Created attachment 333372 [details]
useradd errno clear patch

Description of problem:
Noticed a problem where useradd would fail on a system with 'invalid numeric argument' in get_uid() when you supply a UID on the cmdline.  After some liberal printf's I found the message came because errno still retains a previous ERANGE value (34) after a call in get_defaults() from a getgrgid that is never tested on or subsequently cleared.  Before test conditions relying on errno are thrown, errno should be set to 0 since libs are not supposed to set/change the value unless they encounter an error.

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Version-Release number of selected component (if applicable):
Tested on shadow-utils-4.0.17-14.el5 & shadow-utils-4.1.2-9


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Results from debug:
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From orig line Printf in get_uid(): 256 : Modified to:
val = strtol (uidstr, &errptr, 10);
    if (*errptr || errno == ERANGE || val < 0) {
        fprintf (stderr,
             _("%s: invalid numeric argument '%s', val: '%li' < 0, errno = '%i', ptr = '%c' @addr:%p\n"), Prog,
             uidstr, val, errno,*errptr,*errptr);
        exit (E_BAD_ARG);
    }
----
From orig line Printf get_defaults(): 311
 def_group = val;
/* local, no need for xgetgrgid */
if ((grp = getgrgid (def_group))) {
  if (errno != 0 ) {
    fprintf (stderr, _("get_def:primgroup_if1: Previous Errno value of '%i' present. Buf is '%s', str is '%s'; DEFsize '%i'; GrpSize '%i'; GrName '%s', GrPass '%s', GrID '%u', GrMem '%s'.\n"),errno,buf,cp,sizeof(def_group),sizeof(getgrgid (def_group)),grp->gr_name,grp->gr_passwd,grp->gr_gid,grp->gr_mem);
  }

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./useradd -u 123456 -G test -c"TEST_USER" TEST_USER
get_def:primgroup_if1: Previous Errno value of '34' present. Buf is 'GROUP=100', str is '100'; DEFsize '4'; GrpSize '8'; GrName 'users', GrPass 'x', GrID '100', GrMem '=�'.
useradd: invalid numeric argument '123456', val: '123456' < 0, errno = '34', ptr = '' @addr:(nil)




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Additional info:
I've yet to RC the orig error for ERANGE, but future tests on value of errno after stdlib calls should honestly clear it first to reduce false failures.  If ERANGE errors or others are important from earlier calls, I don't believe its good practice to waterfall them through till later sections.  With that I'll continue to debug the reason for the ERANGE, for that reason I've submitted a patch (attached) to clear errno before current tests.