add memfd

src/build.sh

@@ -14,3 +14,4 @@ gcc signals-nested.cpp -g -o ../signals-nested -lrt
 gcc signals-nested-2.cpp -g -o ../signals-nested-2 -lpthread
 gcc smc-shmatdt.cpp -g -o ../smc-shmatdt
 gcc prot-growsdown.cpp -g -o ../prot-growsdown
+gcc memfd.cpp -g -o ../memfd

src/memfd.cpp

@@ -0,0 +1,39 @@
+#include <sys/mman.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+void test() {
+	int fd = memfd_create("/bin/sudo", 0);
+	printf("pid: %d, fd: %d\n", getpid(), fd);
+
+	struct stat st;
+	fstat(fd, &st);
+	printf("dev: %lu, ino: %lu\n", st.st_dev, st.st_ino);
+
+	char syml[512];
+	char temp[512];
+	sprintf(syml, "/proc/%d/fd/%d", getpid(), fd);
+	auto rv = readlink(syml, temp, 511);
+	temp[rv] = 0;
+	printf("file: %s\n", temp);
+}
+
+void mmaptest() {
+	auto ptr = (char*)mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_ANON | MAP_SHARED, 0, 0);
+	auto ptr2 = (char*)mremap(ptr, 0, 8192, MREMAP_MAYMOVE);
+	auto ptr3 = (char*)mremap(ptr, 4096, 8192, MREMAP_MAYMOVE);
+	ptr3[0] = 1;
+	ptr2[1] = 1;
+	printf("%p, %p, %p\n", ptr, ptr2, ptr3);
+	printf("Expecting bus error\n");
+	ptr2[4096] = 1; // BUS_ERROR
+	ptr3[4096] = 1; // BUS_ERROR
+	//printf("%d, %d, %d, %d\n", ptr2[0], ptr3[0], ptr2[0], ptr3[0]);
+}
+
+int main() {
+	test();
+	mmaptest();
+}