libcamera: shared_mem_object: Fix compilation with uClibc

uClibc doesn't provide a memfd_create() implementation. Fix it by using
a direct syscall when the function isn't available.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/meson.build b/meson.build
index 740ead1b..39e4947f 100644
--- a/meson.build
+++ b/meson.build
@@ -82,6 +82,10 @@ if cc.has_header_symbol('locale.h', 'locale_t', prefix : '#define _GNU_SOURCE')
     config_h.set('HAVE_LOCALE_T', 1)
 endif
 
+if cc.has_header_symbol('sys/mman.h', 'memfd_create', prefix : '#define _GNU_SOURCE')
+    config_h.set('HAVE_MEMFD_CREATE', 1)
+endif
+
 if cc.has_header_symbol('stdlib.h', 'secure_getenv', prefix : '#define _GNU_SOURCE')
     config_h.set('HAVE_SECURE_GETENV', 1)
 endif
diff --git a/src/libcamera/shared_mem_object.cpp b/src/libcamera/shared_mem_object.cpp
index b018fb3b..e8cb59f7 100644
--- a/src/libcamera/shared_mem_object.cpp
+++ b/src/libcamera/shared_mem_object.cpp
@@ -12,6 +12,8 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -56,7 +58,11 @@ SharedMem::SharedMem() = default;
  */
 SharedMem::SharedMem(const std::string &name, std::size_t size)
 {
+#if HAVE_MEMFD_CREATE
 	int fd = memfd_create(name.c_str(), MFD_CLOEXEC);
+#else
+	int fd = syscall(SYS_memfd_create, name.c_str(), MFD_CLOEXEC);
+#endif
 	if (fd < 0)
 		return;