From: Nick Bowler <nbowler@draconx.ca>
Date: Wed, 22 Apr 2015 01:47:44 +0000 (-0400)
Subject: Update DX_COMMAND_OUTPUT to handle newlines and backslashes.
X-Git-Url: http://git.draconx.ca/gitweb/dxcommon.git/commitdiff_plain/e5cf340e0235a578efb05d004ec1a230d3ddb987

Update DX_COMMAND_OUTPUT to handle newlines and backslashes.

The 'read' builtin eats backslashes from the input, so this macro fails
to properly handle output containing backslashes.  Since the -r option
is not portable according to the Autoconf manual, fix up the input by
escaping all backslashes.

While we're at it, remove the "feature" which converts newlines to
spaces because it seems rather silly.
---

diff --git a/m4/cmdout.m4 b/m4/cmdout.m4
index 5aa3925..90aa13e 100644
--- a/m4/cmdout.m4
+++ b/m4/cmdout.m4
@@ -1,4 +1,4 @@
-dnl Copyright © 2014 Nick Bowler
+dnl Copyright © 2014-2015 Nick Bowler
 dnl
 dnl License WTFPL2: Do What The Fuck You Want To Public License, version 2.
 dnl This is free software: you are free to do what the fuck you want to.
@@ -7,30 +7,30 @@ dnl There is NO WARRANTY, to the extent permitted by law.
 dnl DX_COMMAND_OUTPUT(variable, command, [action-if-ok], [action-if-failed])
 dnl
 dnl Helper to capture standard output of a shell command.  If the command
-dnl is successful then variable is assigned with its output (with newlines
-dnl converted to spaces), and action-if-ok is performed.  Otherwise, if
-dnl the command is unsuccessful, then variable is not changed, and
-dnl action-if-failed is performed.
+dnl is successful then variable is assigned with its output, and action-if-ok
+dnl is performed.  Otherwise, if the command is unsuccessful, then variable
+dnl is not changed, and action-if-failed is performed.
 AC_DEFUN([DX_COMMAND_OUTPUT], [AC_REQUIRE([_DX_COMMAND_OUTPUT_SETUP])dnl
-AS_IF([$2 >conftest.out 2>&AS_MESSAGE_LOG_FD],
-	[m4_do([dx_fn_cmdout_collect_output $1],
-		[m4_ifnblank([$3], [m4_newline([$3])])])],
-	[$4])
-rm -f conftest.out
-])
+AS_IF([$2 >conftest.do0 2>&AS_MESSAGE_LOG_FD],
+  [m4_do([dx_fn_cmdout_collect_output $1],
+    [m4_ifnblank([$3], [m4_newline([$3])])])],
+  [$4])
+rm -f conftest.do0 conftest.do1])
 
 AC_DEFUN_ONCE([_DX_COMMAND_OUTPUT_SETUP], [m4_divert_push([INIT_PREPARE])dnl
-# Helper function to store the contents of conftest.out into a shell variable.
+# Helper function to store the contents of conftest.do0 into a shell variable.
 dx_fn_cmdout_collect_output () {
   AS_UNSET([$][1])
-  exec 3<conftest.out
+  # Double up backslashes as they will be stripped by read.
+  sed 's/\\/\\\\/g' conftest.do0 >conftest.do1 || return
+  exec 3<conftest.do1
   _dx_save_IFS=$IFS
   IFS=
   while read _dx_tmp <&3
   do
-AS_VAR_SET_IF([$][1],
-	[AS_VAR_APPEND([$][1], [" $_dx_tmp"])],
-	[AS_VAR_SET([$][1], [$_dx_tmp])])
+    AS_VAR_SET_IF([$][1],
+      [AS_VAR_APPEND([$][1], ["$as_nl$_dx_tmp"])],
+      [AS_VAR_SET([$][1], [$_dx_tmp])])
   done
   IFS=$_dx_save_IFS
   exec 3<&-
diff --git a/tests/macros.at b/tests/macros.at
index f57ecae..a5c8c5d 100644
--- a/tests/macros.at
+++ b/tests/macros.at
@@ -78,3 +78,25 @@ TEST_AUTORECONF
 TEST_CONFIGURE
 
 AT_CLEANUP
+
+AT_SETUP([DX_COMMAND_OUTPUT])
+
+AT_DATA([expout],
+[[   leading whitespace
+trailing whitespace     @&t@
+embedded\ backslashes
+      @&t@
+backslash\
+newline
+]])
+
+TEST_CONFIGURE_AC(
+[[DX_COMMAND_OUTPUT([var], [cat expout])
+AS@&t@_ECHO(["$var"]) >test.out
+]])
+TEST_AUTORECONF
+TEST_CONFIGURE
+
+AT_CHECK([cat test.out], [0], [expout])
+
+AT_CLEANUP