Implemented handling of NETTLE_FAT_OVERRIDE, for arm.

ChangeLog

 2015-01-20  Niels Möller  <nisse@lysator.liu.se>
 
+	* fat-arm.c (get_arm_features): Check NETTLE_FAT_OVERRIDE
+	environment variable.
+
 	* fat-x86_64.c (get_x86_features): New function. Check
 	NETTLE_FAT_OVERRIDE environment variable.
 	(fat_init): Use it.

fat-arm.c

@@ -52,17 +52,44 @@ struct arm_features
   int have_neon;
 };
 
+#define SKIP(s, slen, literal, llen)				\
+  (((slen) >= (llen) && memcmp ((s), (literal), llen) == 0)	\
+   ? ((slen) -= (llen), (s) += (llen), 1) : 0)
+#define MATCH(s, slen, literal, llen)				\
+  ((slen) == (llen) && memcmp ((s), (literal), llen) == 0)
+
 static void
 get_arm_features (struct arm_features *features)
+{
+  const char *s;
+  features->arch_version = 5;
+  features->have_neon = 0;
+
+  s = secure_getenv (ENV_OVERRIDE);
+  if (s)
+    for (;;)
+      {
+	const char *sep = strchr (s, ',');
+	size_t length = sep ? (size_t) (sep - s) : strlen(s);
+
+	if (SKIP (s, length, "arch:", 5))
+	  {
+	    if (length == 1 && *s >= '0' && *s <= '9')
+	      features->arch_version = *s - '0';
+	  }
+	else if (MATCH (s, length, "neon", 4))
+	  features->have_neon = 1;
+	if (!sep)
+	  break;
+	s = sep + 1;
+      }
+  else
     {
       FILE *f;
       char line[200];
       int seen_arch = 0;
       int seen_features = 0;
 
-  features->arch_version = 5;
-  features->have_neon = 0;
-
       f = fopen ("/proc/cpuinfo", "r");
       if (!f)
 	return;
@@ -104,6 +131,7 @@ get_arm_features (struct arm_features *features)
 	}
       fclose (f);
     }
+}
 
 DECLARE_FAT_FUNC(_nettle_aes_encrypt, aes_crypt_internal_func)
 DECLARE_FAT_FUNC_VAR(aes_encrypt, aes_crypt_internal_func, arm)
@@ -127,9 +155,9 @@ fat_init (void)
 
   verbose = getenv (ENV_VERBOSE) != NULL;
   if (verbose)
-    fprintf (stderr,
-	     "libnettle: cpu arch: %u, neon: %s\n",
-	     features.arch_version, features.have_neon ? "yes" : "no");
+    fprintf (stderr, "libnettle: cpu features: arch:%d%s\n",
+	     features.arch_version,
+	     features.have_neon ? ",neon" : "");
 
   if (features.arch_version >= 6)
     {