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tracegdb.c
304 lines (295 loc) · 7.7 KB
/
tracegdb.c
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#include "carppriv.h"
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
typedef struct {
void *from;
void *to;
int readsyms;
int dbinfo;
char *name;
} SharedLib;
static void
shared_lib_free (SharedLib *lib) {
if (!lib)
return;
free(lib->name);
free(lib);
}
/* Looks through the list of libs and finds if the given address is between the
from and to addresses of the contained libraries. */
static char *
get_lib_name (List *libs, void *addr) {
List *item;
for (item = libs; item; item = item->next) {
SharedLib *lib = item->data;
if (lib->from <= addr && addr <= lib->to)
return strdup(lib->name);
}
return NULL;
}
/* Parses gdb's stdout fd after requesting a backtrace. The result is stored
in a linked list of FuncInfo structures. */
static List *
parse_stack_trace (int gdb) {
int i;
int parentheses_are_off = 0;
char c;
char buf[4096];
List *stack = NULL;
FuncInfo *f;
List *libs = NULL;
SharedLib *lib;
enum {
NONE,
ADDR,
FUNC,
ARGS,
FILE,
LINE,
LIB,
QUOTE,
FROMADDR,
TOADDR,
SYMS,
SONAME
} state = NONE, prev_state = NONE;
while (read(gdb, &c, 1)) {
switch (state) {
case NONE:
if (c == '#') {
f = calloc(sizeof (FuncInfo), 1);
while (read(gdb, &c, 1))
if (!isdigit(c))
break;
while (read(gdb, &c, 1))
if (!isspace(c)) {
buf[0] = c;
i = 1;
state = isdigit(c) ? ADDR : FUNC;
break;
}
}
else if (!stack && c == '0') {
lib = calloc(sizeof (SharedLib), 1);
state = FROMADDR;
buf[0] = c;
i = 1;
}
else if (stack && c == '(') {
read(gdb, buf, 3);
if (!strncmp(buf, "gdb", 3))
goto done;
}
else if (!stack && c == 'N') {
read(gdb, buf, 7);
if (!strncmp(buf, "o stack", 7))
goto done;
}
break;
case FROMADDR:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
sscanf(buf, "%p", &lib->from);
read(gdb, buf, 1);
state = TOADDR;
}
break;
case TOADDR:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
sscanf(buf, "%p", &lib->to);
read(gdb, buf, 1);
state = SYMS;
}
break;
case SYMS:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
if (eq(buf, "Yes"))
lib->readsyms = 1;
read(gdb, buf, 3);
if (strncmp(buf, "(*)", 3))
lib->dbinfo = 1;
while (read(gdb, &c, 1))
if (!isspace(c)) {
buf[0] = c;
i = 1;
break;
}
state = SONAME;
}
break;
case SONAME:
if (c != '\n') {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
lib->name = strdup(buf);
libs = list_push(libs, lib);
state = NONE;
}
break;
case ADDR:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
sscanf(buf, "%p", &f->addr);
f->lib = get_lib_name(libs, f->addr);
read(gdb, buf, 3);
state = FUNC;
}
break;
case FUNC:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
f->func = strdup(buf);
state = ARGS;
}
break;
case ARGS:
buf[i++] = c;
if (c == '(')
parentheses_are_off++;
else if (c == ')') {
parentheses_are_off--;
if (parentheses_are_off)
continue;
buf[i] = 0;
i = 0;
f->args = strdup(buf);
read(gdb, &c, 1);
if (c == '\n') {
stack = list_push(stack, f);
state = NONE;
break;
}
read(gdb, buf, 3);
if (!strncmp(buf, "at ", 3)) {
state = FILE;
}
else if (!strncmp(buf, "fro", 3)) {
state = LIB;
read(gdb, buf, 2);
}
else {
free(f);
state = NONE;
}
}
else if (c == '"') {
prev_state = ARGS;
state = QUOTE;
}
break;
case QUOTE:
buf[i++] = c;
if (c == '\\') {
read(gdb, &c, 1);
buf[i++] = c;
}
else if (c == '"')
state = prev_state;
break;
case LIB:
if (!isspace(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
if (!f->lib)
f->lib = strdup(buf);
stack = list_push(stack, f);
state = NONE;
}
break;
case FILE:
if (c != ':') {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
f->file = strdup(buf);
state = LINE;
}
break;
case LINE:
if (isdigit(c)) {
buf[i++] = c;
}
else {
buf[i] = 0;
i = 0;
f->line = atoi(buf);
stack = list_push(stack, f);
state = NONE;
}
break;
}
}
done:
list_free(libs, shared_lib_free);
return stack;
}
/* Spawns a gdb process and returns a linked list of the backtrace */
List *
get_stack_trace () {
int in_fd[2], out_fd[2], status;
pid_t pid;
List *stack;
if (pipe(in_fd) == -1 || pipe(out_fd) == -1) {
perror("pipe()");
return NULL;
}
write(in_fd[1], "info sharedlibrary\n", 19);
write(in_fd[1], "backtrace\n", 10);
write(in_fd[1], "quit\n", 5);
pid = fork();
if (pid == -1) {
perror("fork()");
return NULL;
}
else if (pid == 0) {
char pidstr[16];
dup2(in_fd[0], 0);
dup2(out_fd[1], 1);
dup2(out_fd[1], 2);
snprintf(pidstr, sizeof pidstr, "%d", getppid());
execlp("gdb", "gdb", "--nx", "--pid", pidstr, NULL);
perror("execlp()");
exit(0);
}
stack = parse_stack_trace(out_fd[0]);
close(in_fd[0]);
close(in_fd[1]);
close(out_fd[0]);
close(out_fd[1]);
waitpid(pid, &status, 0);
return stack;
}