Exceptions list - Unix ENOENT not the name of the exception - what is?

Discussion in 'Ruby' started by Graham Nicholls, Jul 2, 2004.

  1. Hi,
    I'm trying to open a file, and if the user hasn't given an extension, adding
    one, but I can't find out what exception to use. If I leave off the rescue
    statements, then I see ENOENT, so try using that, but get a NameError -
    ENOENT is the Unix error, not Ruby's. So, what is the exception for a
    missing file on IO.foreach, and how in general can I get a list of
    exceptions or find out which is the right one to use?

    eg:


    if $include_header
    orig_hdr_fname=header_fname
    begin
    IO.foreach(header_fname) do |hdr_line|
    # Allow comments in header files:
    opfile.write(hdr_line) if hdr_line !~ /^\s*#/
    end
    rescue IOError <---- THIS IS THE PROBLEM
    header_fname=header_fname+"frt"
    printf("Error reading header file %s - trying
    %s\n",orig_hdr_fname,header_fname)
    retry
    rescue => err
    printf("Error opening header file %s\n",err)
    exit(BAD_FILE)
    end
    Thanks
     
    Graham Nicholls, Jul 2, 2004
    #1
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  2. Try rescuing Errno::ENOENT.

    -austin
     
    Austin Ziegler, Jul 2, 2004
    #2
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  3. Doh!
    Thanks

    Graham
     
    Graham Nicholls, Jul 2, 2004
    #3
  4. Graham Nicholls

    Dick Davies Guest

    Out of interest, is there anyway of knowing what exceptions a given
    class can raise?

    I'd expect not, but I've been wrong before (as any regulars on this list
    will know).
     
    Dick Davies, Jul 2, 2004
    #4
  5. As far as I know, no. However, I have also read that the "promised"
    list of exceptions (cf Java) is more problematic than useful (ISTR
    something on Joel on Software about it). However, using the classtree
    method (http://www.rubygarden.org/ruby?ASCIIClassHierarchyGenerator),
    you can call:

    class_tree(Exception, false, false)

    And get a tree of possible exceptions. That's where I found Errno::ENOENT.

    -austin
     
    Austin Ziegler, Jul 2, 2004
    #5
  6. Errno::ENOENT.

    In this case catching Exception should have helped, too. Or am I missing
    something?

    begin
    File.open("not possibly found here")
    rescue Exception => e
    p e
    puts e.class
    end

    Yields this in IRB:

    irb(main):001:0> begin
    irb(main):002:1* File.open("not possibly found here")
    irb(main):003:1> rescue Exception => e
    irb(main):004:1> p e
    irb(main):005:1> puts e.class
    irb(main):006:1> end
    #<Errno::ENOENT: No such file or directory - not possibly found here>
    Errno::ENOENT
    => nil

    Regards

    robert
     
    Robert Klemme, Jul 2, 2004
    #6
  7. Graham Nicholls

    Ara.T.Howard Guest

    ~/build/ruby > grep 'VALUE rb_e' *c
    error.c:VALUE rb_eException;
    error.c:VALUE rb_eSystemExit;
    error.c:VALUE rb_eInterrupt;
    error.c:VALUE rb_eSignal;
    error.c:VALUE rb_eFatal;
    error.c:VALUE rb_eStandardError;
    error.c:VALUE rb_eRuntimeError;
    error.c:VALUE rb_eTypeError;
    error.c:VALUE rb_eArgError;
    error.c:VALUE rb_eIndexError;
    error.c:VALUE rb_eRangeError;
    error.c:VALUE rb_eNameError;
    error.c:VALUE rb_eNoMethodError;
    error.c:VALUE rb_eSecurityError;
    error.c:VALUE rb_eNotImpError;
    error.c:VALUE rb_eNoMemError;
    error.c:VALUE rb_eScriptError;
    error.c:VALUE rb_eSyntaxError;
    error.c:VALUE rb_eLoadError;
    error.c:VALUE rb_eSystemCallError;
    eval.c:static VALUE rb_eLocalJumpError;
    eval.c:static VALUE rb_eSysStackError;
    eval.c:static VALUE rb_eval _((VALUE,NODE*));
    eval.c:static VALUE rb_eThreadError;
    io.c:VALUE rb_eEOFError;
    io.c:VALUE rb_eIOError;
    numeric.c:VALUE rb_eZeroDivError;
    numeric.c:VALUE rb_eFloatDomainError;
    re.c:static VALUE rb_eRegexpError;

    these are most of the errors, all the Errno::xxx errors are made by
    SystemCallError:

    ~ > cat syserr.rb
    255.times do |errno|
    se = SystemCallError.new(errno)
    next if se.message[%r/unknown error/io]
    printf "%-3.3d : %s\n", errno, se.inspect
    end

    ~ > ruby syserr.rb
    000 : #<SystemCallError: Success>
    001 : #<Errno::EPERM: Operation not permitted>
    002 : #<Errno::ENOENT: No such file or directory>
    003 : #<Errno::ESRCH: No such process>
    004 : #<Errno::EINTR: Interrupted system call>
    005 : #<Errno::EIO: Input/output error>
    006 : #<Errno::ENXIO: No such device or address>
    007 : #<Errno::E2BIG: Argument list too long>
    008 : #<Errno::ENOEXEC: Exec format error>
    009 : #<Errno::EBADF: Bad file descriptor>
    010 : #<Errno::ECHILD: No child processes>
    011 : #<Errno::EAGAIN: Resource temporarily unavailable>
    012 : #<Errno::ENOMEM: Cannot allocate memory>
    013 : #<Errno::EACCES: Permission denied>
    014 : #<Errno::EFAULT: Bad address>
    015 : #<Errno::ENOTBLK: Block device required>
    016 : #<Errno::EBUSY: Device or resource busy>
    017 : #<Errno::EEXIST: File exists>
    018 : #<Errno::EXDEV: Invalid cross-device link>
    019 : #<Errno::ENODEV: No such device>
    020 : #<Errno::ENOTDIR: Not a directory>
    021 : #<Errno::EISDIR: Is a directory>
    022 : #<Errno::EINVAL: Invalid argument>
    023 : #<Errno::ENFILE: Too many open files in system>
    024 : #<Errno::EMFILE: Too many open files>
    025 : #<Errno::ENOTTY: Inappropriate ioctl for device>
    026 : #<Errno::ETXTBSY: Text file busy>
    027 : #<Errno::EFBIG: File too large>
    028 : #<Errno::ENOSPC: No space left on device>
    029 : #<Errno::ESPIPE: Illegal seek>
    030 : #<Errno::EROFS: Read-only file system>
    031 : #<Errno::EMLINK: Too many links>
    032 : #<Errno::EPIPE: Broken pipe>
    033 : #<Errno::EDOM: Numerical argument out of domain>
    034 : #<Errno::ERANGE: Numerical result out of range>
    035 : #<Errno::EDEADLK: Resource deadlock avoided>
    036 : #<Errno::ENAMETOOLONG: File name too long>
    037 : #<Errno::ENOLCK: No locks available>
    038 : #<Errno::ENOSYS: Function not implemented>
    039 : #<Errno::ENOTEMPTY: Directory not empty>
    040 : #<Errno::ELOOP: Too many levels of symbolic links>
    042 : #<Errno::ENOMSG: No message of desired type>
    043 : #<Errno::EIDRM: Identifier removed>
    044 : #<Errno::ECHRNG: Channel number out of range>
    045 : #<Errno::EL2NSYNC: Level 2 not synchronized>
    046 : #<Errno::EL3HLT: Level 3 halted>
    047 : #<Errno::EL3RST: Level 3 reset>
    048 : #<Errno::ELNRNG: Link number out of range>
    049 : #<Errno::EUNATCH: Protocol driver not attached>
    050 : #<Errno::ENOCSI: No CSI structure available>
    051 : #<Errno::EL2HLT: Level 2 halted>
    052 : #<Errno::EBADE: Invalid exchange>
    053 : #<Errno::EBADR: Invalid request descriptor>
    054 : #<Errno::EXFULL: Exchange full>
    055 : #<Errno::ENOANO: No anode>
    056 : #<Errno::EBADRQC: Invalid request code>
    057 : #<Errno::EBADSLT: Invalid slot>
    059 : #<Errno::EBFONT: Bad font file format>
    060 : #<Errno::ENOSTR: Device not a stream>
    061 : #<Errno::ENODATA: No data available>
    062 : #<Errno::ETIME: Timer expired>
    063 : #<Errno::ENOSR: Out of streams resources>
    064 : #<Errno::ENONET: Machine is not on the network>
    065 : #<Errno::ENOPKG: Package not installed>
    066 : #<Errno::EREMOTE: Object is remote>
    067 : #<Errno::ENOLINK: Link has been severed>
    068 : #<Errno::EADV: Advertise error>
    069 : #<Errno::ESRMNT: Srmount error>
    070 : #<Errno::ECOMM: Communication error on send>
    071 : #<Errno::EPROTO: Protocol error>
    072 : #<Errno::EMULTIHOP: Multihop attempted>
    073 : #<Errno::EDOTDOT: RFS specific error>
    074 : #<Errno::EBADMSG: Bad message>
    075 : #<Errno::EOVERFLOW: Value too large for defined data type>
    076 : #<Errno::ENOTUNIQ: Name not unique on network>
    077 : #<Errno::EBADFD: File descriptor in bad state>
    078 : #<Errno::EREMCHG: Remote address changed>
    079 : #<Errno::ELIBACC: Can not access a needed shared library>
    080 : #<Errno::ELIBBAD: Accessing a corrupted shared library>
    081 : #<Errno::ELIBSCN: .lib section in a.out corrupted>
    082 : #<Errno::ELIBMAX: Attempting to link in too many shared libraries>
    083 : #<Errno::ELIBEXEC: Cannot exec a shared library directly>
    084 : #<Errno::EILSEQ: Invalid or incomplete multibyte or wide character>
    085 : #<Errno::ERESTART: Interrupted system call should be restarted>
    086 : #<Errno::ESTRPIPE: Streams pipe error>
    087 : #<Errno::EUSERS: Too many users>
    088 : #<Errno::ENOTSOCK: Socket operation on non-socket>
    089 : #<Errno::EDESTADDRREQ: Destination address required>
    090 : #<Errno::EMSGSIZE: Message too long>
    091 : #<Errno::EPROTOTYPE: Protocol wrong type for socket>
    092 : #<Errno::ENOPROTOOPT: Protocol not available>
    093 : #<Errno::EPROTONOSUPPORT: Protocol not supported>
    094 : #<Errno::ESOCKTNOSUPPORT: Socket type not supported>
    095 : #<Errno::EOPNOTSUPP: Operation not supported>
    096 : #<Errno::EPFNOSUPPORT: Protocol family not supported>
    097 : #<Errno::EAFNOSUPPORT: Address family not supported by protocol>
    098 : #<Errno::EADDRINUSE: Address already in use>
    099 : #<Errno::EADDRNOTAVAIL: Cannot assign requested address>
    100 : #<Errno::ENETDOWN: Network is down>
    101 : #<Errno::ENETUNREACH: Network is unreachable>
    102 : #<Errno::ENETRESET: Network dropped connection on reset>
    103 : #<Errno::ECONNABORTED: Software caused connection abort>
    104 : #<Errno::ECONNRESET: Connection reset by peer>
    105 : #<Errno::ENOBUFS: No buffer space available>
    106 : #<Errno::EISCONN: Transport endpoint is already connected>
    107 : #<Errno::ENOTCONN: Transport endpoint is not connected>
    108 : #<Errno::ESHUTDOWN: Cannot send after transport endpoint shutdown>
    109 : #<Errno::ETOOMANYREFS: Too many references: cannot splice>
    110 : #<Errno::ETIMEDOUT: Connection timed out>
    111 : #<Errno::ECONNREFUSED: Connection refused>
    112 : #<Errno::EHOSTDOWN: Host is down>
    113 : #<Errno::EHOSTUNREACH: No route to host>
    114 : #<Errno::EALREADY: Operation already in progress>
    115 : #<Errno::EINPROGRESS: Operation now in progress>
    116 : #<Errno::ESTALE: Stale NFS file handle>
    117 : #<Errno::EUCLEAN: Structure needs cleaning>
    118 : #<Errno::ENOTNAM: Not a XENIX named type file>
    119 : #<Errno::ENAVAIL: No XENIX semaphores available>
    120 : #<Errno::EISNAM: Is a named type file>
    121 : #<Errno::EREMOTEIO: Remote I/O error>
    122 : #<Errno::EDQUOT: Disk quota exceeded>
    123 : #<SystemCallError: No medium found>
    124 : #<SystemCallError: Wrong medium type>
    125 : #<SystemCallError: Operation canceled>


    cheers.

    -a
    --
    ===============================================================================
    | EMAIL :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
    | PHONE :: 303.497.6469
    | A flower falls, even though we love it;
    | and a weed grows, even though we do not love it.
    | --Dogen
    ===============================================================================
     
    Ara.T.Howard, Jul 2, 2004
    #7
  8. This will work, but catch-all rescue blocks like that can be
    dangerous, as they can mask user interrupts, missing method errors,
    etc. Using the most specific exception class that still covers the
    errors you expect to see in a block means that unexpected errors will
    be thrown up to higher levels on the stack, which is exactly what
    should happen.

    Lennon
     
    Lennon Day-Reynolds, Jul 3, 2004
    #8
  9.  
    Robert Klemme, Jul 5, 2004
    #9
  10. In Message-Id: <>
    Actually no extra code is needed in this case:
    -e:1:in `initialize': No such file or directory - no_such_file (Errno::ENOENT)
    from -e:1:in `open'
    from -e:1

    As you can see, a class of an exception raised is showed in () of the
    message.

    Just FYI.
     
    YANAGAWA Kazuhisa, Jul 5, 2004
    #10
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