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dns: honor resolv.conf symlinks (lp:324233)

Browse source 
Based on a patch from Alexander Sack, but hugely
modified by me to make use of allocated realpath results
instead of stack-based arrays, and to fix an omission in
the original patch that would still have used the
non-realpath-resolved path to /etc/resolv.conf when doing
the atomic rename of the tempfile to resolv.conf.
This commit is contained in:
Dan Williams 2009-10-20 15:03:12 -07:00
parent c9d2d977dd
commit 5761e328b8
1 changed files with 42 additions and 15 deletions
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57
src/named-manager/nm-named-manager.c
View file

@ -388,14 +388,29 @@ update_resolv_conf (const char *domain,
const char *iface,
GError **error)
{
const char *tmp_resolv_conf = RESOLV_CONF ".tmp";
char tmp_resolv_conf_realpath [PATH_MAX];
char *tmp_resolv_conf;
char *tmp_resolv_conf_realpath;
char *resolv_conf_realpath;
FILE *f;
int do_rename = 1;
int old_errno = 0;
if (!realpath (tmp_resolv_conf, tmp_resolv_conf_realpath))
strcpy (tmp_resolv_conf_realpath, tmp_resolv_conf);
g_return_val_if_fail (error != NULL, FALSE);
/* Find the real path of resolv.conf; it could be a symlink to something */
resolv_conf_realpath = realpath (RESOLV_CONF, NULL);
if (!resolv_conf_realpath)
resolv_conf_realpath = strdup (RESOLV_CONF);
/* Build up the real path for the temp resolv.conf that we're about to
* write out.
*/
tmp_resolv_conf = g_strdup_printf ("%s.tmp", resolv_conf_realpath);
tmp_resolv_conf_realpath = realpath (tmp_resolv_conf, NULL);
if (!tmp_resolv_conf_realpath)
tmp_resolv_conf_realpath = strdup (tmp_resolv_conf);
g_free (tmp_resolv_conf);
tmp_resolv_conf = NULL;
if ((f = fopen (tmp_resolv_conf_realpath, "w")) == NULL) {
do_rename = 0;
@ -409,8 +424,11 @@ update_resolv_conf (const char *domain,
g_strerror (old_errno),
RESOLV_CONF,
g_strerror (errno));
return FALSE;
goto out;
}
/* Update tmp_resolv_conf_realpath so the error message on fclose()
* failure will be correct.
*/
strcpy (tmp_resolv_conf_realpath, RESOLV_CONF);
}
@ -418,25 +436,34 @@ update_resolv_conf (const char *domain,
if (fclose (f) < 0) {
if (*error == NULL) {
/* only set an error here if write_resolv_conf() was successful,
* since its error is more important.
*/
g_set_error (error,
NM_NAMED_MANAGER_ERROR,
NM_NAMED_MANAGER_ERROR_SYSTEM,
"Could not close %s: %s\n",
tmp_resolv_conf_realpath,
g_strerror (errno));
NM_NAMED_MANAGER_ERROR,
NM_NAMED_MANAGER_ERROR_SYSTEM,
"Could not close %s: %s\n",
tmp_resolv_conf_realpath,
g_strerror (errno));
}
}
/* Don't rename the tempfile over top of the existing resolv.conf if there
* was an error writing it out.
*/
if (*error == NULL && do_rename) {
if (rename (tmp_resolv_conf, RESOLV_CONF) < 0) {
if (rename (tmp_resolv_conf_realpath, resolv_conf_realpath) < 0) {
g_set_error (error,
NM_NAMED_MANAGER_ERROR,
NM_NAMED_MANAGER_ERROR_SYSTEM,
"Could not replace " RESOLV_CONF ": %s\n",
g_strerror (errno));
NM_NAMED_MANAGER_ERROR,
NM_NAMED_MANAGER_ERROR_SYSTEM,
"Could not replace " RESOLV_CONF ": %s\n",
g_strerror (errno));
}
}
out:
free (tmp_resolv_conf_realpath);
free (resolv_conf_realpath);
return *error ? FALSE : TRUE;
}