Re: [libvirt] [Resend][PATCH 1/3] Add dnsmasq module
Satoru SATOH wrote:
This patch adds the files implements dnsmasq (hostsfile) module.
Here is some feedback not on the overall structure or utility,
but more on a few implementation details that stood out.
...
diff --git a/src/util/dnsmasq.c b/src/util/dnsmasq.c
...
+static void
+dhcphostFree(dnsmasqDhcpHost *host)
+{
+ VIR_FREE(host->host);
+}
+
+static void
+hostsfileFree(dnsmasqHostsfile *hostsfile)
+{
+ int i;
Making that
unsigned int i;
is slightly better (if possible[*]),
since it's obvious "i" will never need to be signed.
[*] whether it is possible depends on the type of the nhosts
member and the set of gcc warnings enabled. Build with
--enable-compile-warnings=error to check.
+
+ if (hostsfile->hosts) {
+ for (i = 0; i < hostsfile->nhosts; i++)
+ dhcphostFree(&hostsfile->hosts[i]);
+
+ VIR_FREE(hostsfile->hosts);
+
+ hostsfile->nhosts = 0;
+ }
+
+ hostsfile->path[0] = '\0';
+
+ VIR_FREE(hostsfile);
+}
...
+static dnsmasqHostsfile *
+hostsfileNew(const char *name,
+ const char *config_dir)
+{
+ int err;
+ dnsmasqHostsfile *hostsfile;
+
+ if (VIR_ALLOC(hostsfile) < 0)
+ return NULL;
+
+ hostsfile->hosts = NULL;
+ hostsfile->nhosts = 0;
+
+ if ((err = virFileMakePath(config_dir))) {
+ virReportSystemError(err, _("cannot create config directory
'%s'"),
+ config_dir);
+ goto error;
+ }
+
+ if (virFileBuildPath(config_dir, name, ".hostsfile", hostsfile->path,
+ sizeof(hostsfile->path)) < 0) {
+ virReportSystemError(err,
+ _("config filename '%s/%s.%s' is too long"),
+ config_dir, name, ".hostsfile");
+ goto error;
+ }
+
+ return hostsfile;
+
+ error:
+ hostsfileFree(hostsfile);
+ return NULL;
+}
+
+static int
+hostsfileWrite(const char *path, dnsmasqDhcpHost *hosts, int nhosts)
+{
+ char tmp[PATH_MAX];
It's good to avoid use of PATH_MAX.
Declare it like this instead, ...
char *tmp;
+ FILE *f;
+ int istmp;
+ int i;
+
+ if (nhosts == 0 && unlink(path) == 0)
+ return 0;
+
+ if (snprintf(tmp, PATH_MAX, "%s.new", path) >= PATH_MAX)
+ return EINVAL;
... and here, use virAsprintf instead of snprintf.
If the name ends up being too long, you'll catch it when fopen fails.
+ istmp = 1;
+
+ if (!(f = fopen(tmp, "w"))) {
+ istmp = 0;
+ if (!(f = fopen(path, "w")))
+ return errno;
+ }
+
+ for (i = 0; i < nhosts; i++) {
+ if (fputs(hosts[i].host, f) == EOF || fputc('\n', f) == EOF) {
+ fclose(f);
fclose may well clobber the fputs-set errno.
Save it, with this, just before the fclose.
int saved_errno = errno
+ if (istmp)
+ unlink(tmp);
unlink may clobber errno, too.
So here, you should use "return saved_errno;"
+ return errno;
+ }
+ }
+
+ fclose(f);
The fputs calls can succeed, yet fclose's write or close
can still fail. So you must check for fclose failure, too.
+
+ if (istmp && rename(tmp, path) < 0) {
Save errno here too, so unlink can't clobber it.
int saved_errno = errno
+ unlink(tmp);
+ return errno;
and use saved_errno here.
+ }
+
+ if (istmp)
+ unlink(tmp);
+
+ return 0;
+}