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mc/lib/strutil/filevercmp.c

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/*
Copyright (C) 1995 Ian Jackson <iwj10@cus.cam.ac.uk>
Copyright (C) 2001 Anthony Towns <aj@azure.humbug.org.au>
Copyright (C) 2008-2022 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdlib.h>
#include <limits.h>
#include "lib/strutil.h"
/*** global variables ****************************************************************************/
/*** file scope macro definitions ****************************************************************/
/*** file scope type declarations ****************************************************************/
/*** forward declarations (file scope functions) *************************************************/
/*** file scope variables ************************************************************************/
/* --------------------------------------------------------------------------------------------- */
/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */
/* Return the length of a prefix of @s that corresponds to the suffix defined by this extended
* regular expression in the C locale: (\.[A-Za-z~][A-Za-z0-9~]*)*$
*
* Use the longest suffix matching this regular expression, except do not use all of s as a suffix
* if s is nonempty.
*
* If *len is -1, s is a string; set *lem to s's length.
* Otherwise, *len should be nonnegative, s is a char array, and *len does not change.
*/
static ssize_t
file_prefixlen (const char *s, ssize_t *len)
{
size_t n = (size_t) (*len); /* SIZE_MAX if N == -1 */
size_t i = 0;
size_t prefixlen = 0;
while (TRUE)
{
gboolean done;
if (*len < 0)
done = s[i] == '\0';
else
done = i == n;
if (done)
{
*len = (ssize_t) i;
return (ssize_t) prefixlen;
}
i++;
prefixlen = i;
while (i + 1 < n && s[i] == '.' && (g_ascii_isalpha (s[i + 1]) || s[i + 1] == '~'))
for (i += 2; i < n && (g_ascii_isalnum (s[i]) || s[i] == '~'); i++)
;
}
}
/* --------------------------------------------------------------------------------------------- */
/* Return a version sort comparison value for @s's byte at position @pos.
*
* @param s a string
* @param pos a position in @s
* @param len a length of @s. If @pos == @len, sort before all non-'~' bytes.
*/
static int
order (const char *s, size_t pos, size_t len)
{
unsigned char c;
if (pos == len)
return (-1);
c = s[pos];
if (g_ascii_isdigit (c))
return 0;
if (g_ascii_isalpha (c))
return c;
if (c == '~')
return (-2);
g_assert (UCHAR_MAX <= (INT_MAX - 1 - 2) / 2);
return (int) c + UCHAR_MAX + 1;
}
/* --------------------------------------------------------------------------------------------- */
/* Slightly modified verrevcmp function from dpkg
*
* This implements the algorithm for comparison of version strings
* specified by Debian and now widely adopted. The detailed
* specification can be found in the Debian Policy Manual in the
* section on the 'Version' control field. This version of the code
* implements that from s5.6.12 of Debian Policy v3.8.0.1
* https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
*
* @param s1 first char array to compare
* @param s1_len length of @s1
* @param s2 second char array to compare
* @param s2_len length of @s2
*
* @return an integer less than, equal to, or greater than zero, if @s1 is <, == or > than @s2.
*/
static int
verrevcmp (const char *s1, ssize_t s1_len, const char *s2, ssize_t s2_len)
{
ssize_t s1_pos = 0;
ssize_t s2_pos = 0;
while (s1_pos < s1_len || s2_pos < s2_len)
{
int first_diff = 0;
while ((s1_pos < s1_len && !g_ascii_isdigit (s1[s1_pos]))
|| (s2_pos < s2_len && !g_ascii_isdigit (s2[s2_pos])))
{
int s1_c, s2_c;
s1_c = order (s1, s1_pos, s1_len);
s2_c = order (s2, s2_pos, s2_len);
if (s1_c != s2_c)
return (s1_c - s2_c);
s1_pos++;
s2_pos++;
}
while (s1_pos < s1_len && s1[s1_pos] == '0')
s1_pos++;
while (s2_pos < s2_len && s2[s2_pos] == '0')
s2_pos++;
while (s1_pos < s1_len && s2_pos < s2_len
&& g_ascii_isdigit (s1[s1_pos]) && g_ascii_isdigit (s2[s2_pos]))
{
if (first_diff == 0)
first_diff = s1[s1_pos] - s2[s2_pos];
s1_pos++;
s2_pos++;
}
if (s1_pos < s1_len && g_ascii_isdigit (s1[s1_pos]))
return 1;
if (s2_pos < s2_len && g_ascii_isdigit (s2[s2_pos]))
return (-1);
if (first_diff != 0)
return first_diff;
}
return 0;
}
/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */
/* Compare version strings.
*
* @param s1 first string to compare
* @param s2 second string to compare
*
* @return an integer less than, equal to, or greater than zero, if @s1 is <, == or > than @s2.
*/
int
filevercmp (const char *s1, const char *s2)
{
return filenvercmp (s1, -1, s2, -1);
}
/* --------------------------------------------------------------------------------------------- */
/* Compare version strings.
*
* @param a first string to compare
* @param alen length of @a or (-1)
* @param b second string to compare
* @param blen length of @b or (-1)
*
* @return an integer less than, equal to, or greater than zero, if @s1 is <, == or > than @s2.
*/
int
filenvercmp (const char *a, ssize_t alen, const char *b, ssize_t blen)
{
gboolean aempty, bempty;
ssize_t aprefixlen, bprefixlen;
gboolean one_pass_only;
int result;
/* Special case for empty versions. */
aempty = alen < 0 ? a[0] == '\0' : alen == 0;
bempty = blen < 0 ? b[0] == '\0' : blen == 0;
if (aempty)
return (bempty ? 0 : -1);
if (bempty)
return 1;
/* Special cases for leading ".": "." sorts first, then "..", then other names with leading ".",
then other names. */
if (a[0] == '.')
{
gboolean adot, bdot;
gboolean adotdot, bdotdot;
if (b[0] != '.')
return (-1);
adot = alen < 0 ? a[1] == '\0' : alen == 1;
bdot = blen < 0 ? b[1] == '\0' : blen == 1;
if (adot)
return (bdot ? 0 : -1);
if (bdot)
return 1;
adotdot = a[1] == '.' && (alen < 0 ? a[2] == '\0' : alen == 2);
bdotdot = b[1] == '.' && (blen < 0 ? b[2] == '\0' : blen == 2);
if (adotdot)
return (bdotdot ? 0 : -1);
if (bdotdot)
return 1;
}
else if (b[0] == '.')
return 1;
/* Cut file suffixes. */
aprefixlen = file_prefixlen (a, &alen);
bprefixlen = file_prefixlen (b, &blen);
/* If both suffixes are empty, a second pass would return the same thing. */
one_pass_only = aprefixlen == alen && bprefixlen == blen;
result = verrevcmp (a, aprefixlen, b, bprefixlen);
/* Return the initial result if nonzero, or if no second pass is needed.
Otherwise, restore the suffixes and try again. */
return (result != 0 || one_pass_only ? result : verrevcmp (a, alen, b, blen));
}
/* --------------------------------------------------------------------------------------------- */
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