rm_/lib/rpmatch.c
2022-07-28 14:16:50 +08:00

177 lines
6.0 KiB
C

/* Determine whether string value is affirmation or negative response
according to current locale's data.
Copyright (C) 1996, 1998, 2000, 2002-2003, 2006-2022 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <stdlib.h>
#include <stdbool.h>
#include <stddef.h>
#if ENABLE_NLS
# include <sys/types.h>
# include <limits.h>
# include <string.h>
# if HAVE_LANGINFO_YESEXPR
# include <langinfo.h>
# endif
# include <regex.h>
# include "gettext.h"
# define _(msgid) gettext (msgid)
# define N_(msgid) gettext_noop (msgid)
# if HAVE_LANGINFO_YESEXPR
/* Return the localized regular expression pattern corresponding to
ENGLISH_PATTERN. NL_INDEX can be used with nl_langinfo.
The resulting string may only be used until the next nl_langinfo call. */
static const char *
localized_pattern (const char *english_pattern, nl_item nl_index,
bool posixly_correct)
{
const char *translated_pattern;
/* We prefer to get the patterns from a PO file. It would be possible to
always use nl_langinfo (YESEXPR) instead of _("^[yY]"), and
nl_langinfo (NOEXPR) instead of _("^[nN]"), if we could assume that the
system's locale support is good. But this is not the case e.g. on Cygwin.
The localizations of gnulib.pot are of better quality in general.
Also, if we use locale info from non-free systems that don't have a
'localedef' command, we deprive the users of the freedom to localize
this pattern for their preferred language.
But some programs, such as 'cp', 'mv', 'rm', 'find', 'xargs', are
specified by POSIX to use nl_langinfo (YESEXPR). We implement this
behaviour if POSIXLY_CORRECT is set, for the sake of these programs. */
/* If the user wants strict POSIX compliance, use nl_langinfo. */
if (posixly_correct)
{
translated_pattern = nl_langinfo (nl_index);
/* Check against a broken system return value. */
if (translated_pattern != NULL && translated_pattern[0] != '\0')
return translated_pattern;
}
/* Look in the gnulib message catalog. */
translated_pattern = _(english_pattern);
if (translated_pattern == english_pattern)
{
/* The gnulib message catalog provides no translation.
Try the system's message catalog. */
translated_pattern = nl_langinfo (nl_index);
/* Check against a broken system return value. */
if (translated_pattern != NULL && translated_pattern[0] != '\0')
return translated_pattern;
/* Fall back to English. */
translated_pattern = english_pattern;
}
return translated_pattern;
}
# else
# define localized_pattern(english_pattern,nl_index,posixly_correct) \
_(english_pattern)
# endif
static int
try (const char *response, const char *pattern, char **lastp, regex_t *re)
{
if (*lastp == NULL || strcmp (pattern, *lastp) != 0)
{
char *safe_pattern;
/* The pattern has changed. */
if (*lastp != NULL)
{
/* Free the old compiled pattern. */
regfree (re);
free (*lastp);
*lastp = NULL;
}
/* Put the PATTERN into safe memory before calling regcomp.
(regcomp may call nl_langinfo, overwriting PATTERN's storage. */
safe_pattern = strdup (pattern);
if (safe_pattern == NULL)
return -1;
/* Compile the pattern and cache it for future runs. */
if (regcomp (re, safe_pattern, REG_EXTENDED) != 0)
{
free (safe_pattern);
return -1;
}
*lastp = safe_pattern;
}
/* See if the regular expression matches RESPONSE. */
return regexec (re, response, 0, NULL, 0) == 0;
}
#endif
int
rpmatch (const char *response)
{
#if ENABLE_NLS
/* Match against one of the response patterns, compiling the pattern
first if necessary. */
/* We cache the response patterns and compiled regexps here. */
static char *last_yesexpr, *last_noexpr;
static regex_t cached_yesre, cached_nore;
# if HAVE_LANGINFO_YESEXPR
bool posixly_correct = (getenv ("POSIXLY_CORRECT") != NULL);
# endif
const char *yesexpr, *noexpr;
int result;
/* TRANSLATORS: A regular expression testing for an affirmative answer
(english: "yes"). Testing the first character may be sufficient.
Take care to consider upper and lower case.
To enquire the regular expression that your system uses for this
purpose, you can use the command
locale -k LC_MESSAGES | grep '^yesexpr=' */
yesexpr = localized_pattern (N_("^[yY]"), YESEXPR, posixly_correct);
result = try (response, yesexpr, &last_yesexpr, &cached_yesre);
if (result < 0)
return -1;
if (result)
return 1;
/* TRANSLATORS: A regular expression testing for a negative answer
(english: "no"). Testing the first character may be sufficient.
Take care to consider upper and lower case.
To enquire the regular expression that your system uses for this
purpose, you can use the command
locale -k LC_MESSAGES | grep '^noexpr=' */
noexpr = localized_pattern (N_("^[nN]"), NOEXPR, posixly_correct);
result = try (response, noexpr, &last_noexpr, &cached_nore);
if (result < 0)
return -1;
if (result)
return 0;
return -1;
#else
/* Test against "^[yY]" and "^[nN]", hardcoded to avoid requiring regex */
return (*response == 'y' || *response == 'Y' ? 1
: *response == 'n' || *response == 'N' ? 0 : -1);
#endif
}