Some more issues:
1) multi-threading
Assuming util_lookup_group() has to be thread save
my solution wont work reliable, found
> The getgrnam() function need not be thread-safe.
so we have to the reentrant version.
2) errno
Lennart Poettering <lennart@xxxxxxxxxxxxxx> wrote:
> One little comment here: on POSIX getrnam_r() doesn't touch
> errno. Instead it returns the error value as return value.
3) sysconf(_SC_GETGR_R_SIZE_MAX)
obviously wrong documented, its return value can only be used as hint.
IMHO its worth to initiate with some usefull defaults, because
repeatedly calling getgrnam_r does'nt come for free.
4) realloc
if we additionally want to catch realloc failure
this one should do:
gid_t util_lookup_group(struct udev *udev, const char *group)
{
char *endptr;
int buflen;
struct group grbuf;
struct group *gr;
char *mem;
char *buf = NULL;
gid_t gid = 0;
if (strcmp(group, "root") == 0)
return 0;
gid = strtoul(group, &endptr, 10);
if (endptr[0] == '\0')
return gid;
buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
if (buflen < 32)
buflen = 1024;
for (;mem = realloc(buf, buflen); buflen *=2 )
{
buf=mem;
errno=getgrnam_r(group, &grbuf, buf, buflen, &gr);
if (gr != NULL)
gid = gr->gr_gid;
else if (errno == ERANGE)
continue;
else if (errno == 0 || errno == ENOENT || errno == ESRCH)
err(udev, "specified group '%s' unknown\n", group);
else
err(udev, "error resolving group '%s': %m\n", group);
break;
}
if (!mem)
err(udev, "error resolving group '%s': allocating %d bytes failed\n", group,buflen);
if (buf)
free(buf);
return gid;
}
sorry, no patch yet.
currently using numeric gids in udev rules to avoid ERANGE error.
BTW util_lookup_user needs to be checked too.
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