All 64-bit applications can manipulate large files by default. The transitional interfaces described on this page can be used by 32-bit and 64-bit applications to manipulate large files.
In the transitional compilation environment, explicit 64-bit functions, structures, and types are added to the API. Compiling in this environment allows both 32-bit
and 64-bit applications to access files whose size is greater than or equal to 2 Gbyte ( 231 bytes).
The transitional compilation environment exports all the explicit 64-bit functions (xxx64()) and types in addition to all the regular functions (xxx()) and types. Both xxx() and xxx64() functions are available to the program
source. A 32-bit application must use the xxx64() functions in order to access large files. See the lf64(5) manual page for a complete listing of the 64-bit transitional interfaces.
The transitional compilation environment differs from the large file compilation environment, wherein the underlying interfaces are bound to 64-bit functions, structures, and types. An application
compiled in the large file compilation environment is able to use the xxx() source interfaces to access both large and small files, rather than having to explicitly
utilize the transitional xxx64() interface calls to access large files. See the lfcompile(5) manual page for more information regarding the large file compilation environment.
Applications may combine objects produced in the large file compilation environment with objects produced in the transitional compilation environment, but must be careful with respect to interoperability
between those objects. Applications should not declare global variables of types whose sizes change between compilation environments.
For applications that do not wish to conform to the POSIX or X/Open specifications, the 64-bit transitional interfaces are available by default. No compile-time flags need to be set.
Access to Additional Large File Interfaces
Applications that wish to access the transitional interfaces as well as the POSIX or X/Open specification-conforming interfaces should use the following compilation methods and set whichever feature
test macros are appropriate to obtain the desired environment (see standards(5)).
- Set the compile-time flag _LARGEFILE64_SOURCE to 1 before including any headers.
- Use the getconf(1) command with one
or more of the following arguments:
|LFS64_CFLAGS||obtain compilation flags necessary to enable the transitional compilation environment
|LFS64_LDFLAGS||obtain link editor options
|LFS64_LIBS||obtain link library names
|LFS64_LINTFLAGS||obtain lint options