reset HOME, USER(NAME), TMPDIR & SHELL in DropPrivileges

[apt.git] / apt-pkg / contrib / fileutl.h

// -*- mode: cpp; mode: fold -*-
// Description								/*{{{*/
// $Id: fileutl.h,v 1.26 2001/05/07 05:06:52 jgg Exp $
/* ######################################################################
   
   File Utilities
   
   CopyFile - Buffered copy of a single file
   GetLock - dpkg compatible lock file manipulation (fcntl)
   FileExists - Returns true if the file exists
   SafeGetCWD - Returns the CWD in a string with overrun protection 
   
   The file class is a handy abstraction for various functions+classes
   that need to accept filenames.
   
   This source is placed in the Public Domain, do with it what you will
   It was originally written by Jason Gunthorpe.
   
   ##################################################################### */
									/*}}}*/
#ifndef PKGLIB_FILEUTL_H
#define PKGLIB_FILEUTL_H

#include <apt-pkg/macros.h>
#include <apt-pkg/aptconfiguration.h>

#include <string>
#include <vector>
#include <set>
#include <time.h>

#include <zlib.h>

#ifndef APT_8_CLEANER_HEADERS
using std::string;
#endif

/* Define this for python-apt */
#define APT_HAS_GZIP 1

class FileFdPrivate;
class FileFd
{
   friend class FileFdPrivate;
   friend class GzipFileFdPrivate;
   friend class Bz2FileFdPrivate;
   friend class LzmaFileFdPrivate;
   friend class Lz4FileFdPrivate;
   friend class DirectFileFdPrivate;
   friend class PipedFileFdPrivate;
   protected:
   int iFd;
 
   enum LocalFlags {AutoClose = (1<<0),Fail = (1<<1),DelOnFail = (1<<2),
                    HitEof = (1<<3), Replace = (1<<4), Compressed = (1<<5) };
   unsigned long Flags;
   std::string FileName;
   std::string TemporaryFileName;

   public:
   enum OpenMode {
	ReadOnly = (1 << 0),
	WriteOnly = (1 << 1),
	ReadWrite = ReadOnly | WriteOnly,

	Create = (1 << 2),
	Exclusive = (1 << 3),
	Atomic = Exclusive | (1 << 4),
	Empty = (1 << 5),
	BufferedWrite = (1 << 6),

	WriteEmpty = ReadWrite | Create | Empty,
	WriteExists = ReadWrite,
	WriteAny = ReadWrite | Create,
	WriteTemp = ReadWrite | Create | Exclusive,
	ReadOnlyGzip,
	WriteAtomic = ReadWrite | Create | Atomic
   };
   enum CompressMode { Auto = 'A', None = 'N', Extension = 'E', Gzip = 'G', Bzip2 = 'B', Lzma = 'L', Xz = 'X', Lz4='4' };
   
   inline bool Read(void *To,unsigned long long Size,bool AllowEof)
   {
      unsigned long long Jnk;
      if (AllowEof)
	 return Read(To,Size,&Jnk);
      return Read(To,Size);
   }   
   bool Read(void *To,unsigned long long Size,unsigned long long *Actual = 0);
   bool static Read(int const Fd, void *To, unsigned long long Size, unsigned long long * const Actual = 0);
   char* ReadLine(char *To, unsigned long long const Size);
   bool Flush();
   bool Write(const void *From,unsigned long long Size);
   bool static Write(int Fd, const void *From, unsigned long long Size);
   bool Seek(unsigned long long To);
   bool Skip(unsigned long long To);
   bool Truncate(unsigned long long To);
   unsigned long long Tell();
   // the size of the file content (compressed files will be uncompressed first)
   unsigned long long Size();
   // the size of the file itself
   unsigned long long FileSize();
   time_t ModificationTime();

   /* You want to use 'unsigned long long' if you are talking about a file
      to be able to support large files (>2 or >4 GB) properly.
      This shouldn't happen all to often for the indexes, but deb's might be…
      And as the auto-conversation converts a 'unsigned long *' to a 'bool'
      instead of 'unsigned long long *' we need to provide this explicitly -
      otherwise applications magically start to fail… */
   bool Read(void *To,unsigned long long Size,unsigned long *Actual) APT_DEPRECATED_MSG("The Actual variable you pass in should be an unsigned long long")
   {
	unsigned long long R;
	bool const T = Read(To, Size, &R);
	*Actual = R;
	return T;
   }

   bool Open(std::string FileName,unsigned int const Mode,CompressMode Compress,unsigned long const AccessMode = 0666);
   bool Open(std::string FileName,unsigned int const Mode,APT::Configuration::Compressor const &compressor,unsigned long const AccessMode = 0666);
   inline bool Open(std::string const &FileName,unsigned int const Mode, unsigned long const AccessMode = 0666) {
      return Open(FileName, Mode, None, AccessMode);
   };
   bool OpenDescriptor(int Fd, unsigned int const Mode, CompressMode Compress, bool AutoClose=false);
   bool OpenDescriptor(int Fd, unsigned int const Mode, APT::Configuration::Compressor const &compressor, bool AutoClose=false);
   inline bool OpenDescriptor(int Fd, unsigned int const Mode, bool AutoClose=false) {
      return OpenDescriptor(Fd, Mode, None, AutoClose);
   };
   bool Close();
   bool Sync();
   
   // Simple manipulators
   inline int Fd() {return iFd;};
   inline void Fd(int fd) { OpenDescriptor(fd, ReadWrite);};
   gzFile gzFd() APT_DEPRECATED_MSG("Implementation detail, do not use to be able to support bzip2, xz and co") APT_PURE;

   inline bool IsOpen() {return iFd >= 0;};
   inline bool Failed() {return (Flags & Fail) == Fail;};
   inline void EraseOnFailure() {Flags |= DelOnFail;};
   inline void OpFail() {Flags |= Fail;};
   inline bool Eof() {return (Flags & HitEof) == HitEof;};
   inline bool IsCompressed() {return (Flags & Compressed) == Compressed;};
   inline std::string &Name() {return FileName;};

   FileFd(std::string FileName,unsigned int const Mode,unsigned long AccessMode = 0666);
   FileFd(std::string FileName,unsigned int const Mode, CompressMode Compress, unsigned long AccessMode = 0666);
   FileFd();
   FileFd(int const Fd, unsigned int const Mode = ReadWrite, CompressMode Compress = None);
   FileFd(int const Fd, bool const AutoClose);
   virtual ~FileFd();

   private:
   FileFdPrivate * d;
   APT_HIDDEN FileFd & operator=(const FileFd &);
   APT_HIDDEN bool OpenInternDescriptor(unsigned int const Mode, APT::Configuration::Compressor const &compressor);

   // private helpers to set Fail flag and call _error->Error
   APT_HIDDEN bool FileFdErrno(const char* Function, const char* Description,...) APT_PRINTF(3) APT_COLD;
   APT_HIDDEN bool FileFdError(const char* Description,...) APT_PRINTF(2) APT_COLD;
};

bool RunScripts(const char *Cnf);
bool CopyFile(FileFd &From,FileFd &To);
bool RemoveFile(char const * const Function, std::string const &FileName);
int GetLock(std::string File,bool Errors = true);
bool FileExists(std::string File);
bool RealFileExists(std::string File);
bool DirectoryExists(std::string const &Path);
bool CreateDirectory(std::string const &Parent, std::string const &Path);
time_t GetModificationTime(std::string const &Path);
bool Rename(std::string From, std::string To);

std::string GetTempDir();
std::string GetTempDir(std::string const &User);
FileFd* GetTempFile(std::string const &Prefix = "",
                    bool ImmediateUnlink = true,
		    FileFd * const TmpFd = NULL);

/** \brief Ensure the existence of the given Path
 *
 *  \param Parent directory of the Path directory - a trailing
 *  /apt/ will be removed before CreateDirectory call.
 *  \param Path which should exist after (successful) call
 */
bool CreateAPTDirectoryIfNeeded(std::string const &Parent, std::string const &Path);

std::vector<std::string> GetListOfFilesInDir(std::string const &Dir, std::string const &Ext,
					bool const &SortList, bool const &AllowNoExt=false);
std::vector<std::string> GetListOfFilesInDir(std::string const &Dir, std::vector<std::string> const &Ext,
					bool const &SortList);
std::vector<std::string> GetListOfFilesInDir(std::string const &Dir, bool SortList);
std::string SafeGetCWD();
void SetCloseExec(int Fd,bool Close);
void SetNonBlock(int Fd,bool Block);
bool WaitFd(int Fd,bool write = false,unsigned long timeout = 0);
pid_t ExecFork();
pid_t ExecFork(std::set<int> keep_fds);
void MergeKeepFdsFromConfiguration(std::set<int> &keep_fds);
bool ExecWait(pid_t Pid,const char *Name,bool Reap = false);

// check if the given file starts with a PGP cleartext signature
bool StartsWithGPGClearTextSignature(std::string const &FileName);

/** change file attributes to requested known good values
 *
 * The method skips the user:group setting if not root.
 *
 * @param requester is printed as functionname in error cases
 * @param file is the file to be modified
 * @param user is the (new) owner of the file, e.g. _apt
 * @param group is the (new) group owning the file, e.g. root
 * @param mode is the access mode of the file, e.g. 0644
 */
bool ChangeOwnerAndPermissionOfFile(char const * const requester, char const * const file, char const * const user, char const * const group, mode_t const mode);

/**
 * \brief Drop privileges
 *
 * Drop the privileges to the user _apt (or the one specified in
 * APT::Sandbox::User). This does not set the supplementary group
 * ids up correctly, it only uses the default group. Also prevent
 * the process from gaining any new privileges afterwards, at least
 * on Linux.
 *
 * \return true on success, false on failure with _error set
 */
bool DropPrivileges();

// File string manipulators
std::string flNotDir(std::string File);
std::string flNotFile(std::string File);
std::string flNoLink(std::string File);
std::string flExtension(std::string File);
std::string flCombine(std::string Dir,std::string File);

/** \brief Takes a file path and returns the absolute path
 */
std::string flAbsPath(std::string File);
/** \brief removes superfluous /./ and // from path */
APT_HIDDEN std::string flNormalize(std::string file);

// simple c++ glob
std::vector<std::string> Glob(std::string const &pattern, int flags=0);

/** \brief Popen() implementation that execv() instead of using a shell
 *
 * \param Args the execv style command to run
 * \param FileFd is a referenz to the FileFd to use for input or output
 * \param Child a reference to the integer that stores the child pid
 *        Note that you must call ExecWait() or similar to cleanup
 * \param Mode is either FileFd::ReadOnly or FileFd::WriteOnly
 * \param CaptureStderr True if we should capture stderr in addition to stdout.
 *                      (default: True).
 * \return true on success, false on failure with _error set
 */
bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode, bool CaptureStderr);
bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode);


#endif