Support the system call mremap

test/apps/mmap/mmap_and_mremap.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include "../network/test.h"
+
+#define PAGE_SIZE 4096
+
+const char *content = "kjfkljk*wigo&h";
+
+void *x_mmap(void *addr, size_t length, int prot, int flags, int fd,
+	     off_t offset)
+{
+	void *result = mmap(addr, length, prot, flags, fd, offset);
+	if (result == MAP_FAILED) {
+		perror("mmap");
+		exit(EXIT_FAILURE);
+	}
+	return result;
+}
+
+FN_TEST(mmap_and_mremap)
+{
+	char *addr = x_mmap(NULL, 3 * PAGE_SIZE, PROT_READ | PROT_WRITE,
+			    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	TEST_SUCC(munmap(addr, 3 * PAGE_SIZE));
+
+	addr = x_mmap(addr, PAGE_SIZE, PROT_READ | PROT_WRITE,
+		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+	strcpy(addr, content);
+
+	char *addr2 = x_mmap(addr + 2 * PAGE_SIZE, PAGE_SIZE,
+			     PROT_READ | PROT_WRITE,
+			     MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+
+	char *new_addr = mremap(addr, PAGE_SIZE, 3 * PAGE_SIZE, MREMAP_MAYMOVE);
+	if (new_addr == MAP_FAILED) {
+		perror("mremap");
+		exit(EXIT_FAILURE);
+	}
+
+	// The following operation (if uncommented) would cause a segmentation fault.
+	// strcpy(addr, "Writing to old address");
+
+	TEST_RES(strcmp(new_addr, content), _ret == 0);
+	strcpy(new_addr + PAGE_SIZE, "Writing to page 2 (new)");
+	strcpy(new_addr + 2 * PAGE_SIZE, "Writing to page 3 (new)");
+
+	TEST_SUCC(munmap(new_addr, 3 * PAGE_SIZE));
+	TEST_SUCC(munmap(addr2, PAGE_SIZE));
+}
+END_TEST()
+
+FN_TEST(mmap_and_mremap_fixed)
+{
+	char *addr = x_mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE,
+			    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	strcpy(addr, content);
+
+	// Map and unmap a target region to ensure we know it's free
+	char *fixed_addr = x_mmap(NULL, PAGE_SIZE, PROT_NONE,
+				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	TEST_SUCC(munmap(fixed_addr, PAGE_SIZE)); // free it for mremap
+
+	char *new_addr = mremap(addr, PAGE_SIZE, PAGE_SIZE,
+				MREMAP_MAYMOVE | MREMAP_FIXED, fixed_addr);
+	if (new_addr != fixed_addr) {
+		perror("mremap");
+		exit(EXIT_FAILURE);
+	}
+
+	TEST_RES(strcmp(new_addr, content), _ret == 0);
+	TEST_SUCC(munmap(new_addr, PAGE_SIZE));
+}
+END_TEST()

test/apps/scripts/process.sh

@@ -28,6 +28,7 @@ hello_world/hello_world
 itimer/setitimer
 itimer/timer_create
 mmap/mmap_and_fork
+mmap/mmap_and_mremap
 mmap/mmap_shared_filebacked
 mmap/mmap_readahead
 mmap/mmap_vmrss