path: root/src
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authorRich Felker <>2014-02-21 22:25:26 -0500
committerRich Felker <>2014-02-21 22:25:26 -0500
commitdc01e2cbfb290198c03514fe51ed32c1098b774f (patch)
tree79357e35a582f1fea0012d1c9ff1faf4403c2c0e /src
parentfdb3efa5ddfa7120de98f8ae78b5f5dc9e8e2e71 (diff)
add fallback emulation for accept4 on old kernels
the other atomic FD_CLOEXEC interfaces (dup3, pipe2, socket) already had such emulation in place. the justification for doing the emulation here is the same as for the other functions: it allows applications to simply use accept4 rather than having to have their own fallback code for ENOSYS/EINVAL (which one you get is arch-specific!) and there is no reasonable way an application could benefit from knowing the operation is emulated/non-atomic since there is no workaround at the application level for non-atomicity (that is the whole reason these interfaces were added).
Diffstat (limited to 'src')
1 files changed, 12 insertions, 1 deletions
diff --git a/src/network/accept4.c b/src/network/accept4.c
index 6b5c16ce..285d8588 100644
--- a/src/network/accept4.c
+++ b/src/network/accept4.c
@@ -1,9 +1,20 @@
#define _GNU_SOURCE
#include <sys/socket.h>
+#include <errno.h>
+#include <fcntl.h>
#include "syscall.h"
#include "libc.h"
int accept4(int fd, struct sockaddr *restrict addr, socklen_t *restrict len, int flg)
- return socketcall_cp(accept4, fd, addr, len, flg, 0, 0);
+ if (!flg) return accept(fd, addr, len);
+ int ret = socketcall_cp(accept4, fd, addr, len, flg, 0, 0);
+ if (ret>=0 || (errno != ENOSYS && errno != EINVAL)) return ret;
+ ret = accept(fd, addr, len);
+ if (ret<0) return ret;
+ if (flg & SOCK_CLOEXEC)
+ __syscall(SYS_fcntl, ret, F_SETFD, FD_CLOEXEC);
+ if (flg & SOCK_NONBLOCK)
+ __syscall(SYS_fcntl, ret, F_SETFL, O_NONBLOCK);
+ return ret;