Hi systemd-devel team,
I am trying to understand where "vbuf" is initialized in function "token_match_attr()" in file udev-rules.c
... // some code
I am trying to understand where "vbuf" is initialized in function "token_match_attr()" in file udev-rules.c
Below code snippet :
static bool token_match_attr(UdevRuleToken *token, sd_device *dev, UdevEvent *event) { char nbuf[UTIL_NAME_SIZE], vbuf[UTIL_NAME_SIZE]; // Here, vbuf is defined, however not initialized.
const char *name, *value; // Here, value is declared to be of type const char *, however, not initialized.
... ... // some code
...
switch (token->attr_subst_type) { // Event 1 : This evaluates to SUBST_TYPE_PLAIN
...
case SUBST_TYPE_PLAIN: if (sd_device_get_sysattr_value(dev, name, &value) < 0) // Event 2 :The if condition evaluates to false.
return false;
break;
return false;
break;
...// some code
...
}
if (token->attr_match_remove_trailing_whitespace) { // Event 4: If condition evaluates to true
if (value != vbuf) { // Event 5 : vbuf and value are both declared but not initialized. Comparison is done without initializing "vbuf" and "value".
if (value != vbuf) { // Event 5 : vbuf and value are both declared but not initialized. Comparison is done without initializing "vbuf" and "value".
strscpy(vbuf, sizeof(vbuf), value);
value = vbuf;
value = vbuf;
} // End of if.
delete_trailing_chars(vbuf, NULL); // Event 6: trying to delete trailing chars from "vbuf" which is not initialzed. ??
} // End of outer if.
... // some code
} /End of function : token_match_attr()
Below are my queries :
1. Event 5 above, we are comparing two resources ("value" and "vbuf") even before initializing them.
Are we doing this comparision to do decision making based on whether the pointer type variable "value" is pointing to "vbuf" or not.
Query: Kindly confirm whether my understanding is correct.
2. Event 6 above, delete_trailing_chars(vbuf, NULL) is called outside if (value != vbuf).
This implies there may occur a situation where:
step 1 ) if (value != vbuf) condition fails --> step 2 ) vbuf is not initialzed inside the if(value != vbuf) --> step 3 ) delete_trailing_chars(vbuf, NULL).
Here, delete_trailing_chars() called for "vbuf" which is not necessarily initiazlied.
Query: Kindly let me know if my understanding is correct or I am missing something.
Thanks,
Amit
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