// -*- 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 <errno.h> #include <cstring> /*}}}*/ // MMap::MMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0), Base(0), SyncToFd(NULL) { if ((Flags & NoImmMap) != NoImmMap) Map(F); } /*}}}*/ // MMap::MMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0), Base(0), SyncToFd(NULL) { } /*}}}*/ // 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) { if (errno == ENODEV || errno == EINVAL) { // The filesystem doesn't support this particular kind of mmap. // So we allocate a buffer and read the whole file into it. int const dupped_fd = dup(Fd.Fd()); if (dupped_fd == -1) return _error->Errno("mmap", _("Couldn't duplicate file descriptor %i"), Fd.Fd()); Base = new unsigned char[iSize]; SyncToFd = new FileFd (dupped_fd); if (!SyncToFd->Seek(0L) || !SyncToFd->Read(Base, iSize)) return false; } else 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 (SyncToFd != NULL) { delete[] (char *)Base; delete SyncToFd; SyncToFd = NULL; } else { if (munmap((char *)Base, iSize) != 0) _error->WarningE("mmap", _("Unable to close mmap")); } 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 (SyncToFd != NULL) { if (!SyncToFd->Seek(0) || !SyncToFd->Write(Base, iSize)) return false; } else { if (msync((char *)Base, iSize, MS_SYNC) < 0) return _error->Errno("msync", _("Unable to synchronize 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 (SyncToFd != 0) { if (!SyncToFd->Seek(0) || !SyncToFd->Write (((char *)Base)+Start, Stop-Start)) return false; } else { if (msync((char *)Base+(int)(Start/PSize)*PSize,Stop - Start,MS_SYNC) < 0) return _error->Errno("msync", _("Unable to synchronize mmap")); } } #endif return true; } /*}}}*/ // DynamicMMap::DynamicMMap - Constructor /*{{{*/ // --------------------------------------------------------------------- /* */ DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &Workspace, unsigned long const &Grow, unsigned long const &Limit) : MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(Workspace), GrowFactor(Grow), Limit(Limit) { 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 const &WorkSpace, unsigned long const &Grow, unsigned long const &Limit) : MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace), GrowFactor(Grow), Limit(Limit) { if (_error->PendingError() == true) return; // disable Moveable if we don't grow if (Grow == 0) Flags &= ~Moveable; #ifndef __linux__ // kfreebsd doesn't have mremap, so we use the fallback if ((Flags & Moveable) == Moveable) Flags |= Fallback; #endif #ifdef _POSIX_MAPPED_FILES if ((Flags & Fallback) != Fallback) { // 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); iSize = 0; return; } #endif // fallback to a static allocated space Base = new unsigned char[WorkSpace]; memset(Base,0,WorkSpace); 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 is a wrapper around different methods to (try to) grow a mmap (or our char[]-fallback). Encounterable environments: 1. Moveable + !Fallback + linux -> mremap with MREMAP_MAYMOVE 2. Moveable + !Fallback + !linux -> not possible (forbidden by constructor) 3. Moveable + Fallback -> realloc 4. !Moveable + !Fallback + linux -> mremap alone - which will fail in 99,9% 5. !Moveable + !Fallback + !linux -> not possible (forbidden by constructor) 6. !Moveable + Fallback -> not possible [ While Moveable and Fallback stands for the equally named flags and "linux" indicates a linux kernel instead of a freebsd kernel. ] So what you can see here is, that a MMAP which want to be growable need to be moveable to have a real chance but that this method will at least try the nearly impossible 4 to grow it before it finally give up: Never say never. */ bool DynamicMMap::Grow() { if (Limit != 0 && WorkSpace >= Limit) return _error->Error(_("Unable to increase the size of the MMap as the " "limit of %lu bytes is already reached."), Limit); unsigned long const newSize = WorkSpace + 1024*1024; if(Fd != 0) { Fd->Seek(newSize - 1); char C = 0; Fd->Write(&C,sizeof(C)); } if ((Flags & Fallback) != Fallback) { #if defined(_POSIX_MAPPED_FILES) && defined(__linux__) #ifdef MREMAP_MAYMOVE if ((Flags & Moveable) == Moveable) Base = mremap(Base, WorkSpace, newSize, MREMAP_MAYMOVE); else #endif Base = mremap(Base, WorkSpace, newSize, 0); if(Base == MAP_FAILED) return false; #else return false; #endif } else { if ((Flags & Moveable) != Moveable) return false; Base = realloc(Base, newSize); if (Base == NULL) return false; } WorkSpace = newSize; return true; } /*}}}*/