extmod/vfs_posix: Add MICROPY_VFS_POSIX_WRITABLE option.
When this configuration flag is set, VfsPosix instances can be written.
Otherwise, they will always be created "read only".
This flag is useful when fuzzing micropython: Without VfsPosix, the fuzzing
input script cannot be read; but with writable VfsPosix, fuzzing scripts
can potentially perform undesired operations on the host filesystem.
Signed-off-by: Jeff Epler <jepler@gmail.com>
diff --git a/py/mpconfig.h b/py/mpconfig.h
index a1025fe..b812cf0 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1084,6 +1084,11 @@
#define MICROPY_VFS_POSIX (0)
#endif
+// Whether to include support for writable POSIX filesystems.
+#ifndef MICROPY_VFS_POSIX_WRITABLE
+#define MICROPY_VFS_POSIX_WRITABLE (1)
+#endif
+
// Support for VFS FAT component, to mount a FAT filesystem within VFS
#ifndef MICROPY_VFS_FAT
#define MICROPY_VFS_FAT (0)