1 files changed, 123 insertions, 12 deletions

diff --git a/src/os/os_stack.c b/src/os/os_stack.c
index 037080f3..9844930f 100644
--- a/src/os/os_stack.c
+++ b/src/os/os_stack.c
@@ -1,7 +1,7 @@
 /*-
  * See the file LICENSE for redistribution information.
  *
- * Copyright (c) 2001, 2012 Oracle and/or its affiliates.  All rights reserved.
+ * Copyright (c) 2001, 2015 Oracle and/or its affiliates.  All rights reserved.
  *
  * $Id$
  */
@@ -14,32 +14,143 @@
 #include <execinfo.h>
 #endif
 
+#undef __DB_STACK_MAXFRAMES
+#define	__DB_STACK_MAXFRAMES	25
+
 /*
  * __os_stack --
- *	Output a stack trace to the message file handle.
+ *	Output a stack trace in a single write to the error file handle.
  *
- * PUBLIC: void __os_stack __P((ENV *));
+ * PUBLIC: void __os_stack __P((const ENV *));
  */
 void
 __os_stack(env)
-	ENV *env;
+	const ENV *env;
+{
+	/* Adjust by 2 to exclude __os_stack() and __os_stack_top(). */
+	__os_stack_top(env, __DB_STACK_MAXFRAMES - 2, 2);
+}
+
+/*
+ * __os_stack_top --
+ *	Output just a certain range of stack frames to the error file handle.
+ *
+ * PUBLIC: void __os_stack_top __P((const ENV *, unsigned, unsigned));
+ */
+void
+__os_stack_top(env, nframes, skipframes)
+	const ENV *env;
+	unsigned nframes;
+	unsigned skipframes;
 {
 #if defined(HAVE_BACKTRACE) && defined(HAVE_BACKTRACE_SYMBOLS)
-	void *array[200];
-	size_t i, size;
-	char **strings;
+	char buf[__DB_STACK_MAXFRAMES * 80];	/* Allow for 80 chars/line. */
 
+	__os_stack_text(env, buf, sizeof(buf), nframes, skipframes + 1);
+	__db_errx(env, "Top of stack:\n%s", buf);
+#else
+	COMPQUIET(env, NULL);
+	COMPQUIET(nframes, 0);
+	COMPQUIET(skipframes, 0);
+#endif
+}
+
+/*
+ * __os_stack_text --
+ *	'Print' the current stack into a char text buffer.
+ *
+ * PUBLIC: void __os_stack_text
+ * PUBLIC:     __P((const ENV *, char *, size_t, unsigned, unsigned));
+ */
+void
+__os_stack_text(env, result, bufsize, nframes, skip)
+	const ENV *env;
+	char *result;
+	size_t bufsize;
+	unsigned nframes;
+	unsigned skip;
+{
+	DB_MSGBUF mb;
+
+	DB_MSGBUF_INIT(&mb);
+	mb.buf = mb.cur = result;
+	mb.len = bufsize;
+	F_SET(&mb, DB_MSGBUF_PREALLOCATED);
+	__os_stack_msgadd(env, &mb, nframes, skip, NULL);
+}
+
+/*
+ * __os_stack_save --
+ *	Save a certain range of stack frames into the frames argument.
+ *
+ * PUBLIC: int __os_stack_save __P((const ENV *, unsigned, void **));
+ */
+int
+__os_stack_save(env, nframes, frames)
+	const ENV *env;
+	unsigned nframes;
+	void **frames;
+{
+	COMPQUIET(env, NULL);
+#if defined(HAVE_BACKTRACE) && defined(HAVE_BACKTRACE_SYMBOLS)
 	/*
 	 * Solaris and the GNU C library support this interface.  Solaris
 	 * has additional interfaces (printstack and walkcontext), I don't
 	 * know if they offer any additional value or not.
 	 */
-	size = backtrace(array, sizeof(array) / sizeof(array[0]));
-	strings = backtrace_symbols(array, size);
+	return ((int) backtrace(frames, nframes));
+#else
+	COMPQUIET(nframes, 0);
+	COMPQUIET(frames, NULL);
+	return (0);
+#endif
+}
+
+/*
+ * __os_stack_msgadd --
+ *	Decode a stack and add it to a DB_MSGBUF. The stack was either
+ *	previously obtained stack, e.g., from __os_stack_save(), or if it is
+ *	null, the current stack is fetched here.
+ *
+ * PUBLIC: void __os_stack_msgadd
+ * PUBLIC:       __P((const ENV *, DB_MSGBUF *, unsigned, unsigned, void **));
+ */
+void
+__os_stack_msgadd(env, mb, totalframes, skipframes, stack)
+	const ENV *env;
+	DB_MSGBUF *mb;
+	unsigned totalframes;
+	unsigned skipframes;
+	void **stack;
+{
+#if defined(HAVE_BACKTRACE) && defined(HAVE_BACKTRACE_SYMBOLS)
+	char **strings;
+	void *local_frames[__DB_STACK_MAXFRAMES];
+	unsigned i;
+
+	if (stack == NULL) {
+		stack = local_frames;
+		if (totalframes > __DB_STACK_MAXFRAMES)
+			totalframes = __DB_STACK_MAXFRAMES;
+		totalframes = backtrace(local_frames, totalframes);
+		skipframes++;
+	}
+
+	/*
+	 * Solaris and the GNU C library support this interface.  Solaris
+	 * has additional interfaces (printstack and walkcontext) which have
+	 * know if they offer any additional value or not.
+	 */
+	strings = backtrace_symbols(stack, totalframes);
 
-	for (i = 0; i < size; ++i)
-		__db_errx(env, "%s", strings[i]);
+	for (i = skipframes; i < totalframes; ++i)
+		__db_msgadd((ENV *)env, mb, "\t%s\n", strings[i]);
 	free(strings);
-#endif
+#else
 	COMPQUIET(env, NULL);
+	COMPQUIET(mb, NULL);
+	COMPQUIET(totalframes, 0);
+	COMPQUIET(skipframes, 0);
+	COMPQUIET(stack, NULL);
+#endif
 }