Add tests that backtrace and backtrace_symbols produce correctresults

["Joseph S. Myers" <joseph at codesourcery dot com>]

The existing tests of the backtrace and backtrace_symbols functions,
debug/backtrace-tst.c and nptl/tst-backtrace1.c, test essentially
nothing beyond that the functions succeed rather than (for example)
segfaulting.  In particular, they do not test anything about the
correctness of the backtraces generated.

This patch adds some tests that backtraces generated are correct.
(These tests have been in EGLIBC for some time.  There's also another
test there, tst-backtrace6.c, which tests for backtraces involving
noreturn functions - an important case, since people may well want to
backtrace through code that called "abort".  However, that runs into
problems on some architectures when the return address for the
noreturn function is after the end of the calling function.  I think
dealing with such cases reliably would involved a new variant of the
backtrace function that uses _Unwind_GetIPInfo instead of
_Unwind_GetIP to ensure it always produces an address within the
correct function.  So this patch just includes those tests that
already work without needing such new interfaces.)

Tested x86_64 and x86.

2013-01-18  Joseph Myers  <joseph@codesourcery.com>
	    Mark Mitchell  <mark@codesourcery.com>
	    Tom de Vries  <tom@codesourcery.com>
	    Paul Pluzhnikov  <ppluzhnikov@google.com>

	* debug/tst-backtrace2.c: New file.
	* debug/tst-backtrace3.c: Likewise.
	* debug/tst-backtrace4.c: Likewise.
	* debug/tst-backtrace5.c: Likewise.
	* debug/Makefile (CFLAGS-tst-backtrace2.c): New variable.
	(CFLAGS-tst-backtrace3.c): Likewise.
	(CFLAGS-tst-backtrace4.c): Likewise.
	(CFLAGS-tst-backtrace5.c): Likewise.
	(LDFLAGS-tst-backtrace2): Likewise.
	(LDFLAGS-tst-backtrace3): Likewise.
	(LDFLAGS-tst-backtrace4): Likewise.
	(LDFLAGS-tst-backtrace5): Likewise.
	(tests): Add new tests tst-backtrace2, tst-backtrace3,
	tst-backtrace4 and tst-backtrace5.

diff --git a/debug/Makefile b/debug/Makefile
index 40446d4..55017d3 100644
--- a/debug/Makefile
+++ b/debug/Makefile
@@ -121,10 +121,22 @@ LDLIBS-tst-lfschk4 = -lstdc++
 LDLIBS-tst-lfschk5 = -lstdc++
 LDLIBS-tst-lfschk6 = -lstdc++
 
+# backtrace_symbols only works if we link with -rdynamic.  backtrace
+# requires unwind tables on most architectures.
+CFLAGS-tst-backtrace2.c += -funwind-tables
+CFLAGS-tst-backtrace3.c += -funwind-tables
+CFLAGS-tst-backtrace4.c += -funwind-tables
+CFLAGS-tst-backtrace5.c += -funwind-tables
+LDFLAGS-tst-backtrace2 = -rdynamic
+LDFLAGS-tst-backtrace3 = -rdynamic
+LDFLAGS-tst-backtrace4 = -rdynamic
+LDFLAGS-tst-backtrace5 = -rdynamic
+
 tests = backtrace-tst tst-longjmp_chk tst-chk1 tst-chk2 tst-chk3 \
 	tst-lfschk1 tst-lfschk2 tst-lfschk3 test-strcpy_chk test-stpcpy_chk \
 	tst-chk4 tst-chk5 tst-chk6 tst-lfschk4 tst-lfschk5 tst-lfschk6 \
-	tst-longjmp_chk2
+	tst-longjmp_chk2 tst-backtrace2 tst-backtrace3 tst-backtrace4 \
+	tst-backtrace5
 
 tests-ifunc := $(stpcpy_chk strcpy_chk:%=test-%-ifunc)
 tests += $(tests-ifunc)
diff --git a/debug/tst-backtrace2.c b/debug/tst-backtrace2.c
new file mode 100644
index 0000000..e1d4572
--- /dev/null
+++ b/debug/tst-backtrace2.c
@@ -0,0 +1,111 @@
+/* Test backtrace and backtrace_symbols.
+   Copyright (C) 2009-2013 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 <execinfo.h>
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+/* Set to a non-zero value if the test fails.  */
+int ret;
+
+/* Accesses to X are used to prevent optimization.  */
+volatile int x;
+
+/* Called if the test fails.  */
+#define FAIL() \
+  do { printf ("Failure on line %d\n", __LINE__); ret = 1; } while (0)
+
+/* The backtrace should include at least f1, f2, f3, and do_test.  */
+#define NUM_FUNCTIONS 4
+
+/* Use this attribute to prevent inlining, so that all expected frames
+   are present.  */
+#define NO_INLINE __attribute__ ((noinline))
+
+NO_INLINE void
+fn1 (void)
+{
+  void *addresses[NUM_FUNCTIONS];
+  char **symbols;
+  int n;
+  int i;
+
+  /* Get the backtrace addresses.  */
+  n = backtrace (addresses, sizeof (addresses) / sizeof (addresses[0]));
+  printf ("Obtained backtrace with %d functions\n", n);
+  /*  Check that there are at least four functions.  */
+  if (n < NUM_FUNCTIONS)
+    {
+      FAIL ();
+      return;
+    }
+  /* Convert them to symbols.  */
+  symbols = backtrace_symbols (addresses, n);
+  /* Check that symbols were obtained.  */
+  if (symbols == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  for (i = 0; i < n; ++i)
+    printf ("Function %d: %s\n", i, symbols[i]);
+  /* Check that the function names obtained are accurate.  */
+  if (strstr (symbols[0], "fn1") == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  /* Symbol names are not available for static functions, so we do not
+     check f2.  */
+  if (strstr (symbols[2], "fn3") == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  /* Symbol names are not available for static functions, so we do not
+     check do_test.  */
+}
+
+NO_INLINE static int
+fn2 (void)
+{
+  fn1 ();
+  /* Prevent tail calls.  */
+  return x;
+}
+
+NO_INLINE int
+fn3 (void)
+{
+  fn2();
+  /* Prevent tail calls.  */
+  return x;
+}
+
+NO_INLINE static int
+do_test (void)
+{
+  fn3 ();
+  return ret;
+}
diff --git a/debug/tst-backtrace3.c b/debug/tst-backtrace3.c
new file mode 100644
index 0000000..4d3309b
--- /dev/null
+++ b/debug/tst-backtrace3.c
@@ -0,0 +1,95 @@
+/* Test backtrace and backtrace_symbols for recursive calls.
+   Copyright (C) 2010-2013 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 <execinfo.h>
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+/* Set to a non-zero value if the test fails.  */
+int ret;
+
+/* Accesses to X are used to prevent optimization.  */
+volatile int x;
+
+/* Called if the test fails.  */
+#define FAIL() \
+  do { printf ("Failure on line %d\n", __LINE__); ret = 1; } while (0)
+
+/* The backtrace should include at least 3 * fn, and do_test.  */
+#define NUM_FUNCTIONS 4
+
+/* Use this attribute to prevent inlining, so that all expected frames
+   are present.  */
+#define NO_INLINE __attribute__ ((noinline))
+
+NO_INLINE int
+fn (int c)
+{
+  void *addresses[NUM_FUNCTIONS];
+  char **symbols;
+  int n;
+  int i;
+
+  if (c > 0)
+    {
+      fn (c - 1);
+      return x;
+    }
+  /* Get the backtrace addresses.  */
+  n = backtrace (addresses, sizeof (addresses) / sizeof (addresses[0]));
+  printf ("Obtained backtrace with %d functions\n", n);
+  /*  Check that there are at least four functions.  */
+  if (n < NUM_FUNCTIONS)
+    {
+      FAIL ();
+      return 1;
+    }
+  /* Convert them to symbols.  */
+  symbols = backtrace_symbols (addresses, n);
+  /* Check that symbols were obtained.  */
+  if (symbols == NULL)
+    {
+      FAIL ();
+      return 1;
+    }
+  for (i = 0; i < n; ++i)
+    printf ("Function %d: %s\n", i, symbols[i]);
+  /* Check that the function names obtained are accurate.  */
+  for (i = 0; i < n - 1; ++i)
+    if (strstr (symbols[i], "fn") == NULL)
+      {
+	FAIL ();
+	return 1;
+      }
+  /* Symbol names are not available for static functions, so we do not
+     check do_test.  */
+  return x;
+}
+
+NO_INLINE static int
+do_test (void)
+{
+  fn (2);
+  return ret;
+}
diff --git a/debug/tst-backtrace4.c b/debug/tst-backtrace4.c
new file mode 100644
index 0000000..41a3f51
--- /dev/null
+++ b/debug/tst-backtrace4.c
@@ -0,0 +1,134 @@
+/* Test backtrace and backtrace_symbols for signal frames.
+   Copyright (C) 2011-2013 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 <execinfo.h>
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <unistd.h>
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+/* Set to a non-zero value if the test fails.  */
+volatile int ret;
+
+/* Accesses to X are used to prevent optimization.  */
+volatile int x;
+
+/* Called if the test fails.  */
+#define FAIL() \
+  do { printf ("Failure on line %d\n", __LINE__); ret = 1; } while (0)
+
+/* The backtrace should include at least handle_signal, a signal
+   trampoline, 3 * fn, and do_test.  */
+#define NUM_FUNCTIONS 6
+
+/* Use this attribute to prevent inlining, so that all expected frames
+   are present.  */
+#define NO_INLINE __attribute__ ((noinline))
+
+volatile int sig_handled = 0;
+
+void
+handle_signal (int signum)
+{
+  void *addresses[NUM_FUNCTIONS];
+  char **symbols;
+  int n;
+  int i;
+
+  sig_handled = 1;
+
+  /* Get the backtrace addresses.  */
+  n = backtrace (addresses, sizeof (addresses) / sizeof (addresses[0]));
+  printf ("Obtained backtrace with %d functions\n", n);
+  /*  Check that there are at least six functions.  */
+  if (n < NUM_FUNCTIONS)
+    {
+      FAIL ();
+      return;
+    }
+  /* Convert them to symbols.  */
+  symbols = backtrace_symbols (addresses, n);
+  /* Check that symbols were obtained.  */
+  if (symbols == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  for (i = 0; i < n; ++i)
+    printf ("Function %d: %s\n", i, symbols[i]);
+  /* Check that the function names obtained are accurate.  */
+  if (strstr (symbols[0], "handle_signal") == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  /* Do not check name for signal trampoline.  */
+  for (i = 2; i < n - 1; i++)
+    if (strstr (symbols[i], "fn") == NULL)
+      {
+	FAIL ();
+	return;
+      }
+  /* Symbol names are not available for static functions, so we do not
+     check do_test.  */
+}
+
+NO_INLINE int
+fn (int c)
+{
+  pid_t parent_pid, child_pid;
+
+  if (c > 0)
+    {
+      fn (c - 1);
+      return x;
+    }
+
+  signal (SIGUSR1, handle_signal);
+  parent_pid = getpid ();
+
+  child_pid = fork ();
+  if (child_pid == (pid_t) -1)
+    abort ();
+  else if (child_pid == 0)
+    {
+      sleep (1);
+      kill (parent_pid, SIGUSR1);
+      _exit (0);
+    }
+
+  /* In the parent.  */
+  while (sig_handled == 0)
+    ;
+
+  return 0;
+}
+
+NO_INLINE static int
+do_test (void)
+{
+  fn (2);
+  return ret;
+}
diff --git a/debug/tst-backtrace5.c b/debug/tst-backtrace5.c
new file mode 100644
index 0000000..eb16c23
--- /dev/null
+++ b/debug/tst-backtrace5.c
@@ -0,0 +1,148 @@
+/* Test backtrace and backtrace_symbols for signal frames, where a
+   system call was interrupted by a signal.
+   Copyright (C) 2011-2013 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 <execinfo.h>
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <unistd.h>
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+/* Set to a non-zero value if the test fails.  */
+volatile int ret;
+
+/* Accesses to X are used to prevent optimization.  */
+volatile int x;
+
+/* Called if the test fails.  */
+#define FAIL() \
+  do { printf ("Failure on line %d\n", __LINE__); ret = 1; } while (0)
+
+/* The backtrace should include at least handle_signal, a signal
+   trampoline, read, 3 * fn, and do_test.  */
+#define NUM_FUNCTIONS 7
+
+/* Use this attribute to prevent inlining, so that all expected frames
+   are present.  */
+#define NO_INLINE __attribute__ ((noinline))
+
+void
+handle_signal (int signum)
+{
+  void *addresses[NUM_FUNCTIONS];
+  char **symbols;
+  int n;
+  int i;
+
+  /* Get the backtrace addresses.  */
+  n = backtrace (addresses, sizeof (addresses) / sizeof (addresses[0]));
+  printf ("Obtained backtrace with %d functions\n", n);
+  /*  Check that there are at least seven functions.  */
+  if (n < NUM_FUNCTIONS)
+    {
+      FAIL ();
+      return;
+    }
+  /* Convert them to symbols.  */
+  symbols = backtrace_symbols (addresses, n);
+  /* Check that symbols were obtained.  */
+  if (symbols == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  for (i = 0; i < n; ++i)
+    printf ("Function %d: %s\n", i, symbols[i]);
+  /* Check that the function names obtained are accurate.  */
+  if (strstr (symbols[0], "handle_signal") == NULL)
+    {
+      FAIL ();
+      return;
+    }
+  /* Do not check name for signal trampoline.  */
+  i = 2;
+  if (strstr (symbols[i++], "read") == NULL)
+    {
+      /* Perhaps symbols[2] is __kernel_vsyscall?  */
+      if (strstr (symbols[i++], "read") == NULL)
+	{
+	  FAIL ();
+	  return;
+	}
+    }
+  for (; i < n - 1; i++)
+    if (strstr (symbols[i], "fn") == NULL)
+      {
+	FAIL ();
+	return;
+      }
+  /* Symbol names are not available for static functions, so we do not
+     check do_test.  */
+}
+
+NO_INLINE int
+fn (int c)
+{
+  pid_t parent_pid, child_pid;
+  int pipefd[2];
+  char r[1];
+  struct sigaction act;
+
+  if (c > 0)
+    {
+      fn (c - 1);
+      return x;
+    }
+
+  memset (&act, 0, sizeof (act));
+  act.sa_handler = handle_signal;
+  sigemptyset (&act.sa_mask);
+  sigaction (SIGUSR1, &act, NULL);
+  parent_pid = getpid ();
+  if (pipe (pipefd) == -1)
+    abort ();
+
+  child_pid = fork ();
+  if (child_pid == (pid_t) -1)
+    abort ();
+  else if (child_pid == 0)
+    {
+      sleep (1);
+      kill (parent_pid, SIGUSR1);
+      _exit (0);
+    }
+
+  /* In the parent.  */
+  read (pipefd[0], r, 1);
+
+  return 0;
+}
+
+NO_INLINE static int
+do_test (void)
+{
+  fn (2);
+  return ret;
+}

-- 
Joseph S. Myers
joseph@codesourcery.com