Introduce portable.h for ugly hacks

The plan is to hide non-standard stuff in here.  Currently, just
has [[maybe-unused]] from C23.

src/ssh/portable.h

+#ifndef DEUCE_SSH_PLATWRAP_H
+#define DEUCE_SSH_PLATWRAP_H
+
+/*
+ * This file is here to hold all the ugly compiler and platform
+ * "stuff" that ends up being needed.
+ */
+
+#ifdef __has_c_attribute
+ #if __has_c_attribute(maybe_unused)
+  #define MAYBE_UNUSED [[maybe_unused]]
+ #endif
+#endif
+
+#ifndef MAYBE_UNUSED
+ #define MAYBE_UNUSED
+#endif
+
+#endif

src/ssh/ssh-arch.c

@@ -28,7 +28,7 @@ deuce_ssh_serialized_byte_length(deuce_ssh_byte_t val)
 }
 
 void
-deuce_ssh_serialize_byte(deuce_ssh_byte_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_byte(deuce_ssh_byte_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 1 <= bufsz);
 	buf[*pos] = val;
@@ -54,7 +54,7 @@ deuce_ssh_serialized_boolean_length(deuce_ssh_boolean_t val)
 }
 
 void
-deuce_ssh_serialize_boolean(deuce_ssh_boolean_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_boolean(deuce_ssh_boolean_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 1 <= bufsz);
 	buf[*pos] = val;
@@ -78,7 +78,7 @@ deuce_ssh_serialized_uint32_length(deuce_ssh_uint32_t val)
 }
 
 void
-deuce_ssh_serialize_uint32(deuce_ssh_uint32_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_uint32(deuce_ssh_uint32_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 4 <= bufsz);
 	buf[(*pos)++] = (val >> 24) & 0xff;
@@ -106,7 +106,7 @@ deuce_ssh_serialized_uint64_length(deuce_ssh_uint64_t val)
 }
 
 void
-deuce_ssh_serialize_uint64(deuce_ssh_uint64_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_uint64(deuce_ssh_uint64_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 8 <= bufsz);
 	buf[(*pos)++] = (val >> 56) & 0xff;
@@ -156,7 +156,7 @@ deuce_ssh_serialized_string_length(deuce_ssh_string_t val)
 }
 
 void
-deuce_ssh_serialize_string(deuce_ssh_string_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_string(deuce_ssh_string_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 4 + val->length <= bufsz);
 	deuce_ssh_serialize_uint32(val->length, buf, bufsz, pos);
@@ -197,7 +197,7 @@ deuce_ssh_serialized_mpint_length(deuce_ssh_mpint_t val)
 }
 
 void
-deuce_ssh_serialize_mpint(deuce_ssh_mpint_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_mpint(deuce_ssh_mpint_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(*pos + 4 <= bufsz);
 	*pos += BN_bn2mpi(val, &buf[*pos]);
@@ -272,7 +272,7 @@ deuce_ssh_serialized_namelist_length(deuce_ssh_namelist_t val)
 }
 
 void
-deuce_ssh_serialize_namelist(deuce_ssh_namelist_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos)
+deuce_ssh_serialize_namelist(deuce_ssh_namelist_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos)
 {
 	assert(bufsz >= 4);
 

src/ssh/ssh-arch.h

@@ -8,6 +8,8 @@
 
 #include <openssl/bn.h>
 
+#include "portable.h"
+
 // SSH Data Types (internal representations)
 typedef uint8_t deuce_ssh_byte_t;
 typedef bool deuce_ssh_boolean_t;
@@ -52,30 +54,30 @@ typedef struct deuce_ssh_namelist {
 
 ssize_t deuce_ssh_parse_byte(uint8_t * buf, size_t bufsz, deuce_ssh_byte_t *val);
 size_t deuce_ssh_serialized_byte_length(deuce_ssh_byte_t val);
-void deuce_ssh_serialize_byte(deuce_ssh_byte_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_byte(deuce_ssh_byte_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_boolean(uint8_t * buf, size_t bufsz, deuce_ssh_boolean_t *val);
 size_t deuce_ssh_serialized_boolean_length(deuce_ssh_boolean_t val);
-void deuce_ssh_serialize_boolean(deuce_ssh_boolean_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_boolean(deuce_ssh_boolean_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_uint32(uint8_t * buf, size_t bufsz, deuce_ssh_uint32_t *val);
 size_t deuce_ssh_serialized_uint32_length(deuce_ssh_uint32_t val);
-void deuce_ssh_serialize_uint32(deuce_ssh_uint32_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_uint32(deuce_ssh_uint32_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_uint64(uint8_t * buf, size_t bufsz, deuce_ssh_uint64_t *val);
 size_t deuce_ssh_serialized_uint64_length(deuce_ssh_uint64_t val);
-void deuce_ssh_serialize_uint64(deuce_ssh_uint64_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_uint64(deuce_ssh_uint64_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_string(uint8_t * buf, size_t bufsz, deuce_ssh_string_t *val);
 size_t deuce_ssh_serialized_string_length(deuce_ssh_string_t val);
-void deuce_ssh_serialize_string(deuce_ssh_string_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_string(deuce_ssh_string_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_mpint(uint8_t * buf, size_t bufsz, deuce_ssh_mpint_t *val);
 size_t deuce_ssh_serialized_mpint_length(deuce_ssh_mpint_t val);
-void deuce_ssh_serialize_mpint(deuce_ssh_mpint_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_mpint(deuce_ssh_mpint_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 ssize_t deuce_ssh_parse_namelist(uint8_t * buf, size_t bufsz, deuce_ssh_namelist_t *val);
 size_t deuce_ssh_serialized_namelist_length(deuce_ssh_namelist_t val);
-void deuce_ssh_serialize_namelist(deuce_ssh_namelist_t val, uint8_t *buf, [[maybe_unused]] size_t bufsz, size_t *pos);
+void deuce_ssh_serialize_namelist(deuce_ssh_namelist_t val, uint8_t *buf, MAYBE_UNUSED size_t bufsz, size_t *pos);
 
 #endif