2bf88a891f
This is a first attempt to improve the comments of getopt_ulflags.c. Maybe under some aspects the text could be refined, but so far it is already usable and should help people who "avoided getopt_ulflags as the pest" to understand how it works. This patch was created with the help of Vodz, the author of the code, who explained me patiently how getopt_ulflags works and with the help of Paul Fox, who corrected my broken english. So thanks and merits should go to them also.
266 lines
8.3 KiB
C
266 lines
8.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* universal getopt_ulflags implementation for busybox
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*
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* Copyright (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <getopt.h>
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#include <string.h>
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#include <assert.h>
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#include <stdlib.h>
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#include "libbb.h"
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/* Documentation !
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bb_getopt_ulflags (int argc, char **argv, const char *applet_opts, ...)
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The command line options must be declared in const char
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*applet_opts as a string of chars, for example:
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flags = bb_getopt_ulflags(argc, argv, "rnug");
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If one of the given options is found a flag value is added to
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the unsigned long returned by bb_getopt_ulflags.
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The value of this flag is given by the position of the char in
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const char *applet_opts so for example in this case:
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flags = bb_getopt_ulflags(argc, argv, "rnug");
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"r" will add 1
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"n" will add 2
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"u will add 4
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"g" will add 8
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and so on.
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If an argument is required by one of the options add a ":"
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after the char in const char *applet_opts and provide a pointer
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where the arg could be stored if it is found, for example:
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char *pointer_to_arg_for_a;
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char *pointer_to_arg_for_b;
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char *pointer_to_arg_for_c;
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char *pointer_to_arg_for_d;
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flags = bb_getopt_ulflags(argc, argv, "a:b:c:d:",
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&pointer_to_arg_for_a, &pointer_to_arg_for_b,
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&pointer_to_arg_for_c, &pointer_to_arg_for_d);
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The type of the pointer (char* or llist_t *) can be influenced
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by the "*" special character that can be set in const char
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*bb_opt_complementaly (see below).
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const char *bb_opt_complementaly
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":" The colon (":") is used in bb_opt_complementaly as separator
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between groups of two or more chars and/or groups of chars and
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special characters (stating some conditions to be checked).
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"abc" If groups of two or more chars are specified the first char
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is the main option and the other chars are secondary options
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whose flags will be turned on if the main option is found even
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if they are not specifed on the command line, for example:
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bb_opt_complementaly = "abc";
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flags = bb_getopt_ulflags(argc, argv, "abcd")
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If getopt() finds "-a" on the command line, then
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bb_getopt_ulflags's return value will be as if "-a -b -c" were
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found.
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Special characters:
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"-" A dash between two options causes the second of the two
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to be unset (and ignored) if it is given on the command line.
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For example:
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The du applet can have the options "-s" and "-d depth", if
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bb_getopt_ulflags finds -s then -d is unset or if it finds -d
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then -s is unset. (Note: busybox implements the GNU
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"--max-depth" option as "-d".) In this case bb_getopt_ulflags's
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return value has no error flag set (0x80000000UL). To achieve
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this result you must set bb_opt_complementaly = "s-d:d-s".
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Only one flag value is added to bb_getopt_ulflags's return
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value depending on the position of the options on the command
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line. If one of the two options requires an argument pointer
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(":" in const char *applet_opts as in "d:") optarg is set
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accordingly.
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char *smax_print_depth;
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bb_opt_complementaly = "s-d:d-s";
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opt = bb_getopt_ulflags(argc, argv, "sd:" , &smax_print_depth);
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if (opt & 2) {
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max_print_depth = bb_xgetularg10_bnd(smax_print_depth,
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0, INT_MAX);
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}
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"~" A tilde between two options or between an option and a group
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of options means that they are mutually exclusive. Unlike
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the "-" case above, an error will be forced if the options
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are used together.
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For example:
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The cut applet must have only one type of list specified, so
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-b, -c and -f are mutally exclusive and should raise an error
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if specified together. In this case you must set
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bb_opt_complementaly = "b~cf:c~bf:f~bc". If two of the
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mutually exclusive options are found, bb_getopt_ulflags's
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return value will have the error flag set (0x80000000UL) so
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that we can check for it:
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if ((flags & 0x80000000UL)
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bb_show_usage();
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"*" A star after a char in bb_opt_complementaly means that the
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option can occur multiple times:
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For example:
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The grep applet can have one or more "-e pattern" arguments.
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In this case you should use bb_getopt_ulflags() as follows:
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llist_t *patterns=NULL;
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(this pointer must be initializated to NULL if the list is empty
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as required by *llist_add_to(llist_t *old_head, char *new_item).)
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bb_opt_complementaly = "e*";
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bb_getopt_ulflags (argc, argv, "e:", &patterns);
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grep -e user -e root /etc/passwd
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root:x:0:0:root:/root:/bin/bash
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user:x:500:500::/home/user:/bin/bash
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*/
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const char *bb_opt_complementaly;
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typedef struct {
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unsigned char opt;
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char list_flg;
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unsigned long switch_on;
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unsigned long switch_off;
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unsigned long incongruously;
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void **optarg; /* char **optarg or llist_t **optarg */
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} t_complementaly;
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/* You can set bb_applet_long_options for parse called long options */
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static const struct option bb_default_long_options[] = {
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/* { "help", 0, NULL, '?' }, */
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{ 0, 0, 0, 0 }
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};
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const struct option *bb_applet_long_options = bb_default_long_options;
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unsigned long
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bb_getopt_ulflags (int argc, char **argv, const char *applet_opts, ...)
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{
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unsigned long flags = 0;
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t_complementaly complementaly[sizeof(flags) * 8 + 1];
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int c;
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const unsigned char *s;
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t_complementaly *on_off;
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va_list p;
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va_start (p, applet_opts);
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/* skip GNU extension */
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s = applet_opts;
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if(*s == '+' || *s == '-')
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s++;
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c = 0;
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on_off = complementaly;
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for (; *s; s++) {
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if(c >= (sizeof(flags)*8))
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break;
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on_off->opt = *s;
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on_off->switch_on = (1 << c);
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on_off->list_flg = 0;
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on_off->switch_off = 0;
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on_off->incongruously = 0;
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on_off->optarg = NULL;
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if (s[1] == ':') {
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on_off->optarg = va_arg (p, void **);
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do
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s++;
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while (s[1] == ':');
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}
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on_off++;
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c++;
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}
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on_off->opt = 0;
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c = 0;
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for (s = bb_opt_complementaly; s && *s; s++) {
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t_complementaly *pair;
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if (*s == ':') {
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c = 0;
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continue;
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}
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if (c)
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continue;
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for (on_off = complementaly; on_off->opt; on_off++)
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if (on_off->opt == *s)
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break;
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pair = on_off;
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for(s++; *s && *s != ':'; s++) {
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if (*s == '-' || *s == '~') {
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c = *s;
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} else if(*s == '*') {
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pair->list_flg++;
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} else {
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unsigned long *pair_switch = &(pair->switch_on);
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if(c)
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pair_switch = c == '-' ? &(pair->switch_off) : &(pair->incongruously);
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for (on_off = complementaly; on_off->opt; on_off++)
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if (on_off->opt == *s) {
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*pair_switch |= on_off->switch_on;
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break;
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}
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}
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}
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s--;
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}
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while ((c = getopt_long (argc, argv, applet_opts,
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bb_applet_long_options, NULL)) > 0) {
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for (on_off = complementaly; on_off->opt != c; on_off++) {
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if(!on_off->opt)
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bb_show_usage ();
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}
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if(flags & on_off->incongruously)
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flags |= 0x80000000UL;
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flags &= ~on_off->switch_off;
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flags |= on_off->switch_on;
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if(on_off->list_flg) {
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*(llist_t **)(on_off->optarg) =
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llist_add_to(*(llist_t **)(on_off->optarg), optarg);
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} else if (on_off->optarg) {
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*(char **)(on_off->optarg) = optarg;
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}
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}
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return flags;
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}
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