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/***********************************************************************/
/* */
/* Objective Caml */
/* */
/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
/* */
/* Copyright 2000 Institut National de Recherche en Informatique et */
/* en Automatique. All rights reserved. This file is distributed */
/* under the terms of the GNU Library General Public License, with */
/* the special exception on linking described in file ../LICENSE. */
/* */
/***********************************************************************/
/* $Id$ */
/* Stack backtrace for uncaught exceptions */
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include "config.h"
#ifdef HAS_UNISTD
#include <unistd.h>
#endif
#include "mlvalues.h"
#include "alloc.h"
#include "io.h"
#include "instruct.h"
#include "intext.h"
#include "exec.h"
#include "fix_code.h"
#include "startup.h"
#include "stacks.h"
#include "sys.h"
#include "backtrace.h"
CAMLexport int backtrace_active = 0;
CAMLexport int backtrace_pos = 0;
CAMLexport code_t * backtrace_buffer = NULL;
CAMLexport value backtrace_last_exn = Val_unit;
#define BACKTRACE_BUFFER_SIZE 1024
/* Location of fields in the Instruct.debug_event record */
enum { EV_POS = 0,
EV_MODULE = 1,
EV_CHAR = 2,
EV_KIND = 3 };
/* Location of fields in the Lexing.position record. */
enum {
POS_FNAME = 0,
POS_LNUM = 1,
POS_BOL = 2,
POS_CNUM = 3
};
/* Initialize the backtrace machinery */
void init_backtrace(void)
{
backtrace_active = 1;
register_global_root(&backtrace_last_exn);
/* Note: lazy initialization of backtrace_buffer in stash_backtrace
to simplify the interface with the thread libraries */
}
/* Store the return addresses contained in the given stack fragment
into the backtrace array */
void stash_backtrace(value exn, code_t pc, value * sp)
{
code_t end_code = (code_t) ((char *) start_code + code_size);
if (pc != NULL) pc = pc - 1;
if (exn != backtrace_last_exn) {
backtrace_pos = 0;
backtrace_last_exn = exn;
}
if (backtrace_buffer == NULL) {
backtrace_buffer = malloc(BACKTRACE_BUFFER_SIZE * sizeof(code_t));
if (backtrace_buffer == NULL) return;
}
if (backtrace_pos >= BACKTRACE_BUFFER_SIZE) return;
if (pc >= start_code && pc < end_code){
backtrace_buffer[backtrace_pos++] = pc;
}
for (/*nothing*/; sp < trapsp; sp++) {
code_t p = (code_t) *sp;
if (p >= start_code && p < end_code) {
if (backtrace_pos >= BACKTRACE_BUFFER_SIZE) break;
backtrace_buffer[backtrace_pos++] = p;
}
}
}
/* Read the debugging info contained in the current bytecode executable.
Return a Caml array of Caml lists of debug_event records in "events",
or Val_false on failure. */
#ifndef O_BINARY
#define O_BINARY 0
#endif
static value read_debug_info(void)
{
CAMLparam0();
CAMLlocal1(events);
char * exec_name;
int fd;
struct exec_trailer trail;
struct channel * chan;
uint32 num_events, orig, i;
value evl, l;
exec_name = caml_exe_name;
fd = attempt_open(&exec_name, &trail, 1);
if (fd < 0) CAMLreturn(Val_false);
read_section_descriptors(fd, &trail);
if (seek_optional_section(fd, &trail, "DBUG") == -1) {
close(fd);
CAMLreturn(Val_false);
}
chan = open_descriptor_in(fd);
num_events = getword(chan);
events = alloc(num_events, 0);
for (i = 0; i < num_events; i++) {
orig = getword(chan);
evl = input_val(chan);
/* Relocate events in event list */
for (l = evl; l != Val_int(0); l = Field(l, 1)) {
value ev = Field(l, 0);
Field(ev, EV_POS) = Val_long(Long_val(Field(ev, EV_POS)) + orig);
}
/* Record event list */
Store_field(events, i, evl);
}
close_channel(chan);
CAMLreturn(events);
}
/* Search the event for the given PC. Return Val_false if not found. */
static value event_for_location(value events, code_t pc)
{
mlsize_t i;
value pos, l, ev, ev_pos;
Assert(pc >= start_code && pc < start_code + code_size);
pos = Val_long((char *) pc - (char *) start_code);
for (i = 0; i < Wosize_val(events); i++) {
for (l = Field(events, i); l != Val_int(0); l = Field(l, 1)) {
ev = Field(l, 0);
ev_pos = Field(ev, EV_POS);
/* ocamlc sometimes moves an event past a following PUSH instruction;
allow mismatch by 1 instruction. */
if (ev_pos == pos || ev_pos == pos + 8) return ev;
}
}
return Val_false;
}
/* Print the location corresponding to the given PC */
static void print_location(value events, int index)
{
code_t pc = backtrace_buffer[index];
char * info;
value ev;
ev = event_for_location(events, pc);
if (is_instruction(*pc, RAISE)) {
/* Ignore compiler-inserted raise */
if (ev == Val_false) return;
/* Initial raise if index == 0, re-raise otherwise */
if (index == 0)
info = "Raised at";
else
info = "Re-raised at";
} else {
if (index == 0)
info = "Raised by primitive operation at";
else
info = "Called from";
}
if (ev == Val_false) {
fprintf(stderr, "%s unknown location\n", info);
} else {
value ev_char = Field (ev, EV_CHAR);
char *fname = String_val (Field (ev_char, POS_FNAME));
int lnum = Int_val (Field (ev_char, POS_LNUM));
int chr = Int_val (Field (ev_char, POS_CNUM))
- Int_val (Field (ev_char, POS_BOL));
fprintf (stderr, "%s file \"%s\", line %d, character %d\n", info, fname,
lnum, chr);
}
}
/* Print a backtrace */
CAMLexport void print_exception_backtrace(void)
{
value events;
int i;
events = read_debug_info();
if (events == Val_false) {
fprintf(stderr,
"(Program not linked with -g, cannot print stack backtrace)\n");
return;
}
for (i = 0; i < backtrace_pos; i++)
print_location(events, i);
}
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