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|
// -*- mode: cpp; mode: fold -*-
// Description /*{{{*/
/* ######################################################################
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 _DEFAULT_SOURCE
#include <config.h>
#include <apt-pkg/error.h>
#include <apt-pkg/fileutl.h>
#include <apt-pkg/macros.h>
#include <apt-pkg/mmap.h>
#include <cstdint>
#include <cstring>
#include <string>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <apti18n.h>
/*}}}*/
// MMap::MMap - Constructor /*{{{*/
// ---------------------------------------------------------------------
/* */
MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0),
Base(nullptr), SyncToFd(nullptr)
{
if ((Flags & NoImmMap) != NoImmMap)
Map(F);
}
/*}}}*/
// MMap::MMap - Constructor /*{{{*/
// ---------------------------------------------------------------------
/* */
MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0),
Base(nullptr), SyncToFd(nullptr)
{
}
/*}}}*/
// 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"));
// We can't mmap compressed fd's directly, so we need to read it completely
if (Fd.IsCompressed() == true)
{
if ((Flags & ReadOnly) != ReadOnly)
return _error->Error("Compressed file %s can only be mapped readonly", Fd.Name().c_str());
Base = malloc(iSize);
if (unlikely(Base == nullptr))
return _error->Errno("MMap-compressed-malloc", _("Couldn't make mmap of %llu bytes"), iSize);
SyncToFd = new FileFd();
if (Fd.Seek(0L) == false || Fd.Read(Base, iSize) == false)
return _error->Error("Compressed file %s can't be read into mmap", Fd.Name().c_str());
return true;
}
// Map it.
Base = (Flags & Fallback) ? MAP_FAILED : mmap(0,iSize,Prot,Map,Fd.Fd(),0);
if (Base == MAP_FAILED)
{
if (errno == ENODEV || errno == EINVAL || (Flags & Fallback))
{
// The filesystem doesn't support this particular kind of mmap.
// So we allocate a buffer and read the whole file into it.
if ((Flags & ReadOnly) == ReadOnly)
{
// for readonly, we don't need sync, so make it simple
Base = malloc(iSize);
if (unlikely(Base == nullptr))
return _error->Errno("MMap-malloc", _("Couldn't make mmap of %llu bytes"), iSize);
SyncToFd = new FileFd();
return Fd.Read(Base, iSize);
}
// FIXME: Writing to compressed fd's ?
int const dupped_fd = dup(Fd.Fd());
if (dupped_fd == -1)
return _error->Errno("mmap", _("Couldn't duplicate file descriptor %i"), Fd.Fd());
Base = calloc(iSize, 1);
if (unlikely(Base == nullptr))
return _error->Errno("MMap-calloc", _("Couldn't make mmap of %llu bytes"), iSize);
SyncToFd = new FileFd (dupped_fd);
if (!SyncToFd->Seek(0L) || !SyncToFd->Read(Base, iSize))
return false;
}
else
return _error->Errno("MMap-mmap", _("Couldn't make mmap of %llu bytes"), iSize);
}
return true;
}
/*}}}*/
// MMap::Close - Close the map /*{{{*/
// ---------------------------------------------------------------------
/* */
bool MMap::Close(bool DoSync)
{
if ((Flags & UnMapped) == UnMapped || validData() == false || iSize == 0)
return true;
if (DoSync == true)
Sync();
if (SyncToFd != NULL)
{
free(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 - Synchronize the map with the disk /*{{{*/
// ---------------------------------------------------------------------
/* This is done in synchronous mode - the docs indicate that this will
not return till all IO is complete */
bool MMap::Sync()
{
if ((Flags & UnMapped) == UnMapped)
return true;
if ((Flags & ReadOnly) != ReadOnly)
{
if (SyncToFd != NULL)
{
if (!SyncToFd->Seek(0) || !SyncToFd->Write(Base, iSize))
return false;
}
else
{
#ifdef _POSIX_SYNCHRONIZED_IO
if (msync((char *)Base, iSize, MS_SYNC) < 0)
return _error->Errno("msync", _("Unable to synchronize mmap"));
#endif
}
}
return true;
}
/*}}}*/
// MMap::Sync - Synchronize a section of the file to disk /*{{{*/
// ---------------------------------------------------------------------
/* */
bool MMap::Sync(unsigned long Start,unsigned long Stop)
{
if ((Flags & UnMapped) == UnMapped)
return true;
if ((Flags & ReadOnly) != ReadOnly)
{
if (SyncToFd != 0)
{
if (!SyncToFd->Seek(0) ||
!SyncToFd->Write (((char *)Base)+Start, Stop-Start))
return false;
}
else
{
#ifdef _POSIX_SYNCHRONIZED_IO
unsigned long long const PSize = sysconf(_SC_PAGESIZE);
if (msync((char *)Base+(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)
{
// disable Moveable if we don't grow
if (Grow == 0)
this->Flags &= ~Moveable;
#ifndef __linux__
// kfreebsd doesn't have mremap, so we use the fallback
if ((this->Flags & Moveable) == Moveable)
this->Flags |= Fallback;
#endif
unsigned long 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)
{
// disable Moveable if we don't grow
if (Grow == 0)
this->Flags &= ~Moveable;
#ifndef __linux__
// kfreebsd doesn't have mremap, so we use the fallback
if ((this->Flags & Moveable) == Moveable)
this->Flags |= Fallback;
#endif
#ifdef _POSIX_MAPPED_FILES
if ((this->Flags & Fallback) != Fallback) {
// Set the permissions.
int Prot = PROT_READ;
#ifdef MAP_ANONYMOUS
int Map = MAP_PRIVATE | MAP_ANONYMOUS;
#else
int Map = MAP_PRIVATE | MAP_ANON;
#endif
if ((this->Flags & ReadOnly) != ReadOnly)
Prot |= PROT_WRITE;
if ((this->Flags & Public) == Public)
#ifdef MAP_ANONYMOUS
Map = MAP_SHARED | MAP_ANONYMOUS;
#else
Map = MAP_SHARED | MAP_ANON;
#endif
// 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 = calloc(WorkSpace, 1);
iSize = 0;
}
/*}}}*/
// DynamicMMap::~DynamicMMap - Destructor /*{{{*/
// ---------------------------------------------------------------------
/* We truncate the file to the size of the memory data set */
DynamicMMap::~DynamicMMap()
{
if (Fd == 0)
{
if (validData() == false)
return;
#ifdef _POSIX_MAPPED_FILES
munmap(Base, WorkSpace);
#else
free(Base);
#endif
return;
}
unsigned long 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 long Size,unsigned long Aln)
{
unsigned long 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->Fatal(_("Dynamic MMap ran out of room. Please increase the size "
"of APT::Cache-Start. 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)
{
if (unlikely(ItemSize == 0))
{
_error->Fatal("Can't allocate an item of size zero");
return 0;
}
// Look for a matching pool entry
Pool *I;
for (I = Pools; I != Pools + PoolCount; ++I)
{
if (I->ItemSize == ItemSize)
break;
}
// No pool is allocated, use an unallocated one.
if (unlikely(I == Pools + PoolCount))
{
for (I = Pools; I != Pools + PoolCount; ++I)
{
if (I->ItemSize == 0)
break;
}
// Woops, we ran out, the calling code should allocate more.
if (I == Pools + PoolCount)
{
_error->Error("Ran out of allocation pools");
return 0;
}
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;
Pool* oldPools = Pools;
_error->PushToStack();
Result = RawAllocate(size,ItemSize);
bool const newError = _error->PendingError();
_error->MergeWithStack();
if (Pools != oldPools)
I = Pools + (I - oldPools);
// Does the allocation failed ?
if (Result == 0 && newError)
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 aligned to 16 bytes */
unsigned long DynamicMMap::WriteString(const char *String,
unsigned long Len)
{
if (Len == std::numeric_limits<unsigned long>::max())
Len = strlen(String);
_error->PushToStack();
unsigned long Result = RawAllocate(Len+1+sizeof(uint16_t),sizeof(uint16_t));
bool const newError = _error->PendingError();
_error->MergeWithStack();
if (Base == NULL || (Result == 0 && newError))
return 0;
if (Len >= std::numeric_limits<uint16_t>::max())
abort();
uint16_t LenToWrite = Len;
memcpy((char *)Base + Result, &LenToWrite, sizeof(LenToWrite));
Result += + sizeof(LenToWrite);
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);
if (GrowFactor <= 0)
return _error->Error(_("Unable to increase size of the MMap as automatic growing is disabled by user."));
unsigned long long const newSize = WorkSpace + GrowFactor;
if(Fd != 0) {
Fd->Seek(newSize - 1);
char C = 0;
Fd->Write(&C,sizeof(C));
}
unsigned long const poolOffset = Pools - ((Pool*) Base);
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;
else
/* Set new memory to 0 */
memset((char*)Base + WorkSpace, 0, newSize - WorkSpace);
}
Pools =(Pool*) Base + poolOffset;
WorkSpace = newSize;
return true;
}
/*}}}*/
|