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/* ISC license. */
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <sys/inotify.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/sgetopt.h>
#include <skalibs/bytestr.h>
#include <skalibs/strerr2.h>
#include <skalibs/error.h>
#include <skalibs/buffer.h>
#include <skalibs/bufalloc.h>
#include <skalibs/sig.h>
#include <skalibs/siovec.h>
#include <skalibs/djbunix.h>
#include <skalibs/iopause.h>
#include <skalibs/ulong.h>
#define USAGE "s6-logwatch [ -m maxbuffer ] logdir"
#define dieusage() strerr_dieusage(100, USAGE)
#define N 4096
#define IESIZE 100
typedef enum bstate_e bstate_t, *bstate_t_ref ;
enum bstate_e
{
B_TAILING = 0,
B_WAITING = 1
} ;
static void X (void)
{
strerr_diefu1x(101, "follow file state changes (race condition triggered). Sorry.") ;
}
static unsigned long nbcat (int fdcurrent)
{
char buf[N+1] ;
buffer b = BUFFER_INIT(&buffer_read, fdcurrent, buf, N+1) ;
siovec_t v[2] ;
unsigned long bytes = 0 ;
for (;;)
{
int r = sanitize_read(buffer_fill(&b)) ;
if (!r) break ;
if (r < 0)
{
if (errno == EPIPE) break ;
else strerr_diefu1sys(111, "buffer_fill") ;
}
buffer_rpeek(&b, v) ;
if (!bufalloc_putv(bufalloc_1, v, 2))
strerr_diefu1sys(111, "bufalloc_putv") ;
buffer_rseek(&b, r) ;
bytes += r ;
}
return bytes ;
}
int main (int argc, char const *const *argv)
{
char const *dir = "." ;
unsigned long maxlen = 4000 ;
PROG = "s6-logwatch" ;
{
subgetopt_t l = SUBGETOPT_ZERO ;
for (;;)
{
register int opt = subgetopt_r(argc, argv, "m:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'm' : if (!ulong0_scan(l.arg, &maxlen)) dieusage() ; break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
}
if (argc) dir = *argv ;
if (chdir(dir) < 0) strerr_diefu2sys(111, "chdir to ", dir) ;
{
iopause_fd x[1] = { { -1, IOPAUSE_READ, 0 } } ;
int fdcurrent = -1 ;
unsigned long pos = 0 ;
int w ;
bstate_t state = B_TAILING ;
x[0].fd = inotify_init() ;
if (x[0].fd < 0) strerr_diefu1sys(111, "inotify_init") ;
if (ndelay_on(x[0].fd) < 0) strerr_diefu1sys(111, "ndelay_on inotify fd") ;
w = inotify_add_watch(x[0].fd, ".", IN_CREATE | IN_MODIFY | IN_CLOSE_WRITE) ;
if (w < 0) strerr_diefu1sys(111, "inotify_add_watch") ;
if (sig_ignore(SIGPIPE) == -1) strerr_diefu1sys(111, "sig_ignore(SIGPIPE)") ;
fdcurrent = open_readb("current") ;
if (fdcurrent < 0)
if (errno != ENOENT) strerr_diefu1sys(111, "open_readb current") ;
else state = B_WAITING ;
else pos = nbcat(fdcurrent) ;
for (;;)
{
int r ;
if (!bufalloc_flush(bufalloc_1)) strerr_diefu1sys(111, "write to stdout") ;
r = iopause(x, 1, 0, 0) ;
if (r < 0) strerr_diefu1sys(111, "iopause") ;
if (x[0].revents & IOPAUSE_READ)
{
char iebuf[IESIZE] ;
while (bufalloc_len(bufalloc_1) < maxlen)
{
unsigned int i = 0 ;
r = sanitize_read(fd_read(x[0].fd, iebuf, IESIZE)) ;
if (r < 0) strerr_diefu1sys(111, "read from inotify fd") ;
if (!r) break ;
while (i < (unsigned int)r)
{
struct inotify_event *ie = (struct inotify_event *)(iebuf + i) ;
if ((ie->wd != w) || !ie->len || str_diff(ie->name, "current")) goto cont ;
if (ie->mask & IN_MODIFY)
{
if (state) X() ;
pos += nbcat(fdcurrent) ;
}
else if (ie->mask & IN_CLOSE_WRITE)
{
if (state) X() ;
fd_close(fdcurrent) ;
fdcurrent = -1 ;
pos = 0 ;
state = B_WAITING ;
}
else if (ie->mask & IN_CREATE)
{
if (!state) X() ;
fdcurrent = open_readb("current") ;
if (fdcurrent < 0)
{
if (errno != ENOENT) strerr_diefu1sys(111, "open_readb current") ;
else goto cont ;
}
pos = nbcat(fdcurrent) ;
state = B_TAILING ;
}
cont:
i += sizeof(struct inotify_event) + ie->len ;
}
}
}
}
}
return 0 ;
}
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