libio: consolidate add-hoc memory istream_t implementations

In several places, there are ad-hoc istream_t implementations that
read from a memory buffer to test something else stacked on top.

This commit consolidates those ad-hoc implmentations into a proper
one in libio, and uses the chance to remove external files for some
older tests that rely on file I/O instead.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

13 files changed, 247 insertions, 316 deletions

diff --git a/bin/gensquashfs/Makemodule.am b/bin/gensquashfs/Makemodule.am
index 0bb2122..2e14ff6 100644
--- a/bin/gensquashfs/Makemodule.am
+++ b/bin/gensquashfs/Makemodule.am
@@ -35,7 +35,6 @@ test_fstree_from_file_SOURCES = bin/gensquashfs/test/fstree_from_file.c \
 				bin/gensquashfs/src/mkfs.h
 test_fstree_from_file_CPPFLAGS = $(AM_CPPFLAGS)
 test_fstree_from_file_CPPFLAGS += -I$(top_srcdir)/bin/gensquashfs/src
-test_fstree_from_file_CPPFLAGS += -DTESTPATH=$(GENDATADIR)/fstree1.txt
 test_fstree_from_file_LDADD = libcommon.a libfstree.a libio.a libutil.a \
 			libcompat.a
 
@@ -74,6 +73,6 @@ noinst_PROGRAMS += fstree_fuzz
 check_PROGRAMS += $(GENSQUASHFS_TESTS)
 TESTS += $(GENSQUASHFS_TESTS)
 
-EXTRA_DIST += $(GENDATADIR)/xattr1.txt $(GENDATADIR)/fstree1.txt
+EXTRA_DIST += $(GENDATADIR)/xattr1.txt
 EXTRA_DIST += $(GENDATADIR)/fstree_glob1.txt $(GENDATADIR)/fstree_glob2.txt
 EXTRA_DIST += $(GENDATADIR)/fstree_glob3.txt
diff --git a/bin/gensquashfs/test/fstree1.txt b/bin/gensquashfs/test/fstree1.txt
deleted file mode 100644
index 95ee469..0000000
--- a/bin/gensquashfs/test/fstree1.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-# comment line
-slink /slink 0644 2 3 slinktarget
-dir /dir 0755 4 5
-nod /chardev 0600 6 7 c 13 37
-nod /blkdev 0600 8 9 b 42 21
-pipe /pipe 0644 10 11
-dir / 0755 1000 100
-dir "/foo bar" 0755 0 0
-dir "/foo bar/ test \"/" 0755 0 0
-  sock  /sock  0555  12  13  
\ No newline at end of file
diff --git a/bin/gensquashfs/test/fstree_from_file.c b/bin/gensquashfs/test/fstree_from_file.c
index 03591d5..e54111c 100644
--- a/bin/gensquashfs/test/fstree_from_file.c
+++ b/bin/gensquashfs/test/fstree_from_file.c
@@ -7,18 +7,36 @@
 #include "config.h"
 
 #include "util/test.h"
+#include "io/mem.h"
 #include "mkfs.h"
 
+const char *listing =
+"# comment line\n"
+"slink /slink 0644 2 3 slinktarget\n"
+"dir /dir 0755 4 5\n"
+"nod /chardev 0600 6 7 c 13 37\n"
+"nod /blkdev 0600 8 9 b 42 21\n"
+"pipe /pipe 0644 10 11\n"
+"dir / 0755 1000 100\n"
+"dir \"/foo bar\" 0755 0 0\n"
+"dir \"/foo bar/ test \\\"/\" 0755 0 0\n"
+"  sock  /sock  0555  12  13  ";
+
 int main(int argc, char **argv)
 {
 	fstree_defaults_t fsd;
+	istream_t *file;
 	tree_node_t *n;
 	fstree_t fs;
 	(void)argc; (void)argv;
 
+	file = istream_memory_create("memfile", 7, listing, strlen(listing));
+	TEST_NOT_NULL(file);
+
 	TEST_ASSERT(parse_fstree_defaults(&fsd, NULL) == 0);
 	TEST_ASSERT(fstree_init(&fs, &fsd) == 0);
-	TEST_ASSERT(fstree_from_file(&fs, TEST_PATH, NULL) == 0);
+	TEST_ASSERT(fstree_from_file_stream(&fs, file, NULL) == 0);
+	sqfs_drop(file);
 
 	fstree_post_process(&fs);
 	n = fs.root->data.children;
diff --git a/bin/gensquashfs/test/sort_file.c b/bin/gensquashfs/test/sort_file.c
index 8022cff..af50260 100644
--- a/bin/gensquashfs/test/sort_file.c
+++ b/bin/gensquashfs/test/sort_file.c
@@ -9,6 +9,7 @@
 #include "sqfs/block.h"
 #include "util/test.h"
 #include "util/util.h"
+#include "io/mem.h"
 #include "mkfs.h"
 
 static const char *listing =
@@ -108,62 +109,23 @@ static int flags[] = {
 	0,
 };
 
-/*****************************************************************************/
-
-static sqfs_u8 temp_buffer[2048];
-static const char *input_file = NULL;
-
-static void destroy_noop(sqfs_object_t *obj)
-{
-	(void)obj;
-}
-
-static int memfile_load(istream_t *strm)
-{
-	strcpy((char *)temp_buffer, input_file);
-	strm->eof = true;
-	strm->buffer_used = strlen(input_file);
-	return 0;
-}
-
-static const char *get_filename(istream_t *strm)
-{
-	(void)strm;
-	return "memstream";
-}
-
-static istream_t memstream = {
-	.base = {
-		.destroy = destroy_noop,
-	},
-
-	.buffer_used = 0,
-	.buffer_offset = 0,
-	.eof = false,
-	.buffer = temp_buffer,
-
-	.precache = memfile_load,
-	.get_filename = get_filename,
-};
-
-/*****************************************************************************/
-
 int main(int argc, char **argv)
 {
 	fstree_defaults_t fsd;
+	istream_t *memstream;
 	tree_node_t *n;
 	fstree_t fs;
 	size_t i;
 	(void)argc; (void)argv;
 
-	input_file = listing;
-	memstream.buffer_used = 0;
-	memstream.buffer_offset = 0;
-	memstream.eof = false;
+	memstream = istream_memory_create("listing.txt", 1024,
+					  listing, strlen(listing));
+	TEST_NOT_NULL(memstream);
 
 	TEST_ASSERT(parse_fstree_defaults(&fsd, NULL) == 0);
 	TEST_ASSERT(fstree_init(&fs, &fsd) == 0);
-	TEST_ASSERT(fstree_from_file_stream(&fs, &memstream, NULL) == 0);
+	TEST_ASSERT(fstree_from_file_stream(&fs, memstream, NULL) == 0);
+	sqfs_drop(memstream);
 
 	fstree_post_process(&fs);
 
@@ -186,12 +148,11 @@ int main(int argc, char **argv)
 	TEST_EQUAL_UI(i, sizeof(initial_order) / sizeof(initial_order[0]));
 
 
-	input_file = sort_file;
-	memstream.buffer_used = 0;
-	memstream.buffer_offset = 0;
-	memstream.eof = false;
-
-	TEST_ASSERT(fstree_sort_files(&fs, &memstream) == 0);
+	memstream = istream_memory_create("sortfile.txt", 1024,
+					  sort_file, strlen(sort_file));
+	TEST_NOT_NULL(memstream);
+	TEST_ASSERT(fstree_sort_files(&fs, memstream) == 0);
+	sqfs_drop(memstream);
 
 	for (i = 0, n = fs.files; n != NULL; n = n->next_by_type, ++i) {
 		char *path = fstree_get_path(n);
diff --git a/include/io/mem.h b/include/io/mem.h
new file mode 100644
index 0000000..1efd007
--- /dev/null
+++ b/include/io/mem.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * mem.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef IO_MEM_STREAM_H
+#define IO_MEM_STREAM_H
+
+#include "io/istream.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+SQFS_INTERNAL istream_t *istream_memory_create(const char *name, size_t bufsz,
+					       const void *data, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* IO_MEM_STREAM_H */
diff --git a/lib/io/Makemodule.am b/lib/io/Makemodule.am
index 5b5fc7f..7427b42 100644
--- a/lib/io/Makemodule.am
+++ b/lib/io/Makemodule.am
@@ -1,10 +1,10 @@
 libio_a_SOURCES = include/io/istream.h include/io/ostream.h include/io/xfrm.h \
 	include/io/file.h include/io/std.h include/io/dir_entry.h \
-	include/io/dir_iterator.h \
+	include/io/dir_iterator.h include/io/mem.h \
 	lib/io/src/internal.h lib/io/src/ostream.c \
 	lib/io/src/istream.c lib/io/src/get_line.c lib/io/src/xfrm/ostream.c \
 	lib/io/src/xfrm/istream.c lib/io/src/dir_tree_iterator.c \
-	lib/io/src/dir_entry.c
+	lib/io/src/dir_entry.c lib/io/src/mem.c
 libio_a_CFLAGS = $(AM_CFLAGS) $(ZLIB_CFLAGS) $(XZ_CFLAGS)
 libio_a_CFLAGS += $(ZSTD_CFLAGS) $(BZIP2_CFLAGS)
 
@@ -26,7 +26,6 @@ LIBIO_TESTS = test_get_line test_sparse_fb test_istream_read \
 test_get_line_SOURCES = lib/io/test/get_line.c
 test_get_line_LDADD = libio.a libcompat.a
 test_get_line_CPPFLAGS = $(AM_CPPFLAGS)
-test_get_line_CPPFLAGS += -DTESTFILE=$(top_srcdir)/lib/io/test/get_line.txt
 
 test_sparse_fb_SOURCES = lib/io/test/sparse_fb.c
 test_sparse_fb_LDADD = libio.a libutil.a libcompat.a
@@ -97,5 +96,4 @@ endif
 check_PROGRAMS += $(LIBIO_TESTS)
 TESTS += $(LIBIO_TESTS)
 
-EXTRA_DIST += $(top_srcdir)/lib/io/test/get_line.txt
 EXTRA_DIST += $(top_srcdir)/lib/io/test/testdir
diff --git a/lib/io/src/mem.c b/lib/io/src/mem.c
new file mode 100644
index 0000000..4e9f9af
--- /dev/null
+++ b/lib/io/src/mem.c
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * mem.c
+ *
+ * Copyright (C) 2023 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+#include "io/mem.h"
+#include "compat.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+	istream_t base;
+
+	sqfs_u8 *buffer;
+	size_t bufsz;
+
+	const void *data;
+	size_t size;
+
+	char *name;
+} mem_istream_t;
+
+static int mem_in_precache(istream_t *strm)
+{
+	mem_istream_t *mem = (mem_istream_t *)strm;
+	size_t diff = mem->bufsz - strm->buffer_used;
+
+	if (diff > mem->size)
+		diff = mem->size;
+
+	if (diff > 0) {
+		memcpy(mem->buffer + strm->buffer_used, mem->data, diff);
+		strm->buffer_used += diff;
+		mem->data = (const char *)mem->data + diff;
+		mem->size -= diff;
+	}
+
+	if (mem->size == 0)
+		strm->eof = true;
+
+	return 0;
+}
+
+static const char *mem_in_get_filename(istream_t *strm)
+{
+	return ((mem_istream_t *)strm)->name;
+}
+
+static void mem_in_destroy(sqfs_object_t *obj)
+{
+	free(((mem_istream_t *)obj)->buffer);
+	free(((mem_istream_t *)obj)->name);
+	free(obj);
+}
+
+istream_t *istream_memory_create(const char *name, size_t bufsz,
+				 const void *data, size_t size)
+{
+	mem_istream_t *mem = calloc(1, sizeof(*mem));
+	istream_t *strm = (istream_t *)mem;
+
+	if (mem == NULL)
+		return NULL;
+
+	sqfs_object_init(mem, mem_in_destroy, NULL);
+
+	mem->name = strdup(name);
+	if (mem->name == NULL)
+		return sqfs_drop(mem);
+
+	mem->buffer = malloc(bufsz);
+	if (mem->buffer == NULL)
+		return sqfs_drop(mem);
+
+	mem->data = data;
+	mem->size = size;
+	mem->bufsz = bufsz;
+	strm->buffer = mem->buffer;
+	strm->precache = mem_in_precache;
+	strm->get_filename = mem_in_get_filename;
+	return strm;
+}
diff --git a/lib/io/test/get_line.c b/lib/io/test/get_line.c
index 2d0f9b7..bb06b3e 100644
--- a/lib/io/test/get_line.c
+++ b/lib/io/test/get_line.c
@@ -4,9 +4,7 @@
  *
  * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
  */
-#include "config.h"
-
-#include "io/file.h"
+#include "io/mem.h"
 #include "util/test.h"
 
 typedef struct {
@@ -14,7 +12,7 @@ typedef struct {
 	const char *str;
 } line_t;
 
-static void run_test_case(const line_t *lines, size_t count,
+static void run_test_case(const char *raw, const line_t *lines, size_t count,
 			  int flags)
 {
 	size_t i, line_num, old_line_num;
@@ -22,7 +20,7 @@ static void run_test_case(const line_t *lines, size_t count,
 	char *line;
 	int ret;
 
-	fp = istream_open_file(STRVALUE(TESTFILE));
+	fp = istream_memory_create("lines.txt", 512, raw, strlen(raw));
 	TEST_NOT_NULL(fp);
 
 	line_num = 1;
@@ -50,6 +48,19 @@ static void run_test_case(const line_t *lines, size_t count,
 	sqfs_drop(fp);
 }
 
+static const char *file =
+"\r\n"
+"The quick\r\n"
+"  \r\n"
+"  brown fox  \r\n"
+"\r\n"
+"jumps over\r\n"
+"the\r\n"
+"lazy\r\n"
+"\r\n"
+"dog\r\n"
+"\r\n";
+
 static const line_t lines_raw[] = {
 	{ 1, "" },
 	{ 2, "The quick" },
@@ -147,18 +158,18 @@ int main(int argc, char **argv)
 {
 	(void)argc; (void)argv;
 
-	run_test_case(lines_raw, 11, 0);
-	run_test_case(lines_ltrim, 11, ISTREAM_LINE_LTRIM);
-	run_test_case(lines_rtrim, 11, ISTREAM_LINE_RTRIM);
-	run_test_case(lines_trim, 11,
+	run_test_case(file, lines_raw, 11, 0);
+	run_test_case(file, lines_ltrim, 11, ISTREAM_LINE_LTRIM);
+	run_test_case(file, lines_rtrim, 11, ISTREAM_LINE_RTRIM);
+	run_test_case(file, lines_trim, 11,
 		      ISTREAM_LINE_LTRIM | ISTREAM_LINE_RTRIM);
 
-	run_test_case(lines_no_empty, 7, ISTREAM_LINE_SKIP_EMPTY);
-	run_test_case(lines_no_empty_ltrim, 6,
+	run_test_case(file, lines_no_empty, 7, ISTREAM_LINE_SKIP_EMPTY);
+	run_test_case(file, lines_no_empty_ltrim, 6,
 		      ISTREAM_LINE_SKIP_EMPTY | ISTREAM_LINE_LTRIM);
-	run_test_case(lines_no_empty_rtrim, 6,
+	run_test_case(file, lines_no_empty_rtrim, 6,
 		      ISTREAM_LINE_SKIP_EMPTY | ISTREAM_LINE_RTRIM);
-	run_test_case(lines_no_empty_trim, 6,
+	run_test_case(file, lines_no_empty_trim, 6,
 		      ISTREAM_LINE_SKIP_EMPTY | ISTREAM_LINE_LTRIM |
 		      ISTREAM_LINE_RTRIM);
 
diff --git a/lib/io/test/get_line.txt b/lib/io/test/get_line.txt
deleted file mode 100644
index a1994f0..0000000
--- a/lib/io/test/get_line.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-

-The quick

-  

-  brown fox  

-

-jumps over

-the

-lazy

-

-dog

-

diff --git a/lib/io/test/istream_read.c b/lib/io/test/istream_read.c
index 3e4c22f..87e52c5 100644
--- a/lib/io/test/istream_read.c
+++ b/lib/io/test/istream_read.c
@@ -8,72 +8,40 @@
 
 #include "io/istream.h"
 #include "util/test.h"
+#include "io/mem.h"
 
 static const sqfs_u64 end0 = 449;	/* region 1: filled with 'A' */
 static const sqfs_u64 end1 = 521;	/* region 2: filled with 'B' */
 static const sqfs_u64 end2 = 941;	/* region 3: filled with 'C' */
 
-static sqfs_u8 buffer[103];		/* sliding window into the file */
-static sqfs_u64 offset = 0;		/* byte offset into the "file" */
-
-static int dummy_precache(istream_t *strm);
-static const char *dummy_get_filename(istream_t *strm);
-
-static istream_t dummy = {
-	{
-		1,
-		NULL,
-		NULL,
-	},
-	0,
-	0,
-	false,
-	buffer,
-	dummy_precache,
-	dummy_get_filename,
-};
-
-static int dummy_precache(istream_t *strm)
-{
-	sqfs_u8 x;
-
-	TEST_ASSERT(strm == &dummy);
-
-	while (strm->buffer_used < sizeof(buffer)) {
-		if (offset < end0) {
-			x = 'A';
-		} else if (offset < end1) {
-			x = 'B';
-		} else if (offset < end2) {
-			x = 'C';
-		} else {
-			strm->eof = true;
-			break;
-		}
+static sqfs_u8 rd_buffer[941];
 
-		strm->buffer[strm->buffer_used++] = x;
-		++offset;
-	}
-
-	return 0;
+static sqfs_u8 byte_at_offset(sqfs_u64 off)
+{
+	if (off < end0)
+		return 'A';
+	if (off < end1)
+		return 'B';
+	return 'C';
 }
 
-static const char *dummy_get_filename(istream_t *strm)
+static void init_rd_buffer(void)
 {
-	TEST_ASSERT(strm == &dummy);
-	return "dummy file";
+	for (size_t i = 0; i < end2; ++i)
+		rd_buffer[i] = byte_at_offset(i);
 }
 
 int main(int argc, char **argv)
 {
 	sqfs_u8 read_buffer[61];
 	sqfs_u64 read_off = 0;
-	const char *name;
+	istream_t *dummy;
 	(void)argc; (void)argv;
 
-	name = istream_get_filename(&dummy);
-	TEST_NOT_NULL(name);
-	TEST_STR_EQUAL(name, "dummy file");
+	init_rd_buffer();
+	dummy = istream_memory_create("dummy file", 103,
+				      rd_buffer, sizeof(rd_buffer));
+	TEST_NOT_NULL(dummy);
 
 	/* region 1 */
 	while (read_off < end0) {
@@ -82,7 +50,7 @@ int main(int argc, char **argv)
 		if (read_diff > sizeof(read_buffer))
 			read_diff = sizeof(read_buffer);
 
-		int ret = istream_read(&dummy, read_buffer, read_diff);
+		int ret = istream_read(dummy, read_buffer, read_diff);
 		TEST_ASSERT(ret > 0);
 		TEST_ASSERT((size_t)ret <= read_diff);
 
@@ -100,7 +68,7 @@ int main(int argc, char **argv)
 		if (read_diff > sizeof(read_buffer))
 			read_diff = sizeof(read_buffer);
 
-		int ret = istream_read(&dummy, read_buffer, read_diff);
+		int ret = istream_read(dummy, read_buffer, read_diff);
 		TEST_ASSERT(ret > 0);
 		TEST_ASSERT((size_t)ret <= read_diff);
 
@@ -115,7 +83,7 @@ int main(int argc, char **argv)
 	for (;;) {
 		size_t read_diff = sizeof(read_buffer);
 
-		int ret = istream_read(&dummy, read_buffer, read_diff);
+		int ret = istream_read(dummy, read_buffer, read_diff);
 		TEST_ASSERT(ret >= 0);
 		TEST_ASSERT((size_t)ret <= read_diff);
 
@@ -132,5 +100,8 @@ int main(int argc, char **argv)
 		TEST_ASSERT(read_off <= end2);
 	}
 
+	TEST_ASSERT(dummy->eof);
+	TEST_ASSERT(dummy->buffer_offset >= dummy->buffer_used);
+	sqfs_drop(dummy);
 	return EXIT_SUCCESS;
 }
diff --git a/lib/io/test/istream_skip.c b/lib/io/test/istream_skip.c
index 3197b8b..40d4ea4 100644
--- a/lib/io/test/istream_skip.c
+++ b/lib/io/test/istream_skip.c
@@ -8,72 +8,40 @@
 
 #include "io/istream.h"
 #include "util/test.h"
+#include "io/mem.h"
 
 static const sqfs_u64 end0 = 449;	/* region 1: filled with 'A' */
 static const sqfs_u64 end1 = 521;	/* region 2: filled with 'B' */
 static const sqfs_u64 end2 = 941;	/* region 3: filled with 'C' */
 
-static sqfs_u8 buffer[103];		/* sliding window into the file */
-static sqfs_u64 offset = 0;		/* byte offset into the "file" */
+static sqfs_u8 rd_buffer[941];
 
-static int dummy_precache(istream_t *strm);
-static const char *dummy_get_filename(istream_t *strm);
-
-static istream_t dummy = {
-	{
-		1,
-		NULL,
-		NULL,
-	},
-	0,
-	0,
-	false,
-	buffer,
-	dummy_precache,
-	dummy_get_filename,
-};
-
-static int dummy_precache(istream_t *strm)
+static sqfs_u8 byte_at_offset(sqfs_u64 off)
 {
-	sqfs_u8 x;
-
-	TEST_ASSERT(strm == &dummy);
-
-	while (strm->buffer_used < sizeof(buffer)) {
-		if (offset < end0) {
-			x = 'A';
-		} else if (offset < end1) {
-			x = 'B';
-		} else if (offset < end2) {
-			x = 'C';
-		} else {
-			strm->eof = true;
-			break;
-		}
-
-		strm->buffer[strm->buffer_used++] = x;
-		++offset;
-	}
-
-	return 0;
+	if (off < end0)
+		return 'A';
+	if (off < end1)
+		return 'B';
+	return 'C';
 }
 
-static const char *dummy_get_filename(istream_t *strm)
+static void init_rd_buffer(void)
 {
-	TEST_ASSERT(strm == &dummy);
-	return "dummy file";
+	for (size_t i = 0; i < end2; ++i)
+		rd_buffer[i] = byte_at_offset(i);
 }
 
 int main(int argc, char **argv)
 {
 	sqfs_u8 read_buffer[61];
 	sqfs_u64 read_off = 0;
-	const char *name;
+	istream_t *dummy;
 	(void)argc; (void)argv;
 
-	name = istream_get_filename(&dummy);
-	TEST_NOT_NULL(name);
-	TEST_STR_EQUAL(name, "dummy file");
+	init_rd_buffer();
+	dummy = istream_memory_create("dummy file", 103,
+				      rd_buffer, sizeof(rd_buffer));
+	TEST_NOT_NULL(dummy);
 
 	/* region 1 */
 	while (read_off < end0) {
@@ -82,7 +50,7 @@ int main(int argc, char **argv)
 		if (read_diff > sizeof(read_buffer))
 			read_diff = sizeof(read_buffer);
 
-		int ret = istream_read(&dummy, read_buffer, read_diff);
+		int ret = istream_read(dummy, read_buffer, read_diff);
 		TEST_ASSERT(ret > 0);
 		TEST_ASSERT((size_t)ret <= read_diff);
 
@@ -95,7 +63,7 @@ int main(int argc, char **argv)
 
 	/* region 2 */
 	{
-		int ret = istream_skip(&dummy, end2 - end1);
+		int ret = istream_skip(dummy, end2 - end1);
 		TEST_EQUAL_I(ret, 0);
 		read_off += (end2 - end1);
 	}
@@ -104,7 +72,7 @@ int main(int argc, char **argv)
 	for (;;) {
 		size_t read_diff = sizeof(read_buffer);
 
-		int ret = istream_read(&dummy, read_buffer, read_diff);
+		int ret = istream_read(dummy, read_buffer, read_diff);
 		TEST_ASSERT(ret >= 0);
 		TEST_ASSERT((size_t)ret <= read_diff);
 
@@ -121,5 +89,8 @@ int main(int argc, char **argv)
 		TEST_ASSERT(read_off <= end2);
 	}
 
+	TEST_ASSERT(dummy->eof);
+	TEST_ASSERT(dummy->buffer_offset >= dummy->buffer_used);
+	sqfs_drop(dummy);
 	return EXIT_SUCCESS;
 }
diff --git a/lib/io/test/stream_splice.c b/lib/io/test/stream_splice.c
index c5ca38e..5379b39 100644
--- a/lib/io/test/stream_splice.c
+++ b/lib/io/test/stream_splice.c
@@ -8,12 +8,15 @@
 
 #include "io/istream.h"
 #include "io/ostream.h"
+#include "io/mem.h"
 #include "util/test.h"
 
 static const sqfs_u64 end0 = 449;	/* region 1: filled with 'A' */
 static const sqfs_u64 end1 = 521;	/* region 2: filled with 'B' */
 static const sqfs_u64 end2 = 941;	/* region 3: filled with 'C' */
 
+static sqfs_u8 rd_buffer[941];
+
 static sqfs_u8 byte_at_offset(sqfs_u64 off)
 {
 	if (off < end0)
@@ -23,6 +26,12 @@ static sqfs_u8 byte_at_offset(sqfs_u64 off)
 	return 'C';
 }
 
+static void init_rd_buffer(void)
+{
+	for (size_t i = 0; i < end2; ++i)
+		rd_buffer[i] = byte_at_offset(i);
+}
+
 /*****************************************************************************/
 
 static int out_append(ostream_t *strm, const void *data, size_t size);
@@ -57,47 +66,20 @@ static int out_append(ostream_t *strm, const void *data, size_t size)
 
 /*****************************************************************************/
 
-static int in_precache(istream_t *strm);
-
-static sqfs_u8 in_buffer[109];
-static sqfs_u64 in_offset = 0;
-
-static istream_t in = {
-	{ 1, NULL, NULL },
-	0,
-	0,
-	false,
-	in_buffer,
-	in_precache,
-	NULL,
-};
-
-static int in_precache(istream_t *strm)
-{
-	TEST_ASSERT(strm == &in);
-
-	while (strm->buffer_used < sizeof(in_buffer)) {
-		if (in_offset == end2) {
-			strm->eof = true;
-			break;
-		}
-
-		in_buffer[strm->buffer_used++] = byte_at_offset(in_offset++);
-	}
-
-	return 0;
-}
-
-/*****************************************************************************/
-
 int main(int argc, char **argv)
 {
 	sqfs_u64 total = 0;
+	istream_t *in;
 	sqfs_s32 ret;
 	(void)argc; (void)argv;
 
+	init_rd_buffer();
+	in = istream_memory_create("memory_in", 109,
+				   rd_buffer, sizeof(rd_buffer));
+	TEST_NOT_NULL(in);
+
 	for (;;) {
-		ret = ostream_append_from_istream(&out, &in, 211);
+		ret = ostream_append_from_istream(&out, in, 211);
 		TEST_ASSERT(ret >= 0);
 
 		if (ret == 0)
@@ -106,13 +88,13 @@ int main(int argc, char **argv)
 		total += ret;
 		TEST_ASSERT(total <= end2);
 		TEST_ASSERT(out_offset <= end2);
-		TEST_ASSERT(in_offset <= end2);
-		TEST_ASSERT(in_offset >= out_offset);
 		TEST_EQUAL_UI(total, out_offset);
 	}
 
+	TEST_ASSERT(in->eof);
+	TEST_ASSERT(in->buffer_offset >= in->buffer_used);
 	TEST_EQUAL_UI(total, end2);
 	TEST_EQUAL_UI(out_offset, end2);
-	TEST_EQUAL_UI(in_offset, end2);
+	sqfs_drop(in);
 	return EXIT_SUCCESS;
 }
diff --git a/lib/io/test/xfrm.c b/lib/io/test/xfrm.c
index de5c496..d06c558 100644
--- a/lib/io/test/xfrm.c
+++ b/lib/io/test/xfrm.c
@@ -8,6 +8,7 @@
 #include "xfrm/stream.h"
 #include "util/test.h"
 #include "io/xfrm.h"
+#include "io/mem.h"
 
 static const sqfs_u8 blob_in[] = {
 #if defined(DO_XZ)
@@ -363,57 +364,6 @@ static const char orig[] =
 
 /*****************************************************************************/
 
-static const sqfs_u8 *rd_buffer;
-static size_t rd_offset;
-static size_t rd_size;
-static sqfs_u8 mi_buffer[7];
-
-static int mem_precache(istream_t *strm);
-static const char *mem_get_filename(istream_t *strm);
-
-static istream_t mem_istream = {
-	{ 1, NULL, NULL, },
-	0,
-	0,
-	false,
-	mi_buffer,
-	mem_precache,
-	mem_get_filename,
-};
-
-static int mem_precache(istream_t *strm)
-{
-	size_t spc_in, spc_out, diff;
-
-	TEST_ASSERT(strm == &mem_istream);
-	TEST_ASSERT(!strm->eof);
-	TEST_ASSERT(rd_offset < rd_size);
-
-	spc_in = rd_size - rd_offset;
-	spc_out = sizeof(mi_buffer) - strm->buffer_used;
-	diff = spc_in < spc_out ? spc_in : spc_out;
-
-	memcpy(mi_buffer + strm->buffer_used, rd_buffer + rd_offset, diff);
-	strm->buffer_used += diff;
-	rd_offset += diff;
-
-	TEST_ASSERT(strm->buffer_used <= sizeof(mi_buffer));
-	TEST_ASSERT(rd_offset <= rd_size);
-
-	if (rd_offset == rd_size)
-		strm->eof = true;
-
-	return 0;
-}
-
-static const char *mem_get_filename(istream_t *strm)
-{
-	TEST_ASSERT(strm == &mem_istream);
-	return "memory stream";
-}
-
-/*****************************************************************************/
-
 static size_t mo_written = 0;
 static sqfs_u8 mo_buffer[1024];
 static bool mo_flushed = false;
@@ -454,25 +404,28 @@ static int mem_flush(ostream_t *strm)
 
 /*****************************************************************************/
 
-static void run_unpack_test(void)
+static void run_unpack_test(const void *blob, size_t size)
 {
+	istream_t *istream, *mem_istream;
 	xfrm_stream_t *xfrm;
-	istream_t *istream;
 	sqfs_s32 ret;
 	size_t i;
 	char c;
 
+	mem_istream = istream_memory_create("memstream", 7, blob, size);
+	TEST_NOT_NULL(mem_istream);
+
 	xfrm = mkdecompressor();
 	TEST_NOT_NULL(xfrm);
 	TEST_EQUAL_UI(((sqfs_object_t *)xfrm)->refcount, 1);
-	TEST_EQUAL_UI(((sqfs_object_t *)&mem_istream)->refcount, 1);
+	TEST_EQUAL_UI(((sqfs_object_t *)mem_istream)->refcount, 1);
 
-	istream = istream_xfrm_create(&mem_istream, xfrm);
+	istream = istream_xfrm_create(mem_istream, xfrm);
 
 	TEST_NOT_NULL(istream);
 	TEST_EQUAL_UI(((sqfs_object_t *)istream)->refcount, 1);
 	TEST_EQUAL_UI(((sqfs_object_t *)xfrm)->refcount, 2);
-	TEST_EQUAL_UI(((sqfs_object_t *)&mem_istream)->refcount, 2);
+	TEST_EQUAL_UI(((sqfs_object_t *)mem_istream)->refcount, 2);
 
 	for (i = 0; i < (sizeof(orig) - 1); ++i) {
 		ret = istream_read(istream, &c, 1);
@@ -486,14 +439,15 @@ static void run_unpack_test(void)
 	ret = istream_read(istream, &c, 1);
 	TEST_EQUAL_I(ret, 0);
 
-	TEST_EQUAL_UI(mem_istream.buffer_used, 0);
-	TEST_EQUAL_UI(mem_istream.buffer_offset, 0);
-	TEST_EQUAL_UI(rd_offset, rd_size);
+	TEST_EQUAL_UI(mem_istream->buffer_used, 0);
+	TEST_EQUAL_UI(mem_istream->buffer_offset, 0);
+	TEST_ASSERT(mem_istream->eof);
 
 	sqfs_drop(istream);
-	TEST_EQUAL_UI(((sqfs_object_t *)&mem_istream)->refcount, 1);
+	TEST_EQUAL_UI(((sqfs_object_t *)mem_istream)->refcount, 1);
 	TEST_EQUAL_UI(((sqfs_object_t *)xfrm)->refcount, 1);
 	sqfs_drop(xfrm);
+	sqfs_drop(mem_istream);
 }
 
 static void run_pack_test(void)
@@ -542,25 +496,11 @@ int main(int argc, char **argv)
 	(void)argc; (void)argv;
 
 	/* normal stream */
-	rd_buffer = blob_in;
-	rd_offset = 0;
-	rd_size = sizeof(blob_in);
-	mem_istream.buffer_offset = 0;
-	mem_istream.buffer_used = 0;
-	mem_istream.eof = false;
-
-	run_unpack_test();
+	run_unpack_test(blob_in, sizeof(blob_in));
 
 	/* concatenated streams */
 #if !defined(DO_GZIP)
-	rd_buffer = blob_in_concat;
-	rd_offset = 0;
-	rd_size = sizeof(blob_in_concat);
-	mem_istream.buffer_offset = 0;
-	mem_istream.buffer_used = 0;
-	mem_istream.eof = false;
-
-	run_unpack_test();
+	run_unpack_test(blob_in_concat, sizeof(blob_in_concat));
 #else
 	(void)blob_in_concat;
 #endif
@@ -568,13 +508,6 @@ int main(int argc, char **argv)
 	run_pack_test();
 
 	/* restore from compressed */
-	rd_buffer = mo_buffer;
-	rd_offset = 0;
-	rd_size = mo_written;
-	mem_istream.buffer_offset = 0;
-	mem_istream.buffer_used = 0;
-	mem_istream.eof = false;
-
-	run_unpack_test();
+	run_unpack_test(mo_buffer, mo_written);
 	return EXIT_SUCCESS;
 }