--- /dev/null
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * lstack - Simple, singly-linked-list stack implementation
+ *
+ * This code provides a simple implementation of the Stack abstract
+ * data type in terms of a singly linked list.
+ *
+ * License: BSD-MIT
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ *
+ * Example:
+ * #include <ccan/lstack/lstack.h>
+ *
+ * struct arg {
+ * const char *arg;
+ * struct lstack_link sl;
+ * };
+ *
+ * int main(int argc, char *argv[])
+ * {
+ * int i;
+ * struct arg *a;
+ * LSTACK(argstack);
+ *
+ * for (i = 0; i < argc; i++) {
+ * a = malloc(sizeof(*a));
+ * a->arg = argv[i];
+ * lstack_push(&argstack, a, sl);
+ * }
+ *
+ * printf("Command line arguments in reverse:\n");
+ *
+ * while (!lstack_empty(&argstack)) {
+ * a = lstack_pop(&argstack, struct arg, sl);
+ * printf("Argument: %s\n", a->arg);
+ * free(a);
+ * }
+ *
+ * return 0;
+ * }
+ */
+int main(int argc, char *argv[])
+{
+ /* Expect exactly one argument */
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/container_of\n");
+ return 0;
+ }
+
+ return 1;
+}
--- /dev/null
+/* Licensed under BSD-MIT - see LICENSE file for details */
+#ifndef CCAN_LSTACK_H
+#define CCAN_LSTACK_H
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include <ccan/container_of/container_of.h>
+
+/**
+ * struct lstack_link - a stack link
+ * @down: immedately lower entry in the stack, or NULL if this is the bottom.
+ *
+ * This is used as an entry in a stack.
+ *
+ * Example:
+ * struct stacker {
+ * char *name;
+ * struct lstack_link sl;
+ * };
+ */
+struct lstack_link {
+ struct lstack_link *down;
+};
+
+/**
+ * struct lstack - a stack
+ * @b: the top of the stack (NULL if empty)
+ */
+struct lstack {
+ struct lstack_link *top;
+};
+
+/**
+ * LSTACK - define and initialize an empty stack
+ * @name: the name of the lstack.
+ *
+ * The LSTACK macro defines an lstack and initializes it to an empty
+ * stack. It can be prepended by "static" to define a static lstack.
+ *
+ * See also:
+ * lstack_init()
+ *
+ * Example:
+ * LSTACK(my_stack);
+ *
+ * assert(lstack_empty(&my_stack));
+ */
+#define LSTACK(name) \
+ struct lstack name = { NULL, }
+
+/**
+ * lstack_init - initialize a stack
+ * @h: the lstack to set to an empty stack
+ *
+ * Example:
+ * struct lstack *sp = malloc(sizeof(*sp));
+ * lstack_init(sp);
+ */
+static inline void lstack_init(struct lstack *s)
+{
+ s->top = NULL;
+}
+
+/**
+ * lstack_empty - is a stack empty?
+ * @s: the stack
+ *
+ * If the stack is empty, returns true.
+ *
+ * Example:
+ * assert(lstack_empty(sp));
+ */
+static inline bool lstack_empty(const struct lstack *s)
+{
+ return (s->top == NULL);
+}
+
+/**
+ * lstack_entry - convert an lstack_link back into the structure containing it.
+ * @e: the lstack_link
+ * @type: the type of the entry
+ * @member: the lstack_link member of the type
+ *
+ * Example:
+ * struct stacker {
+ * char *name;
+ * struct lstack_link sl;
+ * } st;
+ * assert(lstack_entry(&st.sl, struct stacker, sl) == &st);
+ */
+#define lstack_entry(n, type, member) container_of_or_null(n, type, member)
+
+/**
+ * lstack_top - get top entry in a stack
+ * @s: the stack
+ * @type: the type of stack entries
+ * @member: the lstack_link entry
+ *
+ * If the stack is empty, returns NULL.
+ *
+ * Example:
+ * struct stacker *t;
+ *
+ * t = lstack_top(sp, struct stacker, sl);
+ * assert(lstack_pop(sp, struct stacker, sl) == t);
+ */
+#define lstack_top(s, type, member) \
+ lstack_entry(lstack_top_((s)), type, member)
+static inline struct lstack_link *lstack_top_(const struct lstack *s)
+{
+ return s->top;
+}
+
+/**
+ * lstack_push - add an entry to the top of the stack
+ * @s: the stack to add the node to
+ * @e: the item to push
+ * @member: the lstack_link field of *e
+ *
+ * The lstack_link does not need to be initialized; it will be overwritten.
+ */
+#define lstack_push(s, e, member) \
+ lstack_push_((s), &((e)->member))
+static inline void lstack_push_(struct lstack *s, struct lstack_link *e)
+{
+ e->down = lstack_top_(s);
+ s->top = e;
+}
+
+/**
+ * lstack_pop - remove and return the entry from the top of the stack
+ * @s: the stack
+ * @type: the type of stack entries
+ * @member: the lstack_link field of @type
+ *
+ * Note that this leaves the returned entry's link in an undefined
+ * state; it can be added to another stack, but not deleted again.
+ */
+#define lstack_pop(s, type, member) \
+ lstack_entry(lstack_pop_((s)), type, member)
+static inline struct lstack_link *lstack_pop_(struct lstack *s)
+{
+ struct lstack_link *top;
+
+ if (lstack_empty(s))
+ return NULL;
+
+ top = lstack_top_(s);
+ s->top = top->down;
+ return top;
+}
+
+#endif /* CCAN_LSTACK_H */
--- /dev/null
+#include "config.h"
+
+#include <ccan/lstack/lstack.h>
+#include <ccan/tap/tap.h>
+
+struct stacker {
+ const char *name;
+ struct lstack_link sl;
+};
+
+int main(void)
+{
+ LSTACK(s);
+ struct stacker a = { "Alice" };
+ struct stacker b = { "Bob" };
+ struct stacker c = { "Carol" };
+ struct stacker *stacker;
+
+ /* This is how many tests you plan to run */
+ plan_tests(18);
+
+ ok1(lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == NULL);
+
+ lstack_push(&s, &a, sl);
+
+ ok1(!lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == &a);
+
+ lstack_push(&s, &b, sl);
+
+ ok1(!lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == &b);
+
+ lstack_push(&s, &c, sl);
+
+ ok1(!lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == &c);
+
+ stacker = lstack_pop(&s, struct stacker, sl);
+ ok1(stacker == &c);
+
+ ok1(!lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == &b);
+
+ stacker = lstack_pop(&s, struct stacker, sl);
+ ok1(stacker == &b);
+
+ ok1(!lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == &a);
+
+ stacker = lstack_pop(&s, struct stacker, sl);
+ ok1(stacker == &a);
+
+ ok1(lstack_empty(&s));
+ ok1(lstack_top(&s, struct stacker, sl) == NULL);
+
+ ok1(lstack_pop(&s, struct stacker, sl) == NULL);
+
+ /* This exits depending on whether all tests passed */
+ return exit_status();
+}
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