config/git: import suckless sbase

i currently use the output of sha512sum in several
places of xbmk, which is a bit unreliable in case
output changes.

other cases where i use util outputs in variables
are probably reliable, because i'm using mostly
posix utilities in those.

to mitigate this, i now import suckless sbase, which
has a reasonable sha512sum implementation.

*every* binary it builds is being placed in build.list,
because i'll probably start using more of them.

for example, i may start modifying the "date"
implementation, adding the GNU-specific options that
i need as mentioned on init.sh

i'm importing it in util/ because the sha512sum
util is needed for verifying project sources, so
if sbase itself is a "project source", that means
we can into a chicken and egg bootstrapping problem.

this is sbase at revision:
055cc1ae1b3a13c3d8f25af0a4a3316590efcd48

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/sbase/rm.c

@@ -0,0 +1,87 @@
+/* See LICENSE file for copyright and license details. */
+#include <fcntl.h>
+#include  <string.h>
+
+#include "fs.h"
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-f] [-iRr] file ...\n", argv0);
+}
+
+static int
+forbidden(char *path, struct stat *root)
+{
+	char *s, *t;
+	size_t n;
+	struct stat st;
+	static int w1, w2;
+
+	n = strlen(path);
+	for (t = path + n; t > path && t[-1] == '/'; --t)
+		;
+	for (s = t; s > path && s[-1] != '/'; --s)
+		;
+	n = t - s;
+	if (n == 1 && *s == '.' || n == 2 && s[0] == '.' && s[1] == '.') {
+		if (!w1)
+			weprintf("\".\" and \"..\" may not be removed\n");
+		w1 = 1;
+		return 1;
+	}
+
+	if (stat(path, &st) < 0)
+		return 0;
+	if (st.st_dev == root->st_dev && st.st_ino == root->st_ino) {
+		if (!w2)
+			weprintf("\"/\" may not be removed\n");
+		w2 = 1;
+		return 1;
+	}
+
+	return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+	char *s;
+	struct stat st;
+	struct recursor r = { .fn = rm, .maxdepth = 1, .follow = 'P' };
+
+	ARGBEGIN {
+	case 'f':
+		r.flags |= SILENT | IGNORE;
+		break;
+	case 'i':
+		r.flags |= CONFIRM;
+		break;
+	case 'R':
+	case 'r':
+		r.maxdepth = 0;
+		break;
+	default:
+		usage();
+	} ARGEND
+
+	if (!argc) {
+		if (!(r.flags & IGNORE))
+			usage();
+		else
+			return 0;
+	}
+
+	if (stat("/", &st) < 0)
+		eprintf("stat root:");
+	for (; *argv; argc--, argv++) {
+		if (forbidden(*argv, &st)) {
+			rm_status = 1;
+			continue;
+		}
+		recurse(AT_FDCWD, *argv, NULL, &r);
+	}
+
+	return rm_status || recurse_status;
+}