Hi,
attached you will find a patch that shrinks libbb's last_char_is function.
bloatcheck is:
function old new delta
last_char_is 53 42 -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-11) Total: -11 bytes
text data bss dec hex filename
981219 16907 1872 999998 f423e busybox_old
981208 16907 1872 999987 f4233 busybox_unstripped
Patch for review:
--- libbb/last_char_is.c.orig 2020-07-05 09:54:24.737931000 +0200
+++ libbb/last_char_is.c 2020-07-06 14:29:27.768898574 +0200
@@ -11,14 +11,7 @@
/* Find out if the last character of a string matches the one given */
char* FAST_FUNC last_char_is(const char *s, int c)
{
- if (s) {
- size_t sz = strlen(s);
- /* Don't underrun the buffer if the string length is 0 */
- if (sz != 0) {
- s += sz - 1;
- if ((unsigned char)*s == c)
- return (char*)s;
- }
- }
- return NULL;
-}
+ if (!s || !*s) return NULL;
+ while (*(s + 1)) s++;
+ return (*s == c) ? (char *) s : NULL;
+}
The alternative version:
char* FAST_FUNC last_char_is(const char *s, int c)
{
if (!s || !*s) return NULL;
while (*(++s));
return (*(--s) == c) ? (char *)s : NULL;
}
that was also posted to the list on my system was bigger:
function old new delta
last_char_is 53 46 -7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-7) Total: -7 bytes
Ciao,
Tito
P.S.: test program, if you are aware of other corner cases please tell me:
____________________________________________________________________________
char* last_char_is(const char *s, int c)
{
if (!s || !*s)
return NULL;
while (*(s + 1))
s++;
return (*s == c) ? (char *) s : NULL;
}
int main (int argc, char **argv) {
char *c;
int ret = 0;
printf("Test 1 'prova','a' : ");
c = last_char_is("prova", 'a');
if (c != NULL && *c == 'a') {
puts("PASSED");
} else {
puts("FAILED");
ret |= 1;
}
printf("Test 2 '' ,'x' : ");
c = last_char_is("", 'x');
if (c != NULL) {
puts("FAILED");
ret |= 1;
} else {
puts("PASSED");
}
printf("Test 3 NULL ,'3' : ");
c = last_char_is(NULL, 'e');
if (c != NULL) {
puts("FAILED");
ret |= 1;
} else {
puts("PASSED");
}
printf("Test 4 'prova','x' : ");
c = last_char_is("prova", 'x');
if (c != NULL) {
puts("FAILED");
ret |= 1;
} else {
puts("PASSED");
}
printf("Test 5 'prova','\\n': ");
c = last_char_is("prova", '\n');
if (c != NULL) {
puts("FAILED");
ret |= 1;
} else {
puts("PASSED");
}
printf("Test 6 'prova','\\0': ");
c = last_char_is("prova", 0);
if (c != NULL) {
puts("FAILED");
ret |= 1;
} else {
puts("PASSED");
}
return ret;
}
____________________________________________________________________________________________
Shrink libbb/last_char_is function more.
function old new delta
last_char_is 53 42 -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-11) Total: -11 bytes
Signed-off-by: Tito Ragusa <[email protected]>
--- libbb/last_char_is.c.orig 2020-07-05 09:54:24.737931000 +0200
+++ libbb/last_char_is.c 2020-07-06 14:29:27.768898574 +0200
@@ -11,14 +11,7 @@
/* Find out if the last character of a string matches the one given */
char* FAST_FUNC last_char_is(const char *s, int c)
{
- if (s) {
- size_t sz = strlen(s);
- /* Don't underrun the buffer if the string length is 0 */
- if (sz != 0) {
- s += sz - 1;
- if ((unsigned char)*s == c)
- return (char*)s;
- }
- }
- return NULL;
-}
+ if (!s || !*s) return NULL;
+ while (*(s + 1)) s++;
+ return (*s == c) ? (char *) s : NULL;
+}
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