fix: memrchr() is non-POSIX, check for it on configure

config

@@ -84,6 +84,25 @@ _NCHAN_UTIL_SRCS=" \
   $_nchan_util_dir/nchan_subrequest.c \
 "
 
+#do we have memrchr() on the platform?
+ngx_feature="memrchr()"
+ngx_feature_run=yes
+ngx_feature_incs=" \
+  #include <string.h> 
+  #include <stddef.h> 
+"
+ngx_feature_test=" \
+  const char *str = \"aboobar\"; \
+  const void *place = &str[4]; \
+  const void *found = memrchr(str, 'b', strlen(str)); \
+  if(place != found) { return 1; } \
+"
+. auto/feature
+
+if [ $ngx_found = no ]; then
+  _NCHAN_UTIL_SRCS="$_NCHAN_UTIL_SRCS  $_nchan_util_dir/memrchr.c"
+fi
+
 _NCHAN_STORE_SRCS="\
   ${ngx_addon_dir}/src/store/spool.c \
   ${ngx_addon_dir}/src/store/ngx_rwlock.c \
@@ -101,7 +120,6 @@ _NCHAN_SRCS="\
   $_NCHAN_STORE_SRCS \
 "
 
-
 ngx_module_incs=$ngx_addon_dir/src
 
 have=NGX_HTTP_HEADERS . auto/have

src/store/redis/redis_nodeset_parser.c

@@ -4,6 +4,7 @@
 #include "redis_nginx_adapter.h"
 
 #include <util/nchan_msg.h>
+#include <util/memrchr.h>
 #include <store/store_common.h>
 #include "redis_nodeset_parser.h"
 #include "redis_nodeset.h"

src/util/memrchr.c

@@ -0,0 +1,11 @@
+#include "memrchr.h"
+void *memrchr(const void *s, int c, size_t n) {
+  const char *start = s;
+  const char *end = &start[n]; //one too much on purpose
+  while(--end >= start) { //and this is why
+    if(c == *end) {
+      return (void *)end;
+    }
+  }
+  return NULL;
+}

src/util/memrchr.h

@@ -0,0 +1,8 @@
+#ifndef NCHAN_MEMRCHR_H
+#define NCHAN_MEMRCHR_H
+#include <string.h>
+#include <stddef.h>
+
+void *memrchr(const void *s, int c, size_t n);
+
+#endif /*NCHAN_MEMRCHR_H*/