cmake: detect "bounded" compiler attribute

Signed-off-by: Aris Adamantiadis <aris@0xbadc0de.be>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

ConfigureChecks.cmake

@@ -327,6 +327,11 @@ int main(void) {
 }" HAVE_COMPILER__FUNCTION__)
 
 
+check_c_source_compiles("
+void chacha_keysetup(struct chacha_ctx *x, const u_char *k, u_int kbits)
+    __attribute__((__bounded__(__minbytes__, 2, CHACHA_MINKEYLEN)));
+int main(void) { return 0; }" HAVE_GCC_BOUNDED_ATTRIBUTE)
+
 if (WITH_DEBUG_CRYPTO)
   set(DEBUG_CRYPTO 1)
 endif (WITH_DEBUG_CRYPTO)

config.h.cmake

@@ -199,6 +199,8 @@
 #cmakedefine HAVE_COMPILER__FUNC__ 1
 #cmakedefine HAVE_COMPILER__FUNCTION__ 1
 
+#cmakedefine HAVE_GCC_BOUNDED_ATTRIBUTE 1
+
 /* Define to 1 if you want to enable GSSAPI */
 #cmakedefine WITH_GSSAPI 1
 

include/libssh/chacha.h

@@ -20,13 +20,22 @@ struct chacha_ctx {
 #define CHACHA_BLOCKLEN   64
 
 void chacha_keysetup(struct chacha_ctx *x, const uint8_t *k, uint32_t kbits)
-    __attribute__((__bounded__(__minbytes__, 2, CHACHA_MINKEYLEN)));
+#ifdef HAVE_GCC_BOUNDED_ATTRIBUTE
+    __attribute__((__bounded__(__minbytes__, 2, CHACHA_MINKEYLEN)))
+#endif
+    ;
 void chacha_ivsetup(struct chacha_ctx *x, const uint8_t *iv, const uint8_t *ctr)
+#ifdef HAVE_GCC_BOUNDED_ATTRIBUTE
     __attribute__((__bounded__(__minbytes__, 2, CHACHA_NONCELEN)))
-    __attribute__((__bounded__(__minbytes__, 3, CHACHA_CTRLEN)));
+    __attribute__((__bounded__(__minbytes__, 3, CHACHA_CTRLEN)))
+#endif
+    ;
 void chacha_encrypt_bytes(struct chacha_ctx *x, const uint8_t *m,
     uint8_t *c, uint32_t bytes)
+#ifdef HAVE_GCC_BOUNDED_ATTRIBUTE
     __attribute__((__bounded__(__buffer__, 2, 4)))
-    __attribute__((__bounded__(__buffer__, 3, 4)));
+    __attribute__((__bounded__(__buffer__, 3, 4)))
+#endif
+    ;
 
 #endif    /* CHACHA_H */

include/libssh/poly1305.h

@@ -11,8 +11,11 @@
 
 void poly1305_auth(uint8_t out[POLY1305_TAGLEN], const uint8_t *m, size_t inlen,
     const uint8_t key[POLY1305_KEYLEN])
+#ifdef HAVE_GCC_BOUNDED_ATTRIBUTE
     __attribute__((__bounded__(__minbytes__, 1, POLY1305_TAGLEN)))
     __attribute__((__bounded__(__buffer__, 2, 3)))
-    __attribute__((__bounded__(__minbytes__, 4, POLY1305_KEYLEN)));
+    __attribute__((__bounded__(__minbytes__, 4, POLY1305_KEYLEN)))
+#endif
+    ;
 
 #endif	/* POLY1305_H */