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[PATCH] m4sh: allow trailing newlines in shell conditions
From: |
Eric Blake |
Subject: |
[PATCH] m4sh: allow trailing newlines in shell conditions |
Date: |
Thu, 17 Jul 2014 15:14:33 -0600 |
Dimitrios Apostolou reported confusion in understanding why
his configure.ac was generating a shell syntax error with:
AM_CONDITIONAL([HAVE_LIBXML2],
[test "x$with_libxml2" != xno &&
test "x$ac_cv_lib_xml2_xmlFirstElementChild" = xyes]
)
Root cause was that his trailing newline, coupled with a
'if $2; then' construct in the macro body, resulted in
configure containing:
if test ... xyes
; then
where the semicolon is a syntax error in shell.
While that macro is not under our control, it does highlight
the fact that the shell can use either ; or newline to
terminate a conditional prior to the next keyword in a compound
statement. If we use newline, we gain two benefits - the
configure file is slightly smaller (more lines, but fewer
bytes), and any user that doesn't realize that unquoted
trailing newlines in a macro argument are still significant
can still generate valid shell code when their argument is
used in a shell compound statement.
* lib/m4sugar/m4sh.m4 (AS_IF, _AS_IF, _AS_CLEAN_DIR): Prefer
newline over semicolon to end user-supplied conditionals.
* lib/autoconf/general.m4 (AC_CONFIG_AUX_DIRS): Likewise.
* lib/autoconf/libs.m4 (AC_SEARCH_LIBS): Likewise.
* lib/autoconf/programs.m4 (_AC_PATH_PROGS_FEATURE_CHECK):
Likewise.
* tests/m4sh.at (AS_IF and AS_CASE): Test it.
Signed-off-by: Eric Blake <address@hidden>
---
lib/autoconf/general.m4 | 3 ++-
lib/autoconf/libs.m4 | 3 ++-
lib/autoconf/programs.m4 | 3 ++-
lib/m4sugar/m4sh.m4 | 15 ++++++++++-----
tests/m4sh.at | 4 ++++
5 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index 696a9a1..59d204f 100644
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -1700,7 +1700,8 @@ AC_DEFUN([AC_CONFIG_AUX_DIR_DEFAULT],
# do not automatically need to distribute the other auxiliary files.
AC_DEFUN([AC_CONFIG_AUX_DIRS],
[ac_aux_dir=
-for ac_dir in $1; do
+for ac_dir in $1
+do
if test -f "$ac_dir/install-sh"; then
ac_aux_dir=$ac_dir
ac_install_sh="$ac_aux_dir/install-sh -c"
diff --git a/lib/autoconf/libs.m4 b/lib/autoconf/libs.m4
index 50143d3..55e9468 100644
--- a/lib/autoconf/libs.m4
+++ b/lib/autoconf/libs.m4
@@ -49,7 +49,8 @@ AC_DEFUN([AC_SEARCH_LIBS],
AC_CACHE_CHECK([for library containing $1], [ac_Search],
[ac_func_search_save_LIBS=$LIBS
AC_LANG_CONFTEST([AC_LANG_CALL([], [$1])])
-for ac_lib in '' $2; do
+for ac_lib in '' $2
+do
if test -z "$ac_lib"; then
ac_res="none required"
else
diff --git a/lib/autoconf/programs.m4 b/lib/autoconf/programs.m4
index cdd86ea..32f737a 100644
--- a/lib/autoconf/programs.m4
+++ b/lib/autoconf/programs.m4
@@ -421,7 +421,8 @@ m4_define([_AC_PATH_PROGS_FEATURE_CHECK],
ac_path_$1_found=false
# Loop through the user's path and test for each of PROGNAME-LIST
_AS_PATH_WALK([$5],
- [for ac_prog in $2; do
+ [for ac_prog in $2
+ do
for ac_exec_ext in '' $ac_executable_extensions; do
ac_path_$1="$as_dir$ac_prog$ac_exec_ext"
AS_EXECUTABLE_P(["$ac_path_$1"]) || continue
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index 91cdeac..a94999e 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -618,9 +618,11 @@ done[]_m4_popdef([$1])])
# AS_IF(TEST1, [IF-TRUE1 = :]...[IF-FALSE = :])
# ---------------------------------------------
# Expand into
-# | if TEST1; then
+# | if TEST1
+# | then
# | IF-TRUE1
-# | elif TEST2; then
+# | elif TEST2
+# | then
# | IF-TRUE2
# [...]
# | else
@@ -629,7 +631,8 @@ done[]_m4_popdef([$1])])
# with simplifications when IF-TRUE1 and/or IF-FALSE are empty.
#
m4_define([_AS_IF],
-[elif $1; then :
+[elif $1
+then :
$2
])
m4_define([_AS_IF_ELSE],
@@ -639,7 +642,8 @@ m4_define([_AS_IF_ELSE],
])])
m4_defun([AS_IF],
-[if $1; then :
+[if $1
+then :
$2
m4_map_args_pair([_$0], [_$0_ELSE], m4_shift2($@))]dnl
[fi[]])# AS_IF
@@ -1389,7 +1393,8 @@ _ASBOX])
# Remove all contents from within DIR, including any unwritable
# subdirectories, but leave DIR itself untouched.
m4_define([_AS_CLEAN_DIR],
-[if test -d $1; then
+[if test -d $1
+then
find $1 -type d ! -perm -700 -exec chmod u+rwx {} \;
rm -fr $1/* $1/.[[!.]] $1/.??*
fi])
diff --git a/tests/m4sh.at b/tests/m4sh.at
index 5d3b194..5893389 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -1244,6 +1244,9 @@ AS_IF([false], [:], [ ]) && AS_CASE([foo], [foo], []
) && echo seventeen
m4_define([empty])AS_IF([:], [empty]
) && AS_CASE([foo], [foo], [empty]) && echo eighteen
+dnl Allow for users that don't know to avoid trailing whitespace
+AS_IF([:
+], [echo nineteen])
dnl We can't handle AS_IF([false], [:], [empty]) unless m4_expand is
dnl taught how to handle m4_require. The user is responsible for
dnl avoiding the syntax error in that case.
@@ -1301,6 +1304,7 @@ fifteen
sixteen
seventeen
eighteen
+nineteen
foo1=1 bar1=1
foo2=2 bar2=
foo3=3 bar3=
--
1.9.3
- [PATCH] m4sh: allow trailing newlines in shell conditions,
Eric Blake <=