gen/compat.5

   1 .Dd October 7, 2004
   2 .Os Darwin
   3 .Dt COMPAT 5
   4 .Sh NAME
   5 .Nm compat
   6 .Nd manipulate compatibility settings
   7 .Sh SYNOPSIS
   8 .Ev COMMAND_MODE=legacy|unix2003
   9 .Lp
  10 .Fd #define _POSIX_C_SOURCE
  11 .Fd #define _APPLE_C_SOURE
  12 .Fd #define _NONSTD_SOURCE
  13 .Fd #define __LP64__
  14 .Sh DESCRIPTION
  15 Setting the environment variable
  16 .Ev COMMAND_MODE
  17 to the value legacy causes utility programs to behave as closely to Mac OS X 10.3's utility programs as possible.  When in this mode all of 10.3's flags are accepted, and in some cases extra flags are accepted, but no flags that were used in 10.3 will have been removed or changed in meaning.  Any behavioral changes in this mode are documented in the LEGACY sections of the individual utilities.
  18 .Pp
  19 Setting the environment variable
  20 .Ev COMMAND_MODE
  21 to the value unix03 causes utility programs to obey the
  22 .St -susv3
  23 standards even if doing so would alter the behavior of flags used in 10.3.
  24 .Pp
  25 .Ev COMMAND_MODE's
  26 value is case insensitive and if it is unset or set to something other than legacy or unix03 it behaves as if it were set to unix03.
  27 .Pp
  28 Defining
  29 .Dv _NONSTD_SOURCE
  30 causes library and kernel calls to behave as closely to Mac OS X 10.3's library and kernel calls as possible.  Any behavioral changes in this mode are documented in the LEGACY sections of the individual function calls.
  31 .Pp
  32 Defining any of
  33 .Dv _POSIX_C_SOURCE,
  34 .Dv _APPLE_C_SOURE,
  35 or
  36 .Dv __LP64__
  37 causes library and kernel calls to conform to
  38 .St -susv3
  39 standards even if doing so would alter the behavior of functions used in 10.3.  Defining
  40 .Dv _POSIX_C_SOURCE
  41 also removes functions, types, and other interfaces that are not part of
  42 .St -susv3
  43 from the normal C namespace, while
  44 .Dv _APPLE_C_SOURE
  45 does not.
  46 .Pp
  47 Failing to define any of those symbols currently acts as if you have defined
  48 .Dv _NONSTD_SOURCE
  49 but it is expected that in a future OS X release the default behavior will change to be as if
  50 .Dv _APPLE_C_SOURE
  51 were defined.
  52 .Sh STANDARDS
  53 With COMMAND_MODE set to unix2003 utility functions conform to
  54 .St -susv3
  55 .Pp
  56 With
  57 .Dv _POSIX_C_SOURCE,
  58 .Dv _APPLE_C_SOURE,
  59 or
  60 .Dv __LP64__
  61 system and library calls conform to
  62 .St -susv3
  63 .Sh BUGS
  64 Different parts of a program can be compiled with different compatibility settings.  The resultant program will normally work as expected, for example a regex created by the
  65 .St -susv3
  66 .Fn regcomp 3
  67 can be passed to the legacy
  68 .Fn regfree 3
  69 with no unexpected results.  Some cases are less clear cut, for example
  70 what does the programmer intend when they use the
  71 .Fn -susv3
  72 .Fn regcomp 3
  73 to compile a regex, but the legacy
  74 .Fn regexec 3
  75 to execute it?  Any interpretation will surprise someone.