Add testing for getdents64 syscall buffer sizes.

tests/fs/test_getdents64.cpp

@@ -0,0 +1,53 @@
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+
+#define BUF_SIZE (sizeof(dirent)*2)
+
+int main(int argc, char *argv[])
+{
+  int fd = open(".", O_RDONLY | O_DIRECTORY);
+  assert(fd > 0);
+
+  printf("sizeof(dirent): %d, sizeof(buffer): %d\n", sizeof(dirent), BUF_SIZE);
+
+  bool first = true;
+
+  for(;;)
+  {
+    char buf[BUF_SIZE];
+    int nread = getdents(fd, (dirent*)buf, BUF_SIZE);
+    assert(nread != -1);
+    if (nread == 0)
+      break;
+
+    // In this test, we provide enough space to read two dirent entries at a time.
+    // Test that on the first iteration of the loop we get exactly two entries. (there's at least "." and ".." in each directory)
+    assert(nread == BUF_SIZE || !first);
+    first = false;
+
+    printf("--------------- nread=%d ---------------\n", nread);
+    printf("i-node#  file type  d_reclen  d_off   d_name\n");
+    int bpos = 0;
+    while(bpos < nread)
+    {
+      dirent *d = (dirent *)(buf + bpos);
+      printf("%8ld  ", (long)d->d_ino);
+      char d_type = *(buf + bpos + d->d_reclen - 1);
+      printf("%-10s ", (d_type == DT_REG) ?  "regular" :
+                       (d_type == DT_DIR) ?  "directory" :
+                       (d_type == DT_FIFO) ? "FIFO" :
+                       (d_type == DT_SOCK) ? "socket" :
+                       (d_type == DT_LNK) ?  "symlink" :
+                       (d_type == DT_BLK) ?  "block dev" :
+                       (d_type == DT_CHR) ?  "char dev" : "???");
+      printf("%4d %10lld  %s\n", d->d_reclen, (long long) d->d_off, d->d_name);
+      bpos += d->d_reclen;
+    }
+  }
+}

tests/test_core.py

@@ -4117,6 +4117,10 @@ def test_mount(self):
     src = open(path_from_root('tests', 'fs', 'test_mount.c'), 'r').read()
     self.do_run(src, 'success', force_c=True)
 
+  def test_getdents64(self):
+    src = open(path_from_root('tests', 'fs', 'test_getdents64.cpp'), 'r').read()
+    self.do_run(src, '..')
+
   def test_fwrite_0(self):
     test_path = path_from_root('tests', 'core', 'test_fwrite_0')
     src, output = (test_path + s for s in ('.c', '.out'))