Re: `scm_c_read ()' and `swap_buffer' trick harmful

[ludo@gnu.org (Ludovic Courtès)]

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Hello,

ludo@gnu.org (Ludovic Courtès) writes:

> Thanks for the quick fix!

Attach is a test case for this, please apply (with git-am(1)) and commit
right after your fix.

Once we're done with this, I think we should release 1.8.6.  I'm should
be able to do it this week-end.

Thanks,
Ludo'.


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From ca72bdfec2457b035836bc43afbc5ea20fe8af02 Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Sat, 22 Nov 2008 15:48:16 +0100
Subject: [PATCH] Add C unit test for `scm_c_read ()' and the port API.

* test-suite/standalone/Makefile.am (check_PROGRAMS, TESTS): Add
  `test-scm-c-read'.
  (test_scm_c_read_SOURCES, test_scm_c_read_CFLAGS,
  test_scm_c_read_LDADD): New.
---
 test-suite/standalone/.gitignore        |    1 +
 test-suite/standalone/Makefile.am       |    7 ++
 test-suite/standalone/test-scm-c-read.c |  130 +++++++++++++++++++++++++++++++
 3 files changed, 138 insertions(+), 0 deletions(-)
 create mode 100644 test-suite/standalone/test-scm-c-read.c

diff --git a/test-suite/standalone/.gitignore b/test-suite/standalone/.gitignore
index 78af304..b1f4088 100644
--- a/test-suite/standalone/.gitignore
+++ b/test-suite/standalone/.gitignore
@@ -7,3 +7,4 @@
 /test-with-guile-module
 /test-use-srfi
 /test-scm-with-guile
+/test-scm-c-read
diff --git a/test-suite/standalone/Makefile.am b/test-suite/standalone/Makefile.am
index 6ae5e88..3afd7e5 100644
--- a/test-suite/standalone/Makefile.am
+++ b/test-suite/standalone/Makefile.am
@@ -107,6 +107,13 @@ TESTS += test-conversion
 check_SCRIPTS += test-use-srfi
 TESTS += test-use-srfi
 
+# test-scm-c-read
+test_scm_c_read_SOURCES = test-scm-c-read.c
+test_scm_c_read_CFLAGS = ${test_cflags}
+test_scm_c_read_LDADD = ${top_builddir}/libguile/libguile.la
+check_PROGRAMS += test-scm-c-read
+TESTS += test-scm-c-read
+
 if BUILD_PTHREAD_SUPPORT
 
 # test-with-guile-module
diff --git a/test-suite/standalone/test-scm-c-read.c b/test-suite/standalone/test-scm-c-read.c
new file mode 100644
index 0000000..be8ea80
--- /dev/null
+++ b/test-suite/standalone/test-scm-c-read.c
@@ -0,0 +1,130 @@
+/* Copyright (C) 2008 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* Exercise `scm_c_read ()' and the port type API.  Verify assumptions that
+   can be made by port type implementations.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <libguile.h>
+#include <assert.h>
+
+
+\f
+/* Size of our port's internal buffer.  */
+#define PORT_BUFFER_SIZE 1024
+
+/* Return a new port of type PORT_TYPE.  */
+static inline SCM
+make_port (scm_t_bits port_type)
+{
+  SCM port;
+  char *c_buffer;
+  scm_t_port *c_port;
+
+  c_buffer = scm_gc_calloc (PORT_BUFFER_SIZE, "custom-port-buffer");
+
+  port = scm_new_port_table_entry (port_type);
+
+  /* Attach it the underlying u8vector, which we'll use as PORT's buffer.  */
+  SCM_SETSTREAM (port, (scm_t_bits) c_buffer);
+
+  /* Have the port directly access the buffer (bytevector).  */
+  c_port = SCM_PTAB_ENTRY (port);
+  c_port->read_pos = c_port->read_buf = (unsigned char *) c_buffer;
+  c_port->read_end = (unsigned char *) c_buffer + PORT_BUFFER_SIZE;
+  c_port->read_buf_size = PORT_BUFFER_SIZE;
+
+  /* Mark PORT as open and readable.  */
+  SCM_SET_CELL_TYPE (port, port_type | SCM_OPN | SCM_RDNG);
+
+  return port;
+}
+
+/* Read one byte from PORT.  */
+static int
+fill_input (SCM port)
+{
+  int result;
+  scm_t_port *c_port = SCM_PTAB_ENTRY (port);
+
+  /* Make sure that C_PORT's internal buffer wasn't changed behind our back.
+     See http://lists.gnu.org/archive/html/guile-devel/2008-11/msg00042.html
+     for an example where this assumption matters.  */
+  assert (c_port->read_buf == (unsigned char *) SCM_STREAM (port));
+  assert (c_port->read_buf_size == PORT_BUFFER_SIZE);
+
+  if (c_port->read_pos >= c_port->read_end)
+    result = EOF;
+  else
+    result = (int) *c_port->read_pos++;
+
+  return result;
+}
+
+/* Return true (non-zero) if BUF contains only zeros.  */
+static inline int
+zeroed_buffer_p (const char *buf, size_t len)
+{
+  size_t i;
+
+  for (i = 0; i < len; i++)
+    if (buf[i] != 0)
+      return 0;
+
+  return 1;
+}
+
+/* Run the test.  */
+static void *
+do_start (void *arg)
+{
+  SCM port;
+  scm_t_bits port_type;
+  char buffer[PORT_BUFFER_SIZE + (PORT_BUFFER_SIZE / 2)];
+  size_t read, last_read;
+
+  port_type = scm_make_port_type ("custom-input-port", fill_input, NULL);
+  port = make_port (port_type);
+
+  read = 0;
+  do
+    {
+      last_read = scm_c_read (port, &buffer[read], 123);
+      assert (last_read <= 123);
+      assert (zeroed_buffer_p (&buffer[read], last_read));
+
+      read += last_read;
+    }
+  while (last_read > 0 && read < sizeof (buffer));
+
+  /* We shouldn't be able to read more than what's in PORT's buffer.  */
+  assert (read == PORT_BUFFER_SIZE);
+
+  return NULL;
+}
+
+\f
+int
+main (int argc, char *argv[])
+{
+  scm_with_guile (do_start, NULL);
+
+  return 0;
+}
-- 
1.6.0.3