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Avoid alarm to prevent the setitimer interval from being reset

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This commit is contained in:
Erik van der Kouwe 2009-09-03 20:35:22 +00:00
parent 360dc9104c
commit ec4b567894
1 changed files with 28 additions and 31 deletions
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59
lib/ip/res_send.c
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@ -56,6 +56,7 @@ static char sccsid[] = "@(#)res_send.c 6.27 (Berkeley) 2/24/91";
#include <sys/types.h> #include <sys/types.h>
#include <sys/ioctl.h> #include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <assert.h> #include <assert.h>
#include <errno.h> #include <errno.h>
@ -87,7 +88,6 @@ static int udp_sendto _ARGS(( int fd, const char *buf, unsigned buflen,
ipaddr_t addr, Udpport_t port )); ipaddr_t addr, Udpport_t port ));
static int udp_receive _ARGS(( int fd, char *buf, unsigned buflen, static int udp_receive _ARGS(( int fd, char *buf, unsigned buflen,
time_t timeout )); time_t timeout ));
static void alarm_handler _ARGS(( int sig ));
#endif /* !_MINIX */ #endif /* !_MINIX */
@ -843,13 +843,6 @@ udpport_t port;
return r; return r;
} }
static void alarm_handler(sig)
int sig;
{
signal(SIGALRM, alarm_handler);
alarm(1);
}
static int udp_receive(fd, buf, buflen, timeout) static int udp_receive(fd, buf, buflen, timeout)
int fd; int fd;
char *buf; char *buf;
@ -859,45 +852,49 @@ time_t timeout;
char *newbuf; char *newbuf;
udp_io_hdr_t *udp_io_hdr; udp_io_hdr_t *udp_io_hdr;
int r, terrno; int r, terrno;
void (*u_handler) _ARGS(( int sig )); fd_set readfds;
time_t u_timeout; struct timeval timeval;
newbuf= malloc(sizeof(*udp_io_hdr) + buflen); /* allocate buffer for packet */
newbuf = malloc(sizeof(*udp_io_hdr) + buflen);
if (newbuf == NULL) if (newbuf == NULL)
{ {
errno= ENOMEM; errno = ENOMEM;
return -1; return -1;
} }
/* only read if there is something to be read within timeout seconds */
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
timeval.tv_sec = timeout;
timeval.tv_usec = 0;
r = select(fd + 1, &readfds, NULL, NULL, &timeval);
if (r >= 0 && !FD_ISSET(fd, &readfds))
{
errno = EINTR;
r = -1;
}
u_handler= signal(SIGALRM, alarm_handler); if (r >= 0)
u_timeout= alarm(timeout); r = read(fd, newbuf, sizeof(*udp_io_hdr) + buflen);
r= read(fd, newbuf, sizeof(*udp_io_hdr) + buflen);
terrno= errno;
/* clean up in case of failure */
terrno = errno;
if (r < 0 || r <= sizeof(*udp_io_hdr)) if (r < 0 || r <= sizeof(*udp_io_hdr))
{ {
if (r > 0) if (r > 0)
r= 0; r = 0;
free(newbuf); free(newbuf);
errno = terrno;
alarm(0);
signal(SIGALRM, u_handler);
alarm(u_timeout);
errno= terrno;
return r; return r;
} }
/* copy packet body to caller-provided buffer */
memcpy(buf, newbuf + sizeof(*udp_io_hdr), r - sizeof(*udp_io_hdr)); memcpy(buf, newbuf + sizeof(*udp_io_hdr), r - sizeof(*udp_io_hdr));
free(newbuf); free(newbuf);
alarm(0); return r - sizeof(*udp_io_hdr);
signal(SIGALRM, u_handler);
alarm(u_timeout);
return r-sizeof(*udp_io_hdr);
} }
#endif #endif