src/FileArea.cpp

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2003-2011 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 1998 Vadim Zeitlin ( zeitlin@dptmaths.ens-cachan.fr )
   6 //
   7 // Any parts of this program derived from the xMule, lMule or eMule project,
   8 // or contributed by third-party developers are copyrighted by their
   9 // respective authors.
  10 //
  11 // This program is free software; you can redistribute it and/or modify
  12 // it under the terms of the GNU General Public License as published by
  13 // the Free Software Foundation; either version 2 of the License, or
  14 // (at your option) any later version.
  15 //
  16 // This program is distributed in the hope that it will be useful,
  17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 // GNU General Public License for more details.
  20 //
  21 // You should have received a copy of the GNU General Public License
  22 // along with this program; if not, write to the Free Software
  23 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  24 //
  25
  26
  27 #include "config.h"
  28
  29 #ifdef HAVE_ERRNO_H
  30 #include <errno.h>
  31 #endif
  32
  33 #ifdef HAVE_SIGNAL_H
  34 #include <signal.h>
  35 #endif
  36
  37 #include "FileArea.h"           // Interface declarations.
  38 #include "FileAutoClose.h"      // Needed for CFileAutoClose
  39
  40 #ifndef ENABLE_MMAP
  41 #       define ENABLE_MMAP      0
  42 #endif
  43
  44 #if ENABLE_MMAP && defined(HAVE_MMAP) && defined(HAVE_SYSCONF) && (defined(HAVE__SC_PAGESIZE) || defined(HAVE__SC_PAGE_SIZE))
  45 #       define USE_MMAP
  46 #endif
  47
  48 #ifdef USE_MMAP
  49
  50 #include <sys/mman.h>
  51
  52 #if defined(HAVE_SYSCONF) && defined(HAVE__SC_PAGESIZE)
  53 static const long gs_pageSize = sysconf(_SC_PAGESIZE);
  54 #elif defined(HAVE_SYSCONF) && defined(HAVE__SC_PAGE_SIZE)
  55 static const long gs_pageSize = sysconf(_SC_PAGE_SIZE);
  56 #endif
  57
  58 #endif /* USE_MMAP */
  59
  60 #if !defined(HAVE_SIGACTION) || !defined(SA_SIGINFO) || !defined(USE_MMAP) || defined(__UCLIBC__)
  61
  62 class CFileAreaSigHandler
  63 {
  64 public:
  65         static void Init() {};
  66         static void Add(CFileArea&) {};
  67         static void Remove(CFileArea&) {};
  68 private:
  69         CFileAreaSigHandler() {};
  70 };
  71
  72 #else
  73
  74 class CFileAreaSigHandler
  75 {
  76 public:
  77         static void Init();
  78         static void Add(CFileArea& area);
  79         static void Remove(CFileArea& area);
  80 private:
  81         CFileAreaSigHandler() {};
  82         static wxMutex mutex;
  83         static CFileArea *first;
  84         static bool initialized;
  85         static struct sigaction old_segv, old_bus;
  86         static void Handler(int sig, siginfo_t *info, void *ctx);
  87 };
  88
  89 wxMutex          CFileAreaSigHandler::mutex;
  90 CFileArea *      CFileAreaSigHandler::first;
  91 bool             CFileAreaSigHandler::initialized = false;
  92 struct sigaction CFileAreaSigHandler::old_segv;
  93 struct sigaction CFileAreaSigHandler::old_bus;
  94
  95 /* define MAP_ANONYMOUS for Mac OS X */
  96 #if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
  97 #define MAP_ANONYMOUS MAP_ANON
  98 #endif
  99
 100 // Handle signals.
 101 // The idea is to replace faulted memory with zeroes and mark
 102 // the error in proper CFileArea
 103 void CFileAreaSigHandler::Handler(int sig, siginfo_t *info, void *ctx)
 104 {
 105         CFileArea *cur;
 106         // find the mapped section where violation occurred (if any)
 107         {
 108                 wxMutexLocker lock(mutex);
 109                 cur = first;
 110                 while (cur) {
 111                         if (cur->m_mmap_buffer && info->si_addr >= cur->m_mmap_buffer && info->si_addr < cur->m_mmap_buffer + cur->m_length)
 112                                 break;
 113                         cur = cur->m_next;
 114                 }
 115         }
 116
 117         // mark error if found
 118         if (cur && gs_pageSize > 0) {
 119                 cur->m_error = true;
 120                 char *start_addr = ((char *) info->si_addr) - (((unsigned long) info->si_addr) % gs_pageSize);
 121                 if (mmap(start_addr, gs_pageSize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) != MAP_FAILED)
 122                         return;
 123         }
 124
 125         // call old handler
 126         struct sigaction* sa = (sig == SIGSEGV) ? &old_segv : &old_bus;
 127         if (sa->sa_flags & SA_SIGINFO)
 128                 sa->sa_sigaction(sig, info, ctx);
 129         else if (sa->sa_handler == SIG_DFL || sa->sa_handler == SIG_IGN)
 130                 abort();
 131         else
 132                 sa->sa_handler(sig);
 133 }
 134
 135 void CFileAreaSigHandler::Init()
 136 {
 137         // init error handler if needed
 138         wxMutexLocker lock(mutex);
 139         if (initialized)
 140                 return;
 141
 142         // Set our new signal handler.
 143         // Note that we safe old handlers (propably wx ones) in order
 144         // to be able to call them if signal not handled as desired.
 145         // These handler will be removed by wx code when wx will restore
 146         // old ones
 147         struct sigaction sa;
 148         memset(&sa, 0, sizeof(sa));
 149         sigemptyset(&sa.sa_mask);
 150         sa.sa_sigaction = Handler;
 151         sa.sa_flags = SA_NODEFER|SA_SIGINFO;
 152         if (sigaction(SIGSEGV, &sa, &old_segv))
 153                 return;
 154         if (sigaction(SIGBUS, &sa, &old_bus)) {
 155                 sigaction(SIGSEGV, &old_segv, NULL);
 156                 return;
 157         }
 158         initialized = true;
 159 }
 160
 161 void CFileAreaSigHandler::Add(CFileArea& area)
 162 {
 163         wxMutexLocker lock(mutex);
 164         area.m_next = first;
 165         first = &area;
 166 }
 167
 168 void CFileAreaSigHandler::Remove(CFileArea& area)
 169 {
 170         wxMutexLocker lock(mutex);
 171         CFileArea **cur = &first;
 172         while (*cur) {
 173                 if (*cur == &area) {
 174                         *cur = area.m_next;
 175                         area.m_next = NULL;
 176                         break;
 177                 }
 178                 cur = &(*cur)->m_next;
 179         }
 180 }
 181 #endif
 182
 183 CFileArea::CFileArea()
 184         : m_buffer(NULL), m_mmap_buffer(NULL), m_length(0), m_next(NULL), m_file(NULL), m_error(false)
 185 {
 186         CFileAreaSigHandler::Init();
 187 }
 188
 189
 190 CFileArea::~CFileArea()
 191 {
 192         Close();
 193         CheckError();
 194 }
 195
 196 bool CFileArea::Close()
 197 {
 198         if (m_buffer != NULL && m_mmap_buffer == NULL)
 199         {
 200                 delete[] m_buffer;
 201                 m_buffer = NULL;
 202         }
 203 #ifdef USE_MMAP
 204         if (m_mmap_buffer)
 205         {
 206                 munmap(m_mmap_buffer, m_length);
 207                 // remove from list
 208                 CFileAreaSigHandler::Remove(*this);
 209                 m_buffer = NULL;
 210                 m_mmap_buffer = NULL;
 211                 if (m_file) {
 212                         m_file->Unlock();
 213                         m_file = NULL;
 214                 }
 215         }
 216 #endif
 217         return true;
 218 }
 219
 220
 221 void CFileArea::ReadAt(CFileAutoClose& file, uint64 offset, size_t count)
 222 {
 223         Close();
 224
 225 #ifdef USE_MMAP
 226         uint64 offEnd = offset + count;
 227         if (gs_pageSize > 0 && offEnd < 0x100000000ull) {
 228                 uint64 offStart = offset & (~((uint64)gs_pageSize-1));
 229                 m_length = offEnd - offStart;
 230                 void *p = mmap(NULL, m_length, PROT_READ, MAP_SHARED, file.fd(), offStart);
 231                 if (p != MAP_FAILED) {
 232                         m_file = &file;
 233                         m_mmap_buffer = (uint8_t*) p;
 234                         m_buffer = m_mmap_buffer + (offset - offStart);
 235
 236                         // add to list to catch errors correctly
 237                         CFileAreaSigHandler::Add(*this);
 238                         return;
 239                 }
 240         }
 241         file.Unlock();
 242 #endif
 243         m_buffer = new uint8_t[count];
 244         file.ReadAt(m_buffer, offset, count);
 245 }
 246
 247 #ifdef USE_MMAP
 248 void CFileArea::StartWriteAt(CFileAutoClose& file, uint64 offset, size_t count)
 249 {
 250         Close();
 251
 252         uint64 offEnd = offset + count;
 253         if (file.GetLength() >= offEnd && gs_pageSize > 0 && offEnd < 0x100000000ull) {
 254                 uint64 offStart = offset & (~((uint64)gs_pageSize-1));
 255                 m_length = offEnd - offStart;
 256                 void *p = mmap(NULL, m_length, PROT_READ|PROT_WRITE, MAP_SHARED, file.fd(), offStart);
 257                 if (p != MAP_FAILED)
 258                 {
 259                         m_file = &file;
 260                         m_mmap_buffer = (uint8_t*) p;
 261                         m_buffer = m_mmap_buffer + (offset - offStart);
 262
 263                         // add to list to catch errors correctly
 264                         CFileAreaSigHandler::Add(*this);
 265                         return;
 266                 }
 267                 file.Unlock();
 268         }
 269         m_buffer = new uint8_t[count];
 270 }
 271 #else
 272 void CFileArea::StartWriteAt(CFileAutoClose&, uint64, size_t count)
 273 {
 274         Close();
 275         m_buffer = new uint8_t[count];
 276 }
 277 #endif
 278
 279
 280 bool CFileArea::FlushAt(CFileAutoClose& file, uint64 offset, size_t count)
 281 {
 282         if (!m_buffer)
 283                 return false;
 284
 285 #ifdef USE_MMAP
 286         if (m_mmap_buffer) {
 287                 if (msync(m_mmap_buffer, m_length, MS_SYNC))
 288                         return false;
 289                 Close();
 290                 return true;
 291         }
 292 #endif
 293         file.WriteAt(m_buffer, offset, count);
 294         Close();
 295         return true;
 296 }
 297
 298 void CFileArea::CheckError()
 299 {
 300         bool err = m_error;
 301         m_error = false;
 302         if (err)
 303                 throw CIOFailureException(wxT("Read error, failed to read from file."));
 304 }
 305