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

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• Hash : 84c3f9cf
  Author :
  Date : 2011-11-02T22:34:51
  

  New module 'unlinkat', split off from module 'openat'.
  
  * m4/unlinkat.m4: New file, extracted from m4/openat.m4.
  * m4/openat.m4 (gl_FUNC_OPENAT): Don't set GNULIB_UNLINKAT,
  REPLACE_UNLINKAT, HAVE_UNLINKAT. Don't test for unlinkat.
  * modules/unlinkat: New file, extracted from modules/openat. Correct
  the dependency conditions.
  * modules/openat (Files): Remove lib/unlinkat.c.
  (Depends-on): Remove rmdir, unlink.
  (configure.ac): Remove AC_LIBOBJ of unlinkat.
  * modules/unlinkat-tests: New file, extracted from modules/openat-tests.
  * modules/openat-tests (Files): Remove tests/test-unlinkat.c,
  tests/test-rmdir.h, tests/test-unlink.h.
  (Depends-on): Remove unlinkdir.
  (Makefile.am): Remove rules for test-unlinkat.
  * doc/posix-functions/unlinkat.texi: Mention module 'unlinkat' instead
  of module 'openat'.
  * NEWS: Mention the change.
  * modules/linkat-tests (Depends-on): Add unlinkat.
  * modules/mkfifoat-tests (Depends-on): Likewise.
  * modules/readlinkat-tests (Depends-on): Likewise.
  

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• doc/posix-functions/unlinkat.texi

• @node unlinkat
  @section @code{unlinkat}
  @findex unlinkat
  
  POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/unlinkat.html}
  
  Gnulib module: unlinkat
  
  Portability problems fixed by Gnulib:
  @itemize
  @item
  This function is missing on some platforms:
  glibc 2.3.6, MacOS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8,
  AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Cygwin 1.5.x, mingw, MSVC 9, Interix 3.5, BeOS.
  But the replacement function is not safe to be used in libraries and is not multithread-safe.
  @item
  Some systems mistakenly succeed on @code{unlinkat(fd,"file/",flag)}:
  GNU/Hurd, Solaris 9.
  @item
  Some platforms declare this function in @code{fcntl.h} instead of
  @code{unistd.h}:
  Cygwin 1.7.1.
  @end itemize
  
  Portability problems not fixed by Gnulib:
  @itemize
  @item
  When @code{unlinkat(fd,name,AT_REMOVEDIR)} fails because the specified
  directory is not empty, the @code{errno} value is system dependent.
  @item
  POSIX requires that @code{unlinkdir(fd,"link-to-empty/",AT_REMOVEDIR)}
  remove @file{empty} and leave @file{link-to-empty} as a dangling
  symlink.  This is counter-intuitive, so some systems fail with
  @code{ENOTDIR} instead:
  glibc
  @item
  Some systems allow a superuser to unlink directories, even though this
  can cause file system corruption.  The error given if a process is not
  permitted to unlink directories varies across implementations; it is
  not always the POSIX value of @code{EPERM}.  Meanwhile, if a process
  has the ability to unlink directories, POSIX requires that
  @code{unlinkat(fd,"symlink-to-dir/",0)} remove @file{dir} and leave
  @file{symlink-to-dir} dangling; this behavior is counter-intuitive.
  The gnulib module unlinkdir can help determine whether code must be
  cautious of unlinking directories.
  @item
  Removing an open file is non-portable: On Unix this allows the programs that
  have the file already open to continue working with it; the file's storage
  is only freed when the no process has the file open any more.  On Windows,
  the attempt to remove an open file fails.
  @end itemize
  

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