Seeking and reading large files in a Linux C++ application

by

fseek64 is a C function. To make it available you’ll have to define _FILE_OFFSET_BITS=64 before including the system headers That will more or less define fseek to be actually fseek64. Or do it in the compiler arguments e.g.
gcc -D_FILE_OFFSET_BITS=64 ….

http://www.suse.de/~aj/linux_lfs.html has a great overviw of large file support on linux:

  • Compile your programs with “gcc -D_FILE_OFFSET_BITS=64”. This forces all file access calls to use the 64 bit variants. Several types change also, e.g. off_t becomes off64_t. It’s therefore important to always use the correct types and to not use e.g. int instead of off_t. For portability with other platforms you should use getconf LFS_CFLAGS which will return -D_FILE_OFFSET_BITS=64 on Linux platforms but might return something else on e.g. Solaris. For linking, you should use the link flags that are reported via getconf LFS_LDFLAGS. On Linux systems, you do not need special link flags.
  • Define _LARGEFILE_SOURCE and _LARGEFILE64_SOURCE. With these defines you can use the LFS functions like open64 directly.
  • Use the O_LARGEFILE flag with open to operate on large files.

More Related Contents:

  1. _GNU_SOURCE and __USE_GNU
  2. some problems about c++ try catch [closed]
  3. How to compile a program with limit time (5s), using MinGW-Gnu C++
  4. How do I find the location of the executable in C? [duplicate]
  5. print call stack in C or C++
  6. C++ Dynamic Shared Library on Linux
  7. How to get memory usage at runtime using C++?
  8. How can I create directory tree in C++/Linux?
  9. Compiling a C++ program with GCC
  10. How to create a single instance application in C or C++
  11. Send and Receive a file in socket programming in Linux with C/C++ (GCC/G++)
  12. Is it safe to fork from within a thread?
  13. Sharing a global/static variable between a process and DLL
  14. Linking libstdc++ statically: any gotchas?
  15. Why does the library linker flag sometimes have to go at the end using GCC?
  16. C++ new operator thread safety in linux and gcc 4
  17. How to programmatically cause a core dump in C/C++
  18. Linking g++ 4.8 to libstdc++
  19. How to pretty-print STL containers in GDB?
  20. Could you recommend some guides about Epoll on Linux [closed]
  21. C and C++ programming on Ubuntu 11.10 [closed]
  22. “relocation R_X86_64_32S against ” linking Error
  23. Linux c++ error: undefined reference to ‘dlopen’
  24. How to fix: /usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.15′ not found
  25. version `CXXABI_1.3.8′ not found (required by …) [duplicate]
  26. Exception running boost asio ssl example
  27. Find available network interfaces in C/C++? [closed]
  28. Check keypress in C++ on Linux
  29. How to get the username in C/C++ in Linux?
  30. How to assert if a std::mutex is locked?

Leave a Comment