From 3534b428629be185e096be99e3bd5fdfe32d5544 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Thu, 18 Sep 2014 18:55:44 +0000 Subject: initial commit with rc for skalibs-2.0.0.0 --- src/libstddjb/doublefork.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 src/libstddjb/doublefork.c (limited to 'src/libstddjb/doublefork.c') diff --git a/src/libstddjb/doublefork.c b/src/libstddjb/doublefork.c new file mode 100644 index 0000000..5a1f7b1 --- /dev/null +++ b/src/libstddjb/doublefork.c @@ -0,0 +1,53 @@ +/* ISC license. */ + +#include +#include +#include +#include +#include +#include +#include + +pid_t doublefork () +{ + char pack[8] ; + int fd[2] ; + pid_t child ; + if (pipe(fd) == -1) return -1 ; + child = fork() ; + switch (child) + { + case -1: + { + register int e = errno ; + fd_close(fd[1]) ; + fd_close(fd[0]) ; + errno = e ; + return -1 ; + } + case 0: + { + pid_t pid ; + fd_close(fd[0]) ; + pid = fork() ; + switch (pid) + { + case -1: _exit(errno) ; + case 0: fd_close(fd[1]) ; return 0 ; + } + uint64_pack_big(pack, (uint64)pid) ; + _exit((allwrite(fd[1], pack, 8) < 8) ? errno : 0) ; + } + } + fd_close(fd[1]) ; + { + uint64 grandchild = 0 ; + int wstat ; + if (allread(fd[0], pack, 8) < 8) grandchild = 1 ; + fd_close(fd[0]) ; + wait_pid(child, &wstat) ; + if (grandchild) return (errno = WIFSIGNALED(wstat) ? EINTR : WEXITSTATUS(wstat), -1) ; + uint64_unpack_big(pack, &grandchild) ; + return (pid_t)grandchild ; + } +} -- cgit v1.2.3