Added a configure script to emulate GNU autoconf and related changes.

Changes included in this set:

 * Added strlcat() and strlcpy() from OpenBSD, always use them if the
   system does not have them built in.
 * Changed an array of PATH_MAX size allocated in the stack, to a dynamically
   allocated buffer from heap. This should reduce memory usage a bit.
 * Simplify code that implemented a homegrown realpath(3) implementation,
   simply use realpath(3).
 * If compiler supports -fstack-protector, build all code with
   -D_FORTIFY_SOURCE=2 and --param ssp-buffer-size=1 so that all
   buffers are protected.

bin/Makefile

@@ -1,4 +1,4 @@
-include ../vars.mk
+-include ../config.mk
 
 SUBDIRS =	xbps-uhelper
 SUBDIRS +=	xbps-repo

bin/xbps-bin/Makefile

@@ -1,5 +1,5 @@
 TOPDIR = ../..
-include $(TOPDIR)/vars.mk
+-include $(TOPDIR)/config.mk
 
 BIN = xbps-bin
 OBJS =  check.o install.o main.o remove.o show-deps.o

bin/xbps-repo/Makefile

@@ -1,5 +1,5 @@
 TOPDIR = ../..
-include $(TOPDIR)/vars.mk
+-include $(TOPDIR)/config.mk
 
 BIN =	xbps-repo
 OBJS =	main.o util.o index.o repository.o

bin/xbps-repo/repository.c

@@ -33,6 +33,7 @@
 
 #include <xbps_api.h>
 #include "defs.h"
+#include "config.h"
 
 struct repoinfo {
 	char *pkgidxver;
@@ -98,54 +99,13 @@ out:
 	return rpi;
 }
 
-static bool
-sanitize_url(char *buf, const char *path)
-{
-	char *dirnp, *basenp, *dir, *base, *tmp;
-	bool rv = false;
-
-	dir = strdup(path);
-	if (dir == NULL)
-		return false;
-
-	base = strdup(path);
-	if (base == NULL) {
-		free(dir);
-		return false;
-	}
-
-	dirnp = dirname(dir);
-	if (strcmp(dirnp, ".") == 0)
-		goto out;
-
-	basenp = basename(base);
-	if (strcmp(basenp, base) == 0)
-		goto out;
-
-	tmp = strncpy(buf, dirnp, PATH_MAX - 1);
-	if (sizeof(*tmp) >= PATH_MAX)
-		goto out;
-
-	buf[strlen(buf) + 1] = '\0';
-	if (strcmp(dirnp, "/"))
-		strncat(buf, "/", 1);
-	strncat(buf, basenp, PATH_MAX - strlen(buf) - 1);
-	rv = true;
-
-out:
-	free(dir);
-	free(base);
-
-	return rv;
-}
-
 int
 unregister_repository(const char *uri)
 {
 	char idxstr[PATH_MAX];
 	int rv = 0;
 
-	if (!sanitize_url(idxstr, uri))
+	if (!realpath(uri, idxstr))
 		return errno;
 
 	if ((rv = xbps_repository_unregister(idxstr)) != 0) {
@@ -168,7 +128,7 @@ register_repository(const char *uri)
 	int rv = 0;
 
 	if (xbps_check_is_repo_string_remote(uri)) {
-		if (!sanitize_url(idxstr, uri))
+		if (!realpath(uri, idxstr))
 			return errno;
 
 		printf("Fetching remote package index at %s...\n", uri);
@@ -186,7 +146,7 @@ register_repository(const char *uri)
 
 		plist = xbps_get_pkg_index_plist(idxstr);
 	} else {
-		if (!sanitize_url(idxstr, uri))
+		if (!realpath(uri, idxstr))
 			return errno;
 
 		/*
@@ -226,7 +186,7 @@ register_repository(const char *uri)
 	}
 
 	printf("Added package index at %s (v%s) with %ju packages.\n",
-	    uri, rpi->pkgidxver, rpi->totalpkgs);
+	    idxstr, rpi->pkgidxver, rpi->totalpkgs);
 
 out:
 	if (rpi != NULL)

bin/xbps-uhelper/Makefile

@@ -1,5 +1,5 @@
 TOPDIR = ../..
-include $(TOPDIR)/vars.mk
+-include $(TOPDIR)/config.mk
 
 BIN = xbps-uhelper
 

bin/xbps-uhelper/main.c

@@ -102,9 +102,9 @@ main(int argc, char **argv)
 {
 	prop_dictionary_t dict;
 	const char *version;
-	char *plist, *pkgname, *pkgver, *in_chroot_env, *root = "";
+	char *plist, *pkgname, *pkgver, *in_chroot_env, *root = "", *hash;
 	bool in_chroot = false;
-	int c, rv = 0;
+	int i, c, rv = 0;
 
 	while ((c = getopt(argc, argv, "Var:")) != -1) {
 		switch (c) {
@@ -299,9 +299,6 @@ main(int argc, char **argv)
 		if (argc < 2)
 			usage();
 
-		char *hash;
-		int i;
-
 		for (i = 1; i < argc; i++) {
 			hash = xbps_get_file_hash(argv[i]);
 			if (hash == NULL) {
@@ -320,7 +317,6 @@ main(int argc, char **argv)
 			usage();
 
 		xbps_fetch_set_cache_connection(0, 0);
-		int i;
 
 		for (i = 1; i < argc; i++) {
 			rv = xbps_fetch_file(argv[i], ".", false, "v");