tests: add mmap_private test

Author: franciscozdo

bin/utest/mmap.c

@@ -2,6 +2,7 @@
 #include "util.h"
 
 #include <errno.h>
+#include <sched.h>
 #include <setjmp.h>
 #include <signal.h>
 #include <stdint.h>
@@ -124,6 +125,62 @@ TEST_ADD(munmap) {
   return 0;
 }
 
+static volatile int sigcont_handled = 0;
+
+static void sigcont_handler(int signo) {
+  printf("sigusr1 handled!\n");
+  sigcont_handled = 1;
+}
+
+TEST_ADD(mmap_private) {
+  signal(SIGCONT, sigcont_handler);
+  char *addr;
+  int ppid = getpid();
+  size_t pgsz = getpagesize();
+
+  /* mmap & munmap one page */
+  addr = mmap_anon_prw(NULL, pgsz);
+  assert(addr != (char *)MAP_FAILED);
+
+  pid_t pid = fork();
+  assert(pid >= 0);
+
+  sprintf(addr, "parent");
+
+  if (pid == 0) {
+    /* child */
+    printf("Child read: '%s'\n", addr);
+    /* Check and modify. */
+    string_eq(addr, "parent");
+    sprintf(addr, "child");
+    printf("Child written: '%s'\n", addr);
+
+    /* Wait for parent to check and modify its memory. */
+    kill(ppid, SIGCONT);
+    while (!sigcont_handled)
+      sched_yield();
+
+    printf("Child read again: '%s'\n", addr);
+    string_eq(addr, "child");
+    return 0;
+  }
+
+  /* Wait for child to check and modify its memory. */
+  while (!sigcont_handled)
+    sched_yield();
+
+  printf("Parent read: '%s'\n", addr);
+  /* Check and modify. */
+  string_eq(addr, "parent");
+  sprintf(addr, "parent again");
+
+  /* Resume child. */
+  kill(pid, SIGCONT);
+
+  wait_for_child_exit(pid, 0);
+  return 0;
+}
+
 #define NPAGES 8
 
 TEST_ADD(mmap_prot_none) {

sys/tests/utest.c

@@ -68,6 +68,7 @@ UTEST_ADD(vmmap_rodata_access);
 
 UTEST_ADD(mmap);
 UTEST_ADD(munmap);
+UTEST_ADD(mmap_private);
 UTEST_ADD(munmap_sigsegv);
 UTEST_ADD(munmap_many_1);
 UTEST_ADD(munmap_many_2);