// -*- mode: cpp; mode: fold -*- // Description /*{{{*/ // $Id: mmap.cc,v 1.22 2001/05/27 05:19:30 jgg Exp $ /* ###################################################################### MMap Class - Provides 'real' mmap or a faked mmap using read(). MMap cover class. Some broken versions of glibc2 (libc6) have a broken definition of mmap that accepts a char * -- all other systems (and libc5) use void *. We can't safely do anything here that would be portable, so libc6 generates warnings -- which should be errors, g++ isn't properly strict. ##################################################################### */ /*}}}*/ // Include Files /*{{{*/ #define _BSD_SOURCE #include <apt-pkg/mmap.h> #include <apt-pkg/error.h> #include <apti18n.h> #include <sys/mman.h> #include <sys/stat.h> #include <unistd.h> #include <fcntl.h> #include <stdlib.h> #include <cstring> /*}}}*/ // MMap::MMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0), Base(0) { if ((Flags & NoImmMap) != NoImmMap) Map(F); } /*}}}*/ // MMap::MMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0), Base(0) { } /*}}}*/ // MMap::~MMap - Destructor /*{{{*/ // --------------------------------------------------------------------- /* */ MMap::~MMap() { Close(); } /*}}}*/ // MMap::Map - Perform the mapping /*{{{*/ // --------------------------------------------------------------------- /* */ bool MMap::Map(FileFd &Fd) { iSize = Fd.Size(); // Set the permissions. int Prot = PROT_READ; int Map = MAP_SHARED; if ((Flags & ReadOnly) != ReadOnly) Prot |= PROT_WRITE; if ((Flags & Public) != Public) Map = MAP_PRIVATE; if (iSize == 0) return _error->Error(_("Can't mmap an empty file")); // Map it. Base = mmap(0,iSize,Prot,Map,Fd.Fd(),0); if (Base == (void *)-1) return _error->Errno("mmap",_("Couldn't make mmap of %lu bytes"),iSize); return true; } /*}}}*/ // MMap::Close - Close the map /*{{{*/ // --------------------------------------------------------------------- /* */ bool MMap::Close(bool DoSync) { if ((Flags & UnMapped) == UnMapped || Base == 0 || iSize == 0) return true; if (DoSync == true) Sync(); if (munmap((char *)Base,iSize) != 0) _error->Warning("Unable to munmap"); iSize = 0; Base = 0; return true; } /*}}}*/ // MMap::Sync - Syncronize the map with the disk /*{{{*/ // --------------------------------------------------------------------- /* This is done in syncronous mode - the docs indicate that this will not return till all IO is complete */ bool MMap::Sync() { if ((Flags & UnMapped) == UnMapped) return true; #ifdef _POSIX_SYNCHRONIZED_IO if ((Flags & ReadOnly) != ReadOnly) if (msync((char *)Base,iSize,MS_SYNC) < 0) return _error->Errno("msync","Unable to write mmap"); #endif return true; } /*}}}*/ // MMap::Sync - Syncronize a section of the file to disk /*{{{*/ // --------------------------------------------------------------------- /* */ bool MMap::Sync(unsigned long Start,unsigned long Stop) { if ((Flags & UnMapped) == UnMapped) return true; #ifdef _POSIX_SYNCHRONIZED_IO unsigned long PSize = sysconf(_SC_PAGESIZE); if ((Flags & ReadOnly) != ReadOnly) if (msync((char *)Base+(int)(Start/PSize)*PSize,Stop - Start,MS_SYNC) < 0) return _error->Errno("msync","Unable to write mmap"); #endif return true; } /*}}}*/ // DynamicMMap::DynamicMMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace) : MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(WorkSpace) { if (_error->PendingError() == true) return; unsigned long EndOfFile = Fd->Size(); if (EndOfFile > WorkSpace) WorkSpace = EndOfFile; else if(WorkSpace > 0) { Fd->Seek(WorkSpace - 1); char C = 0; Fd->Write(&C,sizeof(C)); } Map(F); iSize = EndOfFile; } /*}}}*/ // DynamicMMap::DynamicMMap - Constructor for a non-file backed map /*{{{*/ // --------------------------------------------------------------------- /* We try here to use mmap to reserve some space - this is much more cooler than the fallback solution to simply allocate a char array and could come in handy later than we are able to grow such an mmap */ DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long WorkSpace) : MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace) { if (_error->PendingError() == true) return; #ifdef _POSIX_MAPPED_FILES // Set the permissions. int Prot = PROT_READ; int Map = MAP_PRIVATE | MAP_ANONYMOUS; if ((Flags & ReadOnly) != ReadOnly) Prot |= PROT_WRITE; if ((Flags & Public) == Public) Map = MAP_SHARED | MAP_ANONYMOUS; // use anonymous mmap() to get the memory Base = (unsigned char*) mmap(0, WorkSpace, Prot, Map, -1, 0); if(Base == MAP_FAILED) _error->Errno("DynamicMMap",_("Couldn't make mmap of %lu bytes"),WorkSpace); #else // fallback to a static allocated space Base = new unsigned char[WorkSpace]; memset(Base,0,WorkSpace); #endif iSize = 0; } /*}}}*/ // DynamicMMap::~DynamicMMap - Destructor /*{{{*/ // --------------------------------------------------------------------- /* We truncate the file to the size of the memory data set */ DynamicMMap::~DynamicMMap() { if (Fd == 0) { #ifdef _POSIX_MAPPED_FILES munmap(Base, WorkSpace); #else delete [] (unsigned char *)Base; #endif return; } unsigned long EndOfFile = iSize; iSize = WorkSpace; Close(false); if(ftruncate(Fd->Fd(),EndOfFile) < 0) _error->Errno("ftruncate", _("Failed to truncate file")); } /*}}}*/ // DynamicMMap::RawAllocate - Allocate a raw chunk of unaligned space /*{{{*/ // --------------------------------------------------------------------- /* This allocates a block of memory aligned to the given size */ unsigned long DynamicMMap::RawAllocate(unsigned long Size,unsigned long Aln) { unsigned long Result = iSize; if (Aln != 0) Result += Aln - (iSize%Aln); iSize = Result + Size; // try to grow the buffer while(Result + Size > WorkSpace) { if(!Grow()) { _error->Error(_("Dynamic MMap ran out of room. Please increase the size " "of APT::Cache-Limit. Current value: %lu. (man 5 apt.conf)"), WorkSpace); return 0; } } return Result; } /*}}}*/ // DynamicMMap::Allocate - Pooled aligned allocation /*{{{*/ // --------------------------------------------------------------------- /* This allocates an Item of size ItemSize so that it is aligned to its size in the file. */ unsigned long DynamicMMap::Allocate(unsigned long ItemSize) { // Look for a matching pool entry Pool *I; Pool *Empty = 0; for (I = Pools; I != Pools + PoolCount; I++) { if (I->ItemSize == 0) Empty = I; if (I->ItemSize == ItemSize) break; } // No pool is allocated, use an unallocated one if (I == Pools + PoolCount) { // Woops, we ran out, the calling code should allocate more. if (Empty == 0) { _error->Error("Ran out of allocation pools"); return 0; } I = Empty; I->ItemSize = ItemSize; I->Count = 0; } unsigned long Result = 0; // Out of space, allocate some more if (I->Count == 0) { const unsigned long size = 20*1024; I->Count = size/ItemSize; Result = RawAllocate(size,ItemSize); // Does the allocation failed ? if (Result == 0 && _error->PendingError()) return 0; I->Start = Result; } else Result = I->Start; I->Count--; I->Start += ItemSize; return Result/ItemSize; } /*}}}*/ // DynamicMMap::WriteString - Write a string to the file /*{{{*/ // --------------------------------------------------------------------- /* Strings are not aligned to anything */ unsigned long DynamicMMap::WriteString(const char *String, unsigned long Len) { if (Len == (unsigned long)-1) Len = strlen(String); unsigned long Result = RawAllocate(Len+1,0); if (Result == 0 && _error->PendingError()) return 0; memcpy((char *)Base + Result,String,Len); ((char *)Base)[Result + Len] = 0; return Result; } /*}}}*/ // DynamicMMap::Grow - Grow the mmap /*{{{*/ // --------------------------------------------------------------------- /* This method will try to grow the mmap we currently use. This doesn't work most of the time because we can't move the mmap around in the memory for now as this would require to adjust quite a lot of pointers but why we should not at least try to grow it before we give up? */ bool DynamicMMap::Grow() { #if defined(_POSIX_MAPPED_FILES) && defined(__linux__) unsigned long newSize = WorkSpace + 1024*1024; if(Fd != 0) { Fd->Seek(newSize - 1); char C = 0; Fd->Write(&C,sizeof(C)); } Base = mremap(Base, WorkSpace, newSize, 0); if(Base == MAP_FAILED) return false; WorkSpace = newSize; return true; #else return false; #endif } /*}}}*/