process: Use environ from unistd.h if available

CMakeLists.txt

@@ -263,7 +263,9 @@ if(NOT WIN32)
 		check_symbol_exists(utimes "sys/time.h" INNOEXTRACT_HAVE_UTIMES)
 	endif()
 	check_symbol_exists(posix_spawnp "spawn.h" INNOEXTRACT_HAVE_POSIX_SPAWNP)
-	if(NOT INNOEXTRACT_HAVE_POSIX_SPAWNP)
+	if(INNOEXTRACT_HAVE_POSIX_SPAWNP)
+		check_symbol_exists(environ "unistd.h" INNOEXTRACT_HAVE_UNISTD_ENVIRON)
+	else()
 		check_symbol_exists(fork "unistd.h" INNOEXTRACT_HAVE_FORK)
 		check_symbol_exists(execvp "unistd.h" INNOEXTRACT_HAVE_EXECVP)
 	endif()

src/configure.hpp.in

@@ -41,6 +41,7 @@
 
 // Process functions
 #cmakedefine01 INNOEXTRACT_HAVE_POSIX_SPAWNP
+#cmakedefine01 INNOEXTRACT_HAVE_UNISTD_ENVIRON
 #cmakedefine01 INNOEXTRACT_HAVE_FORK
 #cmakedefine01 INNOEXTRACT_HAVE_EXECVP
 #cmakedefine01 INNOEXTRACT_HAVE_WAITPID

src/util/process.cpp

@@ -37,6 +37,7 @@
 
 #if INNOEXTRACT_HAVE_POSIX_SPAWNP
 #include <spawn.h>
+#if !INNOEXTRACT_HAVE_UNISTD_ENVIRON
 extern "C" {
 #if defined(__FreeBSD__) && defined(__GNUC__) && __GNUC__ >= 4
 /*
@@ -48,7 +49,10 @@ extern char ** environ __attribute__((visibility("default")));
 extern char ** environ;
 #endif
 }
-#else
+#endif
+#endif
+
+#if INNOEXTRACT_HAVE_UNISTD_ENVIRON || (INNOEXTRACT_HAVE_FORK && INNOEXTRACT_HAVE_EXECVP)
 #include <unistd.h>
 #endif