lib/argmatch.c

   1 /* argmatch.c -- find a match for a string in an array
   2
   3    Copyright (C) 1990, 1998-1999, 2001-2007, 2009-2020 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 #define _(msgid) gettext (msgid)
  33
  34 #include "error.h"
  35 #include "quotearg.h"
  36 #include "getprogname.h"
  37
  38 #if USE_UNLOCKED_IO
  39 # include "unlocked-io.h"
  40 #endif
  41
  42 /* When reporting an invalid argument, show nonprinting characters
  43    by using the quoting style ARGMATCH_QUOTING_STYLE.  Do not use
  44    literal_quoting_style.  */
  45 #ifndef ARGMATCH_QUOTING_STYLE
  46 # define ARGMATCH_QUOTING_STYLE locale_quoting_style
  47 #endif
  48
  49 /* Non failing version of argmatch call this function after failing. */
  50 #ifndef ARGMATCH_DIE
  51 # include "exitfail.h"
  52 # define ARGMATCH_DIE exit (exit_failure)
  53 #endif
  54
  55 #ifdef ARGMATCH_DIE_DECL
  56 ARGMATCH_DIE_DECL;
  57 #endif
  58
  59 static void
  60 __argmatch_die (void)
  61 {
  62   ARGMATCH_DIE;
  63 }
  64
  65 /* Used by XARGMATCH and XARGCASEMATCH.  See description in argmatch.h.
  66    Default to __argmatch_die, but allow caller to change this at run-time. */
  67 argmatch_exit_fn argmatch_die = __argmatch_die;
  68
  69 \f
  70 /* If ARG is an unambiguous match for an element of the
  71    NULL-terminated array ARGLIST, return the index in ARGLIST
  72    of the matched element, else -1 if it does not match any element
  73    or -2 if it is ambiguous (is a prefix of more than one element).
  74
  75    If VALLIST is none null, use it to resolve ambiguities limited to
  76    synonyms, i.e., for
  77      "yes", "yop" -> 0
  78      "no", "nope" -> 1
  79    "y" is a valid argument, for 0, and "n" for 1.  */
  80
  81 ptrdiff_t
  82 argmatch (const char *arg, const char *const *arglist,
  83           const void *vallist, size_t valsize)
  84 {
  85   size_t i;                     /* Temporary index in ARGLIST.  */
  86   size_t arglen;                /* Length of ARG.  */
  87   ptrdiff_t matchind = -1;      /* Index of first nonexact match.  */
  88   bool ambiguous = false;       /* If true, multiple nonexact match(es).  */
  89
  90   arglen = strlen (arg);
  91
  92   /* Test all elements for either exact match or abbreviated matches.  */
  93   for (i = 0; arglist[i]; i++)
  94     {
  95       if (!strncmp (arglist[i], arg, arglen))
  96         {
  97           if (strlen (arglist[i]) == arglen)
  98             /* Exact match found.  */
  99             return i;
 100           else if (matchind == -1)
 101             /* First nonexact match found.  */
 102             matchind = i;
 103           else
 104             {
 105               /* Second nonexact match found.  */
 106               if (vallist == NULL
 107                   || memcmp ((char const *) vallist + valsize * matchind,
 108                              (char const *) vallist + valsize * i, valsize))
 109                 {
 110                   /* There is a real ambiguity, or we could not
 111                      disambiguate. */
 112                   ambiguous = true;
 113                 }
 114             }
 115         }
 116     }
 117   if (ambiguous)
 118     return -2;
 119   else
 120     return matchind;
 121 }
 122
 123 /* Error reporting for argmatch.
 124    CONTEXT is a description of the type of entity that was being matched.
 125    VALUE is the invalid value that was given.
 126    PROBLEM is the return value from argmatch.  */
 127
 128 void
 129 argmatch_invalid (const char *context, const char *value, ptrdiff_t problem)
 130 {
 131   char const *format = (problem == -1
 132                         ? _("invalid argument %s for %s")
 133                         : _("ambiguous argument %s for %s"));
 134
 135   error (0, 0, format, quotearg_n_style (0, ARGMATCH_QUOTING_STYLE, value),
 136          quote_n (1, context));
 137 }
 138
 139 /* List the valid arguments for argmatch.
 140    ARGLIST is the same as in argmatch.
 141    VALLIST is a pointer to an array of values.
 142    VALSIZE is the size of the elements of VALLIST */
 143 void
 144 argmatch_valid (const char *const *arglist,
 145                 const void *vallist, size_t valsize)
 146 {
 147   size_t i;
 148   const char *last_val = NULL;
 149
 150   /* We try to put synonyms on the same line.  The assumption is that
 151      synonyms follow each other */
 152   fputs (_("Valid arguments are:"), stderr);
 153   for (i = 0; arglist[i]; i++)
 154     if ((i == 0)
 155         || memcmp (last_val, (char const *) vallist + valsize * i, valsize))
 156       {
 157         fprintf (stderr, "\n  - %s", quote (arglist[i]));
 158         last_val = (char const *) vallist + valsize * i;
 159       }
 160     else
 161       {
 162         fprintf (stderr, ", %s", quote (arglist[i]));
 163       }
 164   putc ('\n', stderr);
 165 }
 166
 167 /* Never failing versions of the previous functions.
 168
 169    CONTEXT is the context for which argmatch is called (e.g.,
 170    "--version-control", or "$VERSION_CONTROL" etc.).  Upon failure,
 171    calls the (supposed never to return) function EXIT_FN. */
 172
 173 ptrdiff_t
 174 __xargmatch_internal (const char *context,
 175                       const char *arg, const char *const *arglist,
 176                       const void *vallist, size_t valsize,
 177                       argmatch_exit_fn exit_fn)
 178 {
 179   ptrdiff_t res = argmatch (arg, arglist, vallist, valsize);
 180   if (res >= 0)
 181     /* Success. */
 182     return res;
 183
 184   /* We failed.  Explain why. */
 185   argmatch_invalid (context, arg, res);
 186   argmatch_valid (arglist, vallist, valsize);
 187   (*exit_fn) ();
 188
 189   return -1; /* To please the compilers. */
 190 }
 191
 192 /* Look for VALUE in VALLIST, an array of objects of size VALSIZE and
 193    return the first corresponding argument in ARGLIST */
 194 const char *
 195 argmatch_to_argument (const void *value,
 196                       const char *const *arglist,
 197                       const void *vallist, size_t valsize)
 198 {
 199   size_t i;
 200
 201   for (i = 0; arglist[i]; i++)
 202     if (!memcmp (value, (char const *) vallist + valsize * i, valsize))
 203       return arglist[i];
 204   return NULL;
 205 }
 206
 207 #ifdef TEST
 208 /*
 209  * Based on "getversion.c" by David MacKenzie <djm@gnu.ai.mit.edu>
 210  */
 211
 212 /* When to make backup files.  */
 213 enum backup_type
 214 {
 215   /* Never make backups.  */
 216   no_backups,
 217
 218   /* Make simple backups of every file.  */
 219   simple_backups,
 220
 221   /* Make numbered backups of files that already have numbered backups,
 222      and simple backups of the others.  */
 223   numbered_existing_backups,
 224
 225   /* Make numbered backups of every file.  */
 226   numbered_backups
 227 };
 228
 229 /* Two tables describing arguments (keys) and their corresponding
 230    values */
 231 static const char *const backup_args[] =
 232 {
 233   "no", "none", "off",
 234   "simple", "never",
 235   "existing", "nil",
 236   "numbered", "t",
 237   0
 238 };
 239
 240 static const enum backup_type backup_vals[] =
 241 {
 242   no_backups, no_backups, no_backups,
 243   simple_backups, simple_backups,
 244   numbered_existing_backups, numbered_existing_backups,
 245   numbered_backups, numbered_backups
 246 };
 247
 248 int
 249 main (int argc, const char *const *argv)
 250 {
 251   const char *cp;
 252   enum backup_type backup_type = no_backups;
 253
 254   if (argc > 2)
 255     {
 256       fprintf (stderr, "Usage: %s [VERSION_CONTROL]\n", getprogname ());
 257       exit (1);
 258     }
 259
 260   if ((cp = getenv ("VERSION_CONTROL")))
 261     backup_type = XARGMATCH ("$VERSION_CONTROL", cp,
 262                              backup_args, backup_vals);
 263
 264   if (argc == 2)
 265     backup_type = XARGMATCH (getprogname (), argv[1],
 266                              backup_args, backup_vals);
 267
 268   printf ("The version control is '%s'\n",
 269           ARGMATCH_TO_ARGUMENT (backup_type, backup_args, backup_vals));
 270
 271   return 0;
 272 }
 273 #endif