From 096220df5d30ed92e2280731f98fd8014d78c44d Mon Sep 17 00:00:00 2001
From: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
Date: Sun, 1 Nov 2009 01:04:31 +0100
Subject: [PATCH] Micro-optimization of config.status substitution.

* lib/autoconf/status.m4 (_AC_OUTPUT_FILES_PREPARE): No need to
concatenate an empty second string, when we have exactly 148
characters to substitute.
* tests/torture.at (Substitute a 2000-byte string): Add test
exposure for runs of backslashes near the 148 character limit.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
---
 ChangeLog              |  7 +++++++
 lib/autoconf/status.m4 |  4 ++--
 tests/torture.at       | 38 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 39854166..2640226d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2009-10-31  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
+	Micro-optimization of config.status substitution.
+	* lib/autoconf/status.m4 (_AC_OUTPUT_FILES_PREPARE): No need to
+	concatenate an empty second string, when we have exactly 148
+	characters to substitute.
+	* tests/torture.at (Substitute a 2000-byte string): Add test
+	exposure for runs of backslashes near the 148 character limit.
+
 	Fix testsuite failure on AIX 4.3.3.
 	* lib/autoconf/general.m4 (_AC_RUN_LOG_LIMIT): Remove conftest.err
 	also if it is empty.
diff --git a/lib/autoconf/status.m4 b/lib/autoconf/status.m4
index 84ee6c3d..e921d97f 100644
--- a/lib/autoconf/status.m4
+++ b/lib/autoconf/status.m4
@@ -462,7 +462,7 @@ s/'"$ac_delim"'$//
 t delim
 :nl
 h
-s/\(.\{]_AC_AWK_LITERAL_LIMIT[\}\).*/\1/
+s/\(.\{]_AC_AWK_LITERAL_LIMIT[\}\)..*/\1/
 t more1
 s/["\\]/\\&/g; s/^/"/; s/$/\\n"\\/
 p
@@ -476,7 +476,7 @@ s/.\{]_AC_AWK_LITERAL_LIMIT[\}//
 t nl
 :delim
 h
-s/\(.\{]_AC_AWK_LITERAL_LIMIT[\}\).*/\1/
+s/\(.\{]_AC_AWK_LITERAL_LIMIT[\}\)..*/\1/
 t more2
 s/["\\]/\\&/g; s/^/"/; s/$/"/
 p
diff --git a/tests/torture.at b/tests/torture.at
index 8f220131..ea3acd49 100644
--- a/tests/torture.at
+++ b/tests/torture.at
@@ -729,6 +729,9 @@ AT_CLEANUP
 # So we'll just test a 2000-byte value, and for awk, we test a line with
 # almost 1000 words, and one variable with 5 lines of 2000 bytes each:
 # multi-line values should allow to get around the limitations.
+# We also test runs of around 148 backslashes: they need to be escaped,
+# and 148 is the portable limit for awk string literals.  config.status
+# uses concatenation to generate longer strings.
 
 AT_SETUP([Substitute a 2000-byte string])
 
@@ -738,6 +741,13 @@ AT_DATA([Bar.in], [@bar@
 ])
 AT_DATA([Baz.in], [@baz@
 ])
+AT_DATA([Boo.in], [@b147@
+@b148@
+@b149@
+@b295@
+@b296@
+@b297@
+])
 
 AT_DATA([configure.ac],
 [[AC_INIT
@@ -747,13 +757,38 @@ baz="]m4_for([m], 1, 100,, ... ... ... ... ....)[
 "
 baz=$baz$baz$baz$baz$baz
 AC_SUBST([baz])
+b29='\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'
+b147=$b29$b29$b29$b29$b29'\\'
+b148=$b147'\'
+b149=$b148'\'
+b295=$b147$b147'\'
+b296=$b295'\'
+b297=$b296'\'
+AC_SUBST([b147])
+AC_SUBST([b148])
+AC_SUBST([b149])
+AC_SUBST([b295])
+AC_SUBST([b296])
+AC_SUBST([b297])
 AC_PROG_AWK
-AC_CONFIG_FILES([Foo Bar Baz])
+AC_CONFIG_FILES([Foo Bar Baz Boo])
 AC_OUTPUT
 ]])
 
 cp "$abs_top_srcdir/build-aux/install-sh" .
 
+b29='\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'
+b147=$b29$b29$b29$b29$b29'\\'
+b295=$b147$b147'\'
+cat >Boo-exp <<EOF
+$b147
+$b147\\
+$b147\\\\
+$b295
+$b295\\
+$b295\\\\
+EOF
+
 AT_CHECK_AUTOCONF
 # Check both awk and the result of AC_PROG_AWK
 for awk_arg in Foo= AWK=awk; do
@@ -766,6 +801,7 @@ for awk_arg in Foo= AWK=awk; do
   [m4_for([n], 1, 5,, m4_for([m], 1, 100,, ... ... ... ... ....)
 )])
   AT_CHECK([cat Baz], 0, [stdout])
+  AT_CHECK([diff Boo-exp Boo])
 done
 AT_CLEANUP
 
-- 
2.47.2