kc3-lang/gnulib/doc/posix-functions/environ.texi

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• Hash : 04a9dd8f
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  Date : 2021-04-17T15:29:16
  

  doc: Update for FreeBSD 11.0, 12.0, 13.0.
  
  * doc/posix-headers/*.texi: Update.
  * doc/glibc-headers/*.texi: Update.
  * doc/posix-functions/*.texi: Likewise.
  * doc/pastposix-functions/*.texi: Likewise.
  * doc/glibc-functions/*.texi: Likewise.
  * m4/ptsname_r.m4 (gl_FUNC_PTSNAME_R): Update cross-compilation guess.
  

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• doc/posix-functions/environ.texi

• @node environ
  @section @code{environ}
  @findex environ
  
  POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/environ.html}
  
  Gnulib module: environ
  
  Portability problems fixed by Gnulib:
  @itemize
  @item
  POSIX does not require this variable to be declared, and it is indeed not
  declared on some platforms:
  macOS 11.1, FreeBSD 13.0, NetBSD 5.0, OpenBSD 3.8, IRIX 6.5, Solaris 11.4.
  @item
  On macOS, this variable is not declared.  Up to Mac OS X 10.4, one can use
  @smallexample
  extern char **environ;
  @end smallexample
  to get the variable declared.  This does not work any more, however, in
  shared libraries on macOS 11.1.  Here is a workaround: Instead, one can use
  @smallexample
  #include <crt_externs.h>
  #define environ (*_NSGetEnviron())
  @end smallexample
  This works at all versions of macOS.
  @item
  On Cygwin in 64-bit mode, references to this variable cause a link error when
  the option @code{-Wl,--disable-auto-import} is in use.
  @end itemize
  
  Portability problems not fixed by Gnulib:
  @itemize
  @item
  The address of this variable is not a compile-time constant on some platforms:
  mingw.
  @item
  Assigning NULL to @code{environ} to clear all variables is not
  portable; better is to assign @code{environ} to one-element array
  containing a NULL pointer.  That said, an empty environment is not
  portable either, as some systems may require particular environment
  variables (such as @code{PATH}) to be present in order to operate
  consistently.
  @end itemize
  

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