@prindex @command{install-sh}
Some Autoconf macros require auxiliary scripts. @code{AC_PROG_INSTALL}
-and @code{AC_PROG_@w{MKDIR_P}} (@pxref{Particular Programs}) require a
+(@pxref{Particular Programs}) requires a
fallback implementation of @command{install} called @file{install-sh},
and the @code{AC_CANONICAL} macros (@pxref{Manual Configuration})
require the system-identification scripts @file{config.sub} and
two instances of the program attempt to make the same directory at
nearly the same time.
-This macro uses the @samp{mkdir -p} command if possible. Otherwise, it
-falls back on invoking @command{install-sh} with the @option{-d} option,
-so your package should
-contain @file{install-sh} as described under @code{AC_PROG_INSTALL}.
-An @file{install-sh} file that predates Autoconf 2.60 or Automake 1.10
-is vulnerable to race conditions, so if you want to support parallel
-installs from
-different packages into the same directory you need to make sure you
-have an up-to-date @file{install-sh}. In particular, be careful about
-using @samp{autoreconf -if} if your Automake predates Automake 1.10.
+This macro uses the equivalent of the @samp{mkdir -p} command. Ancient
+versions of @command{mkdir} are vulnerable to race conditions, so if you
+want to support parallel installs from different packages into the same
+directory you should use a non-ancient @command{mkdir}.
This macro is related to the @code{AS_MKDIR_P} macro (@pxref{Programming
in M4sh}), but it sets an output variable intended for use in other
might invoke @code{$(MKDIR_P) -m 0 dir} to create an inaccessible
directory, and conversely a makefile should use @code{$(MKDIR_P) --
$(FOO)} if @var{FOO} might yield a value that begins with @samp{-}.
-Finally, @code{AS_MKDIR_P} does not check for race condition
-vulnerability, whereas @code{AC_PROG_MKDIR_P} does.
-
-@samp{@@MKDIR_P@@} is special, as its value may vary for different
-configuration files.
The result of the test can be overridden by setting the variable
@code{MKDIR_P} or the cache variable @code{ac_cv_path_mkdir}.
@defmac AS_MKDIR_P (@var{file-name})
@asindex{MKDIR_P}
Make the directory @var{file-name}, including intervening directories
-as necessary. This is equivalent to @samp{mkdir -p -- @var{file-name}},
-except that it is portable to older versions of @command{mkdir} that
-lack support for the @option{-p} option or for the @option{--}
-delimiter (@pxref{mkdir, , Limitations of Usual Tools}). Also,
-@code{AS_MKDIR_P}
-succeeds if @var{file-name} is a symbolic link to an existing directory,
-even though Posix is unclear whether @samp{mkdir -p} should
-succeed in that case. If creation of @var{file-name} fails, exit the
-script.
+as necessary. This is equivalent to @samp{mkdir -p -- @var{file-name}}.
+If creation of @var{file-name} fails, exit the script.
Also see the @code{AC_PROG_MKDIR_P} macro (@pxref{Particular Programs}).
@end defmac
@c ------------------
@prindex @command{mkdir}
@cindex Making directories
-No @command{mkdir} option is portable to older systems. Instead of
-@samp{mkdir -p @var{file-name}}, you should use
-@code{AS_MKDIR_P(@var{file-name})} (@pxref{Programming in M4sh})
-or @code{AC_PROG_MKDIR_P} (@pxref{Particular Programs}).
-
Combining the @option{-m} and @option{-p} options, as in @samp{mkdir -m
go-w -p @var{dir}}, often leads to trouble. FreeBSD
@command{mkdir} incorrectly attempts to change the permissions of
Posix does not clearly specify whether @samp{mkdir -p foo}
should succeed when @file{foo} is a symbolic link to an already-existing
-directory. The GNU Core Utilities 5.1.0 @command{mkdir}
-succeeds, but Solaris @command{mkdir} fails.
+directory. The GNU @command{mkdir}
+succeeds, but Solaris 10 @command{mkdir} fails.
Traditional @code{mkdir -p} implementations suffer from race conditions.
For example, if you invoke @code{mkdir -p a/b} and @code{mkdir -p a/c}
at the same time, both processes might detect that @file{a} is missing,
one might create @file{a}, then the other might try to create @file{a}
-and fail with a @code{File exists} diagnostic. The GNU Core
-Utilities (@samp{fileutils} version 4.1), FreeBSD 5.0,
-NetBSD 2.0.2, and OpenBSD 2.4 are known to be
-race-free when two processes invoke @code{mkdir -p} simultaneously, but
-earlier versions are vulnerable. Solaris @command{mkdir} is still
-vulnerable as of Solaris 10, and other traditional Unix systems are
+and fail with a @code{File exists} diagnostic. Solaris 10 @command{mkdir}
+is vulnerable, and other traditional Unix systems are
probably vulnerable too. This possible race is harmful in parallel
builds when several Make rules call @code{mkdir -p} to
construct directories. You may use
-@code{install-sh -d} as a safe replacement, provided this script is
-recent enough; the copy shipped with Autoconf 2.60 and Automake 1.10 is
-OK, but copies from older versions are vulnerable.
-
+@code{install-sh -d} as a safe replacement, for example by setting
+@samp{MKDIR_P='/path/to/install-sh -d'} in the environment of
+@command{configure}, assuming the package distributes @file{install-sh}.
@item @command{mkfifo}
@itemx @command{mknod}
# Do not use -m 0755 and let people choose whatever they expect by
# setting umask.
#
-# We cannot accept any implementation of 'mkdir' that recognizes '-p'.
-# Some implementations (such as Solaris 8's) are vulnerable to race conditions:
+# Some implementations (such as Solaris 10's) are vulnerable to race conditions:
# if a parallel make tries to run 'mkdir -p a/b' and 'mkdir -p a/c'
# concurrently, both version can detect that a/ is missing, but only
-# one can create it and the other will error out. Consequently we
-# restrict ourselves to known race-free implementations.
+# one can create it and the other will error out. Users of these
+# implementations should install and use GNU mkdir instead;
+# on Solaris 10, this is /opt/sfw/bin/mkdir.
#
# Automake used to define mkdir_p as 'mkdir -p .', in order to
# allow $(mkdir_p) to be used without argument. As in
# $(mkdir_p) $(somedir)
# where $(somedir) is conditionally defined. However we don't do
# that for MKDIR_P.
-# 1. before we restricted the check to GNU mkdir, 'mkdir -p .' was
-# reported to fail in read-only directories. The system where this
-# happened has been forgotten.
-# 2. in practice we call $(MKDIR_P) on directories such as
+# * in practice we call $(MKDIR_P) on directories such as
# $(MKDIR_P) "$(DESTDIR)$(somedir)"
# and we don't want to create $(DESTDIR) if $(somedir) is empty.
# To support the latter case, we have to write
# so $(MKDIR_P) always has an argument.
# We will have better chances of detecting a missing test if
# $(MKDIR_P) complains about missing arguments.
-# 3. $(MKDIR_P) is named after 'mkdir -p' and we don't expect this
+# * $(MKDIR_P) is named after 'mkdir -p' and we don't expect this
# to accept no argument.
-# 4. having something like 'mkdir .' in the output is unsightly.
+# * having something like 'mkdir .' in the output is unsightly.
#
-# On NextStep and OpenStep, the 'mkdir' command does not
-# recognize any option. It will interpret all options as
-# directories to create.
AN_MAKEVAR([MKDIR_P], [AC_PROG_MKDIR_P])
AC_DEFUN_ONCE([AC_PROG_MKDIR_P],
[AC_REQUIRE_AUX_FILE([install-sh])dnl
if test ${ac_cv_path_mkdir+y}; then
MKDIR_P="$ac_cv_path_mkdir -p"
else
- # As a last resort, use the slow shell script. Don't cache a
- # value for MKDIR_P within a source directory, because that will
- # break other packages using the cache if that directory is
- # removed, or if the value is a relative name.
- MKDIR_P="$ac_install_sh -d"
+ # As a last resort, use plain mkdir -p,
+ # in the hope it doesn't have the bugs of ancient mkdir.
+ MKDIR_P='mkdir -p'
fi
fi
dnl status.m4 does special magic for MKDIR_P instead of AC_SUBST,
projects / thirdparty / autoconf.git / commitdiff
