Re: [libvirt] [Resend][PATCH 1/3] Add dnsmasq module
Thanks a lot for your detailed feedback!
On Tue, Apr 20, 2010 at 07:42:45PM +0200, Jim Meyering wrote:
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.
absolutely right.
fixed locally and will post it again.
> +
> + 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, ...
I understand.
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.
ok, replaced locally.
> + 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.
done.
> + }
> +
> + if (istmp)
> + unlink(tmp);
> +
> + return 0;
> +}
--
Thanks,
Satoru SATOH