Author: Armin Rigo <[email protected]>
Branch:
Changeset: r2768:7c0b1fadb4da
Date: 2016-09-15 08:39 +0200
http://bitbucket.org/cffi/cffi/changeset/7c0b1fadb4da/
Log: Warn when implicitly casting between "char *" and a different
pointer type, like C does (there is no special-case of "char *" in
C)
diff --git a/c/_cffi_backend.c b/c/_cffi_backend.c
--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -128,7 +128,7 @@
#define CT_VOID 512 /* void */
/* other flags that may also be set in addition to the base flag: */
-#define CT_CAST_ANYTHING 1024 /* 'char *' and 'void *' only */
+#define CT_IS_VOIDCHAR_PTR 1024
#define CT_PRIMITIVE_FITS_LONG 2048
#define CT_IS_OPAQUE 4096
#define CT_IS_ENUM 8192
@@ -1358,9 +1358,26 @@
}
}
if (ctinit != ct) {
- if ((ct->ct_flags & CT_CAST_ANYTHING) ||
- (ctinit->ct_flags & CT_CAST_ANYTHING))
- ; /* accept void* or char* as either source or target */
+ int combined_flags = ct->ct_flags | ctinit->ct_flags;
+ if (combined_flags & CT_IS_VOID_PTR)
+ ; /* accept "void *" as either source or target */
+ else if (combined_flags & CT_IS_VOIDCHAR_PTR) {
+ /* for backward compatibility, accept "char *" as either
+ source of target. This is not what C does, though,
+ so emit a warning that will eventually turn into an
+ error. */
+ char *msg = (ct->ct_flags & CT_IS_VOIDCHAR_PTR ?
+ "implicit cast to 'char *' from a different pointer type: "
+ "will be forbidden in the future (check that the types "
+ "are as you expect; use an explicit ffi.cast() if they "
+ "are correct)" :
+ "implicit cast from 'char *' to a different pointer type: "
+ "will be forbidden in the future (check that the types "
+ "are as you expect; use an explicit ffi.cast() if they "
+ "are correct)");
+ if (PyErr_WarnEx(PyExc_UserWarning, msg, 1))
+ return -1;
+ }
else {
expected = "pointer to same type";
goto cannot_convert;
@@ -2476,7 +2493,7 @@
if (PyBytes_Check(init)) {
/* from a string: just returning the string here is fine.
We assume that the C code won't modify the 'char *' data. */
- if ((ctptr->ct_flags & CT_CAST_ANYTHING) ||
+ if ((ctptr->ct_flags & CT_IS_VOIDCHAR_PTR) ||
((ctitem->ct_flags & (CT_PRIMITIVE_SIGNED|CT_PRIMITIVE_UNSIGNED))
&& (ctitem->ct_size == sizeof(char)))) {
#if defined(CFFI_MEM_DEBUG) || defined(CFFI_MEM_LEAK)
@@ -3929,7 +3946,7 @@
if ((ctitem->ct_flags & CT_VOID) ||
((ctitem->ct_flags & CT_PRIMITIVE_CHAR) &&
ctitem->ct_size == sizeof(char)))
- td->ct_flags |= CT_CAST_ANYTHING; /* 'void *' or 'char *' only */
+ td->ct_flags |= CT_IS_VOIDCHAR_PTR; /* 'void *' or 'char *' only */
unique_key[0] = ctitem;
return get_unique_type(td, unique_key, 1);
}
@@ -5903,7 +5920,7 @@
return NULL;
}
ct = ((CDataObject *)arg)->c_type;
- if (!(ct->ct_flags & CT_CAST_ANYTHING)) {
+ if (!(ct->ct_flags & CT_IS_VOIDCHAR_PTR)) {
PyErr_Format(PyExc_TypeError,
"expected a 'cdata' object with a 'void *' out of "
"new_handle(), got '%s'", ct->ct_name);
diff --git a/c/test_c.py b/c/test_c.py
--- a/c/test_c.py
+++ b/c/test_c.py
@@ -3676,3 +3676,25 @@
check_dir(pp, [])
check_dir(pp[0], ['a1', 'a2'])
check_dir(pp[0][0], ['a1', 'a2'])
+
+def test_char_pointer_conversion():
+ import warnings
+ BCharP = new_pointer_type(new_primitive_type("char"))
+ BIntP = new_pointer_type(new_primitive_type("int"))
+ BVoidP = new_pointer_type(new_void_type())
+ z1 = cast(BCharP, 0)
+ z2 = cast(BIntP, 0)
+ z3 = cast(BVoidP, 0)
+ with warnings.catch_warnings(record=True) as w:
+ newp(new_pointer_type(BIntP), z1) # warn
+ assert len(w) == 1
+ newp(new_pointer_type(BVoidP), z1) # fine
+ assert len(w) == 1
+ newp(new_pointer_type(BCharP), z2) # warn
+ assert len(w) == 2
+ newp(new_pointer_type(BVoidP), z2) # fine
+ assert len(w) == 2
+ newp(new_pointer_type(BCharP), z3) # fine
+ assert len(w) == 2
+ newp(new_pointer_type(BIntP), z3) # fine
+ assert len(w) == 2
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