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logging.c
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logging.c
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#define _DEFAULT_SOURCE /* for strdup(), glibc >= 2.20 */
#define _BSD_SOURCE /* for strdup() */
#include <sys/types.h>
#include <errno.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "logging.h"
int loglevel = LOG_NOTICE; /* only print NOTICE, ERROR, CRIT, ... */
static const char *g_progname; /* XXX? maybe share this with root.o */
void initlog(const char *name)
{
openlog(name, LOG_CONS|LOG_PID, LOG_AUTHPRIV);
g_progname = strdup(name);
}
/*
* Return a string in the format "<tag>: <format><suffix>".
*
* Caller must free returned string.
*/
char *makeformat(const char *tag, const char *format, const char *suffix)
{
char *fmt = NULL; size_t fmtmax, fmtlen;
fmtmax = strlen(tag) + strlen(": ") + strlen(format) + strlen(suffix) + 1;
fmt = malloc(fmtmax * sizeof *format);
if (fmt == NULL) {
return NULL;
}
fmtlen = snprintf(fmt, fmtmax, "%s: %s%s", tag, format, suffix);
if (fmtlen >= fmtmax) {
/* Don't call writescreen or writelog, since that's how we got here. */
fprintf(stderr, "root: Unable to make log format\n");
syslog(LOG_CRIT, "root: Unable to make log format");
exit(1);
}
return fmt;
}
void writelog(int priority, const char *format, va_list ap)
{
char *logformat = NULL;
char *escapedusername = NULL;
uid_t ruid;
ruid = getuid();
escapedusername = escape_percents(get_username(ruid));
logformat = makeformat(escapedusername, format, "");
vsyslog(priority, logformat, ap);
free(escapedusername);
free(logformat);
}
void writescreen(int priority, const char *format, va_list ap)
{
char *screenformat = NULL;
char *escapedprogname = NULL;
/* only print messages at loglevel or "lower" priority */
/* with syslog, lowest means most important */
if (priority > loglevel) {
return;
}
escapedprogname = escape_percents(g_progname);
screenformat = makeformat(escapedprogname, format, "\n");
vfprintf(stderr, screenformat, ap);
free(escapedprogname);
free(screenformat);
}
void debug(const char *format, ...)
{
va_list ap;
va_start(ap, format);
writelog(LOG_DEBUG, format, ap);
va_end(ap);
va_start(ap, format);
writescreen(LOG_DEBUG, format, ap);
va_end(ap);
}
void error(const char *format, ...)
{
va_list ap;
va_start(ap, format);
writelog(LOG_ERR, format, ap);
va_end(ap);
va_start(ap, format);
writescreen(LOG_ERR, format, ap);
va_end(ap);
}
/*
* XXX how to escape control characters,
* e.g. what if command name contains backspaces?
*/
void info(const char *format, ...)
{
va_list ap;
va_start(ap, format);
writelog(LOG_INFO, format, ap);
va_end(ap);
va_start(ap, format);
writescreen(LOG_INFO, format, ap);
va_end(ap);
}
/*
* Print the given message on stderr.
*
* Arguments are just log printf.
*
* Note that print does not add an implicit newline.
*/
void print(const char *format, ...)
{
va_list ap;
va_start(ap, format);
vfprintf(stderr, format, ap);
va_end(ap);
}
char *get_username(uid_t uid)
{
struct passwd *ppw = getpwuid(uid);
if (ppw == NULL) {
return "Unknown user";
}
return ppw->pw_name;
}
/* caller must free returned string */
char *escape_percents(const char *string)
{
char *escaped;
size_t length;
size_t spos, epos;
if (string == NULL) {
return NULL;
}
length = strlen(string);
escaped = malloc(length * 2 + 1);
if (escaped == NULL) {
return NULL;
}
for (spos = 0, epos = 0; string[spos] != '\0'; spos++) {
if (string[spos] == '%') {
escaped[epos++] = '%';
escaped[epos++] = '%';
}
else {
escaped[epos++] = string[spos];
}
}
escaped[epos] = '\0';
return escaped;
}
/* vim: set ts=4 sw=4 tw=0 et:*/