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su.c: be more predictable

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Always parse first non-option as username.
This commit is contained in:
Harm te Hennepe 2018-03-27 00:45:03 +02:00
parent 45b4187596
commit d877e3fcac
2 changed files with 24 additions and 30 deletions
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41
man/su.1.xml
View File

@ -85,12 +85,16 @@
<cmdsynopsis>
<command>su</command>
<arg choice='opt'>
<replaceable>options</replaceable>
<replaceable>options</replaceable>
</arg>
<arg choice='opt'>
<arg choice='plain'>
<replaceable>username</replaceable>
</arg>
<replaceable>-</replaceable>
</arg>
<arg choice='opt'>
<replaceable>username</replaceable>
<arg choice='opt'>
<replaceable>args</replaceable>
</arg>
</arg>
</cmdsynopsis>
</refsynopsisdiv>
@ -98,26 +102,21 @@
<refsect1 id='description'>
<title>DESCRIPTION</title>
<para>
The <command>su</command> command is used to become another user during
a login session. Invoked without a <option>username</option>,
<command>su</command> defaults to
becoming the superuser. The optional argument <option>-</option> may
be used to provide an environment similar to what the user would
expect had the user logged in directly.
The <command>su</command> command is used to become another user during a
login session. Invoked without a <option>username</option>,
<command>su</command> defaults to becoming the superuser. The
<option>-</option> option may be used to provide an environment similar
to what the user would expect had the user logged in directly. The
<option>-c</option> option may be used to treat the next argument as a
command by most shells.
</para>
<para>
Additional arguments may be provided after the username, in which case
they are supplied to the user's login shell. In particular, an
argument of <option>-c</option> will cause the next argument to be
treated as a command by most command interpreters. The command will be
executed by the shell specified in <filename>/etc/passwd</filename>
for the target user.
</para>
<para>
You can use the <option>--</option> argument to separate
<command>su</command> options from the arguments supplied to the shell.
Options are recognized everywhere in the argument list. You can use the
<option>--</option> argument to stop option parsing. The
<option>-</option> option is special: it is also recognized after
<option>--</option>, but has to be placed before
<option>username</option>.
</para>
<para>The user will be prompted for a password, if appropriate. Invalid

13
src/su.c
View File

@ -436,7 +436,7 @@ static void prepare_pam_close_session (void)
static void usage (int status)
{
(void)
fputs (_("Usage: su [options] [LOGIN]\n"
fputs (_("Usage: su [options] [-] [username [args]]\n"
"\n"
"Options:\n"
" -c, --command COMMAND pass COMMAND to the invoked shell\n"
@ -446,7 +446,8 @@ static void usage (int status)
" --preserve-environment do not reset environment variables, and\n"
" keep the same shell\n"
" -s, --shell SHELL use SHELL instead of the default in passwd\n"
"\n"), (E_SUCCESS != status) ? stderr : stdout);
"\n"
"If no username is given, assume root.\n"), (E_SUCCESS != status) ? stderr : stdout);
exit (status);
}
@ -815,13 +816,7 @@ static void process_flags (int argc, char **argv)
}
}
/*
* The next argument must be either a user ID, or some flag to a
* subshell. Pretty sticky since you can't have an argument which
* doesn't start with a "-" unless you specify the new user name.
* Any remaining arguments will be passed to the user's login shell.
*/
if ((optind < argc) && ('-' != argv[optind][0])) {
if (optind < argc) {
STRFCPY (name, argv[optind++]); /* use this login id */
if ((optind < argc) && (strcmp (argv[optind], "--") == 0)) {
optind++;