Workaround for NTFS-3G and Lion's CoreFoundation bug

fuse_wait.c

/*-
 * fuse_wait - Light wrapper around a FUSE mount program that waits
 *             for the "mounted" notification before exiting.
 *
 * Copyright (C) 2007-2009 Erik Larsson
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
 * 02110-1301, USA
 */

/*
 * fuse_wait
 *   Written as a replacement to shadowofged's little utility.
 *   This tool executes a specified mount program with all of its
 *   arguments. The path to the mount program and all its arguments
 *   start at the third argument. The first argument is the mount
 *   point to check for mount notification, and the second argument
 *   is the amount of seconds to wait until timeout.
 *   Primarily used for mounting ntfs-3g filesystems on Mac OS X.
 *
 * Updated 2007-10-07:
 *   I didn't read the man page for waitpid correctly. fuse_wait
 *   thus returned incorrect exit values, but it's fixed now.
 *
 * Updated
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h> // for realpath
#include <CoreFoundation/CoreFoundation.h>

#define VERSION "20090819"

#define FUSE_LISTEN_OBJECT "com.google.filesystems.fusefs.unotifications"
#define FUSE_MOUNT_NOTIFICATION_NAME "com.google.filesystems.fusefs.unotifications.mounted"
#define FUSE_MOUNT_PATH_KEY "kFUSEMountPath"

#ifdef DEBUG
#define DEBUGMODE TRUE
#else
#define DEBUGMODE FALSE
#endif

#if DEBUGMODE
#define LOG_DEBUG(...) do { FILE *debugFile = stderr; fprintf(debugFile, __VA_ARGS__); fflush(debugFile); } while(0)
#else
#define LOG_DEBUG(...)
#endif

#define MIN(X, Y) X < Y ? X : Y

static CFStringRef mountPath = NULL;

/* There seems to be a bug with MacFUSE such that the CFString that
 * it returns for kFUSEMountPath in the dictionary accompanying the
 * com.google.filesystems.fusefs.unotifications.mounted notification
 * is represented as UTF-8 within the internal representation.
 * Probably UTF-8 encoded text represented as UTF-16 values. This
 * function transforms it to a true null terminated UTF-8 string.
 * This function assumes that the target buffer out is at least
 * CFStringGetLength(in) bytes long. */
static void GetCorruptedMacFUSEStringAsUTF8(CFStringRef in, char* out, int outsize) {
  int inLength = CFStringGetLength(in);
  int bytesToWrite = MIN(inLength, outsize-1);
  int i;
  for(i = 0; i < bytesToWrite; ++i)
    out[i] = (char)CFStringGetCharacterAtIndex(in, i);
  out[i] = '\0';
}

/* Debug code for printing entries in the CFDictionary 'userInfo'. */
static void PrintDictEntry(const void *key, const void *value, void *context) {
  char *tmp = NULL;
  char *buffer = calloc(1, 512);
  
  CFStringGetCString(key, buffer, 512, kCFStringEncodingUTF8);
  LOG_DEBUG("    Key:\n");
  LOG_DEBUG("      \"%s\"", buffer);

  CFStringGetCString(value, buffer, 512, kCFStringEncodingUTF8);
  LOG_DEBUG("    Value:\n");
  LOG_DEBUG("      \"%s\"\n", buffer);
  LOG_DEBUG("    Hex:\n");
  LOG_DEBUG("      ");
  for(tmp = buffer; *tmp != '\0'; ++tmp)
    LOG_DEBUG(" %s%hhX", ((*tmp & 0xFF) < 0x10 ? "0" : ""), *tmp);
  LOG_DEBUG("\n");

  GetCorruptedMacFUSEStringAsUTF8(value, buffer, 512);
  LOG_DEBUG("    Value (de-corrupted):\n");
  LOG_DEBUG("      \"%s\"\n", buffer);
  LOG_DEBUG("    Hex (de-corrupted):\n");
  LOG_DEBUG("      ");
  for(tmp = buffer; *tmp != '\0'; ++tmp)
    LOG_DEBUG(" %s%hhX", ((*tmp & 0xFF) < 0x10 ? "0" : ""), *tmp);
  LOG_DEBUG("\n");

  free(buffer);

/*   FILE *dbgoutput = fopen("valuedump-utf32be.txt", "w"); */
/*   memset(buffer, 0, 512); */
/*   CFStringGetCString(value, buffer, 512, kCFStringEncodingUTF32BE); */
/*   fwrite(buffer, 512, 1, dbgoutput); */
/*   fclose(dbgoutput); */
}

/* Callback function which will recieve the 'mounted' notification
 * from FUSE. It is full with debug code... but I'll let it stay
 * that way. */
static void NotificationCallback(CFNotificationCenterRef center,
				 void *observer,
				 CFStringRef name,
				 const void *object,
				 CFDictionaryRef userInfo) {
  if(DEBUGMODE) {
    char buffer[512];
    LOG_DEBUG("Received notification:\n");
    if(CFStringGetCString(name, buffer, 512, kCFStringEncodingUTF8) == true)
      LOG_DEBUG("  Name: %s\n", buffer);
    else
      LOG_DEBUG("  <Cound not get name>\n");
    
    LOG_DEBUG("  userInfo:\n");
    if(userInfo != NULL)
      CFDictionaryApplyFunction(userInfo, PrintDictEntry, NULL);
    else
      LOG_DEBUG("    <null>\n");
  }
  
  if(userInfo != NULL) { // It's only null when testing
    const void *value = NULL;
    LOG_DEBUG("CFDictionaryGetValueIfPresent(%p, \"%s\", %p)\n",
	      userInfo, FUSE_MOUNT_PATH_KEY, &value);

    if(CFDictionaryGetValueIfPresent(userInfo, CFSTR(FUSE_MOUNT_PATH_KEY),
				     &value) == true) {
      LOG_DEBUG("CFStringGetTypeID(%p) == %lu ?\n", value,
		CFStringGetTypeID());
      if(CFGetTypeID((CFStringRef)value) == CFStringGetTypeID()) {
	LOG_DEBUG("  yes.\n");
	LOG_DEBUG("mountPath=%p\n", mountPath);
	if(mountPath != NULL)
	  CFRelease(mountPath); // No memory leaks please.
	LOG_DEBUG("assigning mountpath the value %p\n", value);

	mountPath = (CFStringRef)value;
	CFRetain(mountPath);

	LOG_DEBUG("done with assigning.\n");
#ifdef LION
	CFRunLoopStop(CFRunLoopGetCurrent());
#endif
      }
      else
	LOG_DEBUG("  no.");
    }
  }
}

/* Prints a help text to a stream. */
static void PrintUsage(FILE *stream) {
  /* 80 chars    <-------------------------------------------------------------------------------->*/
  fprintf(stream, "fuse_wait (version " VERSION ") - Wait for MacFUSE mount completion.\n");
  fprintf(stream, "Copyright (C) 2007-2009 Erik Larsson / Tuxera Ltd.\n");
  fprintf(stream, "\n");
  fprintf(stream, "usage: fuse_wait <mountpoint> <timeout> <mount_command> [<args...>]\n");  
  fprintf(stream, "  mountpoint    - where you wish to mount the MacFUSE file system\n");
  fprintf(stream, "  timeout       - time (in seconds) to wait for the mount operation to\n");
  fprintf(stream, "                  complete (may be a floating point value)\n");
  fprintf(stream, "  mount_command - a path to the executable file containing the fuse program\n");
  fprintf(stream, "                  used to mount the file system\n");
  fprintf(stream, "  args          - the arguments that you would normally pass to <mount_command>\n");
  fprintf(stream, "                  (note that this includes the mount point)\n");
}

int main(int argc, char** argv) {
  LOG_DEBUG("[Debug messages enabled]\n");
  if(argc < 4) {
    PrintUsage(stdout);
    return 0;
  }
  
  /* <argv parsing> */
  
  /* Parse argument: mountpoint (CFString) */
  /*CFStringRef mountpoint = CFStringCreateWithCString(kCFAllocatorDefault, 
    argv[1], kCFStringEncodingUTF8); */
  /* Parse argument: mountpointRaw (char*) */
  char *mountpointRaw = argv[1];
  
  /* Parse argument: timeout (double) */
  double timeout;
  {
    CFStringRef timeoutString = CFStringCreateWithCString(kCFAllocatorDefault, 
							  argv[2],
							  kCFStringEncodingUTF8);
    timeout = CFStringGetDoubleValue(timeoutString);
    CFRelease(timeoutString);
    if(timeout == 0.0) {
      fprintf(stdout, "Invalid argument: timeout (\"%s\")\n", argv[2]);
      return -1;
    }
  }
  
  /* Parse argument: mount_command */
  const char *mount_command = argv[3];
  
  /* </argv parsing> */
 
  CFNotificationCenterRef centerRef;
  CFStringRef notificationObjectName = CFSTR(FUSE_LISTEN_OBJECT);
  CFStringRef notificationName = CFSTR(FUSE_MOUNT_NOTIFICATION_NAME);
  //CFRunLoopRef runLoop;
  
  if(DEBUGMODE) {
    LOG_DEBUG("Testing NotificationCallback...\n");
    NotificationCallback(NULL, NULL, notificationObjectName, NULL, NULL);
    LOG_DEBUG("Test completed. Adding observer...\n");
  }
  
  centerRef = CFNotificationCenterGetDistributedCenter();
  //runLoop = CFRunLoopGetCurrent();
  
  /*
   * We need to add ourselves as an observer before the fork, in case the forked
   * process outruns us.
   *
   * Will the child process also be an observer? Possibly, but even if that is
   * the case, it shouldn't seem to make any practical difference (we never
   * enter a CFRunLoop in the child process, at least not before execvp).
   */
  CFNotificationCenterAddObserver(centerRef, NULL, NotificationCallback, notificationName,
				  notificationObjectName, CFNotificationSuspensionBehaviorDrop);

  int forkRetval = fork();
  if(forkRetval == -1) {
    fprintf(stderr, "Could not fork!\n");
    return -1;
  }
  else if(forkRetval != 0) {
    // Parent process
    int childProcessPID = forkRetval;

    int waitpid_status = 0;
    LOG_DEBUG("Waiting for PID %d...\n", childProcessPID);
    int waitpidres = waitpid(childProcessPID, &waitpid_status, 0);
    if(waitpidres == childProcessPID) {
      if(!WIFEXITED(waitpid_status)) {
	LOG_DEBUG("Child process did not exit cleanly! Returning -1.");
	return -1;
      }
      
      int retval = WEXITSTATUS(waitpid_status);
      LOG_DEBUG("PID %d returned with exit code: %d Exiting fuse_wait with this exit code...\n", childProcessPID, retval);
      if(retval != 0) {
	LOG_DEBUG("Exit value indicates an error while executing mount command. Returning without\n");
	LOG_DEBUG("waiting for notification.\n");
	LOG_DEBUG("Returning retval: %d\n", retval);
	return retval;
      }
    }
    else {
      LOG_DEBUG("Abnormal termination of process %d. waitpid returned: %d\n", childProcessPID, waitpidres);
      return -1;
    }
    
    LOG_DEBUG("Running run loop a long time...\n");
    CFStringRef mountPathSnapshot = NULL;
    while(mountPathSnapshot == NULL) {
#ifndef LION
      int crlrimRetval = CFRunLoopRunInMode(kCFRunLoopDefaultMode, timeout, true);
      LOG_DEBUG("Exited from run loop. Let's find out why... crlrimRetval: %d "
        "(handled: %d)\n", crlrimRetval, kCFRunLoopRunHandledSource);
#else
      CFRunLoopRunInMode(kCFRunLoopDefaultMode, timeout, true);
      LOG_DEBUG("Exited from run loop. Let's find out why.\n");
#endif
      mountPathSnapshot = mountPath; // Might have been modified during RunLoop.
#ifndef LION
      if(crlrimRetval != kCFRunLoopRunHandledSource) {
	fprintf(stderr, "Did not receive a signal within %f seconds. "
		"Exiting...\n", timeout);
	return -2;
      }
      else
#endif
      if(mountPathSnapshot != NULL) {
	LOG_DEBUG("mountPathSnapshot: %p\n", mountPathSnapshot);
	
	/*
	 * Convert the CFString that we got back from the CFNotificationCenter
	 * into UTF-8 data. (We assume that UTF-8 is the encoding used by the
	 * system, which is true in Mac OS X.)
	 */
	CFDataRef utf8Data =
	  CFStringCreateExternalRepresentation(NULL, mountPath,
					       kCFStringEncodingUTF8, 0);
	
	if(utf8Data != NULL) {
	  /*
	   * Put the UTF-8 data in a NULL-terminated C-string.
	   */
	  size_t mountPathUTF8Length = CFDataGetLength(utf8Data) + 1;
	  char *mountPathUTF8 = calloc(1, mountPathUTF8Length);
	  CFDataGetBytes(utf8Data, CFRangeMake(0, mountPathUTF8Length - 1),
			 (unsigned char*) mountPathUTF8);
	  
	  //int mountPathUTF8Length = CFStringGetLength(mountPath) + 1;  // null terminator
	  //char *mountPathUTF8 = malloc(mountPathUTF8Length);
	  //memset(mountPathUTF8, 0, mountPathUTF8Length);
	  //GetCorruptedMacFUSEStringAsUTF8(mountPath, mountPathUTF8, mountPathUTF8Length);
	  
	  /*
	   * Canonicalize the two paths, in case one of the pathnames contain
	   * symbolic links, but not the other.
	   */
	  char *canonicalMountPath = malloc(PATH_MAX);
	  char *canonicalMountpoint = malloc(PATH_MAX);
	  memset(canonicalMountPath, 0, PATH_MAX);
	  memset(canonicalMountpoint, 0, PATH_MAX);
	  
	  realpath(mountPathUTF8, canonicalMountPath);
	  realpath(mountpointRaw, canonicalMountpoint);
	  
	  /*
	   * Finally, compare the two paths for equality.
	   */
	  int cmpres = strncmp(canonicalMountPath, canonicalMountpoint, PATH_MAX);
	  
	  if(cmpres != 0) {
	    LOG_DEBUG("Strings NOT equal. cmpres=%d\n", cmpres);
	    LOG_DEBUG("mountPath (UTF-8): \"%s\"\n", canonicalMountPath);
	    LOG_DEBUG("mountpoint (UTF-8): \"%s\"\n", canonicalMountpoint);
	    
	    mountPathSnapshot = NULL;
	  }
	  else
	    LOG_DEBUG("Recieved a signal for the mount point.\n");
	  
	  free(mountPathUTF8);
	  free(canonicalMountPath);
	  free(canonicalMountpoint);
	}

	CFRelease(utf8Data);
      }
    }
    LOG_DEBUG("Run loop done.\n");
    if(mountPath != NULL)
      CFRelease(mountPath);
    
    return 0; // We have previously checked that the return value from the child process is 0. We can't get here if it isn't.
  }
  else { // forkRetval == 0
    // Child process
    const int childargc = argc-3;
    char *childargv[childargc+1];
    childargv[childargc] = NULL; // Null terminated
    int i;
    for(i = 0; i < childargc; ++i)
      childargv[i] = argv[i+(argc-childargc)];
    
    LOG_DEBUG("Contents of argv:\n");
    for(i = 0; i < argc; ++i)
      LOG_DEBUG("  argv[%i]: \"%s\"\n", i, argv[i]);
    
    LOG_DEBUG("Contents of childargv:\n");
    for(i = 0; i < childargc; ++i)
      LOG_DEBUG("  childargv[%i]: \"%s\"\n", i, childargv[i]);
    
    execvp(mount_command, childargv);
    fprintf(stderr, "Could not execute %s!\n", argv[3]);
    return -1;
  }
}