Re: [Libguestfs] [libnbd PATCH v3 13/29] socket activation: avoid manipulating the sign bit

F_SETFD takes an "int", so it stands to reason that FD_CLOEXEC expands to an "int". In turn, it's bad hygiene to manipulate the sign bit of (signed) integers with bit operations: ~FD_CLOEXEC Convert FD_CLOEXEC to "unsigned int" for the bitwise complement operator: ~(unsigned)FD_CLOEXEC The bitwise complement then results in an "unsigned int". "Flags" (of type "int", and having, per POSIX, a non-negative value returned by fcntl(F_GETFD)) will be automatically converted to "unsigned int" by the usual arithmetic conversions for the bitwise AND operator: flags & ~(unsigned)FD_CLOEXEC We could pass the result of *that* to fcntl(), due to (a) the value being in range for "signed int" ("flags" is a non-negative "int", and we're only clearing a value bit), and (b) non-negative "int" values being represented identically by "unsigned int" (C99 6.2.5 p9). But, for clarity, let's cast the result to "int" explicitly: (int)(flags & ~(unsigned)FD_CLOEXEC) Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; --- Notes: context:-U5 generator/states-connect-socket-activation.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/generator/states-connect-socket-activation.c b/generator/states-connect-socket-activation.c index b5e146539cc8..729f37d897fb 100644 --- a/generator/states-connect-socket-activation.c +++ b/generator/states-connect-socket-activation.c @@ -181,11 +181,11 @@ CONNECT_SA.START: int flags = fcntl (s, F_GETFD, 0); if (flags == -1) { nbd_internal_fork_safe_perror ("fcntl: F_GETFD"); _exit (126); } - if (fcntl (s, F_SETFD, flags & ~FD_CLOEXEC) == -1) { + if (fcntl (s, F_SETFD, (int)(flags & ~(unsigned)FD_CLOEXEC)) == -1) { nbd_internal_fork_safe_perror ("fcntl: F_SETFD"); _exit (126); } } _______________________________________________ Libguestfs mailing list Libguestfs(a)redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs