https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99196
Bug ID: 99196
Summary: GCC analyzer doesn't know that error (code != 0, ...)
exits the program
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: rjones at redhat dot com
Target Milestone: ---
https://github.com/libguestfs/libguestfs/blob/f19fd566f6387ce7e4d82409528c9dde374d25e0/daemon/tar.c#L108
tar.c: In function 'read_error_file':
tar.c:113:11: error: use of NULL 'str' where non-null expected [CWE-476]
[-Werror=analyzer-null-argument]
113 | len = strlen (str);
| ^~~~~~~~~~~~
'read_error_file': events 1-7
|
| 109 | if (str == NULL) {
| | ^
| | |
| | (1) following 'true' branch (when 'str' is NULL)...
| 110 | str = strdup ("(no error)");
| | ~~~ ~~~~~~~~~~~~~~~~~~~~~
| | | |
| | | (3) allocated here
| | (2) ...to here
| 111 | if (str == NULL)
| | ~
| | |
| | (4) assuming 'str' is NULL
| | (5) following 'true' branch (when 'str' is NULL)...
| 112 | error (EXIT_FAILURE, errno, "strdup"); /* XXX */
| | ~~~~~
| | |
| | (6) ...to here
| 113 | len = strlen (str);
| | ~~~~~~~~~~~~
| | |
| | (7) argument 1 ('str') NULL where non-null expected
|
In file included from ../gnulib/lib/string.h:41,
from tar.c:23:
/usr/include/string.h:391:15: note: argument 1 of 'strlen' must be non-null
391 | extern size_t strlen (const char *__s)
| ^~~~~~
cc1: all warnings being treated as errors
In the original code if str == NULL, error (EXIT_FAILURE, ...) is
called which exits the program. Therefore strlen (NULL) cannot
be called so the warning is bogus.
https://www.man7.org/linux/man-pages/man3/error.3.html
"If status has a nonzero value, then error() calls exit(3) to
terminate the program using the given value as the exit status."
gcc-11.0.0-0.19.fc35.x86_64
