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Speed up unquoting of quoted double quotes and backslashes.

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This commit is contained in:
Alasdair Kergon 2010-09-28 01:29:06 +00:00
parent 8a075c6123
commit f6b1c45bf1
2 changed files with 51 additions and 21 deletions
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1
WHATS_NEW
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@ -1,5 +1,6 @@
Version 2.02.75 -
=====================================
Speed up unquoting of quoted double quotes and backslashes.
Speed up CRC32 calculations by using a larger lookup table.
Version 2.02.74 - 24th September 2010

71
lib/misc/lvm-string.c
View File

@ -108,33 +108,64 @@ static void _quote_characters(char **out, const char *src,
}
}
static void _unquote_one_character(char *src, const char orig_char,
const char quote_char)
{
char *out;
char s, n;
/* Optimise for the common case where no changes are needed. */
while ((s = *src++)) {
if (s == quote_char &&
((n = *src) == orig_char || n == quote_char)) {
out = src++;
*(out - 1) = n;
while ((s = *src++)) {
if (s == quote_char &&
((n = *src) == orig_char || n == quote_char)) {
s = n;
src++;
}
*out = s;
out++;
}
*out = '\0';
return;
}
}
}
/*
* Unquote each character given in orig_char array and unquote quote_char
* as well. The array ends up with '\0' character. Also save the first
* occurence of each character from orig_char that was found unquoted in
* arr_substr_first_unquoted array. This way we can process several
* characters in one go.
* as well. Also save the first occurrence of each character from orig_char
* that was found unquoted in arr_substr_first_unquoted array. This way we can
* process several characters in one go.
*/
static void _unquote_characters(char *src, const int orig_chars[],
const int quote_char,
static void _unquote_characters(char *src, const char *orig_chars,
const int num_orig_chars,
const char quote_char,
char *arr_substr_first_unquoted[])
{
char *out = src;
int c;
int i;
char c, s, n;
unsigned i;
while (*src) {
for (i = 0; (c = orig_chars[i]); i++) {
if (*src == quote_char &&
(*(src + 1) == c || *(src + 1) == quote_char)) {
while ((s = *src++)) {
for (i = 0; i < num_orig_chars; i++) {
c = orig_chars[i];
if (s == quote_char &&
((n = *src) == c || n == quote_char)) {
s = n;
src++;
break;
}
else if (arr_substr_first_unquoted && (*src == c) &&
!arr_substr_first_unquoted[i])
if (arr_substr_first_unquoted && (s == c) &&
!arr_substr_first_unquoted[i])
arr_substr_first_unquoted[i] = out;
}
*out++ = *src++;
};
*out++ = s;
}
*out = '\0';
@ -229,9 +260,7 @@ char *escape_double_quotes(char *out, const char *src)
*/
void unescape_double_quotes(char *src)
{
const int orig_chars[] = {'\"', '\0'};
_unquote_characters(src, orig_chars, '\\', NULL);
_unquote_one_character(src, '\"', '\\');
}
/*
@ -244,10 +273,10 @@ void unescape_colons_and_at_signs(char *src,
char **substr_first_unquoted_colon,
char **substr_first_unquoted_at_sign)
{
const int orig_chars[] = {':', '@', '\0'};
const char *orig_chars = ":@";
char *arr_substr_first_unquoted[] = {NULL, NULL, NULL};
_unquote_characters(src, orig_chars, '\\', arr_substr_first_unquoted);
_unquote_characters(src, orig_chars, 2, '\\', arr_substr_first_unquoted);
if (substr_first_unquoted_colon)
*substr_first_unquoted_colon = arr_substr_first_unquoted[0];