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-rw-r--r--lib/ccan/container_of/_info63
-rw-r--r--lib/ccan/container_of/container_of.h108
-rw-r--r--lib/ccan/container_of/test/compile_fail-bad-type.c22
-rw-r--r--lib/ccan/container_of/test/compile_fail-types.c22
-rw-r--r--lib/ccan/container_of/test/compile_fail-var-types.c25
-rw-r--r--lib/ccan/container_of/test/run.c26
6 files changed, 266 insertions, 0 deletions
diff --git a/lib/ccan/container_of/_info b/lib/ccan/container_of/_info
new file mode 100644
index 0000000000..2f45ca7ccd
--- /dev/null
+++ b/lib/ccan/container_of/_info
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * container_of - routine for upcasting
+ *
+ * It is often convenient to create code where the caller registers a pointer
+ * to a generic structure and a callback. The callback might know that the
+ * pointer points to within a larger structure, and container_of gives a
+ * convenient and fairly type-safe way of returning to the enclosing structure.
+ *
+ * This idiom is an alternative to providing a void * pointer for every
+ * callback.
+ *
+ * Example:
+ * #include <stdio.h>
+ * #include <ccan/container_of/container_of.h>
+ *
+ * struct timer {
+ * void *members;
+ * };
+ *
+ * struct info {
+ * int my_stuff;
+ * struct timer timer;
+ * };
+ *
+ * static void register_timer(struct timer *timer)
+ * {
+ * //...
+ * }
+ *
+ * static void my_timer_callback(struct timer *timer)
+ * {
+ * struct info *info = container_of(timer, struct info, timer);
+ * printf("my_stuff is %u\n", info->my_stuff);
+ * }
+ *
+ * int main(void)
+ * {
+ * struct info info = { .my_stuff = 1 };
+ *
+ * register_timer(&info.timer);
+ * // ...
+ * return 0;
+ * }
+ *
+ * License: Public domain
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ */
+int main(int argc, char *argv[])
+{
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/check_type\n");
+ return 0;
+ }
+
+ return 1;
+}
diff --git a/lib/ccan/container_of/container_of.h b/lib/ccan/container_of/container_of.h
new file mode 100644
index 0000000000..1c9d147ae0
--- /dev/null
+++ b/lib/ccan/container_of/container_of.h
@@ -0,0 +1,108 @@
+#ifndef CCAN_CONTAINER_OF_H
+#define CCAN_CONTAINER_OF_H
+#include <stddef.h>
+
+#include "config.h"
+#include <ccan/check_type/check_type.h>
+
+/**
+ * container_of - get pointer to enclosing structure
+ * @member_ptr: pointer to the structure member
+ * @containing_type: the type this member is within
+ * @member: the name of this member within the structure.
+ *
+ * Given a pointer to a member of a structure, this macro does pointer
+ * subtraction to return the pointer to the enclosing type.
+ *
+ * Example:
+ * struct foo {
+ * int fielda, fieldb;
+ * // ...
+ * };
+ * struct info {
+ * int some_other_field;
+ * struct foo my_foo;
+ * };
+ *
+ * static struct info *foo_to_info(struct foo *foo)
+ * {
+ * return container_of(foo, struct info, my_foo);
+ * }
+ */
+#define container_of(member_ptr, containing_type, member) \
+ ((containing_type *) \
+ ((char *)(member_ptr) \
+ - container_off(containing_type, member)) \
+ + check_types_match(*(member_ptr), ((containing_type *)0)->member))
+
+/**
+ * container_off - get offset to enclosing structure
+ * @containing_type: the type this member is within
+ * @member: the name of this member within the structure.
+ *
+ * Given a pointer to a member of a structure, this macro does
+ * typechecking and figures out the offset to the enclosing type.
+ *
+ * Example:
+ * struct foo {
+ * int fielda, fieldb;
+ * // ...
+ * };
+ * struct info {
+ * int some_other_field;
+ * struct foo my_foo;
+ * };
+ *
+ * static struct info *foo_to_info(struct foo *foo)
+ * {
+ * size_t off = container_off(struct info, my_foo);
+ * return (void *)((char *)foo - off);
+ * }
+ */
+#define container_off(containing_type, member) \
+ offsetof(containing_type, member)
+
+/**
+ * container_of_var - get pointer to enclosing structure using a variable
+ * @member_ptr: pointer to the structure member
+ * @container_var: a pointer of same type as this member's container
+ * @member: the name of this member within the structure.
+ *
+ * Given a pointer to a member of a structure, this macro does pointer
+ * subtraction to return the pointer to the enclosing type.
+ *
+ * Example:
+ * static struct info *foo_to_i(struct foo *foo)
+ * {
+ * struct info *i = container_of_var(foo, i, my_foo);
+ * return i;
+ * }
+ */
+#if HAVE_TYPEOF
+#define container_of_var(member_ptr, container_var, member) \
+ container_of(member_ptr, typeof(*container_var), member)
+#else
+#define container_of_var(member_ptr, container_var, member) \
+ ((void *)((char *)(member_ptr) - \
+ container_off_var(container_var, member)))
+#endif
+
+/**
+ * container_off_var - get offset of a field in enclosing structure
+ * @container_var: a pointer to a container structure
+ * @member: the name of a member within the structure.
+ *
+ * Given (any) pointer to a structure and a its member name, this
+ * macro does pointer subtraction to return offset of member in a
+ * structure memory layout.
+ *
+ */
+#if HAVE_TYPEOF
+#define container_off_var(var, member) \
+ container_off(typeof(*var), member)
+#else
+#define container_off_var(var, member) \
+ ((char *)&(var)->member - (char *)(var))
+#endif
+
+#endif /* CCAN_CONTAINER_OF_H */
diff --git a/lib/ccan/container_of/test/compile_fail-bad-type.c b/lib/ccan/container_of/test/compile_fail-bad-type.c
new file mode 100644
index 0000000000..b7a1459386
--- /dev/null
+++ b/lib/ccan/container_of/test/compile_fail-bad-type.c
@@ -0,0 +1,22 @@
+#include <ccan/container_of/container_of.h>
+#include <stdlib.h>
+
+struct foo {
+ int a;
+ char b;
+};
+
+int main(int argc, char *argv[])
+{
+ struct foo foo = { .a = 1, .b = 2 };
+ int *intp = &foo.a;
+ char *p;
+
+#ifdef FAIL
+ /* p is a char *, but this gives a struct foo * */
+ p = container_of(intp, struct foo, a);
+#else
+ p = (char *)intp;
+#endif
+ return p == NULL;
+}
diff --git a/lib/ccan/container_of/test/compile_fail-types.c b/lib/ccan/container_of/test/compile_fail-types.c
new file mode 100644
index 0000000000..cae1c7abd2
--- /dev/null
+++ b/lib/ccan/container_of/test/compile_fail-types.c
@@ -0,0 +1,22 @@
+#include <ccan/container_of/container_of.h>
+#include <stdlib.h>
+
+struct foo {
+ int a;
+ char b;
+};
+
+int main(int argc, char *argv[])
+{
+ struct foo foo = { .a = 1, .b = 2 }, *foop;
+ int *intp = &foo.a;
+
+#ifdef FAIL
+ /* b is a char, but intp is an int * */
+ foop = container_of(intp, struct foo, b);
+#else
+ foop = NULL;
+#endif
+ (void) foop; /* Suppress unused-but-set-variable warning. */
+ return intp == NULL;
+}
diff --git a/lib/ccan/container_of/test/compile_fail-var-types.c b/lib/ccan/container_of/test/compile_fail-var-types.c
new file mode 100644
index 0000000000..f254d92102
--- /dev/null
+++ b/lib/ccan/container_of/test/compile_fail-var-types.c
@@ -0,0 +1,25 @@
+#include <ccan/container_of/container_of.h>
+#include <stdlib.h>
+
+struct foo {
+ int a;
+ char b;
+};
+
+int main(int argc, char *argv[])
+{
+ struct foo foo = { .a = 1, .b = 2 }, *foop;
+ int *intp = &foo.a;
+
+#ifdef FAIL
+ /* b is a char, but intp is an int * */
+ foop = container_of_var(intp, foop, b);
+#if !HAVE_TYPEOF
+#error "Unfortunately we don't fail if we don't have typeof."
+#endif
+#else
+ foop = NULL;
+#endif
+ (void) foop; /* Suppress unused-but-set-variable warning. */
+ return intp == NULL;
+}
diff --git a/lib/ccan/container_of/test/run.c b/lib/ccan/container_of/test/run.c
new file mode 100644
index 0000000000..5da440a1e5
--- /dev/null
+++ b/lib/ccan/container_of/test/run.c
@@ -0,0 +1,26 @@
+#include <ccan/container_of/container_of.h>
+#include <ccan/tap/tap.h>
+
+struct foo {
+ int a;
+ char b;
+};
+
+int main(int argc, char *argv[])
+{
+ struct foo foo = { .a = 1, .b = 2 };
+ int *intp = &foo.a;
+ char *charp = &foo.b;
+
+ plan_tests(8);
+ ok1(container_of(intp, struct foo, a) == &foo);
+ ok1(container_of(charp, struct foo, b) == &foo);
+ ok1(container_of_var(intp, &foo, a) == &foo);
+ ok1(container_of_var(charp, &foo, b) == &foo);
+
+ ok1(container_off(struct foo, a) == 0);
+ ok1(container_off(struct foo, b) == offsetof(struct foo, b));
+ ok1(container_off_var(&foo, a) == 0);
+ ok1(container_off_var(&foo, b) == offsetof(struct foo, b));
+ return exit_status();
+}