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rewrite strreplace

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* just do one malloc call

* p = realloc(p, new_size) was not good
(see http://www.iso-9899.info/wiki/Why_not_realloc)

* use more efficient strncpy instead of strncat

Signed-off-by: Xavier Chantry <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Xavier Chantry 2009-09-07 01:15:39 +02:00 • committed by Dan McGee
parent cb1d4195bf
commit 43e16b373b
1 changed files with 52 additions and 35 deletions
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75
src/pacman/util.c
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@ -335,48 +335,65 @@ char *strtrim(char *str)
return(str); return(str);
} }
/* Helper function for strreplace */
static void _strnadd(char **str, const char *append, unsigned int count)
{
if(*str) {
*str = realloc(*str, strlen(*str) + count + 1);
} else {
*str = calloc(sizeof(char), count + 1);
}
strncat(*str, append, count);
}
/* Replace all occurances of 'needle' with 'replace' in 'str', returning /* Replace all occurances of 'needle' with 'replace' in 'str', returning
* a new string (must be free'd) */ * a new string (must be free'd) */
char *strreplace(const char *str, const char *needle, const char *replace) char *strreplace(const char *str, const char *needle, const char *replace)
{ {
const char *p, *q; const char *p = NULL, *q = NULL;
p = q = str; char *newstr = NULL, *newp = NULL;
alpm_list_t *i = NULL, *list = NULL;
size_t needlesz = strlen(needle), replacesz = strlen(replace);
size_t newsz;
char *newstr = NULL; if(!str) {
unsigned int needlesz = strlen(needle), return(NULL);
replacesz = strlen(replace); }
while (1) { p = str;
q = strstr(p, needle);
while(q) {
list = alpm_list_add(list, (char *)q);
p = q + needlesz;
q = strstr(p, needle); q = strstr(p, needle);
if(!q) { /* not found */
if(*p) {
/* add the rest of 'p' */
_strnadd(&newstr, p, strlen(p));
} }
break;
} else { /* found match */ /* no occurences of needle found */
if(!list) {
return(strdup(str));
}
/* size of new string = size of old string + "number of occurences of needle"
* x "size difference between replace and needle" */
newsz = strlen(str) + 1 +
alpm_list_count(list) * (replacesz - needlesz);
newstr = malloc(newsz);
if(!newstr) {
return(NULL);
}
*newstr = '\0';
p = str;
newp = newstr;
for(i = list; i; i = alpm_list_next(i)) {
q = alpm_list_getdata(i);
if(q > p){ if(q > p){
/* add chars between this occurance and last occurance, if any */ /* add chars between this occurence and last occurence, if any */
_strnadd(&newstr, p, q - p); strncpy(newp, p, q - p);
newp += q - p;
} }
_strnadd(&newstr, replace, replacesz); strncpy(newp, replace, replacesz);
newp += replacesz;
p = q + needlesz; p = q + needlesz;
} }
} alpm_list_free(list);
return newstr; if(*p) {
/* add the rest of 'p' */
strcpy(newp, p);
newp += strlen(p);
}
*newp = '\0';
return(newstr);
} }
/** Splits a string into a list of strings using the chosen character as /** Splits a string into a list of strings using the chosen character as