added error pipe in case execve returns - not working yet..

git-svn-id: https://svn.spreadspace.org/gcsd/trunk@47 ac14a137-c7f1-4531-abe0-07747231d213

2 files changed, 131 insertions, 2 deletions

diff --git a/src/l_util.c b/src/l_util.c
index 0b417ac..6ef6236 100644
--- a/src/l_util.c
+++ b/src/l_util.c
@@ -219,6 +219,103 @@ void free_ptrptr(char** ptrptr)
   free(ptrptr);
 }
 
+struct child_struct {
+  pid_t pid_;
+  int fd_;
+  struct child_struct* next_;
+};
+typedef struct child_struct child_t;
+
+child_t* child_get_last(child_t* first)
+{
+  if(!first)
+    return NULL;
+
+  while(first->next_) {
+    first = first->next_;
+  }
+  return first;
+}
+
+int child_add(lua_State *L, pid_t pid, int fd)
+{
+  lua_getglobal(L, LUA_UTILLIBNAME);
+  lua_getfield(L, -1, LUA_UTILCHLIDRENNAME);
+  child_t* first = lua_touserdata(L, -1);
+  lua_pop(L, 1);
+
+  child_t* new_child = malloc(sizeof(child_t));
+  if(!new_child)
+    return -1;
+
+  new_child->pid_ = pid;
+  new_child->fd_ = fd;
+  new_child->next_ = NULL;
+  if(!first) {
+    lua_pushlightuserdata(L, new_child);
+    lua_setfield(L, -2, LUA_UTILCHLIDRENNAME);    
+    lua_pop(L, 1);
+    return 0;
+  }
+  child_get_last(first)->next_ = new_child;
+  lua_pop(L, 1);
+  return 0;
+}
+
+void child_remove(lua_State *L, pid_t pid)
+{
+  lua_getglobal(L, LUA_UTILLIBNAME);
+  lua_getfield(L, -1, LUA_UTILCHLIDRENNAME);
+  child_t* first = lua_touserdata(L, -1);
+  if(!first) {
+    lua_pop(L, 2);
+    return;
+  }
+  lua_pop(L, 1);
+
+  child_t* deletee = first;
+  if(first->pid_ == pid) {
+    lua_pushlightuserdata(L, first->next_);
+    lua_setfield(L, -2, LUA_UTILCHLIDRENNAME);    
+    lua_pop(L, 1);
+    close(deletee->fd_);
+    free(deletee);
+    return;
+  }
+  lua_pop(L, 1);
+  child_t* prev = deletee;
+  deletee = deletee->next_;
+  while(deletee) {
+    if(deletee->pid_ == pid) {
+      prev->next_ = deletee->next_;
+      close(deletee->fd_);
+      free(deletee);
+      return;
+    }
+    prev = deletee;
+    deletee = deletee->next_;
+  }
+}
+
+child_t* child_find(lua_State *L, pid_t pid)
+{
+  lua_getglobal(L, LUA_UTILLIBNAME);
+  lua_getfield(L, -1, LUA_UTILCHLIDRENNAME);
+  child_t* first = lua_touserdata(L, -1);
+  lua_pop(L, 2);
+
+  if(!first)
+    return NULL;
+  
+  while(first) {
+    if(first->pid_ == pid)
+      return first;
+
+    first = first->next_;
+  }
+  return NULL;
+}
+
 static int l_util_exec(lua_State *L)
 {
   const char* script = luaL_checkstring(L, 1);
@@ -231,10 +328,17 @@ static int l_util_exec(lua_State *L)
     return 2;
   }
 
+  int pipefd[2];
+  if(pipe(pipefd) == -1) {
+    lua_pushnil(L);
+    lua_pushstring(L, strerror(errno)); // FIXXXXXME: strerror is not threadsafe!!!
+    return 2;
+  }
+
   if(!pid) {
     int fd;
     for (fd=getdtablesize();fd>=0;--fd) // close all file descriptors
-      close(fd);
+      if(fd != pipefd[1]) close(fd);
 
     char** argv = table_to_argv(L, script, 2);
     char** evp = table_to_evp(L, 3);
@@ -245,11 +349,17 @@ static int l_util_exec(lua_State *L)
     }
 
     execve(script, argv, evp);
+        // if execve returns, an error occurred, but logging doesn't work 
+        // because we closed all file descriptors, so just write errno to
+        // pipe and call exit
+    int ret = write(pipefd[1], (void*)(&errno), sizeof(errno));
     free_ptrptr(argv);
     free_ptrptr(evp);
     lua_close(L);
-    exit(-1);
+    exit(ret);
   }
+  close(pipefd[1]);
+  child_add(L, pid, pipefd[0]);
 
   lua_pushinteger(L, pid);
   return 1;
@@ -270,6 +380,22 @@ static int l_util_waitpid(lua_State *L)
   }
 
   lua_pushinteger(L, pid);
+  child_t* child = child_find(L, pid);
+  if(child) {
+    fd_set rfds;
+    FD_ZERO(&rfds);
+    FD_SET(child->fd_, &rfds);
+    struct timeval tv = { 0 , 0 };
+    if(select(child->fd_+1, &rfds, NULL, NULL, &tv) == 1) {
+      int err = 0;
+      if(read(child->fd_, (void*)(&err), sizeof(err)) >= sizeof(err)) {
+        lua_pushliteral(L, "error");
+        lua_pushstring(L, strerror(errno)); // FIXXXXXME: strerror is not threadsafe!!!
+        return 3;
+      }
+    }
+    child_remove(L, pid);
+  }
   if(WIFEXITED(status)) {
     lua_pushliteral(L, "exit");
     lua_pushinteger(L, WEXITSTATUS(status));
@@ -309,5 +435,7 @@ static const struct luaL_reg util_funcs [] = {
 LUALIB_API int luaopen_util(lua_State *L) 
 {
   luaL_register(L, LUA_UTILLIBNAME, util_funcs);
+  lua_pushlightuserdata(L, NULL);
+  lua_setfield(L, -2, LUA_UTILCHLIDRENNAME);
   return 1;
 }
diff --git a/src/l_util.h b/src/l_util.h
index c0b558a..14422b8 100644
--- a/src/l_util.h
+++ b/src/l_util.h
@@ -36,6 +36,7 @@
 #include <lua.h>
 
 #define LUA_UTILLIBNAME "util"
+#define LUA_UTILCHLIDRENNAME "__children"
 LUALIB_API int luaopen_util(lua_State *L);
 
 #endif