lib/argmatch.c

   1 /* argmatch.c -- find a match for a string in an array
   2
   3    Copyright (C) 1990, 1998-1999, 2001-2007, 2009-2019 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* Written by David MacKenzie <djm@ai.mit.edu>
  20    Modified by Akim Demaille <demaille@inf.enst.fr> */
  21
  22 #include <config.h>
  23
  24 /* Specification.  */
  25 #include "argmatch.h"
  26
  27 #include <stdbool.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #include "gettext.h"
  33 #define _(msgid) gettext (msgid)
  34
  35 #include "error.h"
  36 #include "quotearg.h"
  37 #include "quote.h"
  38 #include "getprogname.h"
  39
  40 #if USE_UNLOCKED_IO
  41 # include "unlocked-io.h"
  42 #endif
  43
  44 /* When reporting an invalid argument, show nonprinting characters
  45    by using the quoting style ARGMATCH_QUOTING_STYLE.  Do not use
  46    literal_quoting_style.  */
  47 #ifndef ARGMATCH_QUOTING_STYLE
  48 # define ARGMATCH_QUOTING_STYLE locale_quoting_style
  49 #endif
  50
  51 /* Non failing version of argmatch call this function after failing. */
  52 #ifndef ARGMATCH_DIE
  53 # include "exitfail.h"
  54 # define ARGMATCH_DIE exit (exit_failure)
  55 #endif
  56
  57 #ifdef ARGMATCH_DIE_DECL
  58 ARGMATCH_DIE_DECL;
  59 #endif
  60
  61 static void
  62 __argmatch_die (void)
  63 {
  64   ARGMATCH_DIE;
  65 }
  66
  67 /* Used by XARGMATCH and XARGCASEMATCH.  See description in argmatch.h.
  68    Default to __argmatch_die, but allow caller to change this at run-time. */
  69 argmatch_exit_fn argmatch_die = __argmatch_die;
  70
  71 \f
  72 /* If ARG is an unambiguous match for an element of the
  73    NULL-terminated array ARGLIST, return the index in ARGLIST
  74    of the matched element, else -1 if it does not match any element
  75    or -2 if it is ambiguous (is a prefix of more than one element).
  76
  77    If VALLIST is none null, use it to resolve ambiguities limited to
  78    synonyms, i.e., for
  79      "yes", "yop" -> 0
  80      "no", "nope" -> 1
  81    "y" is a valid argument, for 0, and "n" for 1.  */
  82
  83 ptrdiff_t
  84 argmatch (const char *arg, const char *const *arglist,
  85           const char *vallist, size_t valsize)
  86 {
  87   size_t i;                     /* Temporary index in ARGLIST.  */
  88   size_t arglen;                /* Length of ARG.  */
  89   ptrdiff_t matchind = -1;      /* Index of first nonexact match.  */
  90   bool ambiguous = false;       /* If true, multiple nonexact match(es).  */
  91
  92   arglen = strlen (arg);
  93
  94   /* Test all elements for either exact match or abbreviated matches.  */
  95   for (i = 0; arglist[i]; i++)
  96     {
  97       if (!strncmp (arglist[i], arg, arglen))
  98         {
  99           if (strlen (arglist[i]) == arglen)
 100             /* Exact match found.  */
 101             return i;
 102           else if (matchind == -1)
 103             /* First nonexact match found.  */
 104             matchind = i;
 105           else
 106             {
 107               /* Second nonexact match found.  */
 108               if (vallist == NULL
 109                   || memcmp (vallist + valsize * matchind,
 110                              vallist + valsize * i, valsize))
 111                 {
 112                   /* There is a real ambiguity, or we could not
 113                      disambiguate. */
 114                   ambiguous = true;
 115                 }
 116             }
 117         }
 118     }
 119   if (ambiguous)
 120     return -2;
 121   else
 122     return matchind;
 123 }
 124
 125 /* Error reporting for argmatch.
 126    CONTEXT is a description of the type of entity that was being matched.
 127    VALUE is the invalid value that was given.
 128    PROBLEM is the return value from argmatch.  */
 129
 130 void
 131 argmatch_invalid (const char *context, const char *value, ptrdiff_t problem)
 132 {
 133   char const *format = (problem == -1
 134                         ? _("invalid argument %s for %s")
 135                         : _("ambiguous argument %s for %s"));
 136
 137   error (0, 0, format, quotearg_n_style (0, ARGMATCH_QUOTING_STYLE, value),
 138          quote_n (1, context));
 139 }
 140
 141 /* List the valid arguments for argmatch.
 142    ARGLIST is the same as in argmatch.
 143    VALLIST is a pointer to an array of values.
 144    VALSIZE is the size of the elements of VALLIST */
 145 void
 146 argmatch_valid (const char *const *arglist,
 147                 const char *vallist, size_t valsize)
 148 {
 149   size_t i;
 150   const char *last_val = NULL;
 151
 152   /* We try to put synonyms on the same line.  The assumption is that
 153      synonyms follow each other */
 154   fputs (_("Valid arguments are:"), stderr);
 155   for (i = 0; arglist[i]; i++)
 156     if ((i == 0)
 157         || memcmp (last_val, vallist + valsize * i, valsize))
 158       {
 159         fprintf (stderr, "\n  - %s", quote (arglist[i]));
 160         last_val = vallist + valsize * i;
 161       }
 162     else
 163       {
 164         fprintf (stderr, ", %s", quote (arglist[i]));
 165       }
 166   putc ('\n', stderr);
 167 }
 168
 169 /* Never failing versions of the previous functions.
 170
 171    CONTEXT is the context for which argmatch is called (e.g.,
 172    "--version-control", or "$VERSION_CONTROL" etc.).  Upon failure,
 173    calls the (supposed never to return) function EXIT_FN. */
 174
 175 ptrdiff_t
 176 __xargmatch_internal (const char *context,
 177                       const char *arg, const char *const *arglist,
 178                       const char *vallist, size_t valsize,
 179                       argmatch_exit_fn exit_fn)
 180 {
 181   ptrdiff_t res = argmatch (arg, arglist, vallist, valsize);
 182   if (res >= 0)
 183     /* Success. */
 184     return res;
 185
 186   /* We failed.  Explain why. */
 187   argmatch_invalid (context, arg, res);
 188   argmatch_valid (arglist, vallist, valsize);
 189   (*exit_fn) ();
 190
 191   return -1; /* To please the compilers. */
 192 }
 193
 194 /* Look for VALUE in VALLIST, an array of objects of size VALSIZE and
 195    return the first corresponding argument in ARGLIST */
 196 const char *
 197 argmatch_to_argument (const char *value,
 198                       const char *const *arglist,
 199                       const char *vallist, size_t valsize)
 200 {
 201   size_t i;
 202
 203   for (i = 0; arglist[i]; i++)
 204     if (!memcmp (value, vallist + valsize * i, valsize))
 205       return arglist[i];
 206   return NULL;
 207 }
 208
 209 #ifdef TEST
 210 /*
 211  * Based on "getversion.c" by David MacKenzie <djm@gnu.ai.mit.edu>
 212  */
 213
 214 /* When to make backup files.  */
 215 enum backup_type
 216 {
 217   /* Never make backups.  */
 218   no_backups,
 219
 220   /* Make simple backups of every file.  */
 221   simple_backups,
 222
 223   /* Make numbered backups of files that already have numbered backups,
 224      and simple backups of the others.  */
 225   numbered_existing_backups,
 226
 227   /* Make numbered backups of every file.  */
 228   numbered_backups
 229 };
 230
 231 /* Two tables describing arguments (keys) and their corresponding
 232    values */
 233 static const char *const backup_args[] =
 234 {
 235   "no", "none", "off",
 236   "simple", "never",
 237   "existing", "nil",
 238   "numbered", "t",
 239   0
 240 };
 241
 242 static const enum backup_type backup_vals[] =
 243 {
 244   no_backups, no_backups, no_backups,
 245   simple_backups, simple_backups,
 246   numbered_existing_backups, numbered_existing_backups,
 247   numbered_backups, numbered_backups
 248 };
 249
 250 int
 251 main (int argc, const char *const *argv)
 252 {
 253   const char *cp;
 254   enum backup_type backup_type = no_backups;
 255
 256   if (argc > 2)
 257     {
 258       fprintf (stderr, "Usage: %s [VERSION_CONTROL]\n", getprogname ());
 259       exit (1);
 260     }
 261
 262   if ((cp = getenv ("VERSION_CONTROL")))
 263     backup_type = XARGMATCH ("$VERSION_CONTROL", cp,
 264                              backup_args, backup_vals);
 265
 266   if (argc == 2)
 267     backup_type = XARGMATCH (getprogname (), argv[1],
 268                              backup_args, backup_vals);
 269
 270   printf ("The version control is '%s'\n",
 271           ARGMATCH_TO_ARGUMENT (backup_type, backup_args, backup_vals));
 272
 273   return 0;
 274 }
 275 #endif