unittest: add compression round-trip tests

Test compress_data()/decompress_data() with zero-filled, repeating
pattern, pseudo-random, and single-byte pages across three LZ4
acceleration levels. Also test page_is_all_zero() edge cases.

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

Author: rst0git

criu/unittest/unit.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <assert.h>
 #include <unistd.h>
 #include <fcntl.h>
@@ -9,6 +10,8 @@
 #include "util.h"
 #include "criu-log.h"
 #include "bfd.h"
+#include "compression.h"
+#include "page.h"
 
 int parse_statement(int i, char *line, char **configuration);
 
@@ -92,6 +95,72 @@ static void test_bwrite(void)
 	free(read_buf);
 }
 
+#ifdef CONFIG_LZ4
+static void test_compress_roundtrip(const char *page, int acceleration)
+{
+	char compressed[PAGE_COMPRESSED_SIZE_BOUND];
+	char decompressed[PAGE_SIZE];
+	int cs;
+
+	cs = compress_data(page, PAGE_SIZE, compressed,
+			   PAGE_COMPRESSED_SIZE_BOUND, acceleration);
+	assert(cs > 0);
+	assert(cs <= PAGE_COMPRESSED_SIZE_BOUND);
+	assert(decompress_data(compressed, cs, PAGE_SIZE, decompressed) == 0);
+	assert(memcmp(page, decompressed, PAGE_SIZE) == 0);
+}
+
+static void test_compression(void)
+{
+	char cbuf[PAGE_COMPRESSED_SIZE_BOUND];
+	char page[PAGE_SIZE];
+	int cs;
+	int accels[] = { 1, 4, 100 };
+
+	/* Zero-page detection */
+	memset(page, 0, PAGE_SIZE);
+	assert(page_is_all_zero(page) == true);
+	page[PAGE_SIZE - 1] = 1;
+	assert(page_is_all_zero(page) == false);
+	page[PAGE_SIZE - 1] = 0;
+	page[0] = 0x42;
+	assert(page_is_all_zero(page) == false);
+
+
+	for (int a = 0; a < 3; a++) {
+		int accel = accels[a];
+
+		/* Zero-filled page: should compress well */
+		memset(cbuf, 0, sizeof(cbuf));
+		memset(page, 0, PAGE_SIZE);
+		cs = compress_data(page, PAGE_SIZE,
+				   cbuf, PAGE_COMPRESSED_SIZE_BOUND, accel);
+		assert(cs > 0 && cs < PAGE_SIZE);
+		test_compress_roundtrip(page, accel);
+
+		/* Repeating pattern */
+		for (int i = 0; i < PAGE_SIZE; i++)
+			page[i] = i & 0xff;
+		test_compress_roundtrip(page, accel);
+
+		/* Pseudo-random data (incompressible) */
+		srand(42);
+		for (int i = 0; i < PAGE_SIZE; i++)
+			page[i] = rand() & 0xff;
+		test_compress_roundtrip(page, accel);
+
+		/* Single non-zero byte */
+		memset(page, 0, PAGE_SIZE);
+		page[0] = 0x42;
+		cs = compress_data(page, PAGE_SIZE,
+				   (char[PAGE_COMPRESSED_SIZE_BOUND]){0},
+				   PAGE_COMPRESSED_SIZE_BOUND, accel);
+		assert(cs > 0 && cs < PAGE_SIZE);
+		test_compress_roundtrip(page, accel);
+	}
+}
+#endif
+
 int main(int argc, char *argv[], char *envp[])
 {
 	char **configuration;
@@ -230,6 +299,10 @@ int main(int argc, char *argv[], char *envp[])
 	/* leaves punctuation in returned string as is */
 	assert(!strcmp(get_relative_path("./a////.///./b//././c", "a"), "b//././c"));
 
+#ifdef CONFIG_LZ4
+	test_compression();
+#endif
+
 	pr_msg("OK\n");
 	return 0;
 }