-/*
- * Copyright (C) 1997-2014 Andre Noll <maan@systemlinux.org>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file daemon.c Some helpers for programs that detach from the console. */
#include <sys/types.h> /* getgrnam() */
#include <grp.h>
#include <signal.h>
+#include <sys/resource.h>
#include "para.h"
#include "daemon.h"
char *hostname;
/** Used for colored log messages. */
char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
+ char *old_cwd;
+ /*
+ * If these pointers are non-NULL, the functions are called from
+ * daemon_log() before and after writing each log message.
+ */
+ void (*pre_log_hook)(void);
+ void (*post_log_hook)(void);
};
static struct daemon the_daemon, *me = &the_daemon;
-/**
- * Activate default log colors.
- *
- * This should be called early if color support is wanted.
- */
-void daemon_set_default_log_colors(void)
+static void daemon_set_default_log_colors(void)
{
int i;
static const char *default_log_colors[NUM_LOGLEVELS] = {
/**
* Set the color for one loglevel.
*
- * \param arg The loglevel/color specifier.
- *
- * \a arg must be of the form "ll:[fg [bg]] [attr]".
+ * \param arg Must be of the form "ll:[fg [bg]] [attr]".
*/
-void daemon_set_log_color_or_die(char const *arg)
+void daemon_set_log_color_or_die(const char *arg)
{
char *p = strchr(arg, ':');
int ret, ll;
color_parse_or_die(p, me->log_colors[ll]);
return;
err:
- PARA_EMERG_LOG("%s: color syntax error\n", arg);
+ PARA_EMERG_LOG("%s: invalid color argument\n", arg);
exit(EXIT_FAILURE);
}
+/**
+ * Initialize color mode if necessary.
+ *
+ * \param color_arg The argument given to --color.
+ * \param color_arg_auto The value for automatic color detection.
+ * \param color_arg_no The value to disable colored log messages.
+ * \param logfile_given In auto mode colors are disabled if this value is true.
+ *
+ * If color_arg equals color_arg_no, color mode is disabled. That is, calls to
+ * para_log() will not produce colored output. If color_arg equals
+ * color_arg_auto, the function detects automatically whether to activate
+ * colors. Otherwise color mode is enabled.
+ *
+ * If color mode is to be enabled, the default colors are set for each
+ * loglevel. They can be overwritten by calling daemon_set_log_color_or_die().
+ *
+ * \return Whether colors have been enabled by the function.
+ */
+bool daemon_init_colors_or_die(int color_arg, int color_arg_auto,
+ int color_arg_no, bool logfile_given)
+{
+ if (color_arg == color_arg_no)
+ return false;
+ if (color_arg == color_arg_auto) {
+ if (logfile_given)
+ return false;
+ if (!isatty(STDERR_FILENO))
+ return false;
+ }
+ daemon_set_flag(DF_COLOR_LOG);
+ daemon_set_default_log_colors();
+ return true;
+}
+
/**
* Init or change the name of the log file.
*
* \param logfile_name The full path of the logfile.
*/
-void daemon_set_logfile(char *logfile_name)
+void daemon_set_logfile(const char *logfile_name)
{
free(me->logfile_name);
me->logfile_name = NULL;
- if (logfile_name)
+ if (!logfile_name)
+ return;
+ if (me->old_cwd && logfile_name[0] != '/')
+ me->logfile_name = make_message("%s/%s", me->old_cwd,
+ logfile_name);
+ else
me->logfile_name = para_strdup(logfile_name);
}
*
* \param loglevel The smallest level that should be logged.
*/
-void daemon_set_loglevel(char *loglevel)
+void daemon_set_loglevel(const char *loglevel)
{
int ret = get_loglevel_by_name(loglevel);
}
/**
- * Set one of the daemon config flags.
+ * Register functions to be called before and after a message is logged.
*
- * \param flag The flag to set.
+ * \param pre_log_hook Called before the message is logged.
+ * \param post_log_hook Called after the message is logged.
*
- * \sa \ref daemon_flags.
+ * The purpose of this function is to provide a primitive for multi-threaded
+ * applications to serialize the access to the log facility, preventing
+ * interleaving log messages. This can be achieved by having the pre-log hook
+ * acquire a lock which blocks the other threads on the attempt to log a
+ * message at the same time. The post-log hook is responsible for releasing
+ * the lock.
+ *
+ * If these hooks are unnecessary, for example because the application is
+ * single-threaded, this function does not need to be called.
*/
-void daemon_set_flag(unsigned flag)
+void daemon_set_hooks(void (*pre_log_hook)(void), void (*post_log_hook)(void))
{
- me->flags |= flag;
+ me->pre_log_hook = pre_log_hook;
+ me->post_log_hook = post_log_hook;
}
/**
- * Clear one of the daemon config flags.
+ * Set one of the daemon config flags.
*
- * \param flag The flag to clear.
+ * \param flag The flag to set.
*
* \sa \ref daemon_flags.
*/
-void daemon_clear_flag(unsigned flag)
+void daemon_set_flag(unsigned flag)
{
- me->flags &= ~flag;
+ me->flags |= flag;
}
static bool daemon_test_flag(unsigned flag)
return me->flags & flag;
}
-static void dummy_sighandler(__a_unused int s)
-{
-}
-
/**
* Do the usual stuff to become a daemon.
*
*
* Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
* parent_waits is false, the parent process terminates immediately.
- * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
- * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
- * daemon process should not detach from the console until the child process
- * has completed its setup.
+ * Otherwise, a pipe is created prior to the fork() and the parent tries to
+ * read a single byte from the reading end of the pipe. The child is supposed
+ * to write to the writing end of the pipe after it completed its setup
+ * procedure successfully. This behaviour is useful to let the parent process
+ * die with an error if the child process aborts early, since in this case the
+ * read() will return non-positive.
+ *
+ * \return This function either succeeds or calls exit(3). If parent_waits is
+ * true, the return value is the file descriptor of the writing end of the
+ * pipe. Otherwise the function returns zero.
*
* \sa fork(2), setsid(2), dup(2), pause(2).
*/
-void daemonize(bool parent_waits)
+int daemonize(bool parent_waits)
{
pid_t pid;
- int null;
+ int null, pipe_fd[2];
- PARA_INFO_LOG("daemonizing\n");
+ if (parent_waits && pipe(pipe_fd) < 0)
+ goto err;
+ PARA_INFO_LOG("subsequent log messages go to %s\n", me->logfile_name?
+ me->logfile_name : "/dev/null");
pid = fork();
if (pid < 0)
goto err;
- if (pid) {
+ if (pid) { /* parent exits */
if (parent_waits) {
- signal(SIGTERM, dummy_sighandler);
- signal(SIGCHLD, dummy_sighandler);
- pause();
+ char c;
+ close(pipe_fd[1]);
+ exit(read(pipe_fd[0], &c, 1) <= 0?
+ EXIT_FAILURE : EXIT_SUCCESS);
}
- exit(EXIT_SUCCESS); /* parent exits */
+ exit(EXIT_SUCCESS);
}
+ if (parent_waits)
+ close(pipe_fd[0]);
/* become session leader */
if (setsid() < 0)
goto err;
+ me->old_cwd = getcwd(NULL, 0);
if (chdir("/") < 0)
goto err;
- null = open("/dev/null", O_RDONLY);
+ null = open("/dev/null", O_RDWR);
if (null < 0)
goto err;
if (dup2(null, STDIN_FILENO) < 0)
if (dup2(null, STDERR_FILENO) < 0)
goto err;
close(null);
- return;
+ return parent_waits? pipe_fd[1] : 0;
err:
PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
exit(EXIT_FAILURE);
*/
void daemon_open_log_or_die(void)
{
- daemon_close_log();
+ FILE *new_log;
+
if (!me->logfile_name)
return;
- me->logfile = fopen(me->logfile_name, "a");
- if (!me->logfile) {
+ new_log = fopen(me->logfile_name, "a");
+ if (!new_log) {
PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
strerror(errno));
exit(EXIT_FAILURE);
}
- setlinebuf(me->logfile);
+ daemon_close_log();
+ me->logfile = new_log;
+ /* equivalent to setlinebuf(), but portable */
+ setvbuf(me->logfile, NULL, _IOLBF, 0);
}
/**
* Log the startup message containing the paraslash version.
+ *
+ * \param name The name of the executable.
+ *
+ * First the given \a name is prefixed with the string "para_". Next the git
+ * version is appended. The resulting string is logged with priority "INFO".
+ */
+void daemon_log_welcome(const char *name)
+{
+ PARA_INFO_LOG("welcome to para_%s-" PACKAGE_VERSION " \n", name);
+}
+
+/**
+ * Renice the calling process.
+ *
+ * \param prio The priority value to set.
+ *
+ * Errors are not considered fatal, but a warning message is logged if the
+ * underlying call to setpriority(2) fails.
*/
-void log_welcome(const char *whoami)
+void daemon_set_priority(int prio)
{
- PARA_INFO_LOG("welcome to %s " PACKAGE_VERSION " ("BUILD_DATE")\n",
- whoami);
+ if (setpriority(PRIO_PROCESS, 0, prio) < 0)
+ PARA_WARNING_LOG("could not set priority to %d: %s\n", prio,
+ strerror(errno));
}
/**
*
* \sa getpwnam(3), getuid(2), setuid(2), getgrnam(2), setgid(2)
*/
-void drop_privileges_or_die(const char *username, const char *groupname)
+void daemon_drop_privileges_or_die(const char *username, const char *groupname)
{
struct passwd *p;
char *tmp;
}
/**
- * Set the server startup time.
+ * Set the startup time.
*
- * \param startuptime The value to store as the server start time.
+ * This should be called once on startup. It sets the start time to the
+ * current time. The stored time is used for retrieving the server uptime.
*
- * This should be called once on startup with \a startuptime either NULL or a
- * pointer to a struct timeval which contains the current time. If \a
- * startuptime is NULL, the server start time is set to the current time.
- *
- * \sa time(2), difftime(3) \ref get_server_uptime(), \ref
- * get_server_uptime_str().
+ * \sa time(2), \ref daemon_get_uptime(), \ref daemon_get_uptime_str().
*/
-void set_server_start_time(const struct timeval *startuptime)
+void daemon_set_start_time(void)
{
- if (startuptime)
- me->startuptime = startuptime->tv_sec;
- else
- time(&me->startuptime);
+ time(&me->startuptime);
}
/**
- * Get the server uptime.
+ * Get the uptime.
*
* \param current_time The current time.
*
*
* \return This returns the server uptime in seconds, i.e. the difference
* between the current time and the value stored previously via \ref
- * set_server_start_time().
+ * daemon_set_start_time().
*/
-time_t get_server_uptime(const struct timeval *current_time)
+time_t daemon_get_uptime(const struct timeval *current_time)
{
time_t t;
/**
* Construct a string containing the current uptime.
*
- * \param current_time See a \ref get_server_uptime().
+ * \param current_time See a \ref daemon_get_uptime().
*
* \return A dynamically allocated string of the form "days:hours:minutes".
- *
- * \sa server_uptime.
*/
-__malloc char *get_server_uptime_str(const struct timeval *current_time)
+__malloc char *daemon_get_uptime_str(const struct timeval *current_time)
{
- long t = get_server_uptime(current_time);
+ long t = daemon_get_uptime(current_time);
return make_message("%li:%02li:%02li", t / 86400,
(t / 3600) % 24, (t / 60) % 60);
}
return;
fp = me->logfile? me->logfile : stderr;
+ if (me->pre_log_hook)
+ me->pre_log_hook();
color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
if (color)
fprintf(fp, "%s", color);
va_end(argp);
if (color)
fprintf(fp, "%s", COLOR_RESET);
+ if (me->post_log_hook)
+ me->post_log_hook();
}
projects / paraslash.git / blobdiff