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.

4 files changed, 18 insertions, 1 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 7be40976f6..2c6e80a3c3 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -390,6 +390,7 @@ atom opt
 atom or
 atom ordered_set
 atom orelse
+atom os_pid
 atom os_type
 atom os_version
 atom ose_bg_proc
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index ebd475f73a..e198be67c7 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2741,7 +2741,8 @@ 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;
@@ -2798,6 +2799,7 @@ 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)
@@ -2898,6 +2900,18 @@ 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;
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 6eac0db363..1431e08610 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -174,6 +174,7 @@ struct port {
     char *name;		         /* String used in the open */
     erts_driver_t* drv_ptr;
     UWord drv_data;
+    pid_t os_pid;                /* Child process ID */
     ErtsProcList *suspended;	 /* List of suspended processes. */
     LineBuf *linebuf;            /* Buffer to hold data not ready for
 				    process to get (line oriented I/O)*/
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index b23b1f628d..3deb386621 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -425,6 +425,7 @@ setup_port(Port* prt, Eterm pid, erts_driver_t *driver,
     sys_strcpy(new_name, name);
     erts_smp_runq_lock(runq);
     erts_smp_port_state_lock(prt);    
+    prt->os_pid = -1;
     prt->status = ERTS_PORT_SFLG_CONNECTED | xstatus;
     prt->snapshot = erts_smp_atomic32_read_nob(&erts_ports_snapshot);    
     old_name = prt->name;