From 9096c63b5deabeb4efb6d60582e61f0ac2672f35 Mon Sep 17 00:00:00 2001
From: Giorge Koulin <giorge.koulin@foundry.com>
Date: Fri, 31 Mar 2023 09:08:48 +0100
Subject: [PATCH] Build `nfd_portal.cpp` on older `glibc` and `dbus` APIs.

<sys/random.h> is available as of [glibc 2.25](https://sourceware.org/legacy-ml/libc-alpha/2017-02/msg00079.html). Add fallback implementation using `syscall` for older versions, adapted from [btzy/nativefiledialog-extended@44e63d5](https://github.com/btzy/nativefiledialog-extended/commit/44e63d5e57960b4312d185312686b966a40b65a2).
`dbus_message_iter_get_element_count` is available as of [D-Bus 1.9.16](https://launchpad.net/debian/+source/dbus/1.9.16-1). Fallback on counting elements manually.
---
 nfd/nfd_portal.cpp | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/nfd/nfd_portal.cpp b/nfd/nfd_portal.cpp
index 8ef9158f..61859e2a 100644
--- a/nfd/nfd_portal.cpp
+++ b/nfd/nfd_portal.cpp
@@ -14,8 +14,16 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/random.h>  // for the random token string
-#include <unistd.h>      // for access()
+#include <unistd.h>  // for access()
+
+#if !defined(__has_include) || !defined(__linux__)
+#include <sys/random.h>  // for getrandom() - the random token string
+#elif __has_include(<sys/random.h>)
+#include <sys/random.h>
+#else  // for GLIBC < 2.25
+#include <sys/syscall.h>
+#define getrandom(buf, sz, flags) syscall(SYS_getrandom, buf, sz, flags)
+#endif
 
 #include "nfd.h"
 
@@ -705,7 +713,17 @@ nfdpathsetsize_t ReadResponseUrisUncheckedGetArraySize(DBusMessage* msg) {
     nfdpathsetsize_t sz = 0;  // Initialization will never be used, but we initialize it to prevent
                               // the uninitialized warning otherwise.
     ReadDict(iter, "uris", [&sz](DBusMessageIter& uris_iter) {
+        // `dbus_message_iter_get_element_count` is available as of [D-Bus 1.9.16](https://launchpad.net/debian/+source/dbus/1.9.16-1).
+#if DBUS_MAJOR_VERSION > 1 || DBUS_MINOR_VERSION > 9 || (DBUS_MINOR_VERSION == 9 && DBUS_MINOR_VERSION >= 16)
         sz = dbus_message_iter_get_element_count(&uris_iter);
+#else // Otherwise fallback on counting elements manually.
+        sz = 0;
+        DBusMessageIter uri_iter;
+        dbus_message_iter_recurse(&uris_iter, &uri_iter);
+        do {
+            ++sz;
+        } while (dbus_message_iter_next(&uri_iter));
+#endif
         return NFD_OKAY;
     });
     return sz;