The klogctl() interface allows changing the console loglevel, but is Linux-specific. The more portable method of reading from _PATH_KLOG is added as an alternative.
Adapted from the Debian kFreeBSD patch at: http://svn.debian.org/viewsvn/d-i/people/slackydeb/kfreebsd/busybox/1.14/debian/klogd.diff Signed-off-by: Jeremie Koenig <[email protected]> --- sysklogd/Config.src | 17 ++++++++- sysklogd/klogd.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 104 insertions(+), 9 deletions(-) diff --git a/sysklogd/Config.src b/sysklogd/Config.src index 41c0d28..1e59872 100644 --- a/sysklogd/Config.src +++ b/sysklogd/Config.src @@ -109,7 +109,6 @@ config FEATURE_LOGREAD_REDUCED_LOCKING config KLOGD bool "klogd" default y - depends on PLATFORM_LINUX help klogd is a utility which intercepts and logs all messages from the Linux kernel and sends the messages @@ -117,6 +116,22 @@ config KLOGD you wish to record the messages produced by the kernel, you should enable this option. +config FEATURE_KLOGD_KLOGCTL + bool "Use the klogctl() interface" + default y + depends on KLOGD && PLATFORM_LINUX + help + The klogd applet supports two interfaces for reading + kernel messages. Linux provides the klogctl() interface + which allows reading messages from the kernel ring buffer + independently from the file system. + + If you answer 'N' here, klogd will use the more portable + approach of reading them from /proc or a device node. + However, this method requires the file to be available. + + If in doubt, say 'Y'. + config LOGGER bool "logger" default y diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c index c54e80a..6811aa3 100644 --- a/sysklogd/klogd.c +++ b/sysklogd/klogd.c @@ -19,14 +19,97 @@ #include "libbb.h" #include <syslog.h> -#include <sys/klog.h> -static void klogd_signal(int sig) + +/* 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. */ + +#if ENABLE_FEATURE_KLOGD_KLOGCTL +# include <sys/klog.h> + +static void klogd_open(void) +{ + /* "Open the log. Currently a NOP" */ + klogctl(1, NULL, 0); +} + +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); +} + +static int klogd_read(char *bufp, int len) +{ + return klogctl(2, bufp, len); +} + +static void klogd_close(void) { /* 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" */ +} + +#else +# include <paths.h> +# 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 = 4 }; + +static void klogd_open(void) +{ + int fd; + + fd = open(_PATH_KLOG, O_RDONLY, 0); + if (fd < 0) { + logmode = LOGMODE_SYSLOG; + bb_perror_msg_and_die("klogd: can't open %s", _PATH_KLOG); + } + xmove_fd(fd, klogfd); +} + +static void klogd_setloglevel(int lvl UNUSED_PARAM) +{ + FILE *f; + + f = fopen("/proc/sys/kernel/printk", "w"); + if (f != NULL) { + fprintf(f, "%d", lvl); + fclose(f); + } else { + syslog(LOG_WARNING, "klogd warning: could not change the" + " console loglevel (%s: %m)", PATH_PRINTK); + } +} + +static int klogd_read(char *bufp, int len) +{ + return read(klogfd, bufp, len); +} + +static void klogd_close(void) +{ + klogd_setloglevel(7); + close(klogfd); +} + +#endif + + +static void klogd_signal(int sig) +{ + klogd_close(); syslog(LOG_NOTICE, "klogd: exiting"); kill_myself_with_sig(sig); } @@ -60,13 +143,10 @@ int klogd_main(int argc UNUSED_PARAM, char **argv) bb_signals(BB_FATAL_SIGS, klogd_signal); signal(SIGHUP, SIG_IGN); - /* "Open the log. Currently a NOP" */ - klogctl(1, NULL, 0); + klogd_open(); - /* "printk() prints a message on the console only if it has a loglevel - * less than console_loglevel". Here we set console_loglevel = i. */ if (i) - klogctl(8, NULL, i); + klogd_setloglevel(i); syslog(LOG_NOTICE, "klogd started: %s", bb_banner); @@ -77,7 +157,7 @@ int klogd_main(int argc UNUSED_PARAM, char **argv) /* "2 -- Read from the log." */ start = log_buffer + used; - n = klogctl(2, start, KLOGD_LOGBUF_SIZE-1 - used); + n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used); if (n < 0) { if (errno == EINTR) continue; -- 1.7.1 _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
