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lfcompile(7)

Standards, Environments, Macros, Character Sets, and miscellany
                                                                  lfcompile(7)



NAME
       lfcompile - large file compilation environment for 32-bit applications

DESCRIPTION
       All  64-bit  applications  can  manipulate  large files by default. The
       methods described on this page allow 32-bit applications to  manipulate
       large files.


       In  the large file compilation environment, source interfaces are bound
       to appropriate 64-bit functions, structures, and  types.  Compiling  in
       this  environment allows 32-bit applications to access files whose size
       is greater than or equal to 2 Gbyte ( 2^31 bytes).


       Each interface named xxx() that needs  to  access  64-bit  entities  to
       access  large files maps to a xxx64() call in the resulting binary. All
       relevant data types are defined to be of  correct  size  (for  example,
       off_t has a typedef definition for a 64-bit entity).


       An  application  compiled  in this 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 lfcompile64(7) manual page for  informa‐
       tion regarding the transitional compilation environment.


       Applications  can be compiled in the large file compilation environment
       by using the following methods:

           o      Use the getconf(1) utility with one or more of the arguments
                  listed  in  the  table below. This method is recommended for
                  portable applications.


                  tab() box; cw(1.68i) |cw(3.82i) lw(1.68i)  |lw(3.82i)  argu‐
                  mentpurpose  _  LFS_CFLAGST{ obtain compilation flags neces‐
                  sary to enable the large  file  compilation  environment  T}
                  LFS_LDFLAGSobtain  link  editor  options LFS_LIBSobtain link
                  library names LFS_LINTFLAGSobtain lint options



           o      Set the compile-time flag  _FILE_OFFSET_BITS  to  64  before
                  including any headers. Applications may combine objects pro‐
                  duced 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 vari‐
                  ables of types whose sizes change between compilation  envi‐
                  ronments.


   Access to Additional Large File Interfaces
       The  fseek()  and  ftell()  functions  do  not  map  to functions named
       fseek64() and ftell64(); rather, the large file additions fseeko()  and
       ftello(),  have  functionality  identical to fseek() and ftell() and do
       map to the 64-bit functions  fseeko64()  and  ftello64().  Applications
       wishing to access large files should use fseeko() and ftello() in place
       of fseek() and ftell(). See the fseek(3C) and  ftell(3C)  manual  pages
       for information about fseeko() and ftello().


       Applications  wishing  to  access  fseeko() and ftello() as well as the
       POSIX and X/Open specification-conforming interfaces should define  the
       macro  _LARGEFILE_SOURCE  to be 1 and set whichever feature test macros
       are appropriate to obtain the desired environment (see standards(7)).

EXAMPLES
       In the following examples, the large file  compilation  environment  is
       accessed  by  invoking  the  getconf  utility with one of the arguments
       listed in the table above. The additional  large  file  interfaces  are
       accessed by specifying -D_LARGEFILE_SOURCE.


       The  examples  that use the form of command substitution specifying the
       command within parentheses preceded by a dollar sign  can  be  executed
       only  in  a POSIX-conforming shell such as the Korn Shell (see ksh(1)).
       In a shell that is not POSIX-conforming, such as the Bourne Shell  (see
       sh(1)) and the C Shell (see csh(1)), the getconf calls must be enclosed
       within grave accent marks, as shown in the second example.

       Example 1 Compile a program with a "large" off_t  that  uses  fseeko(),
       ftello(), and yacc.



       The  following example compiles a program with a "large" off_t and uses
       fseeko(), ftello(), and yacc(1).


         $ c89 -D_LARGEFILE_SOURCE                \
               -D_FILE_OFFSET_BITS=64 -o foo      \
               $(getconf LFS_CFLAGS) y.tab.c b.o  \
               $(getconf LFS_LDFLAGS)             \
               -ly $(getconf LFS_LIBS)


       Example 2 Compile a program with a "large"  off_t  that  does  not  use
       fseeko() and ftello() and has no application specific libraries.


         % c89 -D_FILE_OFFSET_BITS=64     \
               `getconf LFS_CFLAGS` a.c   \
               `getconf LFS_LDFLAGS`      \
               `getconf LFS_LIBS`         \


       Example  3  Compile a program with a "default" off_t that uses fseeko()
       and ftello().


         $ c89 -D_LARGEFILE_SOURCE  a.c


SEE ALSO
       csh(1),  getconf(1),  ksh(1),  sh(1),  yacc(1),  fseek(3C),  ftell(3C),
       lf64(7), lfcompile64(7), standards(7)

NOTES
       Certain  system-specific  or  non-portable interfaces are not usable in
       the large file compilation environment. Known cases are:

           o      Kernel data structures read from /dev/kmem.


           o      Interfaces in the kernel virtual memory library, -lkvm.


           o      Interfaces in the ELF access library, -lelf.


           o      Interfaces to /proc defined in <procfs.h>.


           o      The ustat(2) system call.



       Programs that use these interfaces should not be compiled in the  large
       file  compilation  environment.  As  a partial safeguard against making
       this mistake, including either  of  the  <libelf.h>  or  <sys/procfs.h>
       header files will induce a compilation error when the large file compi‐
       lation environment is enabled.


       In general, caution should be exercised when using any  separately-com‐
       piled  library whose interfaces include data items of type off_t or the
       other redefined types either  directly  or  indirectly,  such  as  with
       'struct stat'. (The redefined types are off_t, rlim_t, ino_t, blkcnt_t,
       fsblkcnt_t, and fsfilcnt_t.) For the large file compilation environment
       to  work  correctly  with  such  a library, the library interfaces must
       include the appropriate xxx64() binary entry points and must have  them
       mapped to the corresponding primary functions when _FILE_OFFSET_BITS is
       set to 64.


       Care should be exercised using any of the printf() or scanf()  routines
       on  variables  of the types mentioned above. In the large file compila‐
       tion environment, these variables should be printed  or  scanned  using
       long long formats.

BUGS
       Symbolic  formats  analogous to those found in <sys/int_fmtio.h> do not
       exist for printing or scanning variables of the types  that  are  rede‐
       fined in the large file compilation environment.



Oracle Solaris 11.4               24 Aug 2009                     lfcompile(7)
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