Use ./configure to detect arc4random and use it if present

Makefile.in

@@ -5,6 +5,7 @@
 # -----------------------------------
 
 CFLAGS+=-pthread -O2
+CFLAGS+=@LIBS@
 
 all: fiche
 

config.h.in

@@ -0,0 +1,2 @@
+#undef HAVE_ARC4RANDOM
+

configure.in

@@ -0,0 +1,20 @@
+AC_INIT([fiche], [0.99])
+AC_CONFIG_SRCDIR([fiche.c])
+AC_CONFIG_HEADERS([config.h])
+
+# Checks for programs.
+AC_PROG_CC
+
+# Function arc4random() is in BSD standard C or GNU systems -lbsd
+AC_SEARCH_LIBS([arc4random], [bsd], [HAVE_ARC4RANDOM="yes"])
+
+# Checks for library functions.
+AC_CHECK_FUNCS([bzero arc4random])
+
+AC_SUBST(HAVE_ARC4RANDOM)
+
+AC_CONFIG_FILES([Makefile])
+AC_OUTPUT
+
+
+

fiche.c

@@ -27,6 +27,7 @@ $ cat fiche.c | nc localhost 9999
 */
 
 #include <sys/param.h>
+#include "config.h"
 #include "fiche.h"
 
 int main(int argc, char **argv)
@@ -274,7 +275,7 @@ void generate_url(char *buffer, char *slug, size_t slug_length, struct client_da
 
     for (i = 0; i <= SLUG_SIZE - 1; i++)
     {
-#if defined(BSD)
+#if defined(HAVE_ARC4RANDOM)
 	int symbol_id = arc4random() % strlen(symbols);
 #else
         int symbol_id = rand_r(&time_seed) % strlen(symbols);
@@ -284,7 +285,7 @@ void generate_url(char *buffer, char *slug, size_t slug_length, struct client_da
 
     while (create_directory(slug) == -1)
     {
-#if defined(BSD)
+#if defined(HAVE_ARC4RANDOM)
 	int symbol_id = arc4random() % strlen(symbols);
 #else
         int symbol_id = rand_r(&time_seed) % strlen(symbols);