https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113329
Bug ID: 113329
Summary: analyzer: False positive analyzer-fd-use-without-check
with dup2()
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: buczek at molgen dot mpg.de
Target Milestone: ---
Using a closed file descriptor as the second argument of dup2() is a valid
usage. It makes sense, because the implicit close of dup2() doesn't return
close errors to the caller, so an explicit close might be preferred.
** Code:
#include <unistd.h>
void f(int oldfd, int newfd) {
close(newfd);
dup2(oldfd, newfd);
}
** Result:
<source>: In function 'f':
<source>:4:5: warning: 'dup2' on possibly invalid file descriptor 'newfd'
[-Wanalyzer-fd-use-without-check]
4 | dup2(oldfd, newfd);
| ^~~~~~~~~~~~~~~~~~
'f': events 1-2
|
| 3 | close(newfd);
| | ^~~~~~~~~~~~
| | |
| | (1) closed here
| 4 | dup2(oldfd, newfd);
| | ~~~~~~~~~~~~~~~~~~
| | |
| | (2) 'newfd' could be invalid
|
Compiler returned: 0
https://gcc.godbolt.org/z/8zac19e15
