ccan/ccan/tal/_info

#include "config.h"
#include <stdio.h>
#include <string.h>

/**
 * tal - compact tree allocator routines (inspired by talloc)
 *
 * Tal is a hierarchical allocator; any pointer allocated by tal can
 * become the parent of another allocation.  When you free that parent,
 * the children (and grandchildren, etc) are automatically freed.
 *
 * This allows you to build complex objects based on their lifetimes, eg:
 *
 *  struct foo *X = tal(NULL, struct foo);
 *  X->val = tal(X, int);
 *
 * and the pointer X->val would be a "child" of the tal context "X";
 * tal_free(X->val) would free X->val as expected, by tal_free(X) would
 * free X and X->val.
 *
 * With an overhead of approximately 4 pointers per object
 * (vs. talloc's 12 pointers), it uses dynamic allocation for
 * destructors and child lists, so those operations can fail.  It does
 * not support talloc's references or failing destructors.
 *
 * See Also:
 *	ccan/tal/str (useful string helpers)
 *
 * Example:
 *	#include <stdio.h>
 *	#include <err.h>
 *	#include <ccan/talloc/talloc.h>
 *
 *	// A structure containing a popened command.
 *	struct command {
 *		FILE *f;
 *		char *command;
 *	};
 *
 *	// When struct command is freed, we also want to pclose pipe.
 *	static void close_cmd(struct command *cmd)
 *	{
 *		pclose(cmd->f);
 *	}
 *
 *	// This function opens a writable pipe to the given command.
 *	static struct command *open_output_cmd(const tal_t *ctx,
 *					       const char *a0, const char *a1)
 *	{
 *		struct command *cmd = tal(ctx, struct command);
 *
 *		if (!cmd)
 *			return NULL;
 *
 *		// Note that tal/str has helpers to make this much easier!
 *		cmd->command = tal_arrz(cmd, char, strlen(a0) + strlen(a1) + 2);
 *		if (!cmd->command) {
 *			tal_free(cmd);
 *			return NULL;
 *		}
 *		strcat(cmd->command, a0);
 *		strcat(cmd->command, " ");
 *		strcat(cmd->command, a1);
 *
 *		cmd->f = popen(cmd->command, "w");
 *		if (!cmd->f) {
 *			tal_free(cmd);
 *			return NULL;
 *		}
 *		tal_add_destructor(cmd, close_cmd);
 *		return cmd;
 *	}
 *
 *	int main(int argc, char *argv[])
 *	{
 *		struct command *cmd;
 *
 *		if (argc != 2)
 *			errx(1, "Usage: %s <command>\n", argv[0]);
 *
 *		cmd = open_output_cmd(NULL, argv[1], "hello");
 *		if (!cmd)
 *			err(1, "Running '%s hello'", argv[1]);
 *		fprintf(cmd->f, "This is a test\n");
 *		tal_free(cmd);
 *		return 0;
 *	}
 *
 * License: BSD-MIT
 */
int main(int argc, char *argv[])
{
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/alignof\n");
		printf("ccan/compiler\n");
		printf("ccan/likely\n");
		printf("ccan/list\n");
		printf("ccan/str\n");
		printf("ccan/take\n");
		printf("ccan/typesafe_cb\n");
		return 0;
	}

	return 1;
}