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/*
* Wildcard matching engine for use with SFTP-based file transfer
* programs (PSFTP, new-look PSCP): since SFTP has no notion of
* getting the remote side to do globbing (and rightly so) we have
* to do it locally, by retrieving all the filenames in a directory
* and checking each against the wildcard pattern.
*/
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "putty.h"
/*
* Definition of wildcard syntax:
*
* - * matches any sequence of characters, including zero.
* - ? matches exactly one character which can be anything.
* - [abc] matches exactly one character which is a, b or c.
* - [a-f] matches anything from a through f.
* - [^a-f] matches anything _except_ a through f.
* - [-_] matches - or _; [^-_] matches anything else. (The - is
* non-special if it occurs immediately after the opening
* bracket or ^.)
* - [a^] matches an a or a ^. (The ^ is non-special if it does
* _not_ occur immediately after the opening bracket.)
* - \*, \?, \[, \], \\ match the single characters *, ?, [, ], \.
* - All other characters are non-special and match themselves.
*/
/*
* Some notes on differences from POSIX globs (IEEE Std 1003.1, 2003 ed.):
* - backslashes act as escapes even within [] bracket expressions
* - does not support [!...] for non-matching list (POSIX are weird);
* NB POSIX allows [^...] as well via "A bracket expression starting
* with an unquoted circumflex character produces unspecified
* results". If we wanted to allow [!...] we might want to define
* [^!] as having its literal meaning (match '^' or '!').
* - none of the scary [[:class:]] stuff, etc
*/
/*
* The wildcard matching technique we use is very simple and
* potentially O(N^2) in running time, but I don't anticipate it
* being that bad in reality (particularly since N will be the size
* of a filename, which isn't all that much). Perhaps one day, once
* PuTTY has grown a regexp matcher for some other reason, I might
* come back and reimplement wildcards by translating them into
* regexps or directly into NFAs; but for the moment, in the
* absence of any other need for the NFA->DFA translation engine,
* anything more than the simplest possible wildcard matcher is
* vast code-size overkill.
*
* Essentially, these wildcards are much simpler than regexps in
* that they consist of a sequence of rigid fragments (? and [...]
* can never match more or less than one character) separated by
* asterisks. It is therefore extremely simple to look at a rigid
* fragment and determine whether or not it begins at a particular
* point in the test string; so we can search along the string
* until we find each fragment, then search for the next. As long
* as we find each fragment in the _first_ place it occurs, there
* will never be a danger of having to backpedal and try to find it
* again somewhere else.
*/
enum {
WC_TRAILINGBACKSLASH = 1,
WC_UNCLOSEDCLASS,
WC_INVALIDRANGE
};
/*
* Error reporting is done by returning various negative values
* from the wildcard routines. Passing any such value to wc_error
* will give a human-readable message.
*/
const char *wc_error(int value)
{
value = abs(value);
switch (value) {
case WC_TRAILINGBACKSLASH:
return "'\' occurred at end of string (expected another character)";
case WC_UNCLOSEDCLASS:
return "expected ']' to close character class";
case WC_INVALIDRANGE:
return "character range was not terminated (']' just after '-')";
}
return "INTERNAL ERROR: unrecognised wildcard error number";
}
/*
* This is the routine that tests a target string to see if an
* initial substring of it matches a fragment. If successful, it
* returns 1, and advances both `fragment' and `target' past the
* fragment and matching substring respectively. If unsuccessful it
* returns zero. If the wildcard fragment suffers a syntax error,
* it returns <0 and the precise value indexes into wc_error.
*/
static int wc_match_fragment(const char **fragment, const char **target)
{
const char *f, *t;
f = *fragment;
t = *target;
/*
* The fragment terminates at either the end of the string, or
* the first (unescaped) *.
*/
while (*f && *f != '*' && *t) {
/*
* Extract one character from t, and one character's worth
* of pattern from f, and step along both. Return 0 if they
* fail to match.
*/
if (*f == '\\') {
/*
* Backslash, which means f[1] is to be treated as a
* literal character no matter what it is. It may not
* be the end of the string.
*/
if (!f[1])
return -WC_TRAILINGBACKSLASH; /* error */
if (f[1] != *t)
return 0; /* failed to match */
f += 2;
} else if (*f == '?') {
/*
* Question mark matches anything.
*/
f++;
} else if (*f == '[') {
int invert = 0;
int matched = 0;
/*
* Open bracket introduces a character class.
*/
f++;
if (*f == '^') {
invert = 1;
f++;
}
while (*f != ']') {
if (*f == '\\')
f++; /* backslashes still work */
if (!*f)
return -WC_UNCLOSEDCLASS; /* error again */
if (f[1] == '-') {
int lower, upper, ourchr;
lower = (unsigned char) *f++;
f++; /* eat the minus */
if (*f == ']')
return -WC_INVALIDRANGE; /* different error! */
if (*f == '\\')
f++; /* backslashes _still_ work */
if (!*f)
return -WC_UNCLOSEDCLASS; /* error again */
upper = (unsigned char) *f++;
ourchr = (unsigned char) *t;
if (lower > upper) {
int t = lower; lower = upper; upper = t;
}
if (ourchr >= lower && ourchr <= upper)
matched = 1;
} else {
matched |= (*t == *f++);
}
}
if (invert == matched)
return 0; /* failed to match character class */
f++; /* eat the ] */
} else {
/*
* Non-special character matches itself.
*/
if (*f != *t)
return 0;
f++;
}
/*
* Now we've done that, increment t past the character we
* matched.
*/
t++;
}
if (!*f || *f == '*') {
/*
* We have reached the end of f without finding a mismatch;
* so we're done. Update the caller pointers and return 1.
*/
*fragment = f;
*target = t;
return 1;
}
/*
* Otherwise, we must have reached the end of t before we
* reached the end of f; so we've failed. Return 0.
*/
return 0;
}
/*
* This is the real wildcard matching routine. It returns 1 for a
* successful match, 0 for an unsuccessful match, and <0 for a
* syntax error in the wildcard.
*/
int wc_match(const char *wildcard, const char *target)
{
int ret;
/*
* Every time we see a '*' _followed_ by a fragment, we just
* search along the string for a location at which the fragment
* matches. The only special case is when we see a fragment
* right at the start, in which case we just call the matching
* routine once and give up if it fails.
*/
if (*wildcard != '*') {
ret = wc_match_fragment(&wildcard, &target);
if (ret <= 0)
return ret; /* pass back failure or error alike */
}
while (*wildcard) {
assert(*wildcard == '*');
while (*wildcard == '*')
wildcard++;
/*
* It's possible we've just hit the end of the wildcard
* after seeing a *, in which case there's no need to
* bother searching any more because we've won.
*/
if (!*wildcard)
return 1;
/*
* Now `wildcard' points at the next fragment. So we
* attempt to match it against `target', and if that fails
* we increment `target' and try again, and so on. When we
* find we're about to try matching against the empty
* string, we give up and return 0.
*/
ret = 0;
while (*target) {
const char *save_w = wildcard, *save_t = target;
ret = wc_match_fragment(&wildcard, &target);
if (ret < 0)
return ret; /* syntax error */
if (ret > 0 && !*wildcard && *target) {
/*
* Final special case - literally.
*
* This situation arises when we are matching a
* _terminal_ fragment of the wildcard (that is,
* there is nothing after it, e.g. "*a"), and it
* has matched _too early_. For example, matching
* "*a" against "parka" will match the "a" fragment
* against the _first_ a, and then (if it weren't
* for this special case) matching would fail
* because we're at the end of the wildcard but not
* at the end of the target string.
*
* In this case what we must do is measure the
* length of the fragment in the target (which is
* why we saved `target'), jump straight to that
* distance from the end of the string using
* strlen, and match the same fragment again there
* (which is why we saved `wildcard'). Then we
* return whatever that operation returns.
*/
target = save_t + strlen(save_t) - (target - save_t);
wildcard = save_w;
return wc_match_fragment(&wildcard, &target);
}
if (ret > 0)
break;
target++;
}
if (ret > 0)
continue;
return 0;
}
/*
* If we reach here, it must be because we successfully matched
* a fragment and then found ourselves right at the end of the
* wildcard. Hence, we return 1 if and only if we are also
* right at the end of the target.
*/
return (*target ? 0 : 1);
}
/*
* Another utility routine that translates a non-wildcard string
* into its raw equivalent by removing any escaping backslashes.
* Expects a target string buffer of anything up to the length of
* the original wildcard. You can also pass NULL as the output
* buffer if you're only interested in the return value.
*
* Returns 1 on success, or 0 if a wildcard character was
* encountered. In the latter case the output string MAY not be
* zero-terminated and you should not use it for anything!
*/
int wc_unescape(char *output, const char *wildcard)
{
while (*wildcard) {
if (*wildcard == '\\') {
wildcard++;
/* We are lenient about trailing backslashes in non-wildcards. */
if (*wildcard) {
if (output)
*output++ = *wildcard;
wildcard++;
}
} else if (*wildcard == '*' || *wildcard == '?' ||
*wildcard == '[' || *wildcard == ']') {
return 0; /* it's a wildcard! */
} else {
if (output)
*output++ = *wildcard;
wildcard++;
}
}
*output = '\0';
return 1; /* it's clean */
}
#ifdef TESTMODE
struct test {
const char *wildcard;
const char *target;
int expected_result;
};
const struct test fragment_tests[] = {
/*
* We exhaustively unit-test the fragment matching routine
* itself, which should save us the need to test all its
* intricacies during the full wildcard tests.
*/
{"abc", "abc", 1},
{"abc", "abd", 0},
{"abc", "abcd", 1},
{"abcd", "abc", 0},
{"ab[cd]", "abc", 1},
{"ab[cd]", "abd", 1},
{"ab[cd]", "abe", 0},
{"ab[^cd]", "abc", 0},
{"ab[^cd]", "abd", 0},
{"ab[^cd]", "abe", 1},
{"ab\\", "abc", -WC_TRAILINGBACKSLASH},
{"ab\\*", "ab*", 1},
{"ab\\?", "ab*", 0},
{"ab?", "abc", 1},
{"ab?", "ab", 0},
{"ab[", "abc", -WC_UNCLOSEDCLASS},
{"ab[c-", "abb", -WC_UNCLOSEDCLASS},
{"ab[c-]", "abb", -WC_INVALIDRANGE},
{"ab[c-e]", "abb", 0},
{"ab[c-e]", "abc", 1},
{"ab[c-e]", "abd", 1},
{"ab[c-e]", "abe", 1},
{"ab[c-e]", "abf", 0},
{"ab[e-c]", "abb", 0},
{"ab[e-c]", "abc", 1},
{"ab[e-c]", "abd", 1},
{"ab[e-c]", "abe", 1},
{"ab[e-c]", "abf", 0},
{"ab[^c-e]", "abb", 1},
{"ab[^c-e]", "abc", 0},
{"ab[^c-e]", "abd", 0},
{"ab[^c-e]", "abe", 0},
{"ab[^c-e]", "abf", 1},
{"ab[^e-c]", "abb", 1},
{"ab[^e-c]", "abc", 0},
{"ab[^e-c]", "abd", 0},
{"ab[^e-c]", "abe", 0},
{"ab[^e-c]", "abf", 1},
{"ab[a^]", "aba", 1},
{"ab[a^]", "ab^", 1},
{"ab[a^]", "abb", 0},
{"ab[^a^]", "aba", 0},
{"ab[^a^]", "ab^", 0},
{"ab[^a^]", "abb", 1},
{"ab[-c]", "ab-", 1},
{"ab[-c]", "abc", 1},
{"ab[-c]", "abd", 0},
{"ab[^-c]", "ab-", 0},
{"ab[^-c]", "abc", 0},
{"ab[^-c]", "abd", 1},
{"ab[\\[-\\]]", "abZ", 0},
{"ab[\\[-\\]]", "ab[", 1},
{"ab[\\[-\\]]", "ab\\", 1},
{"ab[\\[-\\]]", "ab]", 1},
{"ab[\\[-\\]]", "ab^", 0},
{"ab[^\\[-\\]]", "abZ", 1},
{"ab[^\\[-\\]]", "ab[", 0},
{"ab[^\\[-\\]]", "ab\\", 0},
{"ab[^\\[-\\]]", "ab]", 0},
{"ab[^\\[-\\]]", "ab^", 1},
{"ab[a-fA-F]", "aba", 1},
{"ab[a-fA-F]", "abF", 1},
{"ab[a-fA-F]", "abZ", 0},
};
const struct test full_tests[] = {
{"a", "argh", 0},
{"a", "ba", 0},
{"a", "a", 1},
{"a*", "aardvark", 1},
{"a*", "badger", 0},
{"*a", "park", 0},
{"*a", "pArka", 1},
{"*a", "parka", 1},
{"*a*", "park", 1},
{"*a*", "perk", 0},
{"?b*r?", "abracadabra", 1},
{"?b*r?", "abracadabr", 0},
{"?b*r?", "abracadabzr", 0},
};
int main(void)
{
int i;
int fails, passes;
fails = passes = 0;
for (i = 0; i < sizeof(fragment_tests)/sizeof(*fragment_tests); i++) {
const char *f, *t;
int eret, aret;
f = fragment_tests[i].wildcard;
t = fragment_tests[i].target;
eret = fragment_tests[i].expected_result;
aret = wc_match_fragment(&f, &t);
if (aret != eret) {
printf("failed test: /%s/ against /%s/ returned %d not %d\n",
fragment_tests[i].wildcard, fragment_tests[i].target,
aret, eret);
fails++;
} else
passes++;
}
for (i = 0; i < sizeof(full_tests)/sizeof(*full_tests); i++) {
const char *f, *t;
int eret, aret;
f = full_tests[i].wildcard;
t = full_tests[i].target;
eret = full_tests[i].expected_result;
aret = wc_match(f, t);
if (aret != eret) {
printf("failed test: /%s/ against /%s/ returned %d not %d\n",
full_tests[i].wildcard, full_tests[i].target,
aret, eret);
fails++;
} else
passes++;
}
printf("passed %d, failed %d\n", passes, fails);
return 0;
}
#endif
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