fs: support as and as+ flags in stringToFlags()

Author: SirR4T

lib/internal/fs.js

@@ -223,10 +223,14 @@ function stringToFlags(flags) {
  case 'a' : return O_APPEND | O_CREAT | O_WRONLY;
  case 'ax' : // Fall through.
  case 'xa' : return O_APPEND | O_CREAT | O_WRONLY | O_EXCL;
+ case 'as' : // Fall through.
+ case 'sa' : return O_APPEND | O_CREAT | O_WRONLY | O_SYNC;
 
  case 'a+' : return O_APPEND | O_CREAT | O_RDWR;
  case 'ax+': // Fall through.
  case 'xa+': return O_APPEND | O_CREAT | O_RDWR | O_EXCL;
+ case 'as+': // Fall through.
+ case 'sa+': return O_APPEND | O_CREAT | O_RDWR | O_SYNC;
  }
 
  throw new errors.TypeError('ERR_INVALID_OPT_VALUE', 'flags', flags);