stop);
if (Stop == 0)
return false;
for (; Stop[1] == '\r' && Stop < End; Stop++);
if (Stop[1] == '\n')
{
Indexes[TagCount] = Stop - Section;
for (; (Stop[0] == '\n' || Stop[0] == '\r') && Stop < End; Stop++);
return true;
}
Stop++;
}
return false;
}
/*}}}*/
// TagSection::Find - Locate a tag /*{{{*/
// ---------------------------------------------------------------------
/* This searches the section for a tag that matches the given string. */
bool pkgTagSection::Find(const char *Tag,const char *&Start,
const char *&End)
{
unsigned int Length = strlen(Tag);
unsigned char A = tolower(Tag[0]) - 'a';
unsigned char B = tolower(Tag[1]) - 'a';
unsigned char C = tolower(Tag[3]) - 'a';
unsigned int I = AlphaIndexes[((A + C/3)%26) + 26*((B + C/2)%26)];
if (I == 0)
return false;
I--;
for (unsigned int Counter = 0; Counter != TagCount; Counter++,
I = (I+1)%TagCount)
{
const char *St;
St = Section + Indexes[I];
if (strncasecmp(Tag,St,Length) != 0)
continue;
// Make sure the colon is in the right place
const char *C = St + Length;
for (; isspace(*C) != 0; C++);
if (*C != ':')
continue;
// Strip off the gunk from the start end
Start = C;
End = Section + Indexes[I+1];
for (; (isspace(*Start) != 0 || *Start == ':') && Start < End; Start++);
for (; isspace(End[-1]) != 0 && End > Start; End--);
return true;
}
Start = End = 0;
return false;
}
/*}}}*/
// TagSection::FindS - Find a string /*{{{*/
// ---------------------------------------------------------------------
/* */
string pkgTagSection::FindS(const char *Tag)
{
const char *Start;
const char *End;
if (Find(Tag,Start,End) == false)
return string();
return string(Start,End);
}
/*}}}*/
// TagSection::FindI - Find an integer /*{{{*/
// ---------------------------------------------------------------------
/* */
unsigned int pkgTagSection::FindI(const char *Tag)
{
const char *Start;
const char *End;
if (Find(Tag,Start,End) == false)
return 0;
return atoi(string(Start,End).c_str());
}
/*}}}*/
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