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/*
* syslog.c
*
* Issue syslog messages via the kernel printk queue.
*/
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <syslog.h>
#include <unistd.h>
#include <fcntl.h>
/* Maximum size for a kernel message */
#define BUFLEN 1024
/* Logging node */
#define LOGDEV "/dev/kmsg"
/* Max length of ID string */
#define MAXID 31 /* MAXID+5 must be < BUFLEN */
int __syslog_fd = -1;
static char id[MAXID + 1];
static int syslog_flags = 0;
void openlog(const char *ident, int option, int facility)
{
int fd;
(void)option;
(void)facility; /* Unused */
if (__syslog_fd == -1) {
__syslog_fd = fd = open(LOGDEV, O_WRONLY);
if (fd == -1)
return;
fcntl(fd, F_SETFD, (long)FD_CLOEXEC);
}
syslog_flags = option;
strncpy(id, ident ? ident : "", MAXID);
}
void vsyslog(int prio, const char *format, va_list ap)
{
char buf[BUFLEN];
int len;
int fd;
if (__syslog_fd == -1)
openlog(NULL, 0, 0);
buf[0] = '<';
buf[1] = LOG_PRI(prio) + '0';
buf[2] = '>';
len = 3;
if (syslog_flags & LOG_PID)
len += sprintf(buf + 3, "%s[%u]: ", id, getpid());
else if (*id)
len += sprintf(buf + 3, "%s: ", id);
len += vsnprintf(buf + len, BUFLEN - len, format, ap);
if (len > BUFLEN - 1)
len = BUFLEN - 1;
if (buf[len - 1] != '\n')
buf[len++] = '\n';
fd = __syslog_fd;
if (fd == -1)
fd = 2; /* Failed to open log, write to stderr */
write(fd, buf, len);
if (syslog_flags & LOG_PERROR)
_fwrite(buf + 3, len - 3, stderr);
}
void syslog(int prio, const char *format, ...)
{
va_list ap;
va_start(ap, format);
vsyslog(prio, format, ap);
va_end(ap);
}
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