Log stdout and stderr for processes started from the notification area icon

Create a separate thread to write stdout and stderr for processes started from
the notification area icon to the X server log

At the moment, this output doesn't go anywhere useful, which can make it hard
to debug problems with processes started this way.

1 files changed, 125 insertions, 25 deletions

diff --git a/hw/xwin/winprefs.c b/hw/xwin/winprefs.c
index 0209d51f5..a4904710a 100644
--- a/hw/xwin/winprefs.c
+++ b/hw/xwin/winprefs.c
@@ -37,6 +37,8 @@
 #include <stdlib.h>
 #ifdef __CYGWIN__
 #include <sys/resource.h>
+#include <sys/wait.h>
+#include <pthread.h>
 #endif
 #include "win.h"
 
@@ -321,8 +323,120 @@ HandleCustomWM_INITMENU(unsigned long hwndIn,
 	CheckMenuItem (hmenu, pref.menu[i].menuItem[j].commandID, dwExStyle );
   
 }
-    
-/*
+
+#ifdef __CYGWIN__
+static void
+LogLineFromFd(int fd, const char *fdname, int pid)
+{
+#define BUFSIZE 512 /* must be less than internal buffer size used in LogVWrite */
+  char buf[BUFSIZE];
+  char *bufptr = buf;
+
+  /* read from fd until eof, newline or our buffer is full */
+  while ((read(fd, bufptr, 1) > 0) && (bufptr < &(buf[BUFSIZE-1])))
+    {
+      if (*bufptr == '\n')
+        break;
+      bufptr++;
+    }
+
+  /* null terminate and log */
+  *bufptr = 0;
+  if (strlen(buf))
+    ErrorF("(pid %d %s) %s\n", pid, fdname, buf);
+}
+
+static void *
+ExecAndLogThread(void *cmd)
+{
+  int pid;
+  int stdout_filedes[2];
+  int stderr_filedes[2];
+  int status;
+
+  /* Create a pair of pipes */
+  pipe(stdout_filedes);
+  pipe(stderr_filedes);
+
+  switch (pid = fork())
+    {
+    case 0: /* child */
+      {
+        struct rlimit rl;
+        unsigned int fd;
+
+        /* dup write end of pipes onto stderr and stdout */
+        close(STDOUT_FILENO);
+        close(STDERR_FILENO);
+
+        dup2(stdout_filedes[1], STDOUT_FILENO);
+        dup2(stderr_filedes[1], STDERR_FILENO);
+
+        /* Close any open descriptors except for STD* */
+        getrlimit (RLIMIT_NOFILE, &rl);
+        for (fd = STDERR_FILENO+1; fd < rl.rlim_cur; fd++)
+          close(fd);
+
+        /* Disassociate any TTYs */
+        setsid();
+
+        execl ("/bin/sh",
+               "/bin/sh",
+               "-c",
+               cmd,
+               NULL);
+        perror("execl failed");
+        exit(127);
+      }
+      break;
+
+    default: /* parent */
+      {
+        close(stdout_filedes[1]);
+        close(stderr_filedes[1]);
+
+        ErrorF("executing '%s', pid %d\n", (char *)cmd, pid);
+
+        /* read from pipes, write to log, until both are closed */
+        while (TRUE)
+          {
+            fd_set readfds, errorfds;
+            int nfds = max(stdout_filedes[0], stderr_filedes[0])+1;
+            FD_ZERO(&readfds);
+            FD_SET(stdout_filedes[0], &readfds);
+            FD_SET(stderr_filedes[0], &readfds);
+            errorfds = readfds;
+
+            if (select(nfds, &readfds, NULL, &errorfds, NULL) > 0)
+              {
+                if (FD_ISSET(stdout_filedes[0], &readfds))
+                  LogLineFromFd(stdout_filedes[0], "stdout", pid);
+                if (FD_ISSET(stderr_filedes[0], &readfds))
+                  LogLineFromFd(stderr_filedes[0], "stderr", pid);
+
+                if (FD_ISSET(stdout_filedes[0], &errorfds) &&
+                    FD_ISSET(stderr_filedes[0], &errorfds))
+                  break;
+              }
+            else
+              {
+                break;
+              }
+          }
+
+        waitpid(pid, &status, 0);
+      }
+      break;
+
+    case -1: /* error */
+      ErrorF("fork() to run command failed\n");
+    }
+
+  return (void *)status;
+}
+#endif
+
+  /*
  * Searches for the custom WM_COMMAND command ID and performs action.
  * Return TRUE if command is proccessed, FALSE otherwise.
  */
@@ -352,29 +466,15 @@ HandleCustomWM_COMMAND (unsigned long hwndIn,
 		{
 #ifdef __CYGWIN__
 		case CMD_EXEC:
-		  if (fork()==0)
-		    {
-		      struct rlimit rl;
-		      unsigned long i;
-
-		      /* Close any open descriptors except for STD* */
-		      getrlimit (RLIMIT_NOFILE, &rl);
-		      for (i = STDERR_FILENO+1; i < rl.rlim_cur; i++)
-			close(i);
-
-		      /* Disassociate any TTYs */
-		      setsid();
-
-		      execl ("/bin/sh",
-			     "/bin/sh",
-			     "-c",
-			     m->menuItem[j].param,
-			     NULL);
-		      exit (0);
-		    }
-		  else
-		    return TRUE;
-		  break;
+                  {
+                    pthread_t t;
+                    if (!pthread_create(&t, NULL, ExecAndLogThread, m->menuItem[j].param))
+                      pthread_detach(t);
+                    else
+                      ErrorF("Creating command output logging thread failed\n");
+                  }
+                  return TRUE;
+                  break;
 #else
 		case CMD_EXEC:
                   {