diff options
Diffstat (limited to 'lib/m4sugar/m4sh.m4')
| -rw-r--r-- | lib/m4sugar/m4sh.m4 | 78 |
1 files changed, 52 insertions, 26 deletions
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4 index c9e86246..bd4d2b9e 100644 --- a/lib/m4sugar/m4sh.m4 +++ b/lib/m4sugar/m4sh.m4 @@ -300,6 +300,28 @@ dnl We shouldn't have to worry about any traps being active at this point. exit 255])# _AS_REEXEC_WITH_SHELL +# _AS_ENSURE_STANDARD_FDS +# ----------------------- +# Ensure that file descriptors 0, 1, and 2 are open, as a defensive +# measure against weird environments that run configure scripts +# with these descriptors closed. +# `exec m>&n` fails in POSIX sh when fd N is closed, but succeeds +# regardless of whether fd N is open in some old shells, e.g. Solaris +# /bin/sh. This is OK because those shells will be rejected by +# _AS_DETECT_BETTER_SHELL anyway. +# TODO post-2.70: use "backward" redirections when opening these fds, +# so we preserve their unusable state. Needs downstream logic to +# stop on the first failed attempt to write to fd 1 or 2, so we don't +# run through an entire configure script spewing "write error" +# messages when fd 1 is closed. +m4_defun([_AS_ENSURE_STANDARD_FDS], [dnl +# Ensure that fds 0, 1, and 2 are open. +if (exec 3>&0) 2>/dev/null; then :; else exec 0</dev/null; fi +if (exec 3>&1) 2>/dev/null; then :; else exec 1>/dev/null; fi +if (exec 3>&2) ; then :; else exec 2>/dev/null; fi +]) + + # _AS_PREPARE # ----------- # This macro has a very special status. Normal use of M4sh relies @@ -456,18 +478,42 @@ m4_defun([_AS_SHELL_SANITIZE], [m4_text_box([M4sh Initialization.]) AS_BOURNE_COMPATIBLE -_AS_PATH_SEPARATOR_PREPARE -# IFS -# We need space, tab and new line, in precisely that order. Quoting is -# there to prevent editors from complaining about space-tab. -# (If _AS_PATH_WALK were called with IFS unset, it would disable word -# splitting by setting IFS to empty value.) +# Reset variables that may have inherited troublesome values from +# the environment. + +# IFS needs to be set, to space, tab, and newline, in precisely that order. +# (If _AS_PATH_WALK were called with IFS unset, it would have the +# side effect of setting IFS to empty, thus disabling word splitting.) +# Quoting is to prevent editors from complaining about space-tab. as_nl=' ' export as_nl IFS=" "" $as_nl" +PS1='$ ' +PS2='> ' +PS4='+ ' + +# Ensure predictable behavior from utilities with locale-dependent output. +LC_ALL=C +export LC_ALL +LANGUAGE=C +export LANGUAGE + +# We cannot yet rely on "unset" to work, but we need these variables +# to be unset--not just set to an empty or harmless value--now, to +# avoid bugs in old shells (e.g. pre-3.0 UWIN ksh). This construct +# also avoids known problems related to "unset" and subshell syntax +# in other old shells (e.g. bash 2.01 and pdksh 5.2.14). +for as_var in BASH_ENV ENV MAIL MAILPATH CDPATH +do eval test \${$as_var+y} \ + && ( (unset $as_var) || exit 1) >/dev/null 2>&1 && unset $as_var || : +done + +_AS_ENSURE_STANDARD_FDS +_AS_PATH_SEPARATOR_PREPARE + # Find who we are. Look in the path if we contain no directory separator. as_myself= case $[0] in @%:@(( @@ -486,26 +532,6 @@ if test ! -f "$as_myself"; then AS_EXIT fi -# Unset variables that we do not need and which cause bugs (e.g. in -# pre-3.0 UWIN ksh). But do not cause bugs in bash 2.01; the "|| exit 1" -# suppresses any "Segmentation fault" message there. '((' could -# trigger a bug in pdksh 5.2.14. -for as_var in BASH_ENV ENV MAIL MAILPATH -do eval test \${$as_var+y} \ - && ( (unset $as_var) || exit 1) >/dev/null 2>&1 && unset $as_var || : -done -PS1='$ ' -PS2='> ' -PS4='+ ' - -# NLS nuisances. -LC_ALL=C -export LC_ALL -LANGUAGE=C -export LANGUAGE - -# CDPATH. -(unset CDPATH) >/dev/null 2>&1 && unset CDPATH _m4_popdef([AS_EXIT])])# _AS_SHELL_SANITIZE |