# HG changeset patch
# User jbe
# Date 1510756542 -3600
# Node ID 477456cea3610ea1a9f2fc5db24eb6e300f43b51
# Parent  b2282fb8553bb14a598915c7ee8031d8efd197c4
Avoid using WNOWAIT in moonbridge_io.poll(...) for Linux compatibility

diff -r b2282fb8553b -r 477456cea361 moonbridge_io.c
--- a/moonbridge_io.c	Fri Jun 23 15:49:43 2017 +0200
+++ b/moonbridge_io.c	Wed Nov 15 15:35:42 2017 +0100
@@ -114,6 +114,8 @@
 
 typedef struct {
   pid_t pid;
+  int status;
+  int status_valid;
 } moonbr_io_child_t;
 
 volatile sig_atomic_t moonbr_io_sigterm_flag = 0;
@@ -1367,6 +1369,7 @@
   argv[argc] = NULL;
   child = lua_newuserdata(L, sizeof(moonbr_io_child_t));
   child->pid = 0;
+  child->status_valid = 0;
   lua_newtable(L);
   lua_setuservalue(L, -2);
   luaL_setmetatable(L, MOONBR_IO_CHILD_MT_REGKEY);
@@ -1535,10 +1538,13 @@
   int sig;
   child = luaL_checkudata(L, 1, MOONBR_IO_CHILD_MT_REGKEY);
   sig = luaL_optinteger(L, 2, SIGKILL);
-  if (!child->pid) luaL_error(L, "Attempt to kill an already collected child process");
-  if (kill(child->pid, sig)) {
-    moonbr_io_prepare_errmsg();
-    luaL_error(L, "Error in kill call: %s", errmsg);
+  if (!child->pid) {
+    if (!child->status_valid) luaL_error(L, "Attempt to kill an already collected child process");
+  } else {
+    if (kill(child->pid, sig)) {
+      moonbr_io_prepare_errmsg();
+      luaL_error(L, "Error in kill call: %s", errmsg);
+    }
   }
   lua_settop(L, 1);
   return 1;
@@ -1546,31 +1552,35 @@
 
 static int moonbr_io_wait_impl(lua_State *L, int nonblocking) {
   moonbr_io_child_t *child;
-  pid_t waitedpid;
   int status;
   child = luaL_checkudata(L, 1, MOONBR_IO_CHILD_MT_REGKEY);
-  if (!child->pid) luaL_error(L, "Attempt to wait for an already collected child process");
-  while ((waitedpid = waitpid(child->pid, &status, nonblocking ? WNOHANG : 0)) == -1) {
-    if (errno != EINTR) {
-      moonbr_io_prepare_errmsg();
-      luaL_error(L, "Error in waitpid call: %s", errmsg);
+  if (!child->pid) {
+    if (!child->status_valid) luaL_error(L, "Attempt to wait for an already collected child process");
+    status = child->status;
+    child->status_valid = 0;
+  } else {
+    pid_t waitedpid;
+    while ((waitedpid = waitpid(child->pid, &status, nonblocking ? WNOHANG : 0)) == -1) {
+      if (errno != EINTR) {
+        moonbr_io_prepare_errmsg();
+        luaL_error(L, "Error in waitpid call: %s", errmsg);
+      }
     }
+    if (!waitedpid) {
+      lua_pushboolean(L, 0);
+      lua_pushliteral(L, "Process is still running");
+      return 2;
+    }
+    child->pid = 0;
   }
-  if (!waitedpid) {
-    lua_pushboolean(L, 0);
-    lua_pushliteral(L, "Process is still running");
-    return 2;
+  if (WIFEXITED(status)) {
+    lua_pushinteger(L, WEXITSTATUS(status));
+  } else if (WIFSIGNALED(status)) {
+    lua_pushinteger(L, -WTERMSIG(status));
   } else {
-    child->pid = 0;
-    if (WIFEXITED(status)) {
-      lua_pushinteger(L, WEXITSTATUS(status));
-    } else if (WIFSIGNALED(status)) {
-      lua_pushinteger(L, -WTERMSIG(status));
-    } else {
-      luaL_error(L, "Unexpected status value returned by waitpid call");
-    }
-    return 1;
+    luaL_error(L, "Unexpected status value returned by waitpid call");
   }
+  return 1;
 }
 
 static int moonbr_io_wait(lua_State *L) {
@@ -1709,13 +1719,22 @@
                 moonbr_io_sigchld_flag = 0;
                 signal(SIGCHLD, moonbr_io_sigchld_handler);
               }
-              while ((waitedpid = waitpid(child->pid, &status, WNOHANG|WNOWAIT)) == -1) {
-                if (errno != EINTR) {
-                  moonbr_io_prepare_errmsg();
-                  luaL_error(L, "Error in waitpid call: %s", errmsg);
+              if (child->status_valid) {
+                force_wakeup = 1;
+              } else {
+                while ((waitedpid = waitpid(child->pid, &status, WNOHANG)) == -1) {
+                  if (errno != EINTR) {
+                    moonbr_io_prepare_errmsg();
+                    luaL_error(L, "Error in waitpid call: %s", errmsg);
+                  }
+                }
+                if (waitedpid) {
+                  child->pid = 0;
+                  child->status = status;
+                  child->status_valid = 1;
+                  force_wakeup = 1;
                 }
               }
-              if (waitedpid) force_wakeup = 1;
               continue;
             } else {
               fd = lua_tointegerx(L, -2, &isnum);