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udev-event: use in-place whitespace replacement

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Instead of using a temp buffer to replace whitespace in variable
substitutions, just allow util_replace_whitespace to replace in-place.
Add a comment to util_replace_whitespace indicating it is used to replace
in-place, to prevent accidental future breakage.
This commit is contained in:
Dan Streetman 2017-01-26 14:18:10 -05:00
parent 0d53705b65
commit be45268352
2 changed files with 29 additions and 35 deletions
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14
src/libudev/libudev-util.c
View file

@ -161,6 +161,20 @@ void util_remove_trailing_chars(char *path, char c)
path[--len] = '\0';
}
/*
* Copy from 'str' to 'to', while removing all leading and trailing whitespace,
* and replacing each run of consecutive whitespace with a single underscore.
* The chars from 'str' are copied up to the \0 at the end of the string, or
* at most 'len' chars. This appends \0 to 'to', at the end of the copied
* characters.
*
* If 'len' chars are copied into 'to', the final \0 is placed at len+1
* (i.e. 'to[len] = \0'), so the 'to' buffer must have at least len+1
* chars available.
*
* Note this may be called with 'str' == 'to', i.e. to replace whitespace
* in-place in a buffer. This function can handle that situation.
*/
int util_replace_whitespace(const char *str, char *to, size_t len)
{
size_t i, j;

50
src/udev/udev-event.c
View file

@ -95,8 +95,8 @@ enum subst_type {
static size_t subst_format_var(struct udev_event *event, struct udev_device *dev,
enum subst_type type, char *attr,
char **dest, size_t l) {
char *s = *dest;
char *dest, size_t l) {
char *s = dest;
switch (type) {
case SUBST_DEVPATH:
@ -279,9 +279,7 @@ static size_t subst_format_var(struct udev_event *event, struct udev_device *dev
break;
}
*dest = s;
return l;
return s - dest;
}
size_t udev_event_apply_format(struct udev_event *event,
@ -324,10 +322,9 @@ size_t udev_event_apply_format(struct udev_event *event,
for (;;) {
enum subst_type type = SUBST_UNKNOWN;
char attrbuf[UTIL_PATH_SIZE], sbuf[UTIL_PATH_SIZE];
char *attr = NULL, *_s;
size_t _l;
bool replws = replace_whitespace;
char attrbuf[UTIL_PATH_SIZE];
char *attr = NULL;
size_t subst_len;
while (from[0] != '\0') {
if (from[0] == '$') {
@ -396,34 +393,17 @@ subst:
attr = NULL;
}
/* result subst handles space as field separator */
if (type == SUBST_RESULT)
replws = false;
subst_len = subst_format_var(event, dev, type, attr, s, l);
if (replws) {
/* store dest string ptr and remaining len */
_s = s;
_l = l;
/* temporarily use sbuf */
s = sbuf;
l = UTIL_PATH_SIZE;
}
/* SUBST_RESULT handles spaces itself */
if (replace_whitespace && type != SUBST_RESULT)
/* util_replace_whitespace can replace in-place,
* and does nothing if subst_len == 0
*/
subst_len = util_replace_whitespace(s, s, subst_len);
l = subst_format_var(event, dev, type, attr, &s, l);
/* replace whitespace in sbuf and copy to dest */
if (replws) {
size_t tmplen = UTIL_PATH_SIZE - l;
/* restore s and l to dest string values */
s = _s;
l = _l;
/* copy ws-replaced value to s */
tmplen = util_replace_whitespace(sbuf, s, MIN(tmplen, l));
l -= tmplen;
s += tmplen;
}
s += subst_len;
l -= subst_len;
}
out: