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library: improve performance for one 'escape' function

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While this patch has some cosmetic whitespace changes,
more importantly it makes that 'esc_all' function more
efficient. By abandoning the indexed loop approach for
a direct pointer manipulation, we will save 9 iterated
machine instructions, for a total of 33 bytes of code.

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2021-01-12 00:00:00 -06:00 committed by Craig Small
parent 0cf6942be7
commit 031a08f2a7
1 changed files with 18 additions and 21 deletions
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39
proc/escape.c
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@ -26,14 +26,13 @@
#include "escape.h"
#include "readproc.h"
#define SECURE_ESCAPE_ARGS(dst, bytes) do { \
if ((bytes) <= 0) return 0; \
*(dst) = '\0'; \
if ((bytes) >= INT_MAX) return 0; \
} while (0)
static char UTF_tab[] = {
static const char UTF_tab[] = {
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x00 - 0x0F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x10 - 0x1F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x20 - 0x2F
@ -46,34 +45,34 @@ static char UTF_tab[] = {
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, // 0x90 - 0x9F
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, // 0xA0 - 0xAF
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, // 0xB0 - 0xBF
-1,-1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0xC0 - 0xCF, 0xC2 = begins 2
-1,-1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0xC0 - 0xCF
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0xD0 - 0xDF
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, // 0xE0 - 0xEF, 0xE0 = begins 3
4, 4, 4, 4, 4,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, // 0xF0 - 0xFF, 0xF0 = begins 4
}; // ( 0xF5 & beyond invalid )
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, // 0xE0 - 0xEF
4, 4, 4, 4, 4,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, // 0xF0 - 0xFF
};
static const unsigned char ESC_tab[] = {
"@..............................." // 0x00 - 0x1F
"||||||||||||||||||||||||||||||||" // 0x20 - 0x3F
"||||||||||||||||||||||||||||||||" // 0x40 - 0x5f
"|||||||||||||||||||||||||||||||." // 0x60 - 0x7F
"????????????????????????????????" // 0x80 - 0x9F
"????????????????????????????????" // 0xA0 - 0xBF
"????????????????????????????????" // 0xC0 - 0xDF
"????????????????????????????????" // 0xE0 - 0xFF
"@..............................." // 0x00 - 0x1F
"||||||||||||||||||||||||||||||||" // 0x20 - 0x3F
"||||||||||||||||||||||||||||||||" // 0x40 - 0x5f
"|||||||||||||||||||||||||||||||." // 0x60 - 0x7F
"????????????????????????????????" // 0x80 - 0x9F
"????????????????????????????????" // 0xA0 - 0xBF
"????????????????????????????????" // 0xC0 - 0xDF
"????????????????????????????????" // 0xE0 - 0xFF
};
static inline void esc_all (unsigned char *str) {
unsigned char c;
int i;
// if bad locale/corrupt str, replace non-printing stuff
for (i = 0; str[i] != '\0'; i++)
if ((c = ESC_tab[str[i]]) != '|')
str[i] = c;
while (*str) {
if ((c = ESC_tab[*str]) != '|')
*str = c;
++str;
}
}
static inline void esc_ctl (unsigned char *str, int len) {
int i, n;
@ -90,7 +89,6 @@ static inline void esc_ctl (unsigned char *str, int len) {
}
}
int escape_str (unsigned char *dst, const unsigned char *src, int bufsize) {
static int utf_sw = 0;
int n;
@ -113,7 +111,6 @@ int escape_str (unsigned char *dst, const unsigned char *src, int bufsize) {
return n;
}
int escape_command (unsigned char *outbuf, const proc_t *pp, int bytes, unsigned flags) {
int overhead = 0;
int end = 0;