[PATCH] libctf: check for problems with error returns

[Nick Alcock <nick.alcock@oracle.com>]

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.
---
 .../testsuite/libctf-writable/libctf-errors.c | 74 +++++++++++++++++++
 .../libctf-writable/libctf-errors.lk          |  1 +
 2 files changed, 75 insertions(+)
 create mode 100644 libctf/testsuite/libctf-writable/libctf-errors.c
 create mode 100644 libctf/testsuite/libctf-writable/libctf-errors.lk

Your patch looks good, and passes every test I can throw at it. I think
it can go in.  You cleaned up a bunch of outright errors in this area,
too, especially in ctf-dedup: thanks!

(You probably want to adjust the commit log so that the version history
is at the bottom rather than the top, or drop it entirely.)


Here's a testcase that fails on mingw64 in the absence of your patch,
without requiring a cross-build to an ELF arch.  (It also checks at
least one instance of the other classes of error return in libctf.)

I'll push this after your commit goes in.  (I can push it, with an
adjusted commit log, if you want.)

diff --git a/libctf/testsuite/libctf-writable/libctf-errors.c b/libctf/testsuite/libctf-writable/libctf-errors.c
new file mode 100644
index 00000000000..71f8268cfad
--- /dev/null
+++ b/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;
+}
diff --git a/libctf/testsuite/libctf-writable/libctf-errors.lk b/libctf/testsuite/libctf-writable/libctf-errors.lk
new file mode 100644
index 00000000000..b944f73d013
--- /dev/null
+++ b/libctf/testsuite/libctf-writable/libctf-errors.lk
@@ -0,0 +1 @@
+All done.

-- 
2.42.0.271.g85384428f1