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-rw-r--r--apt-pkg/contrib/mmap.cc504
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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;
+}
+ /*}}}*/
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