Add internal facility for dynamic array handling

This is intended as a type-safe alternative to obstacks and
hand-written realloc constructs.  The implementation avoids
writing function pointers to the heap.

1 files changed, 188 insertions, 0 deletions

diff --git a/support/tst-support_capture_subprocess.c b/support/tst-support_capture_subprocess.c
new file mode 100644
index 0000000..5672fba
--- /dev/null
+++ b/support/tst-support_capture_subprocess.c
@@ -0,0 +1,188 @@
+/* Test capturing output from a subprocess.
+   Copyright (C) 2017 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 <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/* Write one byte at *P to FD and advance *P.  Do nothing if *P is
+   '\0'.  */
+static void
+transfer (const unsigned char **p, int fd)
+{
+  if (**p != '\0')
+    {
+      TEST_VERIFY (write (fd, *p, 1) == 1);
+      ++*p;
+    }
+}
+
+/* Determine the order in which stdout and stderr are written.  */
+enum write_mode { out_first, err_first, interleave,
+                  write_mode_last =  interleave };
+
+/* Describe what to write in the subprocess.  */
+struct test
+{
+  char *out;
+  char *err;
+  enum write_mode write_mode;
+  int signal;
+  int status;
+};
+
+/* For use with support_capture_subprocess.  */
+static void
+callback (void *closure)
+{
+  const struct test *test = closure;
+  bool mode_ok = false;
+  switch (test->write_mode)
+    {
+    case out_first:
+      TEST_VERIFY (fputs (test->out, stdout) >= 0);
+      TEST_VERIFY (fflush (stdout) == 0);
+      TEST_VERIFY (fputs (test->err, stderr) >= 0);
+      TEST_VERIFY (fflush (stderr) == 0);
+      mode_ok = true;
+      break;
+    case err_first:
+      TEST_VERIFY (fputs (test->err, stderr) >= 0);
+      TEST_VERIFY (fflush (stderr) == 0);
+      TEST_VERIFY (fputs (test->out, stdout) >= 0);
+      TEST_VERIFY (fflush (stdout) == 0);
+      mode_ok = true;
+      break;
+    case interleave:
+      {
+        const unsigned char *pout = (const unsigned char *) test->out;
+        const unsigned char *perr = (const unsigned char *) test->err;
+        do
+          {
+            transfer (&pout, STDOUT_FILENO);
+            transfer (&perr, STDERR_FILENO);
+          }
+        while (*pout != '\0' || *perr != '\0');
+      }
+      mode_ok = true;
+      break;
+    }
+  TEST_VERIFY (mode_ok);
+
+  if (test->signal != 0)
+    raise (test->signal);
+  exit (test->status);
+}
+
+/* Create a heap-allocated random string of letters.  */
+static char *
+random_string (size_t length)
+{
+  char *result = xmalloc (length + 1);
+  for (size_t i = 0; i < length; ++i)
+    result[i] = 'a' + (rand () % 26);
+  result[length] = '\0';
+  return result;
+}
+
+/* Check that the specific stream from the captured subprocess matches
+   expectations.  */
+static void
+check_stream (const char *what, const struct xmemstream *stream,
+              const char *expected)
+{
+  if (strcmp (stream->buffer, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: captured %s data incorrect\n"
+              "  expected: %s\n"
+              "  actual:   %s\n",
+              what, expected, stream->buffer);
+    }
+  if (stream->length != strlen (expected))
+    {
+      support_record_failure ();
+      printf ("error: captured %s data length incorrect\n"
+              "  expected: %zu\n"
+              "  actual:   %zu\n",
+              what, strlen (expected), stream->length);
+    }
+}
+
+static int
+do_test (void)
+{
+  const int lengths[] = {0, 1, 17, 512, 20000, -1};
+
+  /* Test multiple combinations of support_capture_subprocess.
+
+     length_idx_stdout: Index into the lengths array above,
+       controls how many bytes are written by the subprocess to
+       standard output.
+     length_idx_stderr: Same for standard error.
+     write_mode: How standard output and standard error writes are
+       ordered.
+     signal: Exit with no signal if zero, with SIGTERM if one.
+     status: Process exit status: 0 if zero, 3 if one.  */
+  for (int length_idx_stdout = 0; lengths[length_idx_stdout] >= 0;
+       ++length_idx_stdout)
+    for (int length_idx_stderr = 0; lengths[length_idx_stderr] >= 0;
+         ++length_idx_stderr)
+      for (int write_mode = 0; write_mode < write_mode_last; ++write_mode)
+        for (int signal = 0; signal < 2; ++signal)
+          for (int status = 0; status < 2; ++status)
+            {
+              struct test test =
+                {
+                  .out = random_string (lengths[length_idx_stdout]),
+                  .err = random_string (lengths[length_idx_stderr]),
+                  .write_mode = write_mode,
+                  .signal = signal * SIGTERM, /* 0 or SIGTERM.  */
+                  .status = status * 3,       /* 0 or 3.  */
+                };
+              TEST_VERIFY (strlen (test.out) == lengths[length_idx_stdout]);
+              TEST_VERIFY (strlen (test.err) == lengths[length_idx_stderr]);
+
+              struct support_capture_subprocess result
+                = support_capture_subprocess (callback, &test);
+              check_stream ("stdout", &result.out, test.out);
+              check_stream ("stderr", &result.err, test.err);
+              if (test.signal != 0)
+                {
+                  TEST_VERIFY (WIFSIGNALED (result.status));
+                  TEST_VERIFY (WTERMSIG (result.status) == test.signal);
+                }
+              else
+                {
+                  TEST_VERIFY (WIFEXITED (result.status));
+                  TEST_VERIFY (WEXITSTATUS (result.status) == test.status);
+                }
+              support_capture_subprocess_free (&result);
+              free (test.out);
+              free (test.err);
+            }
+  return 0;
+}
+
+#include <support/test-driver.c>