# HG changeset patch
# User jbe
# Date 1428183144 -7200
# Node ID 9fff0cb4fc65dee29de3f69e31a06e701c182b00
# Parent  88541c2aab4d9375106fbbf929fad124f2ecec5c
Proper handling of out-of-memory errors in xread_nb method

diff -r 88541c2aab4d -r 9fff0cb4fc65 moonbridge.c
--- a/moonbridge.c	Sat Apr 04 22:42:49 2015 +0200
+++ b/moonbridge.c	Sat Apr 04 23:32:24 2015 +0200
@@ -2305,6 +2305,7 @@
 #endif
       stream = luaL_testudata(L, -1, LUA_FILEHANDLE);
       if (stream) {
+        /* in case of file handle, check for pending data in buffer */
         FILE *file = stream->f;
         int flags, chr;
         flockfile(file);
@@ -2396,14 +2397,14 @@
   }
 }
 
-/* New methods for Lua file objects: read until terminator or length exceeded (optional non-blocking) */
+/* New methods for Lua file objects: read until terminator or length exceeded (blocking and non-blocking) */
 static int moonbr_io_xread_impl(lua_State *L, int nonblock) {
   luaL_Stream *stream;
   lua_Integer maxlen;
   const char *terminatorstr;
   size_t terminatorlen;
   FILE *file;
-  int fd, flags, chr, terminator;
+  int chr, terminator;
   luaL_Buffer buf;
   int wouldblock = 0;
   stream = luaL_checkudata(L, 1, LUA_FILEHANDLE);
@@ -2417,15 +2418,6 @@
     lua_pushliteral(L, "Previous error condition on file handle");
     return 2;
   }
-  if (nonblock) {
-    fd = fileno(file);
-    flags = fcntl(fd, F_GETFL, 0);
-    if (flags == -1) goto moonbr_io_xread_impl_error;
-    if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) goto moonbr_io_xread_impl_error;
-  } else {
-    fd = -1;  /* avoids compiler warning */
-    flags = 0;  /* avoids compiler warning */
-  }
   if (!maxlen) maxlen = -1;
   terminator = terminatorlen ? terminatorstr[0] : -1;
   luaL_buffinit(L, &buf);
@@ -2439,7 +2431,6 @@
         } else {
           char errmsg[MOONBR_MAXSTRERRORLEN];
           strerror_r(errno, errmsg, MOONBR_MAXSTRERRORLEN);  /* use thread-safe call in case child created threads */
-          if (fcntl(fd, F_SETFL, flags) == -1) goto moonbr_io_xread_impl_error;
           lua_pushnil(L);
           lua_pushstring(L, errmsg);
           return 2;
@@ -2450,9 +2441,6 @@
     luaL_addchar(&buf, chr);
     if (chr == terminator) break;
   }
-  if (nonblock) {
-    if (fcntl(fd, F_SETFL, flags) == -1) goto moonbr_io_xread_impl_error;
-  }
   luaL_pushresult(&buf);
   if (wouldblock || lua_rawlen(L, -1)) {
     return 1;
@@ -2461,18 +2449,37 @@
     lua_pushliteral(L, "End of file");
     return 2;
   }
-  moonbr_io_xread_impl_error:
-  {
-    char errmsg[MOONBR_MAXSTRERRORLEN];
-    strerror_r(errno, errmsg, MOONBR_MAXSTRERRORLEN);  /* use thread-safe call in case child created threads */
-    return luaL_error(L, "Unexpected error in xread method: %s", errmsg);
-  }
 }
 static int moonbr_io_xread(lua_State *L) {
   return moonbr_io_xread_impl(L, 0);
 }
+static int moonbr_io_xread_nb_impl(lua_State *L) {
+  return moonbr_io_xread_impl(L, 1);
+}
 static int moonbr_io_xread_nb(lua_State *L) {
-  return moonbr_io_xread_impl(L, 1);
+  luaL_Stream *stream;
+  int fd, flags;
+  stream = luaL_checkudata(L, 1, LUA_FILEHANDLE);
+  if (!stream->closef) luaL_error(L, "attempt to use a closed file");
+  lua_pushcfunction(L, moonbr_io_xread_nb_impl);
+  lua_insert(L, 1);
+  lua_settop(L, 4);
+  fd = fileno(stream->f);
+  flags = fcntl(fd, F_GETFL, 0);
+  if (flags == -1) goto moonbr_io_xread_nb_error;
+  if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) goto moonbr_io_xread_nb_error;
+  if (lua_pcall(L, 3, LUA_MULTRET, 0)) {
+    fcntl(fd, F_SETFL, flags);
+    return lua_error(L);
+  }
+  if (fcntl(fd, F_SETFL, flags) == -1) goto moonbr_io_xread_nb_error;
+  return lua_gettop(L);
+  moonbr_io_xread_nb_error:
+  {
+    char errmsg[MOONBR_MAXSTRERRORLEN];
+    strerror_r(errno, errmsg, MOONBR_MAXSTRERRORLEN);  /* use thread-safe call in case child created threads */
+    return luaL_error(L, "Unexpected error in xread_nb method: %s", errmsg);
+  }
 }
 
 /* New methods for Lua file objects: non-blocking writing */