cutils: Provide strchrnul

strchrnul is a GNU extension and thus unavailable on a number of targets.
In the review for a commit removing strchrnul from 9p, I was asked to
create a qemu_strchrnul helper to factor out this functionality.
Do so, and use it in a number of other places in the code base that inlined
the replacement pattern in a place where strchrnul could be used.

Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Greg Kurz <groug@kaod.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/configure b/configure
index 4d12cfbe3f..26944a74be 100755
--- a/configure
+++ b/configure
@@ -4794,6 +4794,21 @@ if compile_prog "" "" ; then
 fi
 
 ##########################################
+# check if we have strchrnul
+
+strchrnul=no
+cat > $TMPC << EOF
+#include <string.h>
+int main(void);
+// Use a haystack that the compiler shouldn't be able to constant fold
+char *haystack = (char*)&main;
+int main(void) { return strchrnul(haystack, 'x') != &haystack[6]; }
+EOF
+if compile_prog "" "" ; then
+    strchrnul=yes
+fi
+
+##########################################
 # check if trace backend exists
 
 $python "$source_path/scripts/tracetool.py" "--backends=$trace_backends" --check-backends  > /dev/null 2> /dev/null
@@ -6276,6 +6291,9 @@ fi
 if test "$sem_timedwait" = "yes" ; then
   echo "CONFIG_SEM_TIMEDWAIT=y" >> $config_host_mak
 fi
+if test "$strchrnul" = "yes" ; then
+  echo "HAVE_STRCHRNUL=y" >> $config_host_mak
+fi
 if test "$byteswap_h" = "yes" ; then
   echo "CONFIG_BYTESWAP_H=y" >> $config_host_mak
 fi