Extend erlang:port_info/1,2 to show the OS pid of a spawned process

When spawning OS (unix) processes with erlang:open_port, store the
resulting unix pid so that it can be queried later on using
erlang:port_info/1,2.

1 files changed, 15 insertions, 1 deletions

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 060a52d220..4dcfe997d4 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2765,7 +2765,8 @@ port_info_1(BIF_ALIST_1)
 	am_id,
 	am_connected,
 	am_input,
-	am_output
+	am_output,
+	am_os_pid
     };
     Eterm items[ASIZE(keys)];
     Eterm result = NIL;
@@ -2822,6 +2823,7 @@ port_info_1(BIF_ALIST_1)
 **    name        String
 **    input       Number of bytes input from port program
 **    output      Number of bytes output to the port program
+**    os_pid      The child's process ID
 */
 
 BIF_RETTYPE port_info_2(BIF_ALIST_2)
@@ -2922,6 +2924,18 @@ static BIF_RETTYPE port_info(Process* p, Eterm portid, Eterm item)
 	hp = HAlloc(p, hsz);
 	res = erts_bld_uint(&hp, NULL, n);
     }
+    else if (item == am_os_pid) {
+        if (prt->os_pid >= 0) {
+            Uint hsz = 3;
+            Uint n = prt->os_pid;
+            (void) erts_bld_uint(NULL, &hsz, n);
+            hp = HAlloc(p, hsz);
+            res = erts_bld_uint(&hp, NULL, n);
+        } else {
+	    hp = HAlloc(p, 3);
+	    res = am_undefined;
+        }
+    }
     else if (item == am_registered_name) {
 	RegProc *reg;
 	reg = prt->reg;