ccan/ccan/alloc/_info.c

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

/**
 * alloc - memory allocator routines
 *
 * The alloc module implements a simple allocator which you can use to
 * dynamically allocate space within a region of memory.  This can be useful
 * for suballocations within a given region, or a memory-mapped file.
 *
 * All metadata is kept within the memory handed to the allocator: you only
 * need hand the pointer and the size of the memory to each call.
 *
 * The region contents is always in offsets, so it can be mapped in different
 * places, but is not endian-safe.
 *
 * Example:
 *	#include <sys/mman.h>
 *	#include <unistd.h>
 *	#include <sys/types.h>
 *	#include <err.h>
 *	#include "alloc/alloc.h"
 *
 *	static void usage(const char *name)
 *	{
 *		errx(1, "Usage: %s --create <mapfile>\n"
 *		     " %s --check <mapfile>\n"
 *		     " %s --alloc <mapfile>\n"
 *		     " %s --free=<offset> <mapfile>\n", name, name, name);
 *	}
 *
 *	// Create a memory mapped file, and allocate from within it
 *	int main(int argc, char *argv[])
 *	{
 *		void *a, *p;
 *		int fd;
 *		enum { CREATE, CHECK, ALLOC, FREE } cmd;
 *
 *		if (argc != 3)
 *			usage(argv[0]);
 *
 *		if (strcmp(argv[1], "--create") == 0)
 *			cmd = CREATE;
 *		else if (strcmp(argv[1], "--check") == 0)
 *			cmd = CHECK;
 *		else if (strcmp(argv[1], "--alloc") == 0)
 *			cmd = ALLOC;
 *		else if (strncmp(argv[1], "--free=", strlen("--free=")) == 0)
 *			cmd = FREE;
 *		else
 *			usage(argv[0]);
 *
 *		if (cmd == CREATE) {
 *			fd = open(argv[2], O_RDWR|O_CREAT|O_EXCL, 0600);
 *			if (fd < 0)
 *				err(1, "Could not create %s", argv[2]);
 *			if (ftruncate(fd, 1048576) != 0)
 *				err(1, "Could not set length on %s", argv[2]);
 *		} else {
 *			fd = open(argv[2], O_RDWR);
 *			if (fd < 0)
 *				err(1, "Could not open %s", argv[2]);
 *		}
 *
 *		a = mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_SHARED, fd,0);
 *		if (a == MAP_FAILED)
 *			err(1, "Could not map %s", argv[2]);
 *
 *		switch (cmd) {
 *		case CREATE:
 *			alloc_init(a, 1048576);
 *			break;
 *		case CHECK:
 *			if (!alloc_check(a, 1048576))
 *				err(1, "Region is corrupt");
 *			break;
 *		case ALLOC:
 *			p = alloc_get(a, 1048576, 1024, 16);
 *			if (!p)
 *				errx(1, "Could not allocate");
 *			printf("%zu\n", (char *)p - (char *)a);
 *			break;
 *		case FREE:
 *			p = (char *)a + atol(argv[1] + strlen("--free="));
 *			alloc_free(a, 1048576, p);
 *			break;
 *		}
 *		return 0;
 *	}
 */
int main(int argc, char *argv[])
{
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/build_assert\n");
		return 0;
	}

	return 1;
}