The question is specific to a pattern that Flawfinder reports:
The snippet
unsigned char child_report;
...
auto readlen = read(pipefd[0], (void *) &child_report, sizeof(child_report));
if(readlen == -1 || readlen != sizeof(child_report)) {
_ret.failure = execute_result::PREIO ; // set some flags to report to the caller
close(pipefd[0]);
return _ret;
}
...
int sec_read = read(pipefd[0], (void *) &child_report, sizeof(child_report));
child_report = 0; // we are not using the read data at all
// we just want to know if the read is successful or not
if (sec_read != 0 && sec_read != -1) { // if success
_ret.failure = execute_result::EXEC; // it means that the child is not able to exec
close(pipefd[0]); // as we set the close-on-exec flag
return _ret; // and we do write after exec in the child
}
I turned out that Codacy (therefore flawfinder) reports such issues on both read:
Check buffer boundaries if used in a loop including recursive loops (CWE-120, CWE-20).
I don't understand.
- There is no loop.
- In the second case we are not using the read data at all
- This is not typical C string, and we don't rely on the ending '\0'
Is there any flaw that I'm not aware of in the code?
