1 files changed, 128 insertions, 0 deletions
diff --git a/lib/libgeom/geom_getxml.c b/lib/libgeom/geom_getxml.c
new file mode 100644
index 000000000000..db509c2ad5da
--- /dev/null
+++ b/lib/libgeom/geom_getxml.c
@@ -0,0 +1,128 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2003 Poul-Henning Kamp
+ * All rights reserved.
+ * Copyright (c) 2022 Alexander Motin <mav@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the authors may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "libgeom.h"
+
+/*
+ * Amount of extra space we allocate to try and anticipate the size of
+ * confxml.
+ */
+#define	GEOM_GETXML_SLACK	4096
+
+/*
+ * Number of times to retry in the face of the size of confxml exceeding
+ * that of our buffer.
+ */
+#define	GEOM_GETXML_RETRIES	4
+
+/*
+ * Size of confxml buffer to request via getxml control request.  It is
+ * expected to be sufficient for single geom and its parents.  In case of
+ * overflow fall back to requesting full confxml via sysctl interface.
+ */
+#define	GEOM_GETXML_BUFFER	65536
+
+char *
+geom_getxml(void)
+{
+	char *p;
+	size_t l = 0;
+	int mib[3];
+	size_t sizep;
+	int retries;
+
+	sizep = sizeof(mib) / sizeof(*mib);
+	if (sysctlnametomib("kern.geom.confxml", mib, &sizep) != 0)
+		return (NULL);
+	if (sysctl(mib, sizep, NULL, &l, NULL, 0) != 0)
+		return (NULL);
+	l += GEOM_GETXML_SLACK;
+
+	for (retries = 0; retries < GEOM_GETXML_RETRIES; retries++) {
+		p = malloc(l);
+		if (p == NULL)
+			return (NULL);
+		if (sysctl(mib, sizep, p, &l, NULL, 0) == 0)
+			return (reallocf(p, strlen(p) + 1));
+
+		free(p);
+
+		if (errno != ENOMEM)
+			return (NULL);
+
+		/*
+		 * Our buffer wasn't big enough. Make it bigger and
+		 * try again.
+		 */
+		l *= 2;
+	}
+
+	return (NULL);
+}
+
+char *
+geom_getxml_geom(const char *class, const char *geom, int parents)
+{
+	struct gctl_req *r;
+	char *p;
+	const char *errstr;
+	int nargs = 0;
+
+	p = malloc(GEOM_GETXML_BUFFER);
+	if (p == NULL)
+		return (NULL);
+	r = gctl_get_handle();
+	gctl_ro_param(r, "class", -1, class);
+	gctl_ro_param(r, "verb", -1, "getxml");
+	gctl_ro_param(r, "parents", sizeof(parents), &parents);
+	if (geom) {
+		gctl_ro_param(r, "arg0", -1, geom);
+		nargs = 1;
+	}
+	gctl_ro_param(r, "nargs", sizeof(nargs), &nargs);
+	p[0] = '\0';
+	gctl_add_param(r, "output", GEOM_GETXML_BUFFER, p,
+	    GCTL_PARAM_WR | GCTL_PARAM_ASCII);
+	errstr = gctl_issue(r);
+	if (errstr != NULL && errstr[0] != '\0') {
+		gctl_free(r);
+		free(p);
+		return (geom_getxml());
+	}
+	gctl_free(r);
+	return (p);
+}