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+*.so
diff --git a/COPYING b/COPYING
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--- /dev/null
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+                   GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
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+(including a cross-claim or counterclaim in a lawsuit) alleging that
+any patent claim is infringed by making, using, selling, offering for
+sale, or importing the Program or any portion of it.
+
+  11. Patents.
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+  A "contributor" is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's "contributor version".
+
+  A contributor's "essential patent claims" are all patent claims
+owned or controlled by the contributor, whether already acquired or
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+  In the following three paragraphs, a "patent license" is any express
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+  If you convey a covered work, knowingly relying on a patent license,
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+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
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+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+  If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
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+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the special requirements of the GNU Affero General Public License,
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+combination as such.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6a20cbb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,33 @@
+.PHONY: test_strings clean
+
+COMMON_OBJECTS=uns.o
+CHENEY_C89_OBJECTS=cheney_c89.o c89_relo.o
+
+CFLAGS=-Wall -Wno-overlength-strings -std=c89 -Werror -pedantic -fPIC -g -Iinclude
+
+libuniversalservice.so: $(COMMON_OBJECTS) $(CHENEY_C89_OBJECTS)
+	$(CC) -shared $(COMMON_OBJECTS) $(CHENEY_C89_OBJECTS) -o libuniversalservice.so
+.c.o:
+	$(CC) $(CFLAGS) $< -c -o $@
+
+#############################################
+## Examples
+#############################################
+
+STRING_TEST_OBJS=examples/string/test_common.o examples/string/uns_string.o
+STRING_TESTS= examples/string/test_small
+
+examples/string/test_small: examples/string/test_small.c $(STRING_TEST_OBJS) libuniversalservice.so
+	$(CC) -I. -Iext $(CFLAGS) examples/string/test_small.c $(STRING_TEST_OBJS) -L. -luniversalservice -o examples/string/test_small
+
+test_strings: $(STRING_TESTS)
+	for i in $(STRING_TESTS); do \
+		LD_LIBRARY_PATH=$$(pwd) valgrind $$i; \
+	done
+
+###################
+## Clean
+##################
+
+clean:
+	rm -f $(STRING_TEST_OBJS) $(STRING_TESTS) $(COMMON_OBJECTS) $(CHENEY_STRING_OBJECTS)
diff --git a/README.rst b/README.rst
new file mode 100644
index 0000000..8745af5
--- /dev/null
+++ b/README.rst
@@ -0,0 +1,32 @@
+=================
+Universal Service
+=================
+
+Universal Service is a collection of garbage collectors written in C.
+
+-------
+License
+-------
+
+Universal Service is licensed under the LGPL-3.0-or-later.
+
+Contrary to popular belief, **static linking LGPL code does not force
+your code to be LGPL.** The LGPL requires you to allow the user to swap
+out the LGPL code for anything that fits the interface, and for you to
+redistribute modifications to the LGPL code. From the
+`GNU Project FAQ <https://www.gnu.org/licenses/gpl-faq.html#LGPLStaticVsDynamic>`_:
+
+> Does the LGPL have different requirements for statically vs dynamically
+> linked modules with a covered work?
+>
+> For the purpose of complying with the LGPL (any extant version: v2, v2.1 or v3):
+>
+> If you statically link against an LGPLed library, you must also
+> provide your application in an object (not necessarily source) format,
+> so that a user has the opportunity to modify the library and relink
+> the application.
+
+You can statically link any LGPL 3.0 code to code of permissive licenses
+(like MIT), and even to source-available license (like the SSPL or the
+Commons Clause) as long as the end user can recompile the program to use
+their own version of the library.
diff --git a/c89_relo.c b/c89_relo.c
new file mode 100644
index 0000000..f215c8f
--- /dev/null
+++ b/c89_relo.c
@@ -0,0 +1,73 @@
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#include <string.h>
+#include <assert.h>
+#include "uns.h"
+#include "internal/c89_relo.h"
+
+typedef struct uns_c89_relo_hdr Hdr;
+
+size_t uns_c89_relo_get_len(void *p)
+{
+	Hdr *hdr = uns_c89_relo_get_hdr(p);
+
+	return (size_t)(hdr->len < 0 ? -hdr->len : hdr->len);
+}
+
+size_t uns_c89_relo_get_record_len(void *p)
+{
+	Hdr *hdr = uns_c89_relo_get_hdr(p);
+
+	if (hdr->len > 0)
+		return 0;
+	return (size_t)(-hdr->len) / sizeof(void *);
+}
+
+void *uns_c89_relo_init(void *p, size_t len_size, int is_record)
+{
+	Hdr *hdr = p;
+
+	assert(len_size < UNS_SWORD_MAX);
+	hdr->relo = NULL;
+	hdr->len = (uns_sword)len_size;
+	if (is_record)
+		hdr->len = -hdr->len;
+
+	return hdr + 1;
+}
+
+static void check_len(void *rec, size_t i)
+{
+	assert(i * sizeof(void *) < uns_c89_relo_get_len(rec));
+}
+
+void uns_c89_relo_record_set(void *rec, size_t i, void *v)
+{
+	check_len(rec, i);
+	memcpy((unsigned char *)rec + i*sizeof(void*), &v, sizeof(v));
+}
+
+void *uns_c89_relo_record_get(void *rec, size_t i)
+{
+	void *v;
+
+	check_len(rec, i);
+	memcpy(&v, (unsigned char *)rec + i*sizeof(void*), sizeof(v));
+
+	return v;
+}
diff --git a/cheney_c89.c b/cheney_c89.c
new file mode 100644
index 0000000..bb66973
--- /dev/null
+++ b/cheney_c89.c
@@ -0,0 +1,192 @@
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#include <stdlib.h>
+#include <limits.h>
+#include <assert.h>
+#include <string.h>
+#include "uns.h"
+#include "internal/c89_relo.h"
+#include "cheney_c89.h"
+
+struct ctx {
+	unsigned char *tospace;
+	unsigned char *tospace_end;
+	unsigned char *tospace_alloc;
+};
+
+const size_t uns_cheney_c89_ctx_size = sizeof(struct ctx);
+
+static void zero_ctx(struct ctx *ctx)
+{
+	ctx->tospace = 0;
+	ctx->tospace_end = 0;
+	ctx->tospace_alloc = 0;
+}
+
+void uns_cheney_c89_deinit(struct uns_gc *gc)
+{
+	struct ctx *ctx = gc->ctx;
+
+	free(ctx->tospace);
+}
+
+/* Allocate without doing bounds checking. This is common code for
+ * collecting (when all values will fit into the tospace) and
+ * allocation (where bounds checking is done beforehand).
+ */
+static void *raw_alloc(struct ctx *ctx, size_t len, int is_record)
+{
+	unsigned char *p;
+
+	p = uns_c89_relo_init(ctx->tospace_alloc, len, is_record);
+	ctx->tospace_alloc = p + len;
+
+	return p;
+}
+
+/* Move an entire object pointed to by p from fromspace to tospace. */
+static unsigned char *relocate(struct uns_gc *gc, unsigned char *p)
+{
+	size_t l;
+	unsigned char *res;
+	struct ctx *ctx = gc->ctx;
+
+	if (!p)
+		return NULL;
+	res = uns_c89_relo_get_relo(p);
+	if (res)
+		return res;
+
+	l = uns_c89_relo_get_len(p);
+	res = raw_alloc(ctx, l, uns_c89_relo_is_record(p));
+	memcpy(res, p, l);
+	gc->after_collection += l;
+
+	uns_c89_relo_set_relo(p, res);
+	return res;
+}
+
+/* Scan each part of the record pointed to by "p" and relocate it. */
+static void scan_record(struct uns_gc *gc, unsigned char *p)
+{
+	size_t l = uns_c89_relo_get_record_len(p);
+	size_t i;
+	void *newp;
+
+	for (i = 0; i < l; i++) {
+		newp = relocate(gc, uns_c89_relo_record_get(p, i));
+		memcpy(p, &newp, sizeof(void *));
+	}
+}
+
+int uns_cheney_c89_collect(struct uns_gc *gc)
+{
+	/* Save fromspace */
+	struct ctx *ctx = gc->ctx;
+	unsigned char *fromspace = ctx->tospace;
+	unsigned char *fromspace_lim = ctx->tospace_alloc;
+	unsigned char *scanptr;
+
+	size_t newlen = gc->next_alloc;
+	struct uns_root_list *root;
+
+	assert(gc->next_alloc >= fromspace_lim - fromspace);
+
+	/* Bail out immediately if allocation fails. This preserves
+	 * the objects as they were.
+	 */
+	ctx->tospace = malloc(newlen);
+	if (!ctx->tospace) {
+		ctx->tospace = fromspace;
+		return 1;
+	}
+
+	/* Setup statistics */
+	gc->before_collection = fromspace_lim - fromspace;
+	gc->after_collection = 0;
+	gc->collection_number += 1;
+
+	ctx->tospace_end = ctx->tospace + newlen;
+	ctx->tospace_alloc = ctx->tospace;
+
+	/* Relocate roots */
+	for (root = gc->roots; root; root = root->next)
+		root->p = relocate(gc, root->p);
+
+	scanptr = ctx->tospace;
+	while (scanptr != ctx->tospace_alloc) {
+		if (uns_c89_relo_is_record(scanptr))
+			scan_record(gc, scanptr);
+		scanptr += uns_c89_relo_get_len(scanptr);
+	}
+
+	free(fromspace);
+	if (gc->after_gc)
+		gc->after_gc(gc);
+	return 1;
+}
+
+static void *alloc(struct uns_gc *gc, size_t bytes, int is_record)
+{
+	struct ctx *ctx = gc->ctx;
+
+	if (ctx->tospace_end - ctx->tospace_alloc < bytes)
+		uns_cheney_c89_collect(gc);
+	if (ctx->tospace_end - ctx->tospace_alloc < bytes)
+		gc->oom(gc);
+
+	return raw_alloc(ctx, bytes, is_record);
+}
+
+void *uns_cheney_c89_alloc(struct uns_gc *gc, size_t bytes)
+{
+	return alloc(gc, bytes, 0);
+}
+
+void *uns_cheney_c89_alloc_record(struct uns_gc *gc, size_t records)
+{
+	size_t i;
+	unsigned char *res = alloc(gc, records*sizeof(void *), 1);
+
+	for (i = 0; i < records; i++)
+		uns_c89_relo_record_set(res, i, NULL);
+
+	return res;
+}
+
+int uns_cheney_c89_init(struct uns_gc *gc)
+{
+	struct ctx *ctx = gc->ctx;
+
+	gc->deinit = uns_cheney_c89_deinit;
+	gc->collect = uns_cheney_c89_collect;
+	gc->alloc = uns_cheney_c89_alloc;
+	gc->alloc_record = uns_cheney_c89_alloc_record;
+	gc->len = uns_c89_relo_get_len;
+	gc->record_set_ptr = uns_c89_relo_record_set;
+	gc->record_get_ptr = uns_c89_relo_record_get;
+
+	zero_ctx(ctx);
+	ctx->tospace = malloc(gc->next_alloc);
+	if (!ctx->tospace)
+		return 0;
+
+	ctx->tospace_alloc = ctx->tospace;
+	ctx->tospace_end = ctx->tospace + gc->next_alloc;
+	return 1;
+}
diff --git a/examples/string/test_common.c b/examples/string/test_common.c
new file mode 100644
index 0000000..de12d93
--- /dev/null
+++ b/examples/string/test_common.c
@@ -0,0 +1,80 @@
+/* Copyright (c) 2024, Peter McGoron
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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 <stdlib.h>
+#include <stdio.h>
+#include "uns.h"
+#include "cheney_c89.h"
+
+/* This file sets up the environment for a test.
+ *
+ * Each test is compiled as a separate program to isolate tests portably.
+ * A test suite is a shell script (or batch file or whatever you want...)
+ */
+
+static void oom(struct uns_gc *gc)
+{
+	(void)gc;
+	fprintf(stderr, "failed: OOM\n");
+	exit(1);
+}
+
+static void after_gc(struct uns_gc *gc)
+{
+	fprintf(stderr,
+	        "The garbage collector has run %ld times\n"
+	        "\tbefore collection: %lu\n"
+	        "\tafter collection: %lu\n",
+	        gc->collection_number,
+	        gc->before_collection,
+	        gc->after_collection
+	);
+
+	if (gc->after_collection >= gc->before_collection/2)
+		gc->next_alloc *= 2;
+}
+
+extern int test(struct uns_gc *gc);
+
+int main(void)
+{
+	static struct uns_gc gc;
+	int i;
+
+	gc.next_alloc = 1024;
+	gc.ctx = malloc(uns_cheney_c89_ctx_size);
+	gc.after_gc = after_gc;
+	gc.oom = oom;
+
+	if (!gc.ctx)
+		return 1;
+	if (!uns_cheney_c89_init(&gc))
+		return 2;
+	gc.next_alloc = 2048;
+
+	i = test(&gc);
+	gc.deinit(&gc);
+	return i;
+}
diff --git a/examples/string/test_large.c b/examples/string/test_large.c
new file mode 100644
index 0000000..dddbbff
--- /dev/null
+++ b/examples/string/test_large.c
@@ -0,0 +1,77 @@
+/* Copyright (c) 2024, Peter McGoron
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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 "uns.h"
+#include "uns_string.h"
+
+int test(struct uns_gc *gc)
+{
+	struct uns_root_list r = {0};
+	size_t i;
+
+	/* MistralAI 8x7B 0.1:
+	 * Prompt: "write a sonnet about garbage collectors (the memory management kind)"
+	 *
+	 * This string constant is larger than the standard's minimum. If
+	 * this test doesn't compile, get a better compiler.
+	 */
+	const char s[] =
+		"To the humble garbagemen of code's dark night,\n"
+		"Who tread through bits and bytes with steady hand.\n"
+		"They roam the heap, in dimly lit sight,\n"
+		"And rescue order from chaos unplanned.\n"
+
+		"With algorithms precise and swift they glide,\n"
+		"Through malloc'd arrays and pointers vast.\n"
+		"Their work essential to keep programs wide,\n"
+		"From crashing down upon us too soon passed.\n"
+
+		"Yet often left unsung are these brave knights,\n"
+		"Whose vigilance keeps our software clean.\n"
+		"In shadows cast by CPUs might,\n"
+		"Unseen forces that make sense of unseen.\n"
+
+		"So here's to you, dear Garbage Collectors all,\n"
+		"Thank you for keeping coding dreams enthralled.\n"
+	;
+
+	uns_string_alloc_into(&gc, &r);
+
+	/* generate lots of garbage */
+	uns_string_alloc_into(&gc, &r);
+	uns_root_add(&gc, &r);
+	for (i = 0; i < 100; i++)
+		uns_string_append_bytes(&gc, &r, s, sizeof(s) - 1);
+	uns_root_remove(&gc, &r);
+
+	/* Generate lots of garbage by being inefficient. */
+	uns_string_alloc_into(&gc, &r);
+	uns_root_add(&gc, &r);
+	for (i = 0; i < sizeof(s) - 1; i++)
+		uns_string_append_char(&gc, &r, s[i]);
+	uns_root_remove(&gc, &r);
+
+	return 0;
+}
diff --git a/examples/string/test_small.c b/examples/string/test_small.c
new file mode 100644
index 0000000..08b2ed2
--- /dev/null
+++ b/examples/string/test_small.c
@@ -0,0 +1,44 @@
+/* Copyright (c) 2024, Peter McGoron
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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 <stdio.h>
+#include "uns.h"
+#include "uns_string.h"
+
+int test(struct uns_gc *gc)
+{
+	struct uns_root_list r = {0};
+	const char s[] = "hello, world";
+
+	uns_string_alloc(gc, &r, 32);
+	uns_root_add(gc, &r);
+	uns_string_append_bytes(gc, &r, s, sizeof(s) - 1);
+
+	printf("%s\n", uns_string_cstring(gc, &r));
+
+	uns_root_remove(gc, &r);
+
+	return 0;
+}
diff --git a/examples/string/uns_string.c b/examples/string/uns_string.c
new file mode 100644
index 0000000..e510fcf
--- /dev/null
+++ b/examples/string/uns_string.c
@@ -0,0 +1,127 @@
+/* Copyright (c) 2024, Peter McGoron
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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 <string.h>
+#include "uns.h"
+#include "uns_string.h"
+
+enum {
+	ALLEN_IND = 0,
+	LEN_IND = 1,
+	BYTES_IND = 2,
+	NUMBER_OF_IND = 3
+};
+
+static size_t get_size_t(struct uns_gc *gc, struct uns_root_list *root, size_t i)
+{
+	size_t r;
+
+	void *p = gc->record_get_ptr(root->p, i);
+	memcpy(&r, p, sizeof(r));
+
+	return r;
+}
+
+static void set_size_t(struct uns_gc *gc, struct uns_root_list *root, size_t i, size_t val)
+{
+	void *p = gc->record_get_ptr(root->p, i);
+	memcpy(p, &val, sizeof(val));
+}
+
+#define set_allen(gc,root,val) set_size_t(gc, root, ALLEN_IND, val)
+#define set_len(gc,root,val) set_size_t(gc, root, LEN_IND, val)
+
+static size_t uns_string_allen(struct uns_gc *gc, struct uns_root_list *root)
+{
+	return get_size_t(gc, root, ALLEN_IND);
+}
+
+size_t uns_string_len(struct uns_gc *gc, struct uns_root_list *root)
+{
+	return get_size_t(gc, root, LEN_IND);
+}
+
+char *uns_string_ptr(struct uns_gc *gc, struct uns_root_list *root)
+{
+	return gc->record_get_ptr(root->p, BYTES_IND);
+}
+
+void uns_string_alloc(struct uns_gc *gc, struct uns_root_list *root, size_t start_len)
+{
+	root->p = gc->alloc_record(gc, NUMBER_OF_IND);
+
+	gc->record_set_ptr(root->p, ALLEN_IND, gc->alloc(gc, sizeof(size_t)));
+	set_allen(gc, root, start_len);
+
+	gc->record_set_ptr(root->p, LEN_IND, gc->alloc(gc, sizeof(size_t)));
+	set_len(gc, root, 0);
+
+	gc->record_set_ptr(root->p, BYTES_IND, gc->alloc(gc, start_len));
+}
+
+void uns_string_resize(struct uns_gc *gc, struct uns_root_list *root, size_t newlen)
+{
+	char *tmp;
+
+	tmp = gc->alloc(gc, newlen);
+	set_allen(gc, root, newlen);
+
+	if (newlen <= uns_string_len(gc, root))
+		set_len(gc, root, newlen);
+	memcpy(tmp, uns_string_ptr(gc, root), uns_string_len(gc, root));
+}
+
+void uns_string_ensure(struct uns_gc *gc, struct uns_root_list *root, size_t extent)
+{
+	size_t used = uns_string_len(gc, root);
+	size_t allen = uns_string_allen(gc, root);
+
+	if (used + extent > allen)
+		uns_string_resize(gc, root, used + extent);
+}
+
+void uns_string_append_bytes(struct uns_gc *gc, struct uns_root_list *to,
+                            const void *from, size_t bytes)
+{
+	size_t len = uns_string_len(gc, to);
+	uns_string_ensure(gc, to, bytes);
+	memcpy(uns_string_ptr(gc, to) + len, from, bytes);
+	set_len(gc, to, len + bytes);
+}
+
+void uns_string_append_char(struct uns_gc *gc, struct uns_root_list *root, char c)
+{
+	uns_string_append_bytes(gc, root, &c, 1);
+}
+
+char *uns_string_cstring(struct uns_gc *gc, struct uns_root_list *root)
+{
+	char *p;
+	uns_string_ensure(gc, root, 1);
+
+	p = uns_string_ptr(gc, root);
+	p[uns_string_len(gc, root)] = 0;
+	return p;
+}
diff --git a/examples/string/uns_string.h b/examples/string/uns_string.h
new file mode 100644
index 0000000..14ae812
--- /dev/null
+++ b/examples/string/uns_string.h
@@ -0,0 +1,53 @@
+#ifndef UNS_STRING_H
+#define UNS_STRING_H
+
+/* Copyright (c) 2024, Peter McGoron
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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 "uns.h"
+
+/* This code implements imperative strings. Imperative strings can be
+ * updated in-place. This requires storing the amount of memory left in
+ * the string, and the length of the string itself.
+ *
+ * String format:
+ * record: [slot 1]             [slot 2]   [slot 3]
+ *            |                    |          |
+ *         size_t                size_t     bytes
+ *        (allocated length)    (used)     (size of used)
+ */
+
+size_t uns_string_len(struct uns_gc *gc, struct uns_root_list *root);
+char *uns_string_ptr(struct uns_gc *gc, struct uns_root_list *root);
+
+/* The following functions may cause a collection. */
+void uns_string_alloc(struct uns_gc *gc, struct uns_root_list *root, size_t start_len);
+void uns_string_resize(struct uns_gc *gc, struct uns_root_list *root, size_t newlen);
+void uns_string_ensure(struct uns_gc *gc, struct uns_root_list *root, size_t extent);
+void uns_string_append_bytes(struct uns_gc *gc, struct uns_root_list *to,
+                            const void *from, size_t bytes);
+void uns_string_append_char(struct uns_gc *gc, struct uns_root_list *root, char c);
+char *uns_string_cstring(struct uns_gc *gc, struct uns_root_list *root);
+#endif
diff --git a/include/cheney_c89.h b/include/cheney_c89.h
new file mode 100644
index 0000000..32f379a
--- /dev/null
+++ b/include/cheney_c89.h
@@ -0,0 +1,33 @@
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef UNS_CHENEY_C89_H
+#define UNS_CHENEY_C89_H
+
+#include "uns.h"
+
+/* Cheney copying collector in pure portable C89. */
+
+void uns_cheney_c89_deinit(struct uns_gc *gc);
+int uns_cheney_c89_init(struct uns_gc *gc);
+int uns_cheney_c89_collect(struct uns_gc *gc);
+void *uns_cheney_c89_alloc(struct uns_gc *gc, size_t bytes);
+void *uns_cheney_c89_alloc_record(struct uns_gc *gc, size_t records);
+
+const extern size_t uns_cheney_c89_ctx_size;
+
+#endif
diff --git a/include/internal/c89_relo.h b/include/internal/c89_relo.h
new file mode 100644
index 0000000..5347aa8
--- /dev/null
+++ b/include/internal/c89_relo.h
@@ -0,0 +1,52 @@
+#ifndef UNS_FORMAT_C89_H
+#define UNS_FORMAT_C89_H
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#include "uns.h"
+
+/* This is a strictly C89+ header format with relocation pointers and
+ * lengths.
+ *
+ * Forwarding pointers need to be stored in the header because in strict
+ * C, arithmetic on pointers is undefined for pointers not pointing into
+ * the same object.
+ *
+ * The length of the string is limited to "len" bytes and is stored as
+ * a `uns_sword`. If the word is negative, then the region is a record,
+ * and if the number is positive then the region is just bytes.
+ */
+
+struct uns_c89_relo_hdr {
+	void *relo;
+	uns_sword len;
+};
+#define uns_c89_relo_get_hdr(p)((struct uns_c89_relo_hdr *)(p) - 1)
+
+size_t uns_c89_relo_get_len(void *p);
+size_t uns_c89_relo_get_record_len(void *p);
+
+#define uns_c89_relo_get_relo(p) (uns_c89_relo_get_hdr(p)->relo)
+#define uns_c89_relo_set_relo(p, v) (uns_c89_relo_get_relo(p) = (v))
+#define uns_c89_relo_is_record(p) (uns_c89_relo_get_hdr(p)->len < 0)
+
+void *uns_c89_relo_init(void *p, size_t len_size, int is_record);
+
+void uns_c89_relo_record_set(void *rec, size_t i, void *v);
+void *uns_c89_relo_record_get(void *rec, size_t i);
+
+#endif
diff --git a/include/uns.h b/include/uns.h
new file mode 100644
index 0000000..1277b32
--- /dev/null
+++ b/include/uns.h
@@ -0,0 +1,104 @@
+#ifndef UNIVERSAL_SERVICE_H
+#define UNIVERSAL_SERVICE_H
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#include <stddef.h>
+#if !defined(UNS_WORD) && __STDC_VERSION__ >= 199101L
+# include <stdint.h>
+# include <limits.h>
+# define UNS_WORD uintptr_t
+# define UNS_SIGNED_WORD intptr_t
+# define UNS_WORD_MAX UINTPTR_MAX
+# define UNS_SWORD_MAX INTPTR_MAX
+# define UNS_SWORD_MIN INTPTR_MIN
+#elif !defined(UNS_WORD)
+# include <limits.h>
+# define UNS_WORD unsigned long
+# define UNS_WORD_MAX ULONG_MAX
+# define UNS_SIGNED_WORD long
+# define UNS_SWORD_MAX LONG_MAX
+# define UNS_SWORD_MIN LONG_MIN
+#endif
+
+typedef UNS_WORD uns_word;
+typedef UNS_SIGNED_WORD uns_sword;
+
+/** Doubly linked list used to
+  *
+  * 1) Store roots of the GC,
+  * 2) Store GC pointers used in C and possibly not pointed-to anywhere
+  *    else in GC space,
+  * 3) Preserve the location of a pointer after it moves.
+  *
+  * A root that is not a part of any GC MUST have ``prev`` and ``next``
+  * set to NULL.
+  */
+struct uns_root_list {
+	struct uns_root_list *prev;
+	void *p;
+	struct uns_root_list *next;
+};
+
+struct uns_gc {
+	void *ctx;
+
+	/* The collector only changes the pointer values of "p".
+	 *
+	 * * The collector never adds or removes roots.
+	 * * The collector never rearranges the order of the container structures.
+	 *
+	 * The roots list can have repeated values.
+	 */
+	struct uns_root_list *roots;
+	size_t next_alloc;
+	void (*oom)(struct uns_gc *);
+	void (*after_gc)(struct uns_gc *);
+
+	size_t before_collection;
+	size_t after_collection;
+	long collection_number;
+
+	void (*deinit)(struct uns_gc *);
+
+	/* These functions, and only these functions, may invalidate
+	 * pointers by either moving them or freeing them.
+	 */
+	int (*collect)(struct uns_gc *);
+	void *(*alloc)(struct uns_gc *, size_t);
+	void *(*alloc_record)(struct uns_gc *, size_t);
+
+	/* These functions MUST NOT cause collections. */
+
+	/* This function is optional. It is only provided if the GC can
+	 * calculate the length of the pointer quickly.
+	 */
+	size_t (*len)(void *);
+
+	void (*record_set_ptr)(void *, size_t, void *);
+	void *(*record_get_ptr)(void *, size_t);
+};
+
+/** Add a root to the GC. The root must point to valid memory, or NULL. */
+void uns_root_add(struct uns_gc *gc, struct uns_root_list *root);
+
+/** Remove a root from the GC. It is OK to remove a root that is not a
+  * part of any GC using this function (the call will have no effect).
+  */
+void uns_root_remove(struct uns_gc *gc, struct uns_root_list *root);
+
+#endif
diff --git a/uns.c b/uns.c
new file mode 100644
index 0000000..4d6eaad
--- /dev/null
+++ b/uns.c
@@ -0,0 +1,39 @@
+/* Copyright (C) 2024 Peter McGoron
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <https://www.gnu.org/licenses/>.
+*/
+
+#include "uns.h"
+
+void uns_root_add(struct uns_gc *gc, struct uns_root_list *root)
+{
+	root->prev = NULL;
+	root->next = gc->roots;
+	gc->roots = root;
+}
+
+void uns_root_remove(struct uns_gc *gc, struct uns_root_list *root)
+{
+	if (root->prev) {
+		root->prev->next = root->next;
+	}
+	if (root->next) {
+		root->next->prev = root->prev;
+	}
+
+	if (gc->roots == root)
+		gc->roots = root->next;
+	root->prev = root->next = NULL;
+}