busybox vgetopt32

/* vi: set sw=4 ts=4: */
/*
 * universal getopt32 implementation for busybox
 *
 * Copyright (C) 2003-2005  Vladimir Oleynik  <[email protected]>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#if ENABLE_LONG_OPTS
# include <getopt.h>
#endif
#include "libbb.h"

//kbuild:lib-y += getopt32.o

/*      Documentation

uint32_t
getopt32(char **argv, const char *applet_opts, ...)

        The command line options are passed as the applet_opts string.

        If one of the given options is found, a flag value is added to
        the return value.

        The flag value is determined by the position of the char in
        applet_opts string.  For example:

        flags = getopt32(argv, "rnug");

        "r" will set 1    (bit 0)
        "n" will set 2    (bit 1)
        "u" will set 4    (bit 2)
        "g" will set 8    (bit 3)

        and so on.  You can also look at the return value as a bit
        field and each option sets one bit.

        On exit, global variable optind is set so that if you
        will do argc -= optind; argv += optind; then
        argc will be equal to number of remaining non-option
        arguments, first one would be in argv[0], next in argv[1] and so on
        (options and their parameters will be moved into argv[]
        positions prior to argv[optind]).

 "o:"   If one of the options requires an argument, then add a ":"
        after the char in applet_opts and provide a pointer to store
        the argument.  For example:

        char *pointer_to_arg_for_a;
        char *pointer_to_arg_for_b;
        char *pointer_to_arg_for_c;
        char *pointer_to_arg_for_d;

        flags = getopt32(argv, "a:b:c:d:",
                        &pointer_to_arg_for_a, &pointer_to_arg_for_b,
                        &pointer_to_arg_for_c, &pointer_to_arg_for_d);

        The type of the pointer may be controlled by "o::" or "o+" in
        the external string opt_complementary (see below for more info).

 "o::"  If option can have an *optional* argument, then add a "::"
        after its char in applet_opts and provide a pointer to store
        the argument.  Note that optional arguments _must_
        immediately follow the option: -oparam, not -o param.

 "o:+"  This means that the parameter for this option is a nonnegative integer.
        It will be processed with xatoi_positive() - allowed range
        is 0..INT_MAX.

        int param;  // "unsigned param;" will also work
        getopt32(argv, "p:+", &param);

 "o:*"  This means that the option can occur multiple times. Each occurrence
        will be saved as a llist_t element instead of char*.

        For example:
        The grep applet can have one or more "-e pattern" arguments.
        In this case you should use getopt32() as follows:

        llist_t *patterns = NULL;

        (this pointer must be initializated to NULL if the list is empty
        as required by llist_add_to_end(llist_t **old_head, char *new_item).)

        getopt32(argv, "e:*", &patterns);

        $ grep -e user -e root /etc/passwd
        root:x:0:0:root:/root:/bin/bash
        user:x:500:500::/home/user:/bin/bash

 "+"    If the first character in the applet_opts string is a plus,
        then option processing will stop as soon as a non-option is
        encountered in the argv array.  Useful for applets like env
        which should not process arguments to subprograms:
        env -i ls -d /
        Here we want env to process just the '-i', not the '-d'.

 "!"    Report bad options, missing required options,
        inconsistent options with all-ones return value (instead of abort).

 "^"    options string is "^optchars""\0""opt_complementary".

uint32_t
getopt32long(char **argv, const char *applet_opts, const char *logopts...)

        This allows you to define long options:

        static const char applet_longopts[] ALIGN1 =
                //"name\0"  has_arg     val
                "verbose\0" No_argument "v"
                ;
        opt = getopt32long(argv, applet_opts, applet_longopts, ...);

        The last element (val) typically is set to
        matching short option from applet_opts. If there is no matching
        char in applet_opts, then:
        - return bit has next position after short options
        - if has_arg is not "No_argument", use ptr for arg also
        - opt_complementary affects it too

        Note: a good applet will make long options configurable via the
        config process and not a required feature.  The current standard
        is to name the config option CONFIG_FEATURE_<applet>_LONG_OPTIONS.

opt_complementary - option modifiers.

 ":"    The colon (":") is used to separate groups of two or more chars
        and/or groups of chars and special characters (stating some
        conditions to be checked).

 "abc"  If groups of two or more chars are specified, the first char
        is the main option and the other chars are secondary options.
        Their flags will be turned on if the main option is found even
        if they are not specified on the command line.  For example:

        flags = getopt32(argv, "^abcd""\0""abc")

        If getopt() finds "-a" on the command line, then
        getopt32's return value will be as if "-a -b -c" were
        found.

 "ww"   Adjacent double options have a counter associated which indicates
        the number of occurrences of the option.
        For example the ps applet needs:
        if w is given once, GNU ps sets the width to 132,
        if w is given more than once, it is "unlimited"

        int w_counter = 0; // must be initialized!
        getopt32(argv, "^w""\0""ww", &w_counter);
        if (w_counter)
                width = (w_counter == 1) ? 132 : INT_MAX;
        else
                get_terminal_width(...&width...);

        w_counter is a pointer to an integer. It has to be passed to
        getopt32() after all other option argument sinks.

        For example: accept multiple -v to indicate the level of verbosity
        and for each -b optarg, add optarg to my_b. Finally, if b is given,
        turn off c and vice versa:

        llist_t *my_b = NULL;
        int verbose_level = 0;
        f = getopt32(argv, "^vb:*c"
            "\0""vv:b-c:c-b"
            , &my_b, &verbose_level);
        if (f & 2)       // -c after -b unsets -b flag
                while (my_b) dosomething_with(llist_pop(&my_b));
        if (my_b)        // but llist is stored if -b is specified
                free_llist(my_b);
        if (verbose_level) printf("verbose level is %d\n", verbose_level);

Special characters:

 "-N"   A dash as the first char in a opt_complementary group followed
        by a single digit (0-9) means that at least N non-option
        arguments must be present on the command line

 "=N"   An equal sign as the first char in a opt_complementary group followed
        by a single digit (0-9) means that exactly N non-option
        arguments must be present on the command line

 "?N"   A "?" as the first char in a opt_complementary group followed
        by a single digit (0-9) means that at most N arguments must be present
        on the command line.

 "V-"   An option with dash before colon or end-of-line results in
        bb_show_usage() being called if this option is encountered.
        This is typically used to implement "print verbose usage message
        and exit" option.

 "a-b"  A dash between two options causes the second of the two
        to be unset (and ignored) if it is given on the command line.

        [FIXME: what if they are the same? like "x-x"? Is it ever useful?]

        For example:
        The du applet has the options "-s" and "-d depth".  If
        getopt32 finds -s, then -d is unset or if it finds -d
        then -s is unset.  (Note:  busybox implements the GNU
        "--max-depth" option as "-d".)  To obtain this behavior, you
        set opt_complementary to "s-d:d-s".  Only one flag value is
        added to getopt32's return value depending on the
        position of the options on the command line.  If one of the
        two options requires an argument pointer (":" in applet_opts
        as in "d:") optarg is set accordingly.

        char *smax_print_depth;

        opt = getopt32(argv, "^sd:x""\0""s-d:d-s:x-x", &smax_print_depth);

        if (opt & 2)
                max_print_depth = atoi(smax_print_depth);
        if (opt & 4)
                printf("Detected odd -x usage\n");

 "a--b" A double dash between two options, or between an option and a group
        of options, means that they are mutually exclusive.  Unlike
        the "-" case above, an error will be forced if the options
        are used together.

        For example:
        The cut applet must have only one type of list specified, so
        -b, -c and -f are mutually exclusive and should raise an error
        if specified together.  In this case you must set
        opt_complementary to "b--cf:c--bf:f--bc".  If two of the
        mutually exclusive options are found, getopt32 will call
        bb_show_usage() and die.

 "x--x" Variation of the above, it means that -x option should occur
        at most once.

 "o+"   A plus after a char in opt_complementary means that the parameter
        for this option is a nonnegative integer. It will be processed
        with xatoi_positive() - allowed range is 0..INT_MAX.

        int param;  // "unsigned param;" will also work
        getopt32(argv, "^p:""\0""p+", &param);

 "o::"  A double colon after a char in opt_complementary means that the
        option can occur multiple times. Each occurrence will be saved as
        a llist_t element instead of char*.

        For example:
        The grep applet can have one or more "-e pattern" arguments.
        In this case you should use getopt32() as follows:

        llist_t *patterns = NULL;

        (this pointer must be initializated to NULL if the list is empty
        as required by llist_add_to_end(llist_t **old_head, char *new_item).)

        getopt32(argv, "^e:""\0""e::", &patterns);

        $ grep -e user -e root /etc/passwd
        root:x:0:0:root:/root:/bin/bash
        user:x:500:500::/home/user:/bin/bash

        "o+" and "o::" can be handled by "o:+" and "o:*" specifiers
        in option string (and it is preferred), but this does not work
        for "long options only" cases, such as tar --exclude=PATTERN,
        wget --header=HDR cases.

 "a?b"  A "?" between an option and a group of options means that
        at least one of them is required to occur if the first option
        occurs in preceding command line arguments.

        For example from "id" applet:

        // Don't allow -n -r -rn -ug -rug -nug -rnug
        flags = getopt32(argv, "^rnug""\0""r?ug:n?ug:u--g:g--u");

        This example allowed only:
        $ id; id -u; id -g; id -ru; id -nu; id -rg; id -ng; id -rnu; id -rng

 "X"    A opt_complementary group with just a single letter means
        that this option is required. If more than one such group exists,
        at least one option is required to occur (not all of them).
        For example from "start-stop-daemon" applet:

        // Don't allow -KS -SK, but -S or -K is required
        flags = getopt32(argv, "^KS...""\0""K:S:K--S:S--K");


        Don't forget to use ':'. For example, "?322-22-23X-x-a"
        is interpreted as "?3:22:-2:2-2:2-3Xa:2--x" -
        max 3 args; count uses of '-2'; min 2 args; if there is
        a '-2' option then unset '-3', '-X' and '-a'; if there is
        a '-2' and after it a '-x' then error out.
        But it's far too obfuscated. Use ':' to separate groups.
*/

/* Code here assumes that 'unsigned' is at least 32 bits wide */

const char *const bb_argv_dash[] = { "-", NULL };

enum {
    PARAM_STRING,
    PARAM_LIST,
    PARAM_INT,
};

typedef struct {
    unsigned char opt_char;
    smallint param_type;
    unsigned switch_on;
    unsigned switch_off;
    unsigned incongruously;
    unsigned requires;
    void **optarg;  /* char**, llist_t** or int *. */
    int *counter;
} t_complementary;

uint32_t option_mask32;

#if ENABLE_LONG_OPTS
static const struct option bb_null_long_options[1] = {
    { 0, 0, 0, 0 }
};
#else
#define vgetopt32(argv,applet_opts,applet_long_options,p) \
    vgetopt32(argv,applet_opts,p)
#endif

/* Please keep getopt32 free from xmalloc */

static uint32_t
vgetopt32(char **argv, const char *applet_opts, const char *applet_long_options, va_list p)
{
    int argc;
    unsigned flags = 0;
    unsigned requires = 0;
    unsigned len;
    t_complementary complementary[33]; /* last stays zero-filled */
    char dont_die_flag;
    int c;
    const unsigned char *s;
    const char *opt_complementary;
    t_complementary *on_off;
#if ENABLE_LONG_OPTS
    const struct option *l_o;
    struct option *long_options = (struct option *) &bb_null_long_options;
#endif
    unsigned trigger;
    int min_arg = 0;
    int max_arg = -1;
    int spec_flgs = 0;

#define SHOW_USAGE_IF_ERROR     1

    on_off = complementary;
    memset(on_off, 0, sizeof(complementary));

    //strlen截取applet_opts部分
    len = strlen(applet_opts);

    /* skip bbox extension */
    opt_complementary = NULL;
    //^表示這個參數中帶有applet_long_options和opt_complementary，中間通過'\0'隔開的
    if (applet_opts[0] == '^') {
        applet_opts++;
        /* point it past terminating NUL */
        opt_complementary = applet_opts + len;
    }

    /* skip another bbox extension */
    dont_die_flag = applet_opts[0];
    //！表示如果失敗了也不要直接崩掉還是要返回
    if (dont_die_flag == '!')
        applet_opts++;

    applet_opts = strcpy(alloca(len + 1), applet_opts);

    /* skip GNU extension */
    s = (const unsigned char *)applet_opts;
    if (*s == '+' || *s == '-')
        s++;
    c = 0;
    while (*s) {
        if (c >= 32)//sizeof(uint32_t)=4B=32b
            break;
        on_off->opt_char = *s;
        on_off->switch_on = (1U << c);//c是字符出現的位置也就是index
        //o: 當一個字符後面加：此時會給這個選項加一個返回值，也就是pointer_to_arg_for_a等等
        if (*++s == ':') {
            on_off->optarg = va_arg(p, void **);
            //o:+ 表示此項是一個正數 o:*：表示此項可以多次出現
            if (s[1] == '+' || s[1] == '*') {
                /* 'o:+' or 'o:*' */
                on_off->param_type = (s[1] == '+') ?
                    PARAM_INT : PARAM_LIST;
                overlapping_strcpy((char*)s + 1, (char*)s + 2);
            }
            /* skip possible 'o::' (or 'o:+:' !) */
            while (*++s == ':')
                continue;
        }
        on_off++;
        c++;
    }

#if ENABLE_LONG_OPTS
    if (applet_long_options) {
        const char *optstr;
        unsigned i, count;

        count = 1;
        //計算長選項的個數
        optstr = applet_long_options;
        while (optstr[0]) {
            optstr += strlen(optstr) + 3; /* skip NUL, has_arg, val */
            count++;
        }
        /* count == no. of longopts + 1 */
        long_options = alloca(count * sizeof(*long_options));
        memset(long_options, 0, count * sizeof(*long_options));
        i = 0;
        //對長選項進行數據初始化
        optstr = applet_long_options;
        while (--count) {
            long_options[i].name = optstr;
            optstr += strlen(optstr) + 1;
            long_options[i].has_arg = (unsigned char)(*optstr++);
            /* long_options[i].flag = NULL; */
            long_options[i].val = (unsigned char)(*optstr++);
            i++;
        }
        //查找這個長選項有沒有添加到主選項列表，沒用就添加進去，直接添加到之前數據的後面
        for (l_o = long_options; l_o->name; l_o++) {
            if (l_o->flag)
                continue;
            for (on_off = complementary; on_off->opt_char; on_off++)
                if (on_off->opt_char == l_o->val)
                    goto next_long;
            if (c >= 32)
                break;
            on_off->opt_char = l_o->val;
            on_off->switch_on = (1U << c);
            if (l_o->has_arg != no_argument)
                on_off->optarg = va_arg(p, void **);
            c++;
 next_long: ;
        }
    }
#endif /* ENABLE_LONG_OPTS */

    s = (const unsigned char *)opt_complementary;
    if (s) for (; *s; s++) {
        t_complementary *pair;
        unsigned *pair_switch;

        if (*s == ':')
            continue;
        c = s[1];
        //
        if (*s == '?') {//？N 表示在命令行裏最多出現N次
            if (c < '0' || c > '9') {
                spec_flgs |= SHOW_USAGE_IF_ERROR;
            } else {
                max_arg = c - '0';
                s++;
            }
            continue;
        }
        if (*s == '-') {//-N 至少要在命令行裏面出現N個非選項的參數
            if (c >= '0' && c <= '9') {
                min_arg = c - '0';
                s++;
            }
            continue;
        }
        if (*s == '=') {//=N 在命令行裏出現恰好N個非選項參數
            min_arg = max_arg = c - '0';
            s++;
            continue;
        }
        //查找對應的選項是不是存在，按道理是必須存在的，不知道你加這個選項修飾符幹什麼
        for (on_off = complementary; on_off->opt_char; on_off++)
            if (on_off->opt_char == *s)
                goto found_opt;
        /* Without this, diagnostic of such bugs is not easy */
        bb_error_msg_and_die("NO OPT %c!", *s);
 found_opt:
        if (c == ':' && s[2] == ':') {//o::表示此項可以多次出現  比如grep -e user -e root /etc/passwd
            on_off->param_type = PARAM_LIST;
            continue;
        }
        if (c == '+' && (s[2] == ':' || s[2] == '\0')) {//o+: or o+'\0' 表示此項是正數
            on_off->param_type = PARAM_INT;
            s++;
            continue;
        }
        if (c == ':' || c == '\0') {//o: or o'\0' 表示此項是必選項
            requires |= on_off->switch_on;
            continue;
        }
        if (c == '-' && (s[2] == ':' || s[2] == '\0')) {//o-: or o-'\0' 表示此項可以忽略
            flags |= on_off->switch_on;
            on_off->incongruously |= on_off->switch_on;
            s++;
            continue;
        }
        if (c == *s) {//ww：表示可以出現無限制
            on_off->counter = va_arg(p, int *);
            s++;
        }
        pair = on_off;
        pair_switch = &pair->switch_on;
        for (s++; *s && *s != ':'; s++) {
            if (*s == '?') {//a ? or ab? or abc?
                pair_switch = &pair->requires;//a?b
            } else if (*s == '-') {//a -  or a--
                if (pair_switch == &pair->switch_off)//a-後面再跟一個-就是a--
                    pair_switch = &pair->incongruously;//a--b 互相排斥的
                else //a-
                    pair_switch = &pair->switch_off;//如果後面直接跟選項就是a-b
            } else {//ab or a?b or a-b or a--b
                for (on_off = complementary; on_off->opt_char; on_off++)
                    if (on_off->opt_char == *s) {
                        /*這個地方pair_swith代表第一個出現的選項的不同的數據的地址，比如是a--bc那麼pair_switch=&pair->incongruously
　　　　　　　　　　        然後當解析到b的時候a的排斥項就多了一個b，到c的時候a的排斥就再多一個c，也就是排斥bc*/
                        *pair_switch |= on_off->switch_on;
                        break;
                    }
            }
        }
        s--;
    }

    /* In case getopt32 was already called:
     * reset libc getopt() internal state.
     * run_nofork_applet() does this, but we might end up here
     * also via gunzip_main() -> gzip_main(). Play safe.
     */
    GETOPT_RESET();

    /* skip 0: some applets cheat: they do not actually HAVE argv[0] */
    argc = 1 + string_array_len(argv + 1);

    /* Note: just "getopt() <= 0" will not work well for
     * "fake" short options, like this one:
     * wget $'-\203' "Test: test" http://kernel.org/
     * (supposed to act as --header, but doesn't) */
#if ENABLE_LONG_OPTS
    while ((c = getopt_long(argc, argv, applet_opts,
            long_options, NULL)) != -1) {
#else
    while ((c = getopt(argc, argv, applet_opts)) != -1) {//getopt glibc可以看源代名
#endif
        /* getopt prints "option requires an argument -- X"
         * and returns '?' if an option has no arg, but one is reqd */
        c &= 0xff; /* fight libc's sign extension */
        for (on_off = complementary; on_off->opt_char != c; on_off++) {
            /* c can be NUL if long opt has non-NULL ->flag,
             * but we construct long opts so that flag
             * is always NULL (see above) */
            if (on_off->opt_char == '\0' /* && c != '\0' */) {
                /* c is probably '?' - "bad option" */
                goto error;
            }
        }
        //存在一個互斥的選項同時存在就不對了
        if (flags & on_off->incongruously)
            goto error;
        trigger = on_off->switch_on & on_off->switch_off;//a-b
        flags &= ~(on_off->switch_off ^ trigger);//!(a-b) 0反轉就是全1 1反轉就是全0 去掉a-b
        flags |= on_off->switch_on ^ trigger;//保留a
        flags ^= trigger;
        if (on_off->counter)
            (*(on_off->counter))++;
        if (optarg) {//這個optarg是getopt產生的一個全局變量 可以看相關代碼
            if (on_off->param_type == PARAM_LIST) {
                llist_add_to_end((llist_t **)(on_off->optarg), optarg);
            } else if (on_off->param_type == PARAM_INT) {
//TODO: xatoi_positive indirectly pulls in printf machinery
                *(unsigned*)(on_off->optarg) = xatoi_positive(optarg);
            } else if (on_off->optarg) {
                *(char **)(on_off->optarg) = optarg;
            }
        }
    }

    /* check depending requires for given options */
    for (on_off = complementary; on_off->opt_char; on_off++) {//a ? b 必須至少出現一個
        if (on_off->requires
         && (flags & on_off->switch_on)
         && (flags & on_off->requires) == 0
        ) {
            goto error;
        }
    }
    if (requires && (flags & requires) == 0)//必選項必須有
        goto error;
    argc -= optind;
    if (argc < min_arg || (max_arg >= 0 && argc > max_arg))
        goto error;

    option_mask32 = flags;
    return flags;

 error:
    if (dont_die_flag != '!')
        bb_show_usage();
    return (int32_t)-1;
}

uint32_t FAST_FUNC
getopt32(char **argv, const char *applet_opts, ...)
{
    uint32_t opt;
    va_list p;

    va_start(p, applet_opts);
    opt = vgetopt32(argv, applet_opts, NULL, p);
    va_end(p);
    return opt;
}

#if ENABLE_LONG_OPTS
uint32_t FAST_FUNC
getopt32long(char **argv, const char *applet_opts, const char *longopts, ...)
{
    uint32_t opt;
    va_list p;

    va_start(p, longopts);
    opt = vgetopt32(argv, applet_opts, longopts, p);
    va_end(p);
    return opt;
}
#endif