commit e51564d1bee5aa8b411328d7d3d75906dfc0a260
parent 98ec7995912af0aaaf9a97c5bc1be17e9b601af9
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 16 Sep 2020 14:57:24 -0300
Details in comments and documentation
Diffstat:
2 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/lstate.h b/lstate.h
@@ -334,6 +334,12 @@ struct lua_State {
/*
** Union of all collectable objects (only for conversions)
+** ISO C99, 6.5.2.3 p.5:
+** "if a union contains several structures that share a common initial
+** sequence [...], and if the union object currently contains one
+** of these structures, it is permitted to inspect the common initial
+** part of any of them anywhere that a declaration of the complete type
+** of the union is visible."
*/
union GCUnion {
GCObject gc; /* common header */
@@ -347,6 +353,11 @@ union GCUnion {
};
+/*
+** ISO C99, 6.7.2.1 p.14:
+** "A pointer to a union object, suitably converted, points to each of
+** its members [...], and vice versa."
+*/
#define cast_u(o) cast(union GCUnion *, (o))
/* macros to convert a GCObject into a specific value */
diff --git a/manual/manual.of b/manual/manual.of
@@ -6813,6 +6813,16 @@ As such, it is only available on some platforms
(Windows, Linux, Mac OS X, Solaris, BSD,
plus other Unix systems that support the @id{dlfcn} standard).
+This function is inherently insecure,
+as it allows Lua to call any function in any readable dynamic
+library in the system.
+(Lua calls any function assuming the function
+has a proper prototype and respects a proper protocol
+@see{lua_CFunction}.
+Therefore,
+calling an arbitrary function in an arbitrary dynamic library
+more often than not results in an access violation.)
+
}
@LibEntry{package.path|
