src/help.c

   1 /*
   2  * Copyright © 2021-2024 Nick Bowler
   3  *
   4  * Helper functions for formatting --help program output.
   5  *
   6  * In order to support localized output, this depends on the Gnulib gettext-h
   7  * and mbswidth modules.  However, if ENABLE_NLS is not defined (or defined to
   8  * 0) then these modules are not required.
   9  *
  10  * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
  11  * This is free software: you are free to do what the fuck you want to.
  12  * There is NO WARRANTY, to the extent permitted by law.
  13  */
  14
  15 #if HAVE_CONFIG_H
  16 #       include <config.h>
  17 #endif
  18 #include <stdio.h>
  19 #include <stddef.h>
  20 #include <string.h>
  21 #include <assert.h>
  22 #include <limits.h>
  23 #include <getopt.h>
  24
  25 #include "help.h"
  26
  27 #ifndef ENABLE_NLS
  28 #       define ENABLE_NLS 0
  29 #endif
  30 #ifndef HELP_GETOPT_LONG_ONLY
  31 #       define HELP_GETOPT_LONG_ONLY 0
  32 #endif
  33
  34 #if ENABLE_NLS
  35 #       include <locale.h>
  36 #       include <gettext.h>
  37 #       include <mbswidth.h>
  38 #else
  39 #       define gettext(s) (s)
  40 #       define pgettext_expr(c, s) (s)
  41 #       define mbsnwidth(a, b, c) (assert(0), 0)
  42 #endif
  43
  44 #define STR_L10N_(x)
  45 #define N_(s) s
  46
  47 /* Returns a single numeric value depending on the type of option:
  48  *
  49  *   6 - if the option has a short option character and an optional argument
  50  *   5 - if the option has a short option character and a mandatory argument
  51  *   4 - if the option has a short option charater and no argument
  52  *   3 - N/A
  53  *   2 - if the option has no short option character and an optional argument
  54  *   1 - if the option has no short option character and a mandatory argument
  55  *   0 - if the option has no short option character and no argument
  56  */
  57 static int option_type(const struct option *opt)
  58 {
  59         int ret = opt->has_arg & 3;
  60
  61 #if !HELP_GETOPT_LONG_ONLY
  62         if (!opt->flag)
  63                 ret |= (opt->val <= CHAR_MAX) << 2;
  64 #endif
  65
  66         return ret;
  67 }
  68
  69 enum {
  70         OPT_SHORT_WITH_OPTIONAL_ARG  = 6,
  71         OPT_SHORT_WITH_MANDATORY_ARG = 5,
  72         OPT_SHORT_WITHOUT_ARG        = 4,
  73         OPT_LONG_WITH_OPTIONAL_ARG   = 2,
  74         OPT_LONG_WITH_MANDATORY_ARG  = 1,
  75         OPT_LONG_WITHOUT_ARG         = 0
  76 };
  77
  78 #if HELP_GETOPT_LONG_ONLY
  79 /* String table generated by gen-strtab.awk from help-glo.str */
  80 #define STRTAB_INITIALIZER \
  81              N_(" -%s [%s]") \
  82         "\0" "%*s%.*s\n" \
  83         "\0" N_(" -%s %s") \
  84         "\0" N_(" -%s") \
  85         ""
  86 enum {
  87         fmt_long_optional_arg = 0,
  88         fmt_long_mandatory_arg = 19,
  89         fmt_long_without_arg = 27,
  90         fmt_desc = 10,
  91         fmt_nl = 17
  92 };
  93 #else
  94 /* String table generated by gen-strtab.awk from help-std.str */
  95 #define STRTAB_INITIALIZER \
  96         STR_L10N_(N_(" --%s[=%s]")) \
  97         STR_L10N_(N_(" --%s=%s")) \
  98         STR_L10N_(N_(" --%s")) \
  99              N_(" -%c, --%s[=%s]") \
 100         "\0" N_(" -%c, --%s=%s") \
 101         "\0" N_(" -%c, --%s") \
 102         "\0" "%*s%.*s\n" \
 103         ""
 104 enum {
 105         fmt_short_optional_arg = 0,
 106         fmt_long_optional_arg = 5,
 107         fmt_short_mandatory_arg = 16,
 108         fmt_long_mandatory_arg = 21,
 109         fmt_short_without_arg = 30,
 110         fmt_long_without_arg = 35,
 111         fmt_desc = 41,
 112         fmt_nl = 48
 113 };
 114 #endif
 115
 116 static const struct optstr {
 117         unsigned char map[HELP_GETOPT_LONG_ONLY ? 3 : 7];
 118         char tab[sizeof (STRTAB_INITIALIZER)];
 119 } optstr = {
 120         {
 121                 offsetof(struct optstr, tab) + fmt_long_without_arg,
 122                 offsetof(struct optstr, tab) + fmt_long_mandatory_arg,
 123                 offsetof(struct optstr, tab) + fmt_long_optional_arg,
 124 #if !HELP_GETOPT_LONG_ONLY
 125                 0,
 126                 offsetof(struct optstr, tab) + fmt_short_without_arg,
 127                 offsetof(struct optstr, tab) + fmt_short_mandatory_arg,
 128                 offsetof(struct optstr, tab) + fmt_short_optional_arg,
 129 #endif
 130         },
 131         STRTAB_INITIALIZER
 132 };
 133
 134 /*
 135  * When NLS is enabled, we assume snprintf is available.  The GNU libintl
 136  * library should provide a suitable fallback if necessary.
 137  */
 138 #if ENABLE_NLS && !defined(help_do_snprintf)
 139 #define help_do_snprintf snprintf
 140 #elif !ENABLE_NLS
 141 #define help_do_snprintf fake_snprintf
 142 static inline int fake_snprintf(char *buf, size_t n, const char *fmt, ...)
 143 {
 144         return -1;
 145 }
 146 #endif
 147
 148 #define has_short_char(type) (!HELP_GETOPT_LONG_ONLY && (type & 4))
 149
 150 int help_print_optstring(const struct option *opt, const char *argname, int l)
 151 {
 152         int type = option_type(opt);
 153         const char *fmt, *nls_arg;
 154         char optstring[256];
 155         int w;
 156
 157         fmt = (char *)&optstr + optstr.map[type];
 158         if (!ENABLE_NLS)
 159                 goto no_translate;
 160
 161         nls_arg = argname ? pgettext_expr(opt->name, argname) : argname;
 162         if (has_short_char(type)) {
 163                 w = help_do_snprintf(optstring, sizeof optstring,
 164                                      gettext(fmt), opt->val, opt->name,
 165                                      nls_arg);
 166         } else {
 167                 w = help_do_snprintf(optstring, sizeof optstring,
 168                                      gettext(fmt), opt->name,
 169                                      nls_arg);
 170         }
 171
 172         if (w < 0 || w >= sizeof optstring)
 173                 goto no_translate;
 174
 175         w = mbsnwidth(optstring, w, 0);
 176         printf("%s", optstring);
 177         goto out;
 178
 179 no_translate:
 180         if (has_short_char(type)) {
 181                 w = printf(fmt, opt->val, opt->name, argname);
 182         } else {
 183                 w = printf(fmt, opt->name, argname);
 184         }
 185 out:
 186         if (w <= 0 || w > l) {
 187                 putchar('\n');
 188                 return 0;
 189         }
 190
 191         return w;
 192 }
 193
 194 void help_print_desc(const struct option *opt, const char *s, int i, int w)
 195 {
 196         if (opt)
 197                 s = pgettext_expr(opt->name, s);
 198
 199         do {
 200                 size_t n = strcspn(s, &optstr.tab[fmt_nl]);
 201
 202                 printf(&optstr.tab[fmt_desc], n ? i-w : 0, "", (int)n, s);
 203                 s += n + (s[n] != '\0');
 204                 w = 0;
 205         } while (*s);
 206 }