[Bug analyzer/114791] New: analyzer: file-leak not detected

[Bug analyzer/114791] New: analyzer: file-leak not detected

[urs at akk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

            Bug ID: 114791
           Summary: analyzer: file-leak not detected
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: urs at akk dot org
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu
             Build: x86_64-pc-linux-gnu

Created attachment 57998
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57998&action=edit
minimal test case

False negative -Wanalyzer-file-leak

gcc build from git @ ef2392236ec629351496d7f299d6a0956080e4d9

gcc-14 -D_DEFAULT_SOURCE -Wall -Wextra -fanalyzer -O2 -v -save-temps
-freport-bug -g -std=c11 -o fleak file-leak.c

doesn't give a warning but it should (value of fp may be overwritten before
released).

[Bug analyzer/114791] analyzer: file-leak not detected

[urs at akk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

--- Comment #1 from Urs Janßen <urs at akk dot org> ---
Created attachment 57999
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57999&action=edit
preprocessed example

[Bug analyzer/114791] analyzer: file-leak not detected

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
   Last reconfirmed|                            |2024-04-21
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug analyzer/114791] analyzer: file-leak not detected

[urs at akk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

--- Comment #3 from Urs Janßen <urs at akk dot org> ---
Comment on attachment 57998
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57998
minimal test case

>#include <sys/types.h>
>#include <sys/stat.h>
>#include <unistd.h>
>#include <stdio.h>
>
>int main(void);
>
>int main(void) {
>    FILE *fp = (FILE *) 0;
>    int i = 0;
>    static const char *list[] = { "/tmp/", "/tmp/a", "/tmp/b", NULL };
>    struct stat st;
>
>    while (list[i] != NULL) {
>        if ((fp = fopen(list[i], "r")) != NULL) {

should be 
if ((fp = fopen(list[i++], "r")) != NULL) {

>            if (fstat(fileno(fp), &st) != -1) {
>                if ((st.st_mode & (S_IFREG | S_IFLNK)) && st.st_size > 0L)
>                    break;
>            }
>            /* missing:
>            fclose(fp);
>            fp = NULL;
>            here */
>        }
>    }
>
>    if (fp)
>        fclose(fp);
>}

[Bug analyzer/114791] analyzer: file-leak not detected

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Interesting, with -O0, there is a warning but that can be turned into a false
positive if you enable the "missing:" section.

[Bug analyzer/114791] analyzer: file-leak not detected

[urs at akk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114791

--- Comment #5 from Urs Janßen <urs at akk dot org> ---
-Wanalyzer-fd-leak has the same issue, no warning given for:

#define _DEFAULT_SOURCE 1
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>

int main(void);

int main(void) {
    int fd = -1;
    int i = 0;
    static const char *list[] = { "/tmp/", "/tmp/a", "/tmp/b", NULL };
    struct stat st;

    while (list[i] != NULL) {
        if ((fd = open(list[i++], O_RDONLY)) != -1) {
            if (fstat(fd, &st) != -1) {
                if ((st.st_mode & (S_IFREG | S_IFLNK)) && st.st_size > 0L)
                    break;
            }
#ifdef NO_FILE_LEAK
            close(fd);
            fd = -1;
#endif /* NO_FILE_LEAK */
        }
    }

    if (fd != -1)
        close(fd);
}