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Check return values of write(), ftruncate(), and fsync().

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This commit is contained in:
Nicholas J. Kain 2010-11-12 04:29:38 -05:00
parent 3d871e612a
commit 5bea46a071
1 changed files with 38 additions and 6 deletions
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44
ifchd.c
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@ -1,5 +1,5 @@
/* ifchd.c - interface change daemon
* Time-stamp: <2010-11-12 04:10:07 njk>
* Time-stamp: <2010-11-12 04:28:47 njk>
*
* (C) 2004 Nicholas J. Kain <njk@aerifal.cx>
*
@ -134,6 +134,24 @@ static void die_nulstr(strlist_t *p)
suicide("FATAL - NULL string in strlist\n", NULL, EXIT_FAILURE);
}
static void safe_write(int fd, const char *buf, int len)
{
ssize_t r;
retry:
r = write(fd, buf, len);
if (r != len) {
if (r == -1) {
if (errno == EINTR)
goto retry;
else
suicide("write returned error\n", NULL, EXIT_FAILURE);
} else {
len -= r;
goto retry;
}
}
}
/* Writes out each element in a strlist as an argument to a keyword in
* a file. */
static void write_resolve_list(const char *keyword, strlist_t *list)
@ -149,9 +167,9 @@ static void write_resolve_list(const char *keyword, strlist_t *list)
buf = p->str;
len = strlen(buf);
if (len) {
write(resolv_conf_fd, keyword, strlen(keyword));
write(resolv_conf_fd, buf, strlen(buf));
write(resolv_conf_fd, "\n", 1);
safe_write(resolv_conf_fd, keyword, strlen(keyword));
safe_write(resolv_conf_fd, buf, strlen(buf));
safe_write(resolv_conf_fd, "\n", 1);
}
p = p->next;
}
@ -160,6 +178,7 @@ static void write_resolve_list(const char *keyword, strlist_t *list)
/* Writes a new resolv.conf based on the information we have received. */
static void write_resolve_conf(int idx)
{
int r;
off_t off;
if (resolv_conf_fd == -1)
@ -175,8 +194,21 @@ static void write_resolve_conf(int idx)
strerror(errno));
return;
}
ftruncate(resolv_conf_fd, off);
fsync(resolv_conf_fd);
retry:
r = ftruncate(resolv_conf_fd, off);
if (r == -1) {
if (errno == EINTR)
goto retry;
log_line("write_resolve_conf: ftruncate returned error: %s\n",
strerror(errno));
return;
}
r = fsync(resolv_conf_fd);
if (r == -1) {
log_line("write_resolve_conf: fsync returned error: %s\n",
strerror(errno));
return;
}
}
/* Decomposes a ' '-delimited flat character array onto a strlist, then