v4l2: v4l2_compat: Selectively disable -Wmissing-declarations

_FORTIFY_SOURCE redirects the open*() calls to __open*_2() functions.
The libcamera V4L2 adaptation layer intercepts those functions to
support applications compiled with _FORTIFY_SOURCE. When _FORTIFY_SOURCE
is not enabled, the C library headers will not provide declarations for
the fortified functions, which will cause missing declaration warnings
when we unable them.

Fix this by disabling the -Wmissing-declarations warnings selectively
for the _FORTIFY_SOURCE functions. To avoid sparkling pragmas around,
move the relevant function definitions next to each other.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 29 insertions, 20 deletions

diff --git a/src/v4l2/v4l2_compat.cpp b/src/v4l2/v4l2_compat.cpp
index db8c465c..66468bf3 100644
--- a/src/v4l2/v4l2_compat.cpp
+++ b/src/v4l2/v4l2_compat.cpp
@@ -56,13 +56,6 @@ LIBCAMERA_PUBLIC int open(const char *path, int oflag, ...)
 						     oflag, mode);
 }
 
-/* _FORTIFY_SOURCE redirects open to __open_2 */
-LIBCAMERA_PUBLIC int __open_2(const char *path, int oflag)
-{
-	assert(!needs_mode(oflag));
-	return open(path, oflag);
-}
-
 #ifndef open64
 LIBCAMERA_PUBLIC int open64(const char *path, int oflag, ...)
 {
@@ -73,12 +66,6 @@ LIBCAMERA_PUBLIC int open64(const char *path, int oflag, ...)
 	return V4L2CompatManager::instance()->openat(AT_FDCWD, path,
 						     oflag | O_LARGEFILE, mode);
 }
-
-LIBCAMERA_PUBLIC int __open64_2(const char *path, int oflag)
-{
-	assert(!needs_mode(oflag));
-	return open64(path, oflag);
-}
 #endif
 
 LIBCAMERA_PUBLIC int openat(int dirfd, const char *path, int oflag, ...)
@@ -90,12 +77,6 @@ LIBCAMERA_PUBLIC int openat(int dirfd, const char *path, int oflag, ...)
 	return V4L2CompatManager::instance()->openat(dirfd, path, oflag, mode);
 }
 
-LIBCAMERA_PUBLIC int __openat_2(int dirfd, const char *path, int oflag)
-{
-	assert(!needs_mode(oflag));
-	return openat(dirfd, path, oflag);
-}
-
 #ifndef openat64
 LIBCAMERA_PUBLIC int openat64(int dirfd, const char *path, int oflag, ...)
 {
@@ -106,13 +87,41 @@ LIBCAMERA_PUBLIC int openat64(int dirfd, const char *path, int oflag, ...)
 	return V4L2CompatManager::instance()->openat(dirfd, path,
 						     oflag | O_LARGEFILE, mode);
 }
+#endif
+
+/*
+ * _FORTIFY_SOURCE redirects open* to __open*_2. Disable the
+ * -Wmissing-declarations warnings, as the functions won't be declared if
+ *  _FORTIFY_SOURCE is not in use.
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmissing-declarations"
+
+LIBCAMERA_PUBLIC int __open_2(const char *path, int oflag)
+{
+	assert(!needs_mode(oflag));
+	return open(path, oflag);
+}
+
+LIBCAMERA_PUBLIC int __open64_2(const char *path, int oflag)
+{
+	assert(!needs_mode(oflag));
+	return open64(path, oflag);
+}
+
+LIBCAMERA_PUBLIC int __openat_2(int dirfd, const char *path, int oflag)
+{
+	assert(!needs_mode(oflag));
+	return openat(dirfd, path, oflag);
+}
 
 LIBCAMERA_PUBLIC int __openat64_2(int dirfd, const char *path, int oflag)
 {
 	assert(!needs_mode(oflag));
 	return openat64(dirfd, path, oflag);
 }
-#endif
+
+#pragma GCC diagnostic pop
 
 LIBCAMERA_PUBLIC int dup(int oldfd)
 {