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// Copyright (c) Meta Platforms, Inc. and affiliates.
// SPDX-License-Identifier: LGPL-2.1-or-later
#include <errno.h>
#include <getopt.h>
#include <locale.h>
#include <spawn.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include "../drgn.h"
#include "../util.h"
extern char **environ;
static struct drgn_error *run_command(const char *which, const char *command,
struct drgn_program *prog)
{
if (!command)
return NULL;
char pid_arg[max_decimal_length(long)];
sprintf(pid_arg, "%ld", (long)getpid());
char prog_arg[2 * sizeof(prog) + 3];
sprintf(prog_arg, "%p", prog);
const char * const argv[] = {
"sh", "-c", command, "sh", pid_arg, prog_arg, NULL
};
pid_t pid;
int errnum =
posix_spawnp(&pid, "sh", NULL, NULL, (char **)argv, environ);
if (errnum)
return drgn_error_create_os("posix_spawnp", errnum, "sh");
int wstatus;
if (waitpid(pid, &wstatus, 0) < 0)
return drgn_error_create_os("waitpid", errno, NULL);
if (!WIFEXITED(wstatus)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s-exec command exited abnormally: %d",
which, wstatus);
}
if (WEXITSTATUS(wstatus) != 0) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s-exec command exited with status %d",
which, WEXITSTATUS(wstatus));
}
return NULL;
}
static inline struct timespec timespec_sub(struct timespec a, struct timespec b)
{
if (a.tv_nsec < b.tv_nsec) {
return (struct timespec){
.tv_sec = a.tv_sec - 1 - b.tv_sec,
.tv_nsec = a.tv_nsec + 1000000000L - b.tv_nsec,
};
} else {
return (struct timespec){
.tv_sec = a.tv_sec - b.tv_sec,
.tv_nsec = a.tv_nsec - b.tv_nsec,
};
}
}
noreturn static void usage(bool error)
{
fprintf(error ? stderr : stdout,
"usage: load_debug_info [OPTION...] [-k|-c CORE|-p PID] [PATH...]\n"
"\n"
"Example libdrgn program that loads default debug information\n"
"\n"
"Options:\n"
" -k, --kernel debug the running kernel\n"
" -c PATH, --core PATH debug the given core dump\n"
" -p PID, --pid PID debug the running process with the given PID\n"
" -T, --time print how long loading debug info took in seconds\n"
" --pre-exec CMD before loading debug info, execute the given shell\n"
" command with the PID of this process and the address\n"
" of the struct drgn_program in hexadecimal as arguments\n"
" --post-exec CMD after loading debug info, execute the given shell\n"
" command with the same arguments as --pre-exec\n"
" -h, --help display this help message and exit\n");
exit(error ? EXIT_FAILURE : EXIT_SUCCESS);
}
int main(int argc, char **argv)
{
setlocale(LC_ALL, "");
struct option long_options[] = {
{"kernel", no_argument, NULL, 'k'},
{"core", required_argument, NULL, 'c'},
{"pid", required_argument, NULL, 'p'},
{"time", no_argument, NULL, 'T'},
{"pre-exec", required_argument, NULL, 'x'},
{"post-exec", required_argument, NULL, 'X'},
{"help", no_argument, NULL, 'h'},
{},
};
bool kernel = false;
const char *core = NULL;
const char *pid = NULL;
bool print_time = false;
const char *pre_exec = NULL;
const char *post_exec = NULL;
for (;;) {
int c = getopt_long(argc, argv, "kc:p:Th", long_options, NULL);
if (c == -1)
break;
switch (c) {
case 'k':
kernel = true;
break;
case 'c':
core = optarg;
break;
case 'p':
pid = optarg;
break;
case 'T':
print_time = true;
break;
case 'x':
pre_exec = optarg;
break;
case 'X':
post_exec = optarg;
break;
case 'h':
usage(false);
default:
usage(true);
}
}
if (kernel + !!core + !!pid > 1)
usage(true);
struct drgn_program *prog;
struct drgn_error *err = drgn_program_create(NULL, &prog);
if (err) {
prog = NULL;
goto out;
}
if (core)
err = drgn_program_set_core_dump(prog, core);
else if (pid)
err = drgn_program_set_pid(prog, atoi(pid) ?: getpid());
else if (kernel)
err = drgn_program_set_kernel(prog);
if (err)
goto out;
err = run_command("pre", pre_exec, prog);
if (err)
goto out;
struct timespec start, end;
if (print_time && clock_gettime(CLOCK_MONOTONIC, &start))
abort();
err = drgn_program_load_debug_info(prog, (const char **)&argv[optind],
argc - optind, kernel || core || pid,
false);
if ((!err || err->code == DRGN_ERROR_MISSING_DEBUG_INFO)
&& print_time && clock_gettime(CLOCK_MONOTONIC, &end))
abort();
if (err && err->code == DRGN_ERROR_MISSING_DEBUG_INFO) {
drgn_error_fwrite(stderr, err);
drgn_error_destroy(err);
} else if (err) {
goto out;
}
err = run_command("post", post_exec, prog);
if (err)
goto out;
if (print_time) {
struct timespec diff = timespec_sub(end, start);
printf("%lld.%09ld\n", (long long)diff.tv_sec, diff.tv_nsec);
}
out:;
int status = err ? EXIT_FAILURE : EXIT_SUCCESS;
if (err) {
drgn_error_fwrite(stderr, err);
drgn_error_destroy(err);
}
drgn_program_destroy(prog);
return status;
}
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