[PATCH] support: Implement TEST_COMPARE_STRING

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[PATCH] support: Implement TEST_COMPARE_STRING

Florian Weimer-5
2018-11-05  Florian Weimer  <[hidden email]>

        Implement TEST_COMPARE_STRING.
        * support/check.h (TEST_COMPARE_STRING): Define.
        (support_test_compare_string): Declare.
        * support/Makefile (libsupport-routines): Add
        support_test_compare_string.
        (tests): Add tst-test_compare_string.
        * support/support_test_compare_string.c: New file.
        * support/tst-test_compare_string.c: Likewise.

diff --git a/support/Makefile b/support/Makefile
index 4d307035b3..2b663fbbfa 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -63,6 +63,7 @@ libsupport-routines = \
   support_shared_allocate \
   support_test_compare_blob \
   support_test_compare_failure \
+  support_test_compare_string \
   support_write_file_string \
   support_test_main \
   support_test_verify_impl \
@@ -198,6 +199,7 @@ tests = \
   tst-support_record_failure \
   tst-test_compare \
   tst-test_compare_blob \
+  tst-test_compare_string \
   tst-xreadlink \
 
 ifeq ($(run-built-tests),yes)
diff --git a/support/check.h b/support/check.h
index b3a4645e92..e6765289f2 100644
--- a/support/check.h
+++ b/support/check.h
@@ -163,6 +163,19 @@ void support_test_compare_blob (const void *left,
                                 const char *right_exp,
                                 const char *right_len_exp);
 
+/* Compare the strings LEFT and RIGHT and report a test failure if
+   they are different.  Also report failure if one of the arguments is
+   a null pointer and the other is not.  The strings should be
+   reasonably short because on mismatch, both are printed.  */
+#define TEST_COMPARE_STRING(left, right)                         \
+  (support_test_compare_string (left, right, __FILE__, __LINE__, \
+                                #left, #right))
+
+void support_test_compare_string (const char *left, const char *right,
+                                  const char *file, int line,
+                                  const char *left_expr,
+                                  const char *right_expr);
+
 /* Internal function called by the test driver.  */
 int support_report_failure (int status)
   __attribute__ ((weak, warn_unused_result));
diff --git a/support/support_test_compare_string.c b/support/support_test_compare_string.c
new file mode 100644
index 0000000000..9958aaeec1
--- /dev/null
+++ b/support/support_test_compare_string.c
@@ -0,0 +1,91 @@
+/* Check two strings for equality.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+static void
+report_length (const char *what, const char *str, size_t length)
+{
+  if (str == NULL)
+    printf ("  %s string: NULL\n", what);
+  else
+    printf ("  %s string: %zu bytes\n", what, length);
+}
+
+static void
+report_string (const char *what, const unsigned char *blob,
+               size_t length, const char *expr)
+{
+  if (length > 0)
+    {
+      printf ("  %s (evaluated from %s):\n", what, expr);
+      char *quoted = support_quote_blob (blob, length);
+      printf ("      \"%s\"\n", quoted);
+      free (quoted);
+
+      fputs ("     ", stdout);
+      for (size_t i = 0; i < length; ++i)
+        printf (" %02X", blob[i]);
+      putc ('\n', stdout);
+    }
+}
+
+static size_t
+string_length_or_zero (const char *str)
+{
+  if (str == NULL)
+    return 0;
+  else
+    return strlen (str);
+}
+
+void
+support_test_compare_string (const char *left, const char *right,
+                             const char *file, int line,
+                             const char *left_expr, const char *right_expr)
+{
+  /* Two null pointers are accepted.  */
+  if (left == NULL && right == NULL)
+    return;
+
+  size_t left_length = string_length_or_zero (left);
+  size_t right_length = string_length_or_zero (right);
+
+  if (left_length != right_length || left == NULL || right == NULL
+      || memcmp (left, right, left_length) != 0)
+    {
+      support_record_failure ();
+      printf ("%s:%d: error: blob comparison failed\n", file, line);
+      if (left_length == right_length && right != NULL && left != NULL)
+        printf ("  string length: %lu bytes\n", left_length);
+      else
+        {
+          report_length ("left", left, left_length);
+          report_length ("right", right, right_length);
+        }
+      report_string ("left", (const unsigned char *) left,
+                     left_length, left_expr);
+      report_string ("right", (const unsigned char *) right,
+                     right_length, right_expr);
+    }
+}
diff --git a/support/tst-test_compare_string.c b/support/tst-test_compare_string.c
new file mode 100644
index 0000000000..2a4b258587
--- /dev/null
+++ b/support/tst-test_compare_string.c
@@ -0,0 +1,107 @@
+/* Basic test for the TEST_COMPARE_STRING macro.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C 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.
+
+   The GNU C 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 the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <support/check.h>
+#include <support/capture_subprocess.h>
+
+static void
+subprocess (void *closure)
+{
+  /* These tests should fail.  They were chosen to cover differences
+     in length (with the same contents), single-bit mismatches, and
+     mismatching null pointers.  */
+  TEST_COMPARE_STRING ("", NULL);             /* Line 29.  */
+  TEST_COMPARE_STRING ("X", "");              /* Line 30.  */
+  TEST_COMPARE_STRING (NULL, "X");            /* Line 31.  */
+  TEST_COMPARE_STRING ("abcd", "abcD");       /* Line 32.  */
+  TEST_COMPARE_STRING ("abcd", NULL);         /* Line 33.  */
+  TEST_COMPARE_STRING (NULL, "abcd");         /* Line 34.  */
+}
+
+/* Same contents, different addresses.  */
+char buffer_abc_1[] = "abc";
+char buffer_abc_2[] = "abc";
+
+static int
+do_test (void)
+{
+  /* This should succeed.  Even if the pointers and array contents are
+     different, zero-length inputs are not different.  */
+  TEST_COMPARE_STRING (NULL, NULL);
+  TEST_COMPARE_STRING ("", "");
+  TEST_COMPARE_STRING (buffer_abc_1, buffer_abc_2);
+  TEST_COMPARE_STRING (buffer_abc_1, "abc");
+
+  struct support_capture_subprocess proc = support_capture_subprocess
+    (&subprocess, NULL);
+
+  /* Discard the reported error.  */
+  support_record_failure_reset ();
+
+  puts ("info: *** subprocess output starts ***");
+  fputs (proc.out.buffer, stdout);
+  puts ("info: *** subprocess output ends ***");
+
+  TEST_VERIFY
+    (strcmp (proc.out.buffer,
+"tst-test_compare_string.c:29: error: blob comparison failed\n"
+"  left string: 0 bytes\n"
+"  right string: NULL\n"
+"tst-test_compare_string.c:30: error: blob comparison failed\n"
+"  left string: 1 bytes\n"
+"  right string: 0 bytes\n"
+"  left (evaluated from \"X\"):\n"
+"      \"X\"\n"
+"      58\n"
+"tst-test_compare_string.c:31: error: blob comparison failed\n"
+"  left string: NULL\n"
+"  right string: 1 bytes\n"
+"  right (evaluated from \"X\"):\n"
+"      \"X\"\n"
+"      58\n"
+"tst-test_compare_string.c:32: error: blob comparison failed\n"
+"  string length: 4 bytes\n"
+"  left (evaluated from \"abcd\"):\n"
+"      \"abcd\"\n"
+"      61 62 63 64\n"
+"  right (evaluated from \"abcD\"):\n"
+"      \"abcD\"\n"
+"      61 62 63 44\n"
+"tst-test_compare_string.c:33: error: blob comparison failed\n"
+"  left string: 4 bytes\n"
+"  right string: NULL\n"
+"  left (evaluated from \"abcd\"):\n"
+"      \"abcd\"\n"
+"      61 62 63 64\n"
+"tst-test_compare_string.c:34: error: blob comparison failed\n"
+"  left string: NULL\n"
+"  right string: 4 bytes\n"
+"  right (evaluated from \"abcd\"):\n"
+"      \"abcd\"\n"
+"      61 62 63 64\n"
+             ) == 0);
+
+  /* Check that there is no output on standard error.  */
+  support_capture_subprocess_check (&proc, "TEST_COMPARE_STRING",
+                                    0, sc_allow_stdout);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
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Re: [PATCH] support: Implement TEST_COMPARE_STRING

Gabriel F. T. Gomes-2
On Mon, 05 Nov 2018, Florian Weimer wrote:

>2018-11-05  Florian Weimer  <[hidden email]>
>
> Implement TEST_COMPARE_STRING.
> * support/check.h (TEST_COMPARE_STRING): Define.
> (support_test_compare_string): Declare.
> * support/Makefile (libsupport-routines): Add
> support_test_compare_string.
> (tests): Add tst-test_compare_string.
> * support/support_test_compare_string.c: New file.
> * support/tst-test_compare_string.c: Likewise.

Looks good to me with a fix to some whitespace problems.

>+/* Compare the strings LEFT and RIGHT and report a test failure if
>+   they are different.  Also report failure if one of the arguments is
>+   a null pointer and the other is not.  The strings should be
>+   reasonably short because on mismatch, both are printed.  */
>+#define TEST_COMPARE_STRING(left, right)                         \
>+  (support_test_compare_string (left, right, __FILE__, __LINE__, \
>+                                #left, #right))
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Spaces instead of tabs.

>+void support_test_compare_string (const char *left, const char *right,
>+                                  const char *file, int line,
>+                                  const char *left_expr,
>+                                  const char *right_expr);
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Likewise, here and throughout the patch.

>+      fputs ("     ", stdout);
>+      for (size_t i = 0; i < length; ++i)
>+        printf (" %02X", blob[i]);

Thanks for adding this hex conversion.  In the recently added test,
tst-ldbl-warn, it would have saved me some time in finding that a new line
wasn't being printed.

(I tried this patch on tst-ldbl-warn, by the way).
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Re: [PATCH] support: Implement TEST_COMPARE_STRING

Florian Weimer-5
* Gabriel F. T. Gomes:

>>+/* Compare the strings LEFT and RIGHT and report a test failure if
>>+   they are different.  Also report failure if one of the arguments is
>>+   a null pointer and the other is not.  The strings should be
>>+   reasonably short because on mismatch, both are printed.  */
>>+#define TEST_COMPARE_STRING(left, right)                         \
>>+  (support_test_compare_string (left, right, __FILE__, __LINE__, \
>>+                                #left, #right))
>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Spaces instead of tabs.

I wasn't aware that we have a policy to use tabs.  Most of my changes
involving new files do not use tabs. 8-/

I personally find tabs problematic because they make it pretty much
impossible to review diffs for correct indentation, which is why I avoid
them in new files.

Thanks,
Florian
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Re: [PATCH] support: Implement TEST_COMPARE_STRING

Gabriel F. T. Gomes-2
On Wed, 07 Nov 2018, Florian Weimer wrote:

>* Gabriel F. T. Gomes:
>
>>>+/* Compare the strings LEFT and RIGHT and report a test failure if
>>>+   they are different.  Also report failure if one of the arguments is
>>>+   a null pointer and the other is not.  The strings should be
>>>+   reasonably short because on mismatch, both are printed.  */
>>>+#define TEST_COMPARE_STRING(left, right)                         \
>>>+  (support_test_compare_string (left, right, __FILE__, __LINE__, \
>>>+                                #left, #right))  
>>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Spaces instead of tabs.  
>
>I wasn't aware that we have a policy to use tabs.  Most of my changes
>involving new files do not use tabs. 8-/

Oh, maybe we don't.  Now I feel embarrassed that I complained about it so
many times.

>I personally find tabs problematic because they make it pretty much
>impossible to review diffs for correct indentation, which is why I avoid
>them in new files.

I agree.
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Re: [PATCH] support: Implement TEST_COMPARE_STRING

Szabolcs Nagy-2
On 07/11/18 11:36, Gabriel F. T. Gomes wrote:

> On Wed, 07 Nov 2018, Florian Weimer wrote:
>
>> * Gabriel F. T. Gomes:
>>
>>>> +/* Compare the strings LEFT and RIGHT and report a test failure if
>>>> +   they are different.  Also report failure if one of the arguments is
>>>> +   a null pointer and the other is not.  The strings should be
>>>> +   reasonably short because on mismatch, both are printed.  */
>>>> +#define TEST_COMPARE_STRING(left, right)                         \
>>>> +  (support_test_compare_string (left, right, __FILE__, __LINE__, \
>>>> +                                #left, #right))  
>>>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> Spaces instead of tabs.  
>>
>> I wasn't aware that we have a policy to use tabs.  Most of my changes
>> involving new files do not use tabs. 8-/
>
> Oh, maybe we don't.  Now I feel embarrassed that I complained about it so
> many times.
>

that's news to me,

why is there an awkward mix of space and tab
indentation everywhere in the code then?

>> I personally find tabs problematic because they make it pretty much
>> impossible to review diffs for correct indentation, which is why I avoid
>> them in new files.
>
> I agree.
>

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Re: [PATCH] support: Implement TEST_COMPARE_STRING

Florian Weimer-5
* Szabolcs Nagy:

> On 07/11/18 11:36, Gabriel F. T. Gomes wrote:
>> On Wed, 07 Nov 2018, Florian Weimer wrote:
>>
>>> * Gabriel F. T. Gomes:
>>>
>>>>> +/* Compare the strings LEFT and RIGHT and report a test failure if
>>>>> +   they are different.  Also report failure if one of the arguments is
>>>>> +   a null pointer and the other is not.  The strings should be
>>>>> +   reasonably short because on mismatch, both are printed.  */
>>>>> +#define TEST_COMPARE_STRING(left, right)                         \
>>>>> +  (support_test_compare_string (left, right, __FILE__, __LINE__, \
>>>>> +                                #left, #right))  
>>>>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>> Spaces instead of tabs.  
>>>
>>> I wasn't aware that we have a policy to use tabs.  Most of my changes
>>> involving new files do not use tabs. 8-/
>>
>> Oh, maybe we don't.  Now I feel embarrassed that I complained about it so
>> many times.
>>
>
> that's news to me,
>
> why is there an awkward mix of space and tab
> indentation everywhere in the code then?

It's the Emacs default.  I don't know about vim.

Have we ever discussed changing it?

Thanks,
Florian