Add gcspawn

Signed-off-by: Laurent Bercot <ska@appnovation.com>

3 files changed, 55 insertions, 2 deletions

diff --git a/src/headers/signed-template b/src/headers/signed-template
index b67b2bd..a3b85eb 100644
--- a/src/headers/signed-template
+++ b/src/headers/signed-template
@@ -1,8 +1,8 @@
 #define @TYPE@_PACK @BYTES@
 #define @type@_pack uint@BITS@_pack
 #define @type@_pack_big uint@BITS@_pack_big
-#define @type@_unpack uint@BITS@_unpack
-#define @type@_unpack_big uint@BITS@_unpack_big
+#define @type@_unpack(pack, p) uint@BITS@_unpack(pack, (uint@BITS@_t *)(p))
+#define @type@_unpack_big(pack, p) uint@BITS@_unpack_big(pack, (uint@BITS@_t *)(p))
 
 #define @TYPE@_FMT (1+UINT@BITS@_FMT)
 #define @type@_fmt int@BITS@_fmt
diff --git a/src/include/skalibs/cspawn.h b/src/include/skalibs/cspawn.h
index fa5c934..061fbfb 100644
--- a/src/include/skalibs/cspawn.h
+++ b/src/include/skalibs/cspawn.h
@@ -85,4 +85,9 @@ extern pid_t child_spawn3 (char const *, char const *const *, char const *const
 
 extern pid_t child_spawn (char const *, char const *const *, char const *const *, int *, size_t) ;
 
+
+ /* cspawn, but running as a grandchild. Uses one fork(). */
+
+extern pid_t gcspawn (char const *, char const *const *, char const *const *, uint16_t, cspawn_fileaction const *, size_t) ;
+
 #endif
diff --git a/src/libstddjb/gcspawn.c b/src/libstddjb/gcspawn.c
new file mode 100644
index 0000000..7e9e602
--- /dev/null
+++ b/src/libstddjb/gcspawn.c
@@ -0,0 +1,48 @@
+/* ISC license. */
+
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <skalibs/types.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/cspawn.h>
+
+pid_t gcspawn (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
+{
+  pid_t pid = 0 ;
+  int wstat ;
+  int p[2] ;
+  char pack[PID_PACK] ;
+  if (pipecoe(p) == -1) return 0 ;
+  pid = fork() ;
+  switch (pid)
+  {
+    case -1:
+    {
+      fd_close(p[1]) ;
+      fd_close(p[0]) ;
+      return 0 ;
+    }
+    case 0:
+    {
+      fd_close(p[0]) ;
+      pid = cspawn(prog, argv, envp, flags, fa, n) ;
+      if (!pid) _exit(errno) ;
+      pid_pack_big(pack, pid) ;
+      _exit(fd_write(p[1], pack, PID_PACK) < PID_PACK ? errno : 0) ;
+    }
+  }
+  fd_close(p[1]) ;
+  if (fd_read(p[0], pack, PID_PACK) < PID_PACK) goto err ;
+  fd_close(p[0]) ;
+  wait_pid(pid, &wstat) ;
+  pid_unpack_big(pack, &pid) ;
+  return pid ;
+
+ err:
+  fd_close(p[0]) ;
+  wait_pid(pid, &wstat) ;
+  return (errno = WIFSIGNALED(wstat) ? EINTR : WEXITSTATUS(wstat), 0) ;
+}