Add "container canaries" to tcon. This allows information about a specific
member of a container structure to be encoded with TCON or TCON_WRAP. Once
that's done, tcon_container_of() and tcon_member_of() can be used to
translate between member and container pointers based on the canary
information, without having to repeat the type and member details.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
ccan/tcon/tcon.h | 81 +++++++++++++++++++++++++++++++
ccan/tcon/test/compile_fail-container1.c | 39 +++++++++++++++
ccan/tcon/test/compile_fail-container1w.c | 35 +++++++++++++
ccan/tcon/test/compile_fail-container2.c | 39 +++++++++++++++
ccan/tcon/test/compile_fail-container2w.c | 35 +++++++++++++
ccan/tcon/test/compile_fail-container3.c | 40 +++++++++++++++
ccan/tcon/test/compile_fail-container3w.c | 36 ++++++++++++++
ccan/tcon/test/compile_fail-container4.c | 40 +++++++++++++++
ccan/tcon/test/compile_fail-container4w.c | 36 ++++++++++++++
ccan/tcon/test/run-container.c | 46 ++++++++++++++++++
10 files changed, 427 insertions(+)
create mode 100644 ccan/tcon/test/compile_fail-container1.c
create mode 100644 ccan/tcon/test/compile_fail-container1w.c
create mode 100644 ccan/tcon/test/compile_fail-container2.c
create mode 100644 ccan/tcon/test/compile_fail-container2w.c
create mode 100644 ccan/tcon/test/compile_fail-container3.c
create mode 100644 ccan/tcon/test/compile_fail-container3w.c
create mode 100644 ccan/tcon/test/compile_fail-container4.c
create mode 100644 ccan/tcon/test/compile_fail-container4w.c
create mode 100644 ccan/tcon/test/run-container.c
diff --git a/ccan/tcon/tcon.h b/ccan/tcon/tcon.h
index bfba23a..4f5897a 100644
--- a/ccan/tcon/tcon.h
+++ b/ccan/tcon/tcon.h
@@ -3,6 +3,8 @@
#define CCAN_TCON_H
#include "config.h"
+#include <stddef.h>
+
/**
* TCON - declare a _tcon type containing canary variables.
* @decls: the semi-colon separated list of type canaries.
@@ -212,4 +214,83 @@
#define tcon_cast(x, canary, expr) ((tcon_type((x), canary))(expr))
#define tcon_cast_ptr(x, canary, expr) ((tcon_ptr_type((x), canary))(expr))
+/**
+ * TCON_CONTAINER - encode information on a specific member of a
+ * containing structure into a "type" canary
+ * @canary: name of the container canary
+ * @container: type of the container structure
+ * @member: name of the member
+ *
+ * Used in the declarations in TCON() or TCON_WRAP(), encode a
+ * "container canary". This encodes the type of @container, the type
+ * of @member within it (with sufficient compiler support) and the
+ * offset of @member within @container.
+ */
+#if HAVE_TYPEOF
+#define TCON_CONTAINER(canary, container, member) \
+ container *_container_##canary; \
+ typeof(((container *)0)->member) *_member_##canary; \
+ TCON_VALUE(_offset_##canary, offsetof(container, member))
+#else
+#define TCON_CONTAINER(canary, container, member) \
+ container *_container_##canary; \
+ void *_member_##canary; \
+ TCON_VALUE(_offset_##canary, offsetof(container, member))
+#endif
+
+/**
+ * tcon_container_of - get pointer to enclosing structure based on a
+ * container canary
+ * @x: the structure containing the TCON
+ * @canary: the name of the container canary
+ * @member_ptr: pointer to a member of the container
+ *
+ * @member_ptr must be a pointer to the member of a container
+ * structure previously recorded in @canary with TCON_CONTAINER.
+ *
+ * tcon_container_of() evaluates to a pointer to the container
+ * structure. With sufficient compiler support, the pointer will be
+ * correctly typed, and the type of @member_ptr will be verified.
+ *
+ * Returns NULL if @member_ptr is NULL.
+ */
+#define tcon_container_of(x, canary, member_ptr) \
+ tcon_cast(tcon_check((x), _member_##canary, (member_ptr)), \
+ _container_##canary, \
+ tcon_container_of_((member_ptr), \
+ tcon_value((x), _offset_##canary)))
+static inline void *tcon_container_of_(void *member_ptr, size_t offset)
+{
+ return member_ptr ? (char *)member_ptr - offset : NULL;
+}
+
+
+/**
+ * tcon_member_of - get pointer to enclosed member structure based on a
+ * container canary
+ * @x: the structure containing the TCON
+ * @canary: the name of the container canary
+ * @container_ptr: pointer to a container
+ *
+ * @container_ptr must be a pointer to a container structure
+ * previously recorded in @canary with TCON_CONTAINER.
+ *
+ * tcon_member_of() evaluates to a pointer to the member of the
+ * container recorded in @canary. With sufficient compiler support,
+ * the pointer will be correctly typed, and the type of @container_ptr
+ * will be verified.
+ *
+ * Returns NULL if @container_ptr is NULL.
+ */
+#define tcon_member_of(x, canary, container_ptr) \
+ tcon_cast(tcon_check((x), _container_##canary, (container_ptr)), \
+ _member_##canary, \
+ tcon_field_((container_ptr), \
+ tcon_value((x), _offset_##canary)))
+static inline void *tcon_field_(void *containerp, size_t offset)
+{
+ return containerp ? (char *)containerp + offset : NULL;
+}
+
+
#endif /* CCAN_TCON_H */
diff --git a/ccan/tcon/test/compile_fail-container1.c
b/ccan/tcon/test/compile_fail-container1.c
new file mode 100644
index 0000000..a67e209
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container1.c
@@ -0,0 +1,39 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+struct info_tcon {
+ struct info_base base;
+ TCON(TCON_CONTAINER(concan, struct outer, inner));
+};
+
+int main(int argc, char *argv[])
+{
+ struct info_tcon info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *innerp = &ovar.outer_val;
+#else
+ struct inner *innerp = &ovar.inner;
+#endif
+
+ return tcon_container_of(&info, concan, innerp) == &ovar;
+}
diff --git a/ccan/tcon/test/compile_fail-container1w.c
b/ccan/tcon/test/compile_fail-container1w.c
new file mode 100644
index 0000000..0226b68
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container1w.c
@@ -0,0 +1,35 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+int main(int argc, char *argv[])
+{
+ TCON_WRAP(struct info_base,
+ TCON_CONTAINER(concan, struct outer, inner)) info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *innerp = &ovar.outer_val;
+#else
+ struct inner *innerp = &ovar.inner;
+#endif
+
+ return tcon_container_of(&info, concan, innerp) == &ovar;
+}
diff --git a/ccan/tcon/test/compile_fail-container2.c
b/ccan/tcon/test/compile_fail-container2.c
new file mode 100644
index 0000000..6cad734
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container2.c
@@ -0,0 +1,39 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+struct info_tcon {
+ struct info_base base;
+ TCON(TCON_CONTAINER(concan, struct outer, inner));
+};
+
+int main(int argc, char *argv[])
+{
+ struct info_tcon info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ char *outerp = NULL;
+#else
+ struct outer *outerp = &ovar;
+#endif
+
+ return tcon_member_of(&info, concan, outerp) == &ovar.inner;
+}
diff --git a/ccan/tcon/test/compile_fail-container2w.c
b/ccan/tcon/test/compile_fail-container2w.c
new file mode 100644
index 0000000..c73123c
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container2w.c
@@ -0,0 +1,35 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+int main(int argc, char *argv[])
+{
+ TCON_WRAP(struct info_base,
+ TCON_CONTAINER(concan, struct outer, inner)) info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ char *outerp = NULL;
+#else
+ struct outer *outerp = &ovar;
+#endif
+
+ return tcon_member_of(&info, concan, outerp) == &ovar.inner;
+}
diff --git a/ccan/tcon/test/compile_fail-container3.c
b/ccan/tcon/test/compile_fail-container3.c
new file mode 100644
index 0000000..97473c8
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container3.c
@@ -0,0 +1,40 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+struct info_tcon {
+ struct info_base base;
+ TCON(TCON_CONTAINER(concan, struct outer, inner));
+};
+
+int main(int argc, char *argv[])
+{
+ struct info_tcon info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *outerp;
+#else
+ struct outer *outerp;
+#endif
+
+ outerp = tcon_container_of(&info, concan, &ovar.inner);
+ return outerp != NULL;
+}
diff --git a/ccan/tcon/test/compile_fail-container3w.c
b/ccan/tcon/test/compile_fail-container3w.c
new file mode 100644
index 0000000..6930b43
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container3w.c
@@ -0,0 +1,36 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+int main(int argc, char *argv[])
+{
+ TCON_WRAP(struct info_base,
+ TCON_CONTAINER(concan, struct outer, inner)) info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *outerp;
+#else
+ struct outer *outerp;
+#endif
+
+ outerp = tcon_container_of(&info, concan, &ovar.inner);
+ return outerp != NULL;
+}
diff --git a/ccan/tcon/test/compile_fail-container4.c
b/ccan/tcon/test/compile_fail-container4.c
new file mode 100644
index 0000000..838ce9b
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container4.c
@@ -0,0 +1,40 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+struct info_tcon {
+ struct info_base base;
+ TCON(TCON_CONTAINER(concan, struct outer, inner));
+};
+
+int main(int argc, char *argv[])
+{
+ struct info_tcon info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *innerp;
+#else
+ struct inner *innerp;
+#endif
+
+ innerp = tcon_member_of(&info, concan, &ovar);
+ return innerp != NULL;
+}
diff --git a/ccan/tcon/test/compile_fail-container4w.c
b/ccan/tcon/test/compile_fail-container4w.c
new file mode 100644
index 0000000..0d7b367
--- /dev/null
+++ b/ccan/tcon/test/compile_fail-container4w.c
@@ -0,0 +1,36 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+int main(int argc, char *argv[])
+{
+ TCON_WRAP(struct info_base,
+ TCON_CONTAINER(concan, struct outer, inner)) info;
+ struct outer ovar;
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error We cannot detect type problems without HAVE_TYPEOF
+#endif
+ int *innerp;
+#else
+ struct inner *innerp;
+#endif
+
+ innerp = tcon_member_of(&info, concan, &ovar);
+ return innerp != NULL;
+}
diff --git a/ccan/tcon/test/run-container.c b/ccan/tcon/test/run-container.c
new file mode 100644
index 0000000..8e1a280
--- /dev/null
+++ b/ccan/tcon/test/run-container.c
@@ -0,0 +1,46 @@
+#include <stdlib.h>
+
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <ccan/tap/tap.h>
+
+struct inner {
+ int inner_val;
+};
+
+struct outer {
+ int outer_val;
+ struct inner inner;
+};
+
+struct info_base {
+ char *infop;
+};
+
+struct info_tcon {
+ struct info_base base;
+ TCON(TCON_CONTAINER(fi, struct outer, inner));
+};
+
+int main(int argc, char *argv[])
+{
+ struct info_tcon info;
+ TCON_WRAP(struct info_base,
+ TCON_CONTAINER(fi, struct outer, inner)) infow;
+ struct outer ovar;
+
+ plan_tests(8);
+
+ ok1(tcon_container_of(&info, fi, &ovar.inner) == &ovar);
+ ok1(tcon_member_of(&info, fi, &ovar) == &ovar.inner);
+ ok1(tcon_container_of(&infow, fi, &ovar.inner) == &ovar);
+ ok1(tcon_member_of(&infow, fi, &ovar) == &ovar.inner);
+
+ /* Check handling of NULLs */
+ ok1(tcon_container_of(&info, fi, NULL) == NULL);
+ ok1(tcon_member_of(&info, fi, NULL) == NULL);
+ ok1(tcon_container_of(&infow, fi, NULL) == NULL);
+ ok1(tcon_member_of(&infow, fi, NULL) == NULL);
+
+ return 0;
+}
--
2.4.3
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