Copy in libbacktrace from gcc

This copies in libbacktrace from the gcc repository as it was in the
commit 62e420293a293608f383d9b9c7f2debd666e9fc9.  GDB is going to
start using this library soon.

A dependency between GDB and libbacktrace has already been added to
the top level Makefile, so, after this commit, when building GDB,
libbacktrace will be built first.  However, libbacktrace is not yet
linked into GDB, or used by GDB in any way.

It is possible to stop libbacktrace being built by configuring the
tree with --disable-libbacktrace.

This commit does NOT update src-release.sh, that will be done in the
next commit, this commit ONLY imports libbacktrace from gcc.  This
means that if you try to make a release of GDB from exactly this
commit then the release tar file will not include libbacktrace.
However, as libbacktrace is an optional dependency this is fine.

1 files changed, 206 insertions, 0 deletions

diff --git a/libbacktrace/backtrace.h b/libbacktrace/backtrace.h
new file mode 100644
index 0000000..caaa66d
--- /dev/null
+++ b/libbacktrace/backtrace.h
@@ -0,0 +1,206 @@
+/* backtrace.h -- Public header file for stack backtrace library.
+   Copyright (C) 2012-2021 Free Software Foundation, Inc.
+   Written by Ian Lance Taylor, Google.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#ifndef BACKTRACE_H
+#define BACKTRACE_H
+
+#include <stddef.h>
+#include <stdio.h>
+
+/* We want to get a definition for uintptr_t, but we still care about
+   systems that don't have <stdint.h>.  */
+#if defined(__GLIBC__) && __GLIBC__ >= 2
+
+#include <stdint.h>
+
+#elif defined(HAVE_STDINT_H)
+
+#include <stdint.h>
+
+#else
+
+/* Systems that don't have <stdint.h> must provide gstdint.h, e.g.,
+   from GCC_HEADER_STDINT in configure.ac.  */
+#include "gstdint.h"
+
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* The backtrace state.  This struct is intentionally not defined in
+   the public interface.  */
+
+struct backtrace_state;
+
+/* The type of the error callback argument to backtrace functions.
+   This function, if not NULL, will be called for certain error cases.
+   The DATA argument is passed to the function that calls this one.
+   The MSG argument is an error message.  The ERRNUM argument, if
+   greater than 0, holds an errno value.  The MSG buffer may become
+   invalid after this function returns.
+
+   As a special case, the ERRNUM argument will be passed as -1 if no
+   debug info can be found for the executable, or if the debug info
+   exists but has an unsupported version, but the function requires
+   debug info (e.g., backtrace_full, backtrace_pcinfo).  The MSG in
+   this case will be something along the lines of "no debug info".
+   Similarly, ERRNUM will be passed as -1 if there is no symbol table,
+   but the function requires a symbol table (e.g., backtrace_syminfo).
+   This may be used as a signal that some other approach should be
+   tried.  */
+
+typedef void (*backtrace_error_callback) (void *data, const char *msg,
+					  int errnum);
+
+/* Create state information for the backtrace routines.  This must be
+   called before any of the other routines, and its return value must
+   be passed to all of the other routines.  FILENAME is the path name
+   of the executable file; if it is NULL the library will try
+   system-specific path names.  If not NULL, FILENAME must point to a
+   permanent buffer.  If THREADED is non-zero the state may be
+   accessed by multiple threads simultaneously, and the library will
+   use appropriate atomic operations.  If THREADED is zero the state
+   may only be accessed by one thread at a time.  This returns a state
+   pointer on success, NULL on error.  If an error occurs, this will
+   call the ERROR_CALLBACK routine.
+
+   Calling this function allocates resources that cannot be freed.
+   There is no backtrace_free_state function.  The state is used to
+   cache information that is expensive to recompute.  Programs are
+   expected to call this function at most once and to save the return
+   value for all later calls to backtrace functions.  */
+
+extern struct backtrace_state *backtrace_create_state (
+    const char *filename, int threaded,
+    backtrace_error_callback error_callback, void *data);
+
+/* The type of the callback argument to the backtrace_full function.
+   DATA is the argument passed to backtrace_full.  PC is the program
+   counter.  FILENAME is the name of the file containing PC, or NULL
+   if not available.  LINENO is the line number in FILENAME containing
+   PC, or 0 if not available.  FUNCTION is the name of the function
+   containing PC, or NULL if not available.  This should return 0 to
+   continuing tracing.  The FILENAME and FUNCTION buffers may become
+   invalid after this function returns.  */
+
+typedef int (*backtrace_full_callback) (void *data, uintptr_t pc,
+					const char *filename, int lineno,
+					const char *function);
+
+/* Get a full stack backtrace.  SKIP is the number of frames to skip;
+   passing 0 will start the trace with the function calling
+   backtrace_full.  DATA is passed to the callback routine.  If any
+   call to CALLBACK returns a non-zero value, the stack backtrace
+   stops, and backtrace returns that value; this may be used to limit
+   the number of stack frames desired.  If all calls to CALLBACK
+   return 0, backtrace returns 0.  The backtrace_full function will
+   make at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   function requires debug info for the executable.  */
+
+extern int backtrace_full (struct backtrace_state *state, int skip,
+			   backtrace_full_callback callback,
+			   backtrace_error_callback error_callback,
+			   void *data);
+
+/* The type of the callback argument to the backtrace_simple function.
+   DATA is the argument passed to simple_backtrace.  PC is the program
+   counter.  This should return 0 to continue tracing.  */
+
+typedef int (*backtrace_simple_callback) (void *data, uintptr_t pc);
+
+/* Get a simple backtrace.  SKIP is the number of frames to skip, as
+   in backtrace.  DATA is passed to the callback routine.  If any call
+   to CALLBACK returns a non-zero value, the stack backtrace stops,
+   and backtrace_simple returns that value.  Otherwise
+   backtrace_simple returns 0.  The backtrace_simple function will
+   make at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   function does not require any debug info for the executable.  */
+
+extern int backtrace_simple (struct backtrace_state *state, int skip,
+			     backtrace_simple_callback callback,
+			     backtrace_error_callback error_callback,
+			     void *data);
+
+/* Print the current backtrace in a user readable format to a FILE.
+   SKIP is the number of frames to skip, as in backtrace_full.  Any
+   error messages are printed to stderr.  This function requires debug
+   info for the executable.  */
+
+extern void backtrace_print (struct backtrace_state *state, int skip, FILE *);
+
+/* Given PC, a program counter in the current program, call the
+   callback function with filename, line number, and function name
+   information.  This will normally call the callback function exactly
+   once.  However, if the PC happens to describe an inlined call, and
+   the debugging information contains the necessary information, then
+   this may call the callback function multiple times.  This will make
+   at least one call to either CALLBACK or ERROR_CALLBACK.  This
+   returns the first non-zero value returned by CALLBACK, or 0.  */
+
+extern int backtrace_pcinfo (struct backtrace_state *state, uintptr_t pc,
+			     backtrace_full_callback callback,
+			     backtrace_error_callback error_callback,
+			     void *data);
+
+/* The type of the callback argument to backtrace_syminfo.  DATA and
+   PC are the arguments passed to backtrace_syminfo.  SYMNAME is the
+   name of the symbol for the corresponding code.  SYMVAL is the
+   value and SYMSIZE is the size of the symbol.  SYMNAME will be NULL
+   if no error occurred but the symbol could not be found.  */
+
+typedef void (*backtrace_syminfo_callback) (void *data, uintptr_t pc,
+					    const char *symname,
+					    uintptr_t symval,
+					    uintptr_t symsize);
+
+/* Given ADDR, an address or program counter in the current program,
+   call the callback information with the symbol name and value
+   describing the function or variable in which ADDR may be found.
+   This will call either CALLBACK or ERROR_CALLBACK exactly once.
+   This returns 1 on success, 0 on failure.  This function requires
+   the symbol table but does not require the debug info.  Note that if
+   the symbol table is present but ADDR could not be found in the
+   table, CALLBACK will be called with a NULL SYMNAME argument.
+   Returns 1 on success, 0 on error.  */
+
+extern int backtrace_syminfo (struct backtrace_state *state, uintptr_t addr,
+			      backtrace_syminfo_callback callback,
+			      backtrace_error_callback error_callback,
+			      void *data);
+
+#ifdef __cplusplus
+} /* End extern "C".  */
+#endif
+
+#endif