configure: check for bash

PCR Bank verification needs bash, so check for bash. While at it use the
autoconf shell construct macros over raw shell syntax which is slightly
more portable.

Examples:
./configure --enable-default-pcr-banks=sha256,sha920
checking which PCR banks to activate by default... configure: error: sha256,sha920 is an invalid list of PCR banks

./configure --enable-default-pcr-banks=sha256,sha512
checking which PCR banks to activate by default... sha256,sha512

./configure
checking which PCR banks to activate by default... sha256

Signed-off-by: William Roberts <william.c.roberts@intel.com>

diff --git a/configure.ac b/configure.ac
index 1d1b2e865a3ffdfdd4f21efa4d096801046ec2f7..a4e6d7f53f3c5812b467eb114051fc70e5693631 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -366,16 +366,22 @@ AC_ARG_ENABLE([default-pcr-banks],
               []
 )
 
-if test "x$enable_default_pcr_banks" != "x"; then
-    DEFAULT_PCR_BANKS="$enable_default_pcr_banks"
-fi
-AC_MSG_CHECKING([which PCR banks to activate by default])
-REGEX="^(sha1|sha256|sha384|sha512)(,(sha1|sha256|sha384|sha512)){0,3}\$"
-if bash -c "[[[ $DEFAULT_PCR_BANKS =~ $REGEX ]]] && exit 0 || exit 1"; then
-       AC_MSG_RESULT([$DEFAULT_PCR_BANKS])
-else
-       AC_MSG_ERROR([$DEFAULT_PCR_BANKS is an invalid list of PCR banks])
-fi
+AC_DEFUN([pcr_bank_checks], [
+    AC_CHECK_PROG([bash], [bash], [yes], [no])
+    AS_IF([test "x$bash" != "xyes"],
+      [AC_MSG_ERROR([PCR bank verification requires bash, but executable not found.])])
+
+    AC_MSG_CHECKING([which PCR banks to activate by default])
+    REGEX="^(sha1|sha256|sha384|sha512)(,(sha1|sha256|sha384|sha512)){0,3}\$"
+    AS_IF([bash -c "[[[ $DEFAULT_PCR_BANKS =~ $REGEX ]]] && exit 0 || exit 1"],
+        [AC_MSG_RESULT([$DEFAULT_PCR_BANKS])],
+        [AC_MSG_ERROR([$DEFAULT_PCR_BANKS is an invalid list of PCR banks])])
+])
+
+AS_IF([test "x$enable_default_pcr_banks" != "x"],[
+     DEFAULT_PCR_BANKS="$enable_default_pcr_banks"
+])
+pcr_bank_checks
 AC_SUBST([DEFAULT_PCR_BANKS])
 
 AC_PATH_PROG([EXPECT], expect)