[PATCH 3/5] autoconf: Preliminary check for working mmap

[Jakub Narebski <jnareb@gmail.com>]

Use AC_FUNC_MMAP check to check if the `mmap' function exists and
works correctly.  (It only checks private fixed mapping of
already-mapped memory.)

Still it is better than having no mmap check at all.
Attention: uses implementation detail of AC_FUNC_MMAP!

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
This patch sent earlier in other patch series and dropped,
as git uses private mapping, not private fixed. I think
that this check is better than no check at all...

 config.mak.in |    2 +-
 configure.ac  |    7 +++++++
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/config.mak.in b/config.mak.in
index 2947560..2c8fd2c 100644
--- a/config.mak.in
+++ b/config.mak.in
@@ -37,6 +37,6 @@ NO_C99_FORMAT=@NO_C99_FORMAT@
 NO_STRCASESTR=@NO_STRCASESTR@
 NO_STRLCPY=@NO_STRLCPY@
 NO_SETENV=@NO_SETENV@
-#NO_MMAP=@NO_MMAP@
+NO_MMAP=@NO_MMAP@
 #NO_ICONV=@NO_ICONV@
 
diff --git a/configure.ac b/configure.ac
index fc5b813..799321e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -249,6 +249,13 @@ AC_CHECK_FUNC(setenv,
 AC_SUBST(NO_SETENV)
 #
 # Define NO_MMAP if you want to avoid mmap.
+AC_FUNC_MMAP
+if test $ac_cv_func_mmap_fixed_mapped != yes; then
+	NO_MMAP=YesPlease
+else
+	NO_MMAP=
+fi
+AC_SUBST(NO_MMAP)
 #
 # Define NO_ICONV if your libc does not properly support iconv.
 
-- 
1.4.1.1