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authorLaurent Bercot <ska-skaware@skarnet.org>2014-09-18 18:55:44 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2014-09-18 18:55:44 +0000
commit3534b428629be185e096be99e3bd5fdfe32d5544 (patch)
tree210ef3198ed66bc7f7b7bf6a85e4579f455e5a36 /src/libstddjb/doublefork.c
downloadskalibs-3534b428629be185e096be99e3bd5fdfe32d5544.tar.xz
initial commit with rc for skalibs-2.0.0.0
Diffstat (limited to 'src/libstddjb/doublefork.c')
-rw-r--r--src/libstddjb/doublefork.c53
1 files changed, 53 insertions, 0 deletions
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 <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/uint64.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/djbunix.h>
+
+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 ;
+ }
+}