[gtk: 2/3] meson: check for madvise()

[Emmanuele Bassi <ebassi src gnome org>]

commit b27ec5ebde495e3d83d63a87a32d136c5f22fa37
Author: Jason Francis <jason@cycles.network>
Date:   Sat Apr 17 19:28:36 2021 -0400

    meson: check for madvise()

 config.h.meson        | 3 +++
 gtk/gtksecurememory.c | 2 +-
 meson.build           | 5 ++++-
 3 files changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/config.h.meson b/config.h.meson
index fc2dd0b3d2..bc1d778f2c 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -76,6 +76,9 @@
 /* Define to 1 if you have a working `mmap' system call. */
 #mesondefine HAVE_MMAP
 
+/* Define to 1 if you have a working `madvise' system call. */
+#mesondefine HAVE_MADVISE
+
 /* Define to 1 if you have the `posix_fallocate' function. */
 #mesondefine HAVE_POSIX_FALLOCATE
 
diff --git a/gtk/gtksecurememory.c b/gtk/gtksecurememory.c
index 6dff307e65..a7aa34c447 100644
--- a/gtk/gtksecurememory.c
+++ b/gtk/gtksecurememory.c
@@ -943,7 +943,7 @@ sec_acquire_pages (size_t *sz,
 
        DEBUG_ALLOC ("gtk-secure-memory: new block ", *sz);
 
-#if defined(MADV_DONTDUMP)
+#if defined(HAVE_MADVISE) && defined(MADV_DONTDUMP)
        if (madvise (pages, *sz, MADV_DONTDUMP) < 0) {
                if (show_warning && gtk_secure_warnings) {
                        /*
diff --git a/meson.build b/meson.build
index 641208158c..d802838d09 100644
--- a/meson.build
+++ b/meson.build
@@ -220,10 +220,13 @@ if cc.compiles(uint128_t_src, name : '__uint128_t available')
   cdata.set('HAVE_UINT128_T', 1)
 endif
 
-# Check for mlock
+# Check for mlock and madvise
 if cc.has_function('mlock', prefix: '#include <sys/mman.h>')
   cdata.set('HAVE_MLOCK', 1)
 endif
+if cc.has_function('madvise', prefix: '#include <sys/mman.h>')
+  cdata.set('HAVE_MADVISE', 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