Index: test/sanitizer_common/TestCases/NetBSD/funopen.cc
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/NetBSD/funopen.cc
@@ -0,0 +1,89 @@
+// RUN: %clangxx -g %s -o %t && %run %t | FileCheck %s
+
+// CHECK: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: CLOSE CALLED
+// CHECK-NEXT: SEEK CALLED; off=100, whence=0
+// CHECK-NEXT: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int cookie_var;
+
+int f_read(void *cookie, char *buf, int len) {
+  assert(cookie == &cookie_var);
+  assert(len >= 6);
+  printf("READ CALLED; len=%d\n", len);
+  return strlcpy(buf, "test\n", len);
+}
+
+int f_write(void *cookie, const char *buf, int len) {
+  assert(cookie == &cookie_var);
+  char *data = strndup(buf, len);
+  assert(data);
+  printf("WRITE CALLED: %s\n", data);
+  free(data);
+  return len;
+}
+
+off_t f_seek(void *cookie, off_t off, int whence) {
+  assert(cookie == &cookie_var);
+  assert(whence == SEEK_SET);
+  printf("SEEK CALLED; off=%d, whence=%d\n", (int)off, whence);
+  return off;
+}
+
+int f_close(void *cookie) {
+  assert(cookie == &cookie_var);
+  printf("CLOSE CALLED\n");
+  return 0;
+}
+
+int main(void) {
+  FILE *fp;
+  char buf[10];
+
+  // 1. read-only variant
+  fp = fropen(&cookie_var, f_read);
+  assert(fp);
+  // verify that fileno() does not crash or report nonsense
+  assert(fileno(fp) == -1);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(!fclose(fp));
+
+  // 2. write-only variant
+  fp = fwopen(&cookie_var, f_write);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fputs("test", fp) >= 0);
+  assert(!fclose(fp));
+
+  // 3. read+write+close
+  fp = funopen(&cookie_var, f_read, f_write, NULL, f_close);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(fputs("test", fp) >= 0);
+  assert(!fclose(fp));
+
+  // 4. read+seek
+  fp = funopen(&cookie_var, f_read, NULL, f_seek, NULL);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fseek(fp, 100, SEEK_SET) == 0);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(!fclose(fp));
+
+  return 0;
+}
Index: test/sanitizer_common/TestCases/NetBSD/funopen2.cc
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/NetBSD/funopen2.cc
@@ -0,0 +1,110 @@
+// RUN: %clangxx -g %s -o %t && %run %t | FileCheck %s
+
+// CHECK: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: CLOSE CALLED
+// CHECK-NEXT: SEEK CALLED; off=100, whence=0
+// CHECK-NEXT: READ CALLED; len={{[0-9]*}}
+// CHECK-NEXT: READ: test
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: FLUSH CALLED
+// CHECK-NEXT: WRITE CALLED: test
+// CHECK-NEXT: FLUSH CALLED
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int cookie_var;
+
+ssize_t f_read(void *cookie, void *buf, size_t len) {
+  assert(cookie == &cookie_var);
+  assert(len >= 6);
+  printf("READ CALLED; len=%zd\n", len);
+  return strlcpy((char*)buf, "test\n", len);
+}
+
+ssize_t f_write(void *cookie, const void *buf, size_t len) {
+  assert(cookie == &cookie_var);
+  char *data = strndup((char*)buf, len);
+  assert(data);
+  printf("WRITE CALLED: %s\n", data);
+  free(data);
+  return len;
+}
+
+off_t f_seek(void *cookie, off_t off, int whence) {
+  assert(cookie == &cookie_var);
+  assert(whence == SEEK_SET);
+  printf("SEEK CALLED; off=%d, whence=%d\n", (int)off, whence);
+  return off;
+}
+
+int f_flush(void *cookie) {
+  assert(cookie == &cookie_var);
+  printf("FLUSH CALLED\n");
+  return 0;
+}
+
+int f_close(void *cookie) {
+  assert(cookie == &cookie_var);
+  printf("CLOSE CALLED\n");
+  return 0;
+}
+
+int main(void) {
+  FILE *fp;
+  char buf[10];
+
+  // 1. read-only variant
+  fp = fropen2(&cookie_var, f_read);
+  assert(fp);
+  // verify that fileno() does not crash or report nonsense
+  assert(fileno(fp) == -1);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(!fclose(fp));
+
+  // 2. write-only variant
+  fp = fwopen2(&cookie_var, f_write);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fputs("test", fp) >= 0);
+  assert(!fclose(fp));
+
+  // 3. read+write+close
+  fp = funopen2(&cookie_var, f_read, f_write, NULL, NULL, f_close);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(fputs("test", fp) >= 0);
+  assert(!fflush(fp));
+  assert(!fclose(fp));
+
+  // 4. read+seek
+  fp = funopen2(&cookie_var, f_read, NULL, f_seek, NULL, NULL);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fseek(fp, 100, SEEK_SET) == 0);
+  assert(fgets(buf, sizeof(buf), fp));
+  printf("READ: %s", buf);
+  assert(!fclose(fp));
+
+  // 5. write+flush
+  fp = funopen2(&cookie_var, NULL, f_write, NULL, f_flush, NULL);
+  assert(fp);
+  assert(fileno(fp) == -1);
+  assert(fputs("test", fp) >= 0);
+  assert(!fflush(fp));
+  assert(fputs("test", fp) >= 0);
+  // NB: fclose() also implicitly calls flush
+  assert(!fclose(fp));
+
+  return 0;
+}