[gtk/ebassi/secure-buffer: 4/7] Check for mlock()

[Emmanuele Bassi <ebassi src gnome org>]

commit 1a0e8beed083af177c04cb6f0b3733b6966e4a59
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Sep 8 17:50:39 2020 +0100

    Check for mlock()
    
    We use it in the secure memory allocator, if it's available.

 config.h.meson | 3 +++
 meson.build    | 5 +++++
 2 files changed, 8 insertions(+)
---
diff --git a/config.h.meson b/config.h.meson
index f6a0ea0187..1968bb9cbe 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -69,6 +69,9 @@
 /* Define to 1 if you have the `mkstemp' function. */
 #mesondefine HAVE_MKSTEMP
 
+/* Define to 1 if you have the `mlock` function. */
+#mesondefine HAVE_MLOCK
+
 /* Define to 1 if you have a working `mmap' system call. */
 #mesondefine HAVE_MMAP
 
diff --git a/meson.build b/meson.build
index 88b3e7c0d5..aa1b6e5c77 100644
--- a/meson.build
+++ b/meson.build
@@ -217,6 +217,11 @@ if cc.compiles(uint128_t_src, name : '__uint128_t available')
   cdata.set('HAVE_UINT128_T', 1)
 endif
 
+# Check for mlock
+if cc.has_function('mlock', prefix: '#include <sys/mman.h>')
+  cdata.set('HAVE_MLOCK', 1)
+endif
+
 # Disable deprecation checks for all libraries we depend on on stable branches.
 # This is so newer versions of those libraries don't cause more warnings with
 # a stable GTK version.