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common/socket_close: don't wait forever.

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The "read until closed" trick doesn't work if the other end doesn't
close (as found in the next patch, where we use DEV_DISCONNECT_DISABLE_AFTER).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2021-12-28 09:55:09 +10:30
parent 35e3c1866e
commit 2fb58772a4
1 changed files with 24 additions and 14 deletions
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38
common/socket_close.c
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@@ -2,6 +2,8 @@
#include <ccan/noerr/noerr.h>
#include <common/socket_close.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
@@ -18,9 +20,15 @@ Simplified (minus all the error checks):
close(fd);
*/
/* makes read() return EINTR */
static void break_read(int signum)
{
}
bool socket_close(int fd)
{
char unused[64];
struct sigaction act, old_act;
int sys_res;
sys_res = shutdown(fd, SHUT_WR);
@@ -29,20 +37,22 @@ bool socket_close(int fd)
return false;
}
for (;;) {
do {
sys_res = read(fd, unused, sizeof(unused));
} while (sys_res < 0 && errno == EINTR);
if (sys_res < 0) {
close_noerr(fd);
return false;
}
if (sys_res == 0)
break;
/* Let's not get too enthusiastic about waiting. */
memset(&act, 0, sizeof(act));
act.sa_handler = break_read;
sigaction(SIGALRM, &act, &old_act);
alarm(5);
while ((sys_res = read(fd, unused, sizeof(unused))) > 0);
alarm(0);
sigaction(SIGALRM, &old_act, NULL);
if (sys_res < 0) {
close_noerr(fd);
return false;
}
if (close(fd) < 0)
return false;
else
return true;
return close(fd) == 0;
}