504 lines
14 KiB
C++
504 lines
14 KiB
C++
// -*- mode: cpp; mode: fold -*-
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// Description /*{{{*/
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/* ######################################################################
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MMap Class - Provides 'real' mmap or a faked mmap using read().
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MMap cover class.
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Some broken versions of glibc2 (libc6) have a broken definition
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of mmap that accepts a char * -- all other systems (and libc5) use
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void *. We can't safely do anything here that would be portable, so
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libc6 generates warnings -- which should be errors, g++ isn't properly
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strict.
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##################################################################### */
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/*}}}*/
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// Include Files /*{{{*/
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#define _DEFAULT_SOURCE
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#include <config.h>
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#include <apt-pkg/error.h>
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#include <apt-pkg/fileutl.h>
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#include <apt-pkg/macros.h>
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#include <apt-pkg/mmap.h>
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#include <cerrno>
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#include <cstdint>
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#include <cstdlib>
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#include <cstring>
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#include <string>
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#include <unistd.h>
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#include <apti18n.h>
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/*}}}*/
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// MMap::MMap - Constructor /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0),
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Base(nullptr), SyncToFd(nullptr)
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{
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if ((Flags & NoImmMap) != NoImmMap)
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Map(F);
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}
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/*}}}*/
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// MMap::MMap - Constructor /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0),
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Base(nullptr), SyncToFd(nullptr)
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{
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}
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/*}}}*/
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// MMap::~MMap - Destructor /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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MMap::~MMap()
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{
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Close();
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}
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/*}}}*/
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// MMap::Map - Perform the mapping /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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bool MMap::Map(FileFd &Fd)
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{
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iSize = Fd.Size();
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// Set the permissions.
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int Prot = PROT_READ;
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int Map = MAP_SHARED;
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if ((Flags & ReadOnly) != ReadOnly)
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Prot |= PROT_WRITE;
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if ((Flags & Public) != Public)
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Map = MAP_PRIVATE;
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if (iSize == 0)
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return _error->Error(_("Can't mmap an empty file"));
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// We can't mmap compressed fd's directly, so we need to read it completely
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if (Fd.IsCompressed() == true)
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{
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if ((Flags & ReadOnly) != ReadOnly)
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return _error->Error("Compressed file %s can only be mapped readonly", Fd.Name().c_str());
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Base = malloc(iSize);
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if (unlikely(Base == nullptr))
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return _error->Errno("MMap-compressed-malloc", _("Couldn't make mmap of %llu bytes"), iSize);
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SyncToFd = new FileFd();
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if (Fd.Seek(0L) == false || Fd.Read(Base, iSize) == false)
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return _error->Error("Compressed file %s can't be read into mmap", Fd.Name().c_str());
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return true;
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}
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// Map it.
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Base = (Flags & Fallback) ? MAP_FAILED : mmap(0,iSize,Prot,Map,Fd.Fd(),0);
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if (Base == MAP_FAILED)
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{
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if (errno == ENODEV || errno == EINVAL || (Flags & Fallback))
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{
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// The filesystem doesn't support this particular kind of mmap.
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// So we allocate a buffer and read the whole file into it.
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if ((Flags & ReadOnly) == ReadOnly)
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{
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// for readonly, we don't need sync, so make it simple
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Base = malloc(iSize);
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if (unlikely(Base == nullptr))
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return _error->Errno("MMap-malloc", _("Couldn't make mmap of %llu bytes"), iSize);
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SyncToFd = new FileFd();
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return Fd.Read(Base, iSize);
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}
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// FIXME: Writing to compressed fd's ?
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int const dupped_fd = dup(Fd.Fd());
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if (dupped_fd == -1)
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return _error->Errno("mmap", _("Couldn't duplicate file descriptor %i"), Fd.Fd());
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Base = calloc(iSize, 1);
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if (unlikely(Base == nullptr))
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return _error->Errno("MMap-calloc", _("Couldn't make mmap of %llu bytes"), iSize);
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SyncToFd = new FileFd (dupped_fd);
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if (!SyncToFd->Seek(0L) || !SyncToFd->Read(Base, iSize))
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return false;
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}
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else
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return _error->Errno("MMap-mmap", _("Couldn't make mmap of %llu bytes"), iSize);
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}
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return true;
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}
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/*}}}*/
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// MMap::Close - Close the map /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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bool MMap::Close(bool DoSync)
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{
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if ((Flags & UnMapped) == UnMapped || validData() == false || iSize == 0)
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return true;
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if (DoSync == true)
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Sync();
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if (SyncToFd != NULL)
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{
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free(Base);
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delete SyncToFd;
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SyncToFd = NULL;
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}
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else
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{
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if (munmap((char *)Base, iSize) != 0)
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_error->WarningE("mmap", _("Unable to close mmap"));
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}
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iSize = 0;
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Base = 0;
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return true;
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}
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/*}}}*/
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// MMap::Sync - Synchronize the map with the disk /*{{{*/
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// ---------------------------------------------------------------------
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/* This is done in synchronous mode - the docs indicate that this will
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not return till all IO is complete */
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bool MMap::Sync()
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{
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if ((Flags & UnMapped) == UnMapped)
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return true;
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if ((Flags & ReadOnly) != ReadOnly)
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{
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if (SyncToFd != NULL)
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{
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if (!SyncToFd->Seek(0) || !SyncToFd->Write(Base, iSize))
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return false;
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}
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else
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{
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#ifdef _POSIX_SYNCHRONIZED_IO
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if (msync((char *)Base, iSize, MS_SYNC) < 0)
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return _error->Errno("msync", _("Unable to synchronize mmap"));
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#endif
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}
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}
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return true;
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}
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/*}}}*/
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// MMap::Sync - Synchronize a section of the file to disk /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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bool MMap::Sync(unsigned long Start,unsigned long Stop)
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{
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if ((Flags & UnMapped) == UnMapped)
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return true;
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if ((Flags & ReadOnly) != ReadOnly)
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{
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if (SyncToFd != 0)
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{
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if (!SyncToFd->Seek(0) ||
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!SyncToFd->Write (((char *)Base)+Start, Stop-Start))
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return false;
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}
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else
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{
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#ifdef _POSIX_SYNCHRONIZED_IO
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unsigned long long const PSize = sysconf(_SC_PAGESIZE);
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if (msync((char *)Base+(Start/PSize)*PSize, Stop - Start, MS_SYNC) < 0)
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return _error->Errno("msync", _("Unable to synchronize mmap"));
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#endif
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}
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}
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return true;
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}
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/*}}}*/
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// DynamicMMap::DynamicMMap - Constructor /*{{{*/
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// ---------------------------------------------------------------------
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/* */
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DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &Workspace,
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unsigned long const &Grow, unsigned long const &Limit) :
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MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(Workspace),
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GrowFactor(Grow), Limit(Limit)
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{
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// disable Moveable if we don't grow
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if (Grow == 0)
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this->Flags &= ~Moveable;
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#ifndef __linux__
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// kfreebsd doesn't have mremap, so we use the fallback
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if ((this->Flags & Moveable) == Moveable)
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this->Flags |= Fallback;
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#endif
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unsigned long long EndOfFile = Fd->Size();
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if (EndOfFile > WorkSpace)
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WorkSpace = EndOfFile;
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else if(WorkSpace > 0)
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{
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Fd->Seek(WorkSpace - 1);
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char C = 0;
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Fd->Write(&C,sizeof(C));
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}
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Map(F);
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iSize = EndOfFile;
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}
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/*}}}*/
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// DynamicMMap::DynamicMMap - Constructor for a non-file backed map /*{{{*/
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// ---------------------------------------------------------------------
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/* We try here to use mmap to reserve some space - this is much more
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cooler than the fallback solution to simply allocate a char array
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and could come in handy later than we are able to grow such an mmap */
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DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace,
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unsigned long const &Grow, unsigned long const &Limit) :
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MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace),
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GrowFactor(Grow), Limit(Limit)
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{
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// disable Moveable if we don't grow
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if (Grow == 0)
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this->Flags &= ~Moveable;
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#ifndef __linux__
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// kfreebsd doesn't have mremap, so we use the fallback
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if ((this->Flags & Moveable) == Moveable)
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this->Flags |= Fallback;
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#endif
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#ifdef _POSIX_MAPPED_FILES
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if ((this->Flags & Fallback) != Fallback) {
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// Set the permissions.
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int Prot = PROT_READ;
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#ifdef MAP_ANONYMOUS
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int Map = MAP_PRIVATE | MAP_ANONYMOUS;
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#else
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int Map = MAP_PRIVATE | MAP_ANON;
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#endif
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if ((this->Flags & ReadOnly) != ReadOnly)
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Prot |= PROT_WRITE;
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if ((this->Flags & Public) == Public)
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#ifdef MAP_ANONYMOUS
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Map = MAP_SHARED | MAP_ANONYMOUS;
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#else
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Map = MAP_SHARED | MAP_ANON;
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#endif
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// use anonymous mmap() to get the memory
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Base = (unsigned char*) mmap(0, WorkSpace, Prot, Map, -1, 0);
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if(Base == MAP_FAILED)
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_error->Errno("DynamicMMap",_("Couldn't make mmap of %lu bytes"),WorkSpace);
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iSize = 0;
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return;
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}
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#endif
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// fallback to a static allocated space
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Base = calloc(WorkSpace, 1);
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iSize = 0;
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}
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/*}}}*/
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// DynamicMMap::~DynamicMMap - Destructor /*{{{*/
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// ---------------------------------------------------------------------
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/* We truncate the file to the size of the memory data set */
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DynamicMMap::~DynamicMMap()
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{
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if (Fd == 0)
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{
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if (validData() == false)
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return;
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#ifdef _POSIX_MAPPED_FILES
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munmap(Base, WorkSpace);
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#else
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free(Base);
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#endif
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return;
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}
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unsigned long long EndOfFile = iSize;
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iSize = WorkSpace;
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Close(false);
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if(ftruncate(Fd->Fd(),EndOfFile) < 0)
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_error->Errno("ftruncate", _("Failed to truncate file"));
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}
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/*}}}*/
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// DynamicMMap::RawAllocate - Allocate a raw chunk of unaligned space /*{{{*/
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// ---------------------------------------------------------------------
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/* This allocates a block of memory aligned to the given size */
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unsigned long DynamicMMap::RawAllocate(unsigned long long Size,unsigned long Aln)
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{
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unsigned long long Result = iSize;
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if (Aln != 0)
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Result += Aln - (iSize%Aln);
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iSize = Result + Size;
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// try to grow the buffer
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while(Result + Size > WorkSpace)
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{
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if(!Grow())
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{
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_error->Fatal(_("Dynamic MMap ran out of room. Please increase the size "
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"of APT::Cache-Start. Current value: %lu. (man 5 apt.conf)"), WorkSpace);
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return 0;
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}
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}
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return Result;
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}
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/*}}}*/
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// DynamicMMap::Allocate - Pooled aligned allocation /*{{{*/
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// ---------------------------------------------------------------------
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/* This allocates an Item of size ItemSize so that it is aligned to its
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size in the file. */
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unsigned long DynamicMMap::Allocate(unsigned long ItemSize)
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{
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if (unlikely(ItemSize == 0))
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{
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_error->Fatal("Can't allocate an item of size zero");
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return 0;
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}
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// Look for a matching pool entry
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Pool *I;
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for (I = Pools; I != Pools + PoolCount; ++I)
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{
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if (I->ItemSize == ItemSize)
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break;
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}
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// No pool is allocated, use an unallocated one.
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if (unlikely(I == Pools + PoolCount))
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{
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for (I = Pools; I != Pools + PoolCount; ++I)
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{
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if (I->ItemSize == 0)
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break;
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}
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// Woops, we ran out, the calling code should allocate more.
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if (I == Pools + PoolCount)
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{
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_error->Error("Ran out of allocation pools");
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return 0;
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}
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I->ItemSize = ItemSize;
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I->Count = 0;
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}
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unsigned long Result = 0;
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// Out of space, allocate some more
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if (I->Count == 0)
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{
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const unsigned long size = 20*1024;
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I->Count = size/ItemSize;
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Pool* oldPools = Pools;
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_error->PushToStack();
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Result = RawAllocate(size,ItemSize);
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bool const newError = _error->PendingError();
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_error->MergeWithStack();
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if (Pools != oldPools)
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I = Pools + (I - oldPools);
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// Does the allocation failed ?
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if (Result == 0 && newError)
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return 0;
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I->Start = Result;
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}
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else
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Result = I->Start;
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I->Count--;
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I->Start += ItemSize;
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return Result/ItemSize;
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}
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/*}}}*/
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// DynamicMMap::WriteString - Write a string to the file /*{{{*/
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// ---------------------------------------------------------------------
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/* Strings are aligned to 16 bytes */
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unsigned long DynamicMMap::WriteString(const char *String,
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unsigned long Len)
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{
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if (Len == std::numeric_limits<unsigned long>::max())
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Len = strlen(String);
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_error->PushToStack();
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unsigned long Result = RawAllocate(Len+1+sizeof(uint16_t),sizeof(uint16_t));
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bool const newError = _error->PendingError();
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_error->MergeWithStack();
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if (Base == NULL || (Result == 0 && newError))
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return 0;
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if (Len >= std::numeric_limits<uint16_t>::max())
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abort();
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uint16_t LenToWrite = Len;
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memcpy((char *)Base + Result, &LenToWrite, sizeof(LenToWrite));
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Result += + sizeof(LenToWrite);
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memcpy((char *)Base + Result,String,Len);
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((char *)Base)[Result + Len] = 0;
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return Result;
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}
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/*}}}*/
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// DynamicMMap::Grow - Grow the mmap /*{{{*/
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// ---------------------------------------------------------------------
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/* This method is a wrapper around different methods to (try to) grow
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a mmap (or our char[]-fallback). Encounterable environments:
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1. Moveable + !Fallback + linux -> mremap with MREMAP_MAYMOVE
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2. Moveable + !Fallback + !linux -> not possible (forbidden by constructor)
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3. Moveable + Fallback -> realloc
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4. !Moveable + !Fallback + linux -> mremap alone - which will fail in 99,9%
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5. !Moveable + !Fallback + !linux -> not possible (forbidden by constructor)
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6. !Moveable + Fallback -> not possible
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[ While Moveable and Fallback stands for the equally named flags and
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"linux" indicates a linux kernel instead of a freebsd kernel. ]
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So what you can see here is, that a MMAP which want to be growable need
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to be moveable to have a real chance but that this method will at least try
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the nearly impossible 4 to grow it before it finally give up: Never say never. */
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bool DynamicMMap::Grow() {
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if (Limit != 0 && WorkSpace >= Limit)
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return _error->Error(_("Unable to increase the size of the MMap as the "
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"limit of %lu bytes is already reached."), Limit);
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if (GrowFactor <= 0)
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return _error->Error(_("Unable to increase size of the MMap as automatic growing is disabled by user."));
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unsigned long long const newSize = WorkSpace + GrowFactor;
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if(Fd != 0) {
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Fd->Seek(newSize - 1);
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char C = 0;
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Fd->Write(&C,sizeof(C));
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}
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unsigned long const poolOffset = Pools - ((Pool*) Base);
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if ((Flags & Fallback) != Fallback) {
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#if defined(_POSIX_MAPPED_FILES) && defined(__linux__)
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#ifdef MREMAP_MAYMOVE
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if ((Flags & Moveable) == Moveable)
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Base = mremap(Base, WorkSpace, newSize, MREMAP_MAYMOVE);
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else
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#endif
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Base = mremap(Base, WorkSpace, newSize, 0);
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if(Base == MAP_FAILED)
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return false;
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#else
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return false;
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#endif
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} else {
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if ((Flags & Moveable) != Moveable)
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return false;
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Base = realloc(Base, newSize);
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if (Base == NULL)
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return false;
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else
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/* Set new memory to 0 */
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memset((char*)Base + WorkSpace, 0, newSize - WorkSpace);
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}
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Pools =(Pool*) Base + poolOffset;
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WorkSpace = newSize;
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return true;
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}
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/*}}}*/
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