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Diffstat (limited to 'apt-inst/extract.cc')
| -rw-r--r-- | apt-inst/extract.cc | 514 |
1 files changed, 514 insertions, 0 deletions
diff --git a/apt-inst/extract.cc b/apt-inst/extract.cc new file mode 100644 index 0000000..35fa015 --- /dev/null +++ b/apt-inst/extract.cc @@ -0,0 +1,514 @@ +// -*- mode: cpp; mode: fold -*- +// Description /*{{{*/ +/* ###################################################################### + + Archive Extraction Directory Stream + + Extraction for each file is a bit of an involved process. Each object + undergoes an atomic backup, overwrite, erase sequence. First the + object is unpacked to '.dpkg.new' then the original is hardlinked to + '.dpkg.tmp' and finally the new object is renamed to overwrite the old + one. From an external perspective the file never ceased to exist. + After the archive has been successfully unpacked the .dpkg.tmp files + are erased. A failure causes all the .dpkg.tmp files to be restored. + + Decisions about unpacking go like this: + - Store the original filename in the file listing + - Resolve any diversions that would effect this file, all checks + below apply to the diverted name, not the real one. + - Resolve any symlinked configuration files. + - If the existing file does not exist then .dpkg-tmp is checked for. + [Note, this is reduced to only check if a file was expected to be + there] + - If the existing link/file is not a directory then it is replaced + regardless + - If the existing link/directory is being replaced by a directory then + absolutely nothing happens. + - If the existing link/directory is being replaced by a link then + absolutely nothing happens. + - If the existing link/directory is being replaced by a non-directory + then this will abort if the package is not the sole owner of the + directory. [Note, this is changed to not happen if the directory + non-empty - that is, it only includes files that are part of this + package - prevents removing user files accidentally.] + - If the non-directory exists in the listing database and it + does not belong to the current package then an overwrite condition + is invoked. + + As we unpack we record the file list differences in the FL cache. If + we need to unroll the FL cache knows which files have been unpacked + and can undo. When we need to erase then it knows which files have not + been unpacked. + + ##################################################################### */ + /*}}}*/ +// Include Files /*{{{*/ +#include <config.h> + +#include <apt-pkg/debversion.h> +#include <apt-pkg/dirstream.h> +#include <apt-pkg/error.h> +#include <apt-pkg/extract.h> +#include <apt-pkg/filelist.h> +#include <apt-pkg/fileutl.h> +#include <apt-pkg/mmap.h> +#include <apt-pkg/pkgcache.h> + +#include <iostream> +#include <string> +#include <dirent.h> +#include <errno.h> +#include <stdio.h> +#include <string.h> +#include <sys/stat.h> + +#include <apti18n.h> + /*}}}*/ +using namespace std; + +static const char *TempExt = "dpkg-tmp"; +//static const char *NewExt = "dpkg-new"; + +// Extract::pkgExtract - Constructor /*{{{*/ +// --------------------------------------------------------------------- +/* */ +pkgExtract::pkgExtract(pkgFLCache &FLCache,pkgCache::VerIterator Ver) : + FLCache(FLCache), Ver(Ver) +{ + FLPkg = FLCache.GetPkg(Ver.ParentPkg().Name(),true); + if (FLPkg.end() == true) + return; + Debug = true; +} + /*}}}*/ +// Extract::DoItem - Handle a single item from the stream /*{{{*/ +// --------------------------------------------------------------------- +/* This performs the setup for the extraction.. */ +bool pkgExtract::DoItem(Item &Itm, int &/*Fd*/) +{ + /* Strip any leading/trailing /s from the filename, then copy it to the + temp buffer and re-apply the leading / We use a class variable + to store the new filename for use by the three extraction funcs */ + char *End = FileName+1; + const char *I = Itm.Name; + for (; *I != 0 && *I == '/'; I++); + *FileName = '/'; + for (; *I != 0 && End < FileName + sizeof(FileName); I++, End++) + *End = *I; + if (End + 20 >= FileName + sizeof(FileName)) + return _error->Error(_("The path %s is too long"),Itm.Name); + for (; End > FileName && End[-1] == '/'; End--); + *End = 0; + Itm.Name = FileName; + + /* Lookup the file. Nde is the file [group] we are going to write to and + RealNde is the actual node we are manipulating. Due to diversions + they may be entirely different. */ + pkgFLCache::NodeIterator Nde = FLCache.GetNode(Itm.Name,End,0,false,false); + pkgFLCache::NodeIterator RealNde = Nde; + + // See if the file is already in the file listing + unsigned long FileGroup = RealNde->File; + for (; RealNde.end() == false && FileGroup == RealNde->File; RealNde++) + if (RealNde.RealPackage() == FLPkg) + break; + + // Nope, create an entry + if (RealNde.end() == true) + { + RealNde = FLCache.GetNode(Itm.Name,End,FLPkg.Offset(),true,false); + if (RealNde.end() == true) + return false; + RealNde->Flags |= pkgFLCache::Node::NewFile; + } + + /* Check if this entry already was unpacked. The only time this should + ever happen is if someone has hacked tar to support capabilities, in + which case this needs to be modified anyhow.. */ + if ((RealNde->Flags & pkgFLCache::Node::Unpacked) == + pkgFLCache::Node::Unpacked) + return _error->Error(_("Unpacking %s more than once"),Itm.Name); + + if (Nde.end() == true) + Nde = RealNde; + + /* Consider a diverted file - We are not permitted to divert directories, + but everything else is fair game (including conf files!) */ + if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0) + { + if (Itm.Type == Item::Directory) + return _error->Error(_("The directory %s is diverted"),Itm.Name); + + /* A package overwriting a diversion target is just the same as + overwriting a normally owned file and is checked for below in + the overwrites mechanism */ + + /* If this package is trying to overwrite the target of a diversion, + that is never, ever permitted */ + pkgFLCache::DiverIterator Div = Nde.Diversion(); + if (Div.DivertTo() == Nde) + return _error->Error(_("The package is trying to write to the " + "diversion target %s/%s"),Nde.DirN(),Nde.File()); + + // See if it is us and we are following it in the right direction + if (Div->OwnerPkg != FLPkg.Offset() && Div.DivertFrom() == Nde) + { + Nde = Div.DivertTo(); + End = FileName + snprintf(FileName,sizeof(FileName)-20,"%s/%s", + Nde.DirN(),Nde.File()); + if (End <= FileName) + return _error->Error(_("The diversion path is too long")); + } + } + + // Deal with symlinks and conf files + if ((RealNde->Flags & pkgFLCache::Node::NewConfFile) == + pkgFLCache::Node::NewConfFile) + { + string Res = flNoLink(Itm.Name); + if (Res.length() > sizeof(FileName)) + return _error->Error(_("The path %s is too long"),Res.c_str()); + if (Debug == true) + clog << "Followed conf file from " << FileName << " to " << Res << endl; + Itm.Name = strcpy(FileName,Res.c_str()); + } + + /* Get information about the existing file, and attempt to restore + a backup if it does not exist */ + struct stat LExisting; + bool EValid = false; + if (lstat(Itm.Name,&LExisting) != 0) + { + // This is bad news. + if (errno != ENOENT) + return _error->Errno("stat",_("Failed to stat %s"),Itm.Name); + + // See if we can recover the backup file + if (Nde.end() == false) + { + char Temp[sizeof(FileName)]; + snprintf(Temp,sizeof(Temp),"%s.%s",Itm.Name,TempExt); + if (rename(Temp,Itm.Name) != 0 && errno != ENOENT) + return _error->Errno("rename",_("Failed to rename %s to %s"), + Temp,Itm.Name); + if (stat(Itm.Name,&LExisting) != 0) + { + if (errno != ENOENT) + return _error->Errno("stat",_("Failed to stat %s"),Itm.Name); + } + else + EValid = true; + } + } + else + EValid = true; + + /* If the file is a link we need to stat its destination, get the + existing file modes */ + struct stat Existing = LExisting; + if (EValid == true && S_ISLNK(Existing.st_mode)) + { + if (stat(Itm.Name,&Existing) != 0) + { + if (errno != ENOENT) + return _error->Errno("stat",_("Failed to stat %s"),Itm.Name); + Existing = LExisting; + } + } + + // We pretend a non-existing file looks like it is a normal file + if (EValid == false) + Existing.st_mode = S_IFREG; + + /* Okay, at this point 'Existing' is the stat information for the + real non-link file */ + + /* The only way this can be a no-op is if a directory is being + replaced by a directory or by a link */ + if (S_ISDIR(Existing.st_mode) != 0 && + (Itm.Type == Item::Directory || Itm.Type == Item::SymbolicLink)) + return true; + + /* Non-Directory being replaced by non-directory. We check for over + writes here. */ + if (Nde.end() == false) + { + if (HandleOverwrites(Nde) == false) + return false; + } + + /* Directory being replaced by a non-directory - this needs to see if + the package is the owner and then see if the directory would be + empty after the package is removed [ie no user files will be + erased] */ + if (S_ISDIR(Existing.st_mode) != 0) + { + if (CheckDirReplace(Itm.Name) == false) + return _error->Error(_("The directory %s is being replaced by a non-directory"),Itm.Name); + } + + if (Debug == true) + clog << "Extract " << string(Itm.Name,End) << endl; +/* if (Count != 0) + return _error->Error(_("Done"));*/ + + return true; +} + /*}}}*/ +// Extract::Finished - Sequence finished, erase the temp files /*{{{*/ +// --------------------------------------------------------------------- +/* */ +APT_PURE bool pkgExtract::Finished() +{ + return true; +} + /*}}}*/ +// Extract::Aborted - Sequence aborted, undo all our unpacking /*{{{*/ +// --------------------------------------------------------------------- +/* This undoes everything that was done by all calls to the DoItem method + and restores the File Listing cache to its original form. It bases its + actions on the flags value for each node in the cache. */ +bool pkgExtract::Aborted() +{ + if (Debug == true) + clog << "Aborted, backing out" << endl; + + pkgFLCache::NodeIterator Files = FLPkg.Files(); + map_ptrloc *Last = &FLPkg->Files; + + /* Loop over all files, restore those that have been unpacked from their + dpkg-tmp entries */ + while (Files.end() == false) + { + // Locate the hash bucket for the node and locate its group head + pkgFLCache::NodeIterator Nde(FLCache,FLCache.HashNode(Files)); + for (; Nde.end() == false && Files->File != Nde->File; Nde++); + if (Nde.end() == true) + return _error->Error(_("Failed to locate node in its hash bucket")); + + if (snprintf(FileName,sizeof(FileName)-20,"%s/%s", + Nde.DirN(),Nde.File()) <= 0) + return _error->Error(_("The path is too long")); + + // Deal with diversions + if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0) + { + pkgFLCache::DiverIterator Div = Nde.Diversion(); + + // See if it is us and we are following it in the right direction + if (Div->OwnerPkg != FLPkg.Offset() && Div.DivertFrom() == Nde) + { + Nde = Div.DivertTo(); + if (snprintf(FileName,sizeof(FileName)-20,"%s/%s", + Nde.DirN(),Nde.File()) <= 0) + return _error->Error(_("The diversion path is too long")); + } + } + + // Deal with overwrites+replaces + for (; Nde.end() == false && Files->File == Nde->File; Nde++) + { + if ((Nde->Flags & pkgFLCache::Node::Replaced) == + pkgFLCache::Node::Replaced) + { + if (Debug == true) + clog << "De-replaced " << FileName << " from " << Nde.RealPackage()->Name << endl; + Nde->Flags &= ~pkgFLCache::Node::Replaced; + } + } + + // Undo the change in the filesystem + if (Debug == true) + clog << "Backing out " << FileName; + + // Remove a new node + if ((Files->Flags & pkgFLCache::Node::NewFile) == + pkgFLCache::Node::NewFile) + { + if (Debug == true) + clog << " [new node]" << endl; + pkgFLCache::Node *Tmp = Files; + Files++; + *Last = Tmp->NextPkg; + Tmp->NextPkg = 0; + + FLCache.DropNode(Tmp - FLCache.NodeP); + } + else + { + if (Debug == true) + clog << endl; + + Last = &Files->NextPkg; + Files++; + } + } + + return true; +} + /*}}}*/ +// Extract::Fail - Extraction of a file Failed /*{{{*/ +// --------------------------------------------------------------------- +/* */ +bool pkgExtract::Fail(Item &Itm,int Fd) +{ + return pkgDirStream::Fail(Itm,Fd); +} + /*}}}*/ +// Extract::FinishedFile - Finished a file /*{{{*/ +// --------------------------------------------------------------------- +/* */ +bool pkgExtract::FinishedFile(Item &Itm,int Fd) +{ + return pkgDirStream::FinishedFile(Itm,Fd); +} + /*}}}*/ +// Extract::HandleOverwrites - See if a replaces covers this overwrite /*{{{*/ +// --------------------------------------------------------------------- +/* Check if the file is in a package that is being replaced by this + package or if the file is being overwritten. Note that if the file + is really a directory but it has been erased from the filesystem + this will fail with an overwrite message. This is a limitation of the + dpkg file information format. + + XX If a new package installs and another package replaces files in this + package what should we do? */ +bool pkgExtract::HandleOverwrites(pkgFLCache::NodeIterator Nde, + bool DiverCheck) +{ + pkgFLCache::NodeIterator TmpNde = Nde; + unsigned long DiverOwner = 0; + unsigned long FileGroup = Nde->File; + for (; Nde.end() == false && FileGroup == Nde->File; Nde++) + { + if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0) + { + /* Store the diversion owner if this is the forward direction + of the diversion */ + if (DiverCheck == true) + DiverOwner = Nde.Diversion()->OwnerPkg; + continue; + } + + pkgFLCache::PkgIterator FPkg(FLCache,Nde.RealPackage()); + if (FPkg.end() == true || FPkg == FLPkg) + continue; + + /* This tests trips when we are checking a diversion to see + if something has already been diverted by this diversion */ + if (FPkg.Offset() == DiverOwner) + continue; + + // Now see if this package matches one in a replace depends + pkgCache::DepIterator Dep = Ver.DependsList(); + bool Ok = false; + for (; Dep.end() == false; ++Dep) + { + if (Dep->Type != pkgCache::Dep::Replaces) + continue; + + // Does the replaces apply to this package? + if (strcmp(Dep.TargetPkg().Name(),FPkg.Name()) != 0) + continue; + + /* Check the version for match. I do not think CurrentVer can be + 0 if we are here.. */ + pkgCache::PkgIterator Pkg = Dep.TargetPkg(); + if (Pkg->CurrentVer == 0) + { + _error->Warning(_("Overwrite package match with no version for %s"),Pkg.Name()); + continue; + } + + // Replaces is met + if (debVS.CheckDep(Pkg.CurrentVer().VerStr(),Dep->CompareOp,Dep.TargetVer()) == true) + { + if (Debug == true) + clog << "Replaced file " << Nde.DirN() << '/' << Nde.File() << " from " << Pkg.Name() << endl; + Nde->Flags |= pkgFLCache::Node::Replaced; + Ok = true; + break; + } + } + + // Negative Hit + if (Ok == false) + return _error->Error(_("File %s/%s overwrites the one in the package %s"), + Nde.DirN(),Nde.File(),FPkg.Name()); + } + + /* If this is a diversion we might have to recurse to process + the other side of it */ + if ((TmpNde->Flags & pkgFLCache::Node::Diversion) != 0) + { + pkgFLCache::DiverIterator Div = TmpNde.Diversion(); + if (Div.DivertTo() == TmpNde) + return HandleOverwrites(Div.DivertFrom(),true); + } + + return true; +} + /*}}}*/ +// Extract::CheckDirReplace - See if this directory can be erased /*{{{*/ +// --------------------------------------------------------------------- +/* If this directory is owned by a single package and that package is + replacing it with something non-directoryish then dpkg allows this. + We increase the requirement to be that the directory is non-empty after + the package is removed */ +bool pkgExtract::CheckDirReplace(string Dir,unsigned int Depth) +{ + // Looping? + if (Depth > 40) + return false; + + if (Dir[Dir.size() - 1] != '/') + Dir += '/'; + + DIR *D = opendir(Dir.c_str()); + if (D == 0) + return _error->Errno("opendir",_("Unable to read %s"),Dir.c_str()); + + string File; + for (struct dirent *Dent = readdir(D); Dent != 0; Dent = readdir(D)) + { + // Skip some files + if (strcmp(Dent->d_name,".") == 0 || + strcmp(Dent->d_name,"..") == 0) + continue; + + // Look up the node + File = Dir + Dent->d_name; + pkgFLCache::NodeIterator Nde = FLCache.GetNode(File.c_str(), + File.c_str() + File.length(),0,false,false); + + // The file is not owned by this package + if (Nde.end() != false || Nde.RealPackage() != FLPkg) + { + closedir(D); + return false; + } + + // See if it is a directory + struct stat St; + if (lstat(File.c_str(),&St) != 0) + { + closedir(D); + return _error->Errno("lstat",_("Unable to stat %s"),File.c_str()); + } + + // Recurse down directories + if (S_ISDIR(St.st_mode) != 0) + { + if (CheckDirReplace(File,Depth + 1) == false) + { + closedir(D); + return false; + } + } + } + + // No conflicts + closedir(D); + return true; +} + /*}}}*/ |