X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=sysklogd%2Fklogd.c;h=27995e57028f09733dbad1d1a0e2c56cbeb7bb26;hb=aeab42e3f4802d67fd5fe03feb0fd4a18903326f;hp=5beec14dbeac05fd42cff1b72f3e3249f24a2765;hpb=b6adbf1be29841501cc49917249e85f273e1df7c;p=oweals%2Fbusybox.git diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c index 5beec14db..27995e570 100644 --- a/sysklogd/klogd.c +++ b/sysklogd/klogd.c @@ -4,7 +4,7 @@ * * Copyright (C) 2001 by Gennady Feldman . * Changes: Made this a standalone busybox module which uses standalone - * syslog() client interface. + * syslog() client interface. * * Copyright (C) 1999-2004 by Erik Andersen * @@ -14,106 +14,252 @@ * * Maintainer: Gennady Feldman as of Mar 12, 2001 * - * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. + * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ +//usage:#define klogd_trivial_usage +//usage: "[-c N] [-n]" +//usage:#define klogd_full_usage "\n\n" +//usage: "Kernel logger\n" +//usage: "\nOptions:" +//usage: "\n -c N Print to console messages more urgent than prio N (1-8)" +//usage: "\n -n Run in foreground" + #include "libbb.h" -#include -#include +#include + + +/* The Linux-specific klogctl(3) interface does not rely on the filesystem and + * allows us to change the console loglevel. Alternatively, we read the + * messages from _PATH_KLOG. */ -static void klogd_signal(int sig ATTRIBUTE_UNUSED) +#if ENABLE_FEATURE_KLOGD_KLOGCTL + +# include + +static void klogd_open(void) { - klogctl(7, NULL, 0); - klogctl(0, 0, 0); - syslog(LOG_NOTICE, "Kernel log daemon exiting"); - exit(EXIT_SUCCESS); + /* "Open the log. Currently a NOP" */ + klogctl(1, NULL, 0); } -#define OPT_LEVEL 1 -#define OPT_FOREGROUND 2 +static void klogd_setloglevel(int lvl) +{ + /* "printk() prints a message on the console only if it has a loglevel + * less than console_loglevel". Here we set console_loglevel = lvl. */ + klogctl(8, NULL, lvl); +} -#define KLOGD_LOGBUF_SIZE BUFSIZ -#define log_buffer bb_common_bufsiz1 +static int klogd_read(char *bufp, int len) +{ + return klogctl(2, bufp, len); +} +# define READ_ERROR "klogctl(2) error" -int klogd_main(int argc, char **argv); -int klogd_main(int argc, char **argv) +static void klogd_close(void) { - int i = i; /* silence gcc */ - char *start; + /* FYI: cmd 7 is equivalent to setting console_loglevel to 7 + * via klogctl(8, NULL, 7). */ + klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */ + klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */ +} - /* do normal option parsing */ - getopt32(argc, argv, "c:n", &start); +#else - if (option_mask32 & OPT_LEVEL) { - /* Valid levels are between 1 and 8 */ - i = xatoul_range(start, 1, 8); +# include +# ifndef _PATH_KLOG +# ifdef __GNU__ +# define _PATH_KLOG "/dev/klog" +# else +# error "your system's _PATH_KLOG is unknown" +# endif +# endif +# define PATH_PRINTK "/proc/sys/kernel/printk" + +enum { klogfd = 3 }; + +static void klogd_open(void) +{ + int fd = xopen(_PATH_KLOG, O_RDONLY); + xmove_fd(fd, klogfd); +} + +static void klogd_setloglevel(int lvl) +{ + FILE *fp = fopen_or_warn(PATH_PRINTK, "w"); + if (fp) { + /* This changes only first value: + * "messages with a higher priority than this + * [that is, with numerically lower value] + * will be printed to the console". + * The other three values in this pseudo-file aren't changed. + */ + fprintf(fp, "%u\n", lvl); + fclose(fp); } +} + +static int klogd_read(char *bufp, int len) +{ + return read(klogfd, bufp, len); +} +# define READ_ERROR "read error" - if (!(option_mask32 & OPT_FOREGROUND)) { +static void klogd_close(void) +{ + klogd_setloglevel(7); + if (ENABLE_FEATURE_CLEAN_UP) + close(klogfd); +} + +#endif + +#define log_buffer bb_common_bufsiz1 +enum { + KLOGD_LOGBUF_SIZE = sizeof(log_buffer), + OPT_LEVEL = (1 << 0), + OPT_FOREGROUND = (1 << 1), +}; + +/* TODO: glibc openlog(LOG_KERN) reverts to LOG_USER instead, + * because that's how they interpret word "default" + * in the openlog() manpage: + * LOG_USER (default) + * generic user-level messages + * and the fact that LOG_KERN is a constant 0. + * glibc interprets it as "0 in openlog() call means 'use default'". + * I think it means "if openlog wasn't called before syslog() is called, + * use default". + * Convincing glibc maintainers otherwise is, as usual, nearly impossible. + * Should we open-code syslog() here to use correct facility? + */ + +int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int klogd_main(int argc UNUSED_PARAM, char **argv) +{ + int i = 0; + char *opt_c; + int opt; + int used; + + opt = getopt32(argv, "c:n", &opt_c); + if (opt & OPT_LEVEL) { + /* Valid levels are between 1 and 8 */ + i = xatou_range(opt_c, 1, 8); + } + if (!(opt & OPT_FOREGROUND)) { bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv); } - openlog("kernel", 0, LOG_KERN); + logmode = LOGMODE_SYSLOG; - /* Set up sig handlers */ - signal(SIGINT, klogd_signal); - signal(SIGKILL, klogd_signal); - signal(SIGTERM, klogd_signal); - signal(SIGHUP, SIG_IGN); + /* klogd_open() before openlog(), since it might use fixed fd 3, + * and openlog() also may use the same fd 3 if we swap them: + */ + klogd_open(); + openlog("kernel", 0, LOG_KERN); + /* + * glibc problem: for some reason, glibc changes LOG_KERN to LOG_USER + * above. The logic behind this is that standard + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html + * says the following about openlog and syslog: + * "LOG_USER + * Messages generated by arbitrary processes. + * This is the default facility identifier if none is specified." + * + * I believe glibc misinterpreted this text as "if openlog's + * third parameter is 0 (=LOG_KERN), treat it as LOG_USER". + * Whereas it was meant to say "if *syslog* is called with facility + * 0 in its 1st parameter without prior call to openlog, then perform + * implicit openlog(LOG_USER)". + * + * As a result of this, eh, feature, standard klogd was forced + * to open-code its own openlog and syslog implementation (!). + * + * Note that prohibiting openlog(LOG_KERN) on libc level does not + * add any security: any process can open a socket to "/dev/log" + * and write a string "<0>Voila, a LOG_KERN + LOG_EMERG message" + * + * Google code search tells me there is no widespread use of + * openlog("foo", 0, 0), thus fixing glibc won't break userspace. + * + * The bug against glibc was filed: + * bugzilla.redhat.com/show_bug.cgi?id=547000 + */ - /* "Open the log. Currently a NOP." */ - klogctl(1, NULL, 0); + if (i) + klogd_setloglevel(i); - /* Set level of kernel console messaging. */ - if (option_mask32 & OPT_LEVEL) - klogctl(8, NULL, i); + signal(SIGHUP, SIG_IGN); + /* We want klogd_read to not be restarted, thus _norestart: */ + bb_signals_recursive_norestart(BB_FATAL_SIGS, record_signo); - syslog(LOG_NOTICE, "klogd started: %s", BB_BANNER); + syslog(LOG_NOTICE, "klogd started: %s", bb_banner); - /* Note: this code does not detect incomplete messages - * (messages not ending with '\n' or just when kernel - * generates too many messages for us to keep up) - * and will split them in two separate lines */ - while (1) { + used = 0; + while (!bb_got_signal) { int n; int priority; + char *start; - n = klogctl(2, log_buffer, KLOGD_LOGBUF_SIZE - 1); + /* "2 -- Read from the log." */ + start = log_buffer + used; + n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used); if (n < 0) { if (errno == EINTR) continue; - syslog(LOG_ERR, "klogd: error from klogctl(2): %d - %m", - errno); + bb_perror_msg(READ_ERROR); break; } - log_buffer[n] = '\n'; - i = 0; - while (i < n) { + start[n] = '\0'; + + /* Process each newline-terminated line in the buffer */ + start = log_buffer; + while (1) { + char *newline = strchrnul(start, '\n'); + + if (*newline == '\0') { + /* This line is incomplete */ + + /* move it to the front of the buffer */ + overlapping_strcpy(log_buffer, start); + used = newline - start; + if (used < KLOGD_LOGBUF_SIZE-1) { + /* buffer isn't full */ + break; + } + /* buffer is full, log it anyway */ + used = 0; + newline = NULL; + } else { + *newline++ = '\0'; + } + + /* Extract the priority */ priority = LOG_INFO; - start = &log_buffer[i]; - if (log_buffer[i] == '<') { - i++; - // kernel never ganerates multi-digit prios - //priority = 0; - //while (log_buffer[i] >= '0' && log_buffer[i] <= '9') { - // priority = priority * 10 + (log_buffer[i] - '0'); - // i++; - //} - if (isdigit(log_buffer[i])) { - priority = (log_buffer[i] - '0'); - i++; + if (*start == '<') { + start++; + if (*start) { + /* kernel never generates multi-digit prios */ + priority = (*start - '0'); + start++; } - if (log_buffer[i] == '>') - i++; - start = &log_buffer[i]; + if (*start == '>') + start++; } - while (log_buffer[i] != '\n') - i++; - log_buffer[i] = '\0'; - syslog(priority, "%s", start); - i++; + /* Log (only non-empty lines) */ + if (*start) + syslog(priority, "%s", start); + + if (!newline) + break; + start = newline; } } + klogd_close(); + syslog(LOG_NOTICE, "klogd: exiting"); + if (bb_got_signal) + kill_myself_with_sig(bb_got_signal); return EXIT_FAILURE; }