X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=daemon.c;h=8f39e86cfe48f18b1c9ed0e86a0039e26258f00f;hb=98cfcef26048bba06975e68a1aad05a8bac0d65d;hp=08366bf10bf907d7e127004c21dc460fb14582ea;hpb=8f826df8fbadd811f6bcc31344e3d8472bd6f2bb;p=~andy%2Ffetchmail diff --git a/daemon.c b/daemon.c index 08366bf1..8f39e86c 100644 --- a/daemon.c +++ b/daemon.c @@ -9,40 +9,17 @@ #include #include #include +#include #include -#ifdef HAVE_SYS_WAIT_H #include -#endif -#ifdef HAVE_FCNTL_H #include -#else /* !HAVE_FCNTL_H */ -#ifdef HAVE_SYS_FCNTL_H -#include -#endif /* HAVE_SYS_FCNTL_H */ -#endif /* !HAVE_FCNTL_H */ #include /* get umask(2) prototyped */ -#if defined(HAVE_UNISTD_H) #include -#endif -#if defined(STDC_HEADERS) #include -#endif -#if defined(QNX) -#include -#endif - -#if !defined(HAVE_SETSID) && defined(SIGTSTP) -#if defined(HAVE_TERMIOS_H) -# include /* for TIOCNOTTY under Linux */ -#endif - -#if !defined(TIOCNOTTY) && defined(HAVE_SGTTY_H) -# include /* for TIOCNOTTY under NEXTSTEP */ -#endif -#endif /* !defined(HAVE_SETSID) && defined(SIGTSTP) */ +#include /* for TIOCNOTTY under Linux */ /* BSD portability hack */ #if !defined(SIGCHLD) && defined(SIGCLD) @@ -52,42 +29,60 @@ #include "fetchmail.h" #include "tunable.h" -RETSIGTYPE +static void sigchld_handler (int sig) /* process SIGCHLD to obtain the exit code of the terminating process */ { - extern volatile int lastsig; /* last signal received */ - pid_t pid; - -#if defined(HAVE_WAITPID) /* the POSIX way */ int status; - while ((pid = waitpid(-1, &status, WNOHANG)) > 0) + while (waitpid(-1, &status, WNOHANG) > 0) continue; /* swallow 'em up. */ -#elif defined(HAVE_WAIT3) /* the BSD way */ -#if defined(HAVE_UNION_WAIT) && !defined(__FreeBSD__) - union wait status; -#else - int status; -#endif + lastsig = SIGCHLD; + (void)sig; +} - while ((pid = wait3(&status, WNOHANG, 0)) > 0) - continue; /* swallow 'em up. */ -#else /* Zooks! Nothing to do but wait(), and hope we don't block... */ - int status; +void null_signal_handler(int sig) { (void)sig; } - wait(&status); +SIGHANDLERTYPE set_signal_handler(int sig, SIGHANDLERTYPE handler) +/* + * This function is called by other parts of the program to + * setup the signal handler after a change to the signal context. + * This is done to improve robustness of the signal handling code. + * It has the same prototype as signal(2). + */ +{ + SIGHANDLERTYPE rethandler; + struct sigaction sa_new, sa_old; + + memset (&sa_new, 0, sizeof sa_new); + sigemptyset (&sa_new.sa_mask); + sa_new.sa_handler = handler; + sa_new.sa_flags = 0; + /* system call should restart on all signals except SIGALRM */ + if (sig != SIGALRM) + sa_new.sa_flags |= SA_RESTART; + if (sig == SIGCHLD) + sa_new.sa_flags |= SA_NOCLDSTOP; + sigaction(sig, &sa_new, &sa_old); + rethandler = sa_old.sa_handler; +#if defined(SIGPWR) + if (sig == SIGCHLD) + sigaction(SIGPWR, &sa_new, NULL); #endif - lastsig = SIGCHLD; + return rethandler; +} + +void deal_with_sigchld(void) +{ + set_signal_handler(SIGCHLD, sigchld_handler); } int -daemonize (const char *logfile, void (*termhook)(int)) +daemonize (const char *logfile) /* detach from control TTY, become process group leader, catch SIGCHLD */ { - int fd; + int fd, logfd; pid_t childpid; - RETSIGTYPE sigchld_handler(int); /* if we are started by init (process 1) via /etc/inittab we needn't bother to detach from our process group context */ @@ -97,13 +92,13 @@ daemonize (const char *logfile, void (*termhook)(int)) /* Ignore BSD terminal stop signals */ #ifdef SIGTTOU - signal(SIGTTOU, SIG_IGN); + set_signal_handler(SIGTTOU, SIG_IGN); #endif #ifdef SIGTTIN - signal(SIGTTIN, SIG_IGN); + set_signal_handler(SIGTTIN, SIG_IGN); #endif #ifdef SIGTSTP - signal(SIGTSTP, SIG_IGN); + set_signal_handler(SIGTSTP, SIG_IGN); #endif /* In case we were not started in the background, fork and let @@ -121,73 +116,55 @@ daemonize (const char *logfile, void (*termhook)(int)) /* Make ourselves the leader of a new process group with no controlling terminal */ -#if defined(HAVE_SETSID) /* POSIX */ /* POSIX makes this soooo easy to do */ if (setsid() < 0) { report(stderr, "setsid (%s)\n", strerror(errno)); return(PS_IOERR); } -#elif defined(SIGTSTP) /* BSD */ - /* change process group */ -#ifndef __EMX__ - setpgrp(0, getpid()); -#endif - /* lose controlling tty */ - if ((fd = open("/dev/tty", O_RDWR)) >= 0) { - ioctl(fd, TIOCNOTTY, (char *) 0); - close(fd); - } -#else /* SVR3 and older */ - /* change process group */ -#ifndef __EMX__ - setpgrp(); -#endif - - /* lose controlling tty */ - signal(SIGHUP, SIG_IGN); - if ((childpid = fork()) < 0) { - report(stderr, "fork (%)\n", strerror(errno)); + +nottyDetach: + + (void)close(0); + + /* Reopen stdin descriptor on /dev/null */ + if (open("/dev/null", O_RDWR) < 0) { /* stdin */ + report(stderr, "cannot open /dev/null: %s\n", strerror(errno)); return(PS_IOERR); } - else if (childpid > 0) { - exit(0); /* parent */ - } -#endif -nottyDetach: + if (logfile) + { + if ((logfd = open(logfile, O_CREAT|O_WRONLY|O_APPEND, 0666)) < 0) { /* stdout */ + report(stderr, "cannot open %s: %s\n", logfile, strerror(errno)); + return PS_IOERR; + } + } else + logfd = 0; /* else use /dev/null */ /* Close any/all open file descriptors */ #if defined(HAVE_GETDTABLESIZE) - for (fd = getdtablesize()-1; fd >= 0; fd--) + fd = getdtablesize() - 1; #elif defined(NOFILE) - for (fd = NOFILE-1; fd >= 0; fd--) + fd = NOFILE - 1; #else /* make an educated guess */ - for (fd = 19; fd >= 0; fd--) + fd = 1023; #endif - { - close(fd); + while (fd >= 1) { + if (fd != logfd) + close(fd); /* not checking this should be safe, no writes */ + -- fd; } - /* Reopen stdin descriptor on /dev/null */ - if ((fd = open("/dev/null", O_RDWR)) < 0) { /* stdin */ - report(stderr, "open: /dev/null (%s)\n", strerror(errno)); - return(PS_IOERR); - } - - if (logfile) - fd = open(logfile, O_CREAT|O_WRONLY|O_APPEND, 0666); /* stdout */ - else - if (dup(fd) < 0) { /* stdout */ + if (dup(logfd) < 0 /* stdout */ + || ((logfd == 0 || logfd >= 3) && dup(logfd) < 0)) { /* stderr */ report(stderr, "dup (%s)\n", strerror(errno)); return(PS_IOERR); - } - if (dup(fd) < 0) { /* stderr */ - report(stderr, "dup (%s)\n", strerror(errno)); - return(PS_IOERR); } +#ifdef HAVE_GETCWD /* move to root directory, so we don't prevent filesystem unmounts */ chdir("/"); +#endif /* set our umask to something reasonable (we hope) */ #if defined(DEF_UMASK) @@ -196,13 +173,26 @@ nottyDetach: umask(022); #endif - /* set up to catch child process termination signals */ - signal(SIGCHLD, sigchld_handler); -#if defined(SIGPWR) - signal(SIGPWR, sigchld_handler); -#endif + deal_with_sigchld(); return(0); } +flag is_a_file(int fd) +/* is the given fd attached to a file? (used to control logging) */ +{ + struct stat stbuf; + + /* + * We'd like just to return 1 on (S_IFREG | S_IFBLK), + * but weirdly enough, Linux ptys seem to have S_IFBLK + * so this test would fail when run on an xterm. + */ + if (isatty(fd) || fstat(fd, &stbuf)) + return(0); + else if (stbuf.st_mode & (S_IFREG)) + return(1); + return(0); +} + /* daemon.c ends here */