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/* ISC license. */
#include <sys/uio.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/inotify.h>
#include <skalibs/types.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/sgetopt.h>
#include <skalibs/strerr.h>
#include <skalibs/error.h>
#include <skalibs/buffer.h>
#include <skalibs/sig.h>
#include <skalibs/djbunix.h>
#include <skalibs/iopause.h>
#define USAGE "s6-logwatch [ logdir ]"
#define dieusage() strerr_dieusage(100, USAGE)
#define B_READING 0
#define B_BLOCKING 1
#define B_WAITING 2
static unsigned int state ;
static int fd ;
static int newcurrent = 0 ;
union inotify_event_u
{
struct inotify_event event ;
char buf[sizeof(struct inotify_event) + NAME_MAX + 1] ;
} ;
static void goteof (void)
{
if (newcurrent)
{
fd_close(fd) ;
fd = open_read("current") ;
if (fd < 0) strerr_diefu1sys(111, "current") ;
newcurrent = 0 ;
state = B_READING ;
}
else state = B_BLOCKING ;
}
static int readit (int fd)
{
struct iovec v[2] ;
ssize_t r ;
buffer_wpeek(buffer_1, v) ;
r = fd_readv(fd, v, 2) ;
switch (r)
{
case -1 : return 0 ;
case 0 : goteof() ; break ;
default : buffer_wseek(buffer_1, r) ;
}
return 1 ;
}
static void maketransition (unsigned int transition)
{
static unsigned char const table[3][3] = {
{ 0x10, 0x00, 0x00 },
{ 0x60, 0x22, 0x00 },
{ 0x40, 0x03, 0x02 }
} ;
unsigned char c = table[state][transition] ;
state = c & 0x0f ;
if (state == 3) strerr_dief1x(101, "current moved twice without being recreated") ;
if (c & 0x10) newcurrent = 1 ;
if (c & 0x20) { fd_close(fd) ; fd = -1 ; }
if (c & 0x40)
{
fd = open_read("current") ;
if (fd < 0) strerr_diefu1sys(111, "current") ;
}
}
static void handle_event (int ifd, int watch)
{
ssize_t r ;
size_t offset = 0 ;
union inotify_event_u u ;
r = read(ifd, u.buf, sizeof(u.buf)) ;
while (r > 0)
{
struct inotify_event *event = (struct inotify_event *)(u.buf + offset) ;
offset += sizeof(struct inotify_event) + event->len ;
r -= sizeof(struct inotify_event) + event->len ;
if (event->wd == watch && !strcmp(event->name, "current"))
{
int transition = -1 ;
if (event->mask & IN_CREATE) transition = 0 ;
else if (event->mask & IN_MOVED_FROM) transition = 1 ;
else if (event->mask & IN_MODIFY) transition = 2 ;
if (transition >= 0) maketransition(transition) ;
}
}
}
int main (int argc, char const *const *argv)
{
iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .fd = 1 } } ;
char const *dir = "." ;
int watch ;
unsigned int maxlen = 4096 ;
PROG = "s6-logwatch" ;
{
subgetopt l = SUBGETOPT_ZERO ;
for (;;)
{
int opt = subgetopt_r(argc, argv, "m:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'm' :
if (!uint0_scan(l.arg, &maxlen)) dieusage() ;
strerr_warnw1x("the -m option is deprecated") ;
break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
}
if (argc) dir = *argv ;
if (chdir(dir) < 0) strerr_diefu2sys(111, "chdir to ", dir) ;
if (!fd_sanitize()) strerr_diefu1sys(111, "sanitize standard fds") ;
x[0].fd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC) ;
if (x[0].fd < 0) strerr_diefu1sys(111, "inotify_init") ;
watch = inotify_add_watch(x[0].fd, ".", IN_CREATE | IN_MOVED_FROM | IN_MODIFY) ;
if (watch < 0) strerr_diefu1sys(111, "inotify_add_watch") ;
fd = open_readb("current") ;
if (fd < 0)
{
if (errno != ENOENT) strerr_diefu3sys(111, "open ", dir, "/current") ;
state = B_WAITING ;
}
else state = B_READING ;
if (!sig_ignore(SIGPIPE)) strerr_diefu1sys(111, "sig_ignore(SIGPIPE)") ;
if (state == B_READING)
{
if (!readit(fd)) strerr_diefu3sys(111, "read from ", dir, "/current") ;
}
for (;;)
{
int r ;
x[1].events = buffer_len(buffer_1) ? IOPAUSE_WRITE : 0 ;
r = iopause(x, 2, 0, 0) ;
if (r < 0) strerr_diefu1sys(111, "iopause") ;
if (x[0].revents & IOPAUSE_EXCEPT) x[0].revents |= IOPAUSE_READ ;
if (x[1].revents & IOPAUSE_EXCEPT) x[1].revents |= IOPAUSE_WRITE ;
if (x[1].revents & IOPAUSE_WRITE)
{
if (!buffer_flush(buffer_1) && !error_isagain(errno))
strerr_diefu1sys(111, "write to stdout") ;
if (x[1].revents & IOPAUSE_EXCEPT) break ;
}
if (state == B_READING && buffer_available(buffer_1))
{
if (!readit(fd)) strerr_diefu3sys(111, "read from ", dir, "/current") ;
}
if (x[0].revents & IOPAUSE_READ) handle_event(x[0].fd, watch) ;
}
return 0 ;
}
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