Changes to error handling.

- API to get error code.
- Errors are submited to message queue by its error code
- Define error codes in libiso_msgs.h

libisofs/libiso_msgs.h

@@ -499,6 +499,58 @@ Range "scdbackup"          :  0x00020000 to 0x0002ffff
 ------------------------------------------------------------------------------
 Range "vreixo"              :  0x00030000 to 0x0003ffff
 
+ 0x0003ffff (FAILURE,HIGH) = Operation canceled
+ 0x0003fffe (FATAL,HIGH)   = Unknown or unexpected fatal error
+ 0x0003fffd (FAILURE,HIGH) = Unknown or unexpected error
+ 0x0003fffc (FATAL,HIGH)   = Internal programming error
+ 0x0003fffb (FAILURE,HIGH) = NULL pointer where NULL not allowed
+ 0x0003fffa (FATAL,HIGH)   = Memory allocation error
+ 0x0003fff9 (FATAL,HIGH)   = Interrupted by a signal
+ 0x0003fff8 (FAILURE,HIGH) = Invalid parameter value
+ 0x0003fff7 (FATAL,HIGH)   = Cannot create a needed thread
+ 0x0003fff6 (FAILURE,HIGH) = Write error
+ 0x0003fff5 (FAILURE,HIGH) = Buffer read error
+ 0x0003ffc0 (FAILURE,HIGH) = Trying to add a node already added to another dir
+ 0x0003ffbf (FAILURE,HIGH) = Node with same name already exist
+ 0x0003ffbe (FAILURE,HIGH) = Trying to remove a node that was not added to dir
+ 0x0003ffbd (FAILURE,HIGH) = A requested node does not exist
+ 0x0003ffbc (FAILURE,HIGH) = Image already bootable
+ 0x0003ffbb (FAILURE,HIGH) = Trying to use an invalid file as boot image
+ 0x0003ff80 (FAILURE,HIGH) = Error on file operation
+ 0x0003ff7f (FAILURE,HIGH) = Trying to open an already openned file
+ 0x0003ff7e (FAILURE,HIGH) = Access to file is not allowed
+ 0x0003ff7d (FAILURE,HIGH) = Incorrect path to file
+ 0x0003ff7c (FAILURE,HIGH) = The file does not exist in the filesystem
+ 0x0003ff7b (FAILURE,HIGH) = Trying to read or close a file not openned
+ 0x0003ff7a (FAILURE,HIGH) = Directory used where no dir is expected
+ 0x0003ff79 (FAILURE,HIGH) = File read error
+ 0x0003ff78 (FAILURE,HIGH) = Not dir used where a dir is expected
+ 0x0003ff77 (FAILURE,HIGH) = Not symlink used where a symlink is expected
+ 0x0003ff76 (FAILURE,HIGH) = Cannot seek to specified location
+ 0x0003ff75 (HINT,MEDIUM)  = File not supported in ECMA-119 tree and ignored 
+ 0x0003ff74 (HINT,MEDIUM)  = File bigger than supported by used standard
+ 0x0003ff73 (SORRY,HIGH)   = File read error during image creation
+ 0x0003ff72 (HINT,MEDIUM)  = Cannot convert filename to requested charset
+ 0x0003ff71 (SORRY,HIGH)   = File cannot be added to the tree
+ 0x0003ff70 (HINT,MEDIUM)  = File path breaks specification constraints
+ 0x0003ff00 (FAILURE,HIGH) = Charset conversion error
+ 0x0003feff (FAILURE,HIGH) = Too much files to mangle
+ 0x0003fec0 (FAILURE,HIGH) = Wrong or damaged Primary Volume Descriptor
+ 0x0003febf (SORRY,HIGH)   = Wrong or damaged RR entry
+ 0x0003febe (SORRY,HIGH)   = Unsupported RR feature
+ 0x0003febd (FAILURE,HIGH) = Wrong or damaged ECMA-119
+ 0x0003febc (FAILURE,HIGH) = Unsupported ECMA-119 feature
+ 0x0003febb (SORRY,HIGH)   = Wrong or damaged El-Torito catalog
+ 0x0003feba (SORRY,HIGH)   = Unsupported El-Torito feature
+ 0x0003feb9 (SORRY,HIGH)   = Cannot patch isolinux boot image
+ 0x0003feb8 (SORRY,HIGH)   = Unsupported SUSP feature
+ 0x0003feb7 (WARNING,HIGH) = Error on a RR entry that can be ignored
+ 0x0003feb6 (HINT,MEDIUM)  = Error on a RR entry that can be ignored
+ 0x0003feb5 (WARNING,HIGH) = Multiple ER SUSP entries found
+ 0x0003feb4 (HINT,MEDIUM)  = Unsupported volume descriptor found
+ 0x0003feb3 (WARNING,HIGH) = El-Torito related warning
+ 0x0003feb2 (SORRY,HIGH)   = Image write cancelled
+
 
 ------------------------------------------------------------------------------
 Range "application"         :  0x00040000 to 0x0004ffff