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function old new delta overlapping_strcpy 15 18 +3 klogd_main 438 436 -2 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
229 lines
5.2 KiB
C
229 lines
5.2 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini klogd implementation for busybox
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*
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* Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>.
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* Changes: Made this a standalone busybox module which uses standalone
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* syslog() client interface.
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*
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* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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*
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* Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
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*
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* "circular buffer" Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com>
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*
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* Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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#include <syslog.h>
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/* The Linux-specific klogctl(3) interface does not rely on the filesystem and
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* allows us to change the console loglevel. Alternatively, we read the
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* messages from _PATH_KLOG. */
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#if ENABLE_FEATURE_KLOGD_KLOGCTL
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# include <sys/klog.h>
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static void klogd_open(void)
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{
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/* "Open the log. Currently a NOP" */
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klogctl(1, NULL, 0);
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}
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static void klogd_setloglevel(int lvl)
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{
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/* "printk() prints a message on the console only if it has a loglevel
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* less than console_loglevel". Here we set console_loglevel = lvl. */
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klogctl(8, NULL, lvl);
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}
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static int klogd_read(char *bufp, int len)
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{
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return klogctl(2, bufp, len);
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}
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# define READ_ERROR "klogctl(2) error"
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static void klogd_close(void)
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{
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/* FYI: cmd 7 is equivalent to setting console_loglevel to 7
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* via klogctl(8, NULL, 7). */
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klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */
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klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */
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}
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#else
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# include <paths.h>
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# ifndef _PATH_KLOG
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# ifdef __GNU__
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# define _PATH_KLOG "/dev/klog"
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# else
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# error "your system's _PATH_KLOG is unknown"
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# endif
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# endif
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# define PATH_PRINTK "/proc/sys/kernel/printk"
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enum { klogfd = 3 };
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static void klogd_open(void)
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{
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int fd = xopen(_PATH_KLOG, O_RDONLY);
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xmove_fd(fd, klogfd);
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}
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static void klogd_setloglevel(int lvl)
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{
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FILE *fp = fopen_or_warn(PATH_PRINTK, "w");
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if (fp) {
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/* This changes only first value:
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* "messages with a higher priority than this
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* [that is, with numerically lower value]
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* will be printed to the console".
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* The other three values in this pseudo-file aren't changed.
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*/
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fprintf(fp, "%u\n", lvl);
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fclose(fp);
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}
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}
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static int klogd_read(char *bufp, int len)
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{
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return read(klogfd, bufp, len);
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}
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# define READ_ERROR "read error"
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static void klogd_close(void)
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{
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klogd_setloglevel(7);
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if (ENABLE_FEATURE_CLEAN_UP)
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close(klogfd);
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}
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#endif
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#define log_buffer bb_common_bufsiz1
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enum {
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KLOGD_LOGBUF_SIZE = sizeof(log_buffer),
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OPT_LEVEL = (1 << 0),
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OPT_FOREGROUND = (1 << 1),
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};
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/* TODO: glibc openlog(LOG_KERN) reverts to LOG_USER instead,
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* because that's how they interpret word "default"
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* in the openlog() manpage:
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* LOG_USER (default)
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* generic user-level messages
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* and the fact that LOG_KERN is a constant 0.
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* glibc interprets it as "0 in openlog() call means 'use default'".
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* I think it means "if openlog wasn't called before syslog() is called,
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* use default".
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* Convincing glibc maintainers otherwise is, as usual, nearly impossible.
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* Should we open-code syslog() here to use correct facility?
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*/
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int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int klogd_main(int argc UNUSED_PARAM, char **argv)
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{
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int i = 0;
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char *opt_c;
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int opt;
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int used;
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opt = getopt32(argv, "c:n", &opt_c);
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if (opt & OPT_LEVEL) {
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/* Valid levels are between 1 and 8 */
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i = xatou_range(opt_c, 1, 8);
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}
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if (!(opt & OPT_FOREGROUND)) {
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bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
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}
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logmode = LOGMODE_SYSLOG;
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/* klogd_open() before openlog(), since it might use fixed fd 3,
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* and openlog() also may use the same fd 3 if we swap them:
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*/
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klogd_open();
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openlog("kernel", 0, LOG_KERN);
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if (i)
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klogd_setloglevel(i);
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bb_signals(BB_FATAL_SIGS, record_signo);
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signal(SIGHUP, SIG_IGN);
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syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
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used = 0;
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while (!bb_got_signal) {
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int n;
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int priority;
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char *start;
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/* "2 -- Read from the log." */
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start = log_buffer + used;
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n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used);
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if (n < 0) {
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if (errno == EINTR)
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continue;
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bb_perror_msg(READ_ERROR);
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break;
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}
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start[n] = '\0';
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/* Process each newline-terminated line in the buffer */
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start = log_buffer;
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while (1) {
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char *newline = strchrnul(start, '\n');
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if (*newline == '\0') {
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/* This line is incomplete */
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/* move it to the front of the buffer */
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overlapping_strcpy(log_buffer, start);
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used = newline - start;
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if (used < KLOGD_LOGBUF_SIZE-1) {
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/* buffer isn't full */
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break;
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}
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/* buffer is full, log it anyway */
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used = 0;
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newline = NULL;
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} else {
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*newline++ = '\0';
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}
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/* Extract the priority */
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priority = LOG_INFO;
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if (*start == '<') {
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start++;
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if (*start) {
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/* kernel never generates multi-digit prios */
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priority = (*start - '0');
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start++;
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}
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if (*start == '>')
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start++;
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}
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/* Log (only non-empty lines) */
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if (*start)
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syslog(priority, "%s", start);
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if (!newline)
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break;
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start = newline;
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}
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}
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klogd_close();
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syslog(LOG_NOTICE, "klogd: exiting");
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if (bb_got_signal)
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kill_myself_with_sig(bb_got_signal);
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return EXIT_FAILURE;
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}
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