Test for multi open of same file

tests_src/test_multi_open_file.c

@@ -0,0 +1,55 @@
+/* Test for fdopen bugs.  */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#undef assert
+#define assert(x) \
+  if (!(x)) \
+    { \
+      fputs ("test failed: " #x "\n", stderr); \
+      retval = 1; \
+      goto the_end; \
+    }
+
+char buffer[256];
+
+int
+main (int argc, char *argv[])
+{
+  char *name;
+  FILE *fp = NULL;
+  int retval = 0;
+  int fd;
+
+  name = tmpnam (NULL);
+  fp = fopen (name, "w");
+  printf("fopen fd: %d\n", fileno(fp));
+  assert (fp != NULL);
+  assert (fileno(fp) == 3);
+  fputs ("foobar and baz", fp);
+  fclose (fp);
+  fp = NULL;
+
+  fd = open (name, O_RDONLY);
+  printf("open fd: %d\n", fd);
+  assert (fd == 3);
+  assert (lseek (fd, 5, SEEK_SET) == 5);
+  /* The file position indicator associated with the new stream is set to
+     the position indicated by the file offset associated with the file
+     descriptor.  */
+  fp = fdopen (fd, "r");
+  printf("fdopen fd: %d\n", fp->_fileno);
+  assert (fp != NULL);
+  assert (fileno(fp) == 3);
+  assert (getc (fp) == 'r');
+  assert (getc (fp) == ' ');
+
+the_end:
+  if (fp != NULL)
+    fclose (fp);
+  unlink (name);
+
+  return retval;
+}