libctf: check for problems with error returns

We do this as a writable test because the only known-affected platforms
(with ssize_t longer than unsigned long) use PE, and we do not have support
for CTF linkage in the PE linker yet.

	PR libctf/30836
	* libctf/testsuite/libctf-writable/libctf-errors.*: New test.

Author: nickalcock

libctf/testsuite/libctf-writable/libctf-errors.c

@@ -0,0 +1,74 @@
+/* Make sure that error returns are correct.  Usually this is trivially
+   true, but on platforms with unusual type sizes all the casting might
+   cause problems with unexpected sign-extension and truncation.  */
+
+#include <ctf-api.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int
+main (int argc, char *argv[])
+{
+  ctf_dict_t *fp;
+  ctf_next_t *i = NULL;
+  size_t boom = 0;
+  ctf_id_t itype, stype;
+  ctf_encoding_t encoding = {0};
+  ctf_membinfo_t mi;
+  ssize_t ret;
+  int err;
+
+  if ((fp = ctf_create (&err)) == NULL)
+    {
+      fprintf (stderr, "%s: cannot create: %s\n", argv[0], ctf_errmsg (err));
+      return 1;
+    }
+
+  /* First error class: int return.  */
+
+  if (ctf_member_count (fp, 1024) >= 0)
+    fprintf (stderr, "int return: non-error return: %i\n",
+             ctf_member_count(fp, 1024));
+
+  /* Second error class: type ID return.  */
+
+  if (ctf_type_reference (fp, 1024) != CTF_ERR)
+    fprintf (stderr, "ctf_id_t return: non-error return: %li\n",
+             ctf_type_reference (fp, 1024));
+
+  /* Third error class: ssize_t return.  Create a type to iterate over first.  */
+
+  if ((itype = ctf_add_integer (fp, CTF_ADD_ROOT, "int", &encoding)) == CTF_ERR)
+    fprintf (stderr, "cannot add int: %s\n", ctf_errmsg (ctf_errno (fp)));
+  else if ((stype = ctf_add_struct (fp, CTF_ADD_ROOT, "foo")) == CTF_ERR)
+    fprintf (stderr, "cannot add struct: %s\n", ctf_errmsg (ctf_errno (fp)));
+  else if (ctf_add_member (fp, stype, "bar", itype) < 0)
+    fprintf (stderr, "cannot add member: %s\n", ctf_errmsg (ctf_errno (fp)));
+
+  if (ctf_member_info (fp, stype, "bar", &mi) < 0)
+    fprintf (stderr, "cannot get member info: %s\n", ctf_errmsg (ctf_errno (fp)));
+
+  /* Iteration should never produce an offset bigger than the offset just returned,
+     and should quickly terminate.  */
+
+  while ((ret = ctf_member_next (fp, stype, &i, NULL, NULL, 0)) >= 0) {
+    if (ret > mi.ctm_offset)
+      fprintf (stderr, "ssize_t return: unexpected offset: %zi\n", ret);
+    if (boom++ > 1000)
+      {
+        fprintf (stderr, "member iteration went on way too long\n");
+        exit (1);
+      }
+  }
+
+  /* Fourth error class (trivial): pointer return.  */
+  if (ctf_type_aname (fp, 1024) != NULL)
+    fprintf (stderr, "pointer return: non-error return: %p\n",
+             ctf_type_aname (fp, 1024));
+
+  ctf_file_close (fp);
+
+  printf("All done.\n");
+
+  return 0;
+}

libctf/testsuite/libctf-writable/libctf-errors.lk

@@ -0,0 +1 @@
+All done.