errno(2)

NAME

errno − error indicator for function calls

SYNOPSIS

#include <errno.h>

extern int errno;

DESCRIPTION

Many functions in the HP-UX operating system indicate an error condition by returning an otherwise out-of-range value (usually -1). Most of these functions set the external variable errno to a non-zero code value that more specifically identifies the particular error condition that was encountered.

All errors detected and the corresponding error code values stored in errno are documented in the ERRORS section on manual pages for those functions that set it.

The value of errno is zero immediately after a successful call to any of the functions described by exec(2) and ptrace(2), but it is never set to zero by any other HP-UX function. Functions for which the use of errno is not described may nevertheless change its value to a non-zero value.

Since errno is not cleared on successful function calls, its value should be checked or used only when an error has been indicated and when the function’s ERRORS section documents the error codes.

Applications should not attempt to take the address of errno, because it may be converted to a macro in a future release.

The following is a complete list of the error codes. The numeric values can be found in <errno.h> but they should not be used in an application program because they can vary from system to system.

E2BIG Arg list too long. An argument and or environment list longer than maximum supported size is presented to a member of the exec() family. Other possibilities include: message size or number of semaphores exceeds system limit (msgop, semop), or too many privileged groups have been set up (setprivgrp).

EACCES Permission denied. An attempt was made to access a file or IPC object in a way forbidden by the protection system.

EADDRINUSE Address already in use. Only one usage of each address is normally permitted.

EADDRNOTAVAIL
Cannot assign requested address. Normally results from an attempt to create a socket with an address not on this machine.

EAFNOSUPPORT
Address family not supported by protocol family. An address incompatible with the requested protocol was used. For example, you should not necessarily expect to be able to use PUP Internet addresses with ARPA Internet protocols.

EAGAIN No more processes. A fork() failed because the system’s process table is full or the user is not allowed to create any more processes, or a semop() or msgop() call would have to block.

EALREADY Operation already in progress. An operation was attempted on a non-blocking object which already had an operation in progress.

EBADF Bad file number. Either a file descriptor refers to no open file, a read (respectively write) request is made to a file which is open only for writing (respectively reading), or the file descriptor is not in the legal range of file descriptors.

EBUSY Device or resource busy. An attempt to mount a device that was already mounted or an attempt was made to dismount a device on which there is an active file (open file, current directory, mounted-on file, active text segment). It will also occur if an attempt is made to enable accounting when it is already enabled. The device or resource is currently unavailable, such as when a non-shareable device file is in use.

ECHILD No child processes. A wait() was executed by a process that had no existing or unwaited-for child processes.

ECONNABORTED
Software caused connection abort. A connection abort was caused internal to your host machine.

ECONNREFUSED
Connection refused. No connection could be made because the target machine actively refused it. This usually results from trying to connect to a service that is inactive on the foreign host.

ECONNRESET Connection reset by peer. A connection was forcibly closed by a peer. This normally results from the peer executing a shutdown() call (see shutdown(2)).

EDEADLK Resource deadlock would occur. A process which has locked a system resource would have been put to sleep while attempting to access another process’ locked resource.

EDESTADDRREQ
Destination address required. A required address was omitted from an operation on a socket.

EDOM Math argument. The argument of a function in the math package (3M) is out of the domain of the function.

EEXIST File exists. An existing file was mentioned in an inappropriate context; e.g., link().

EFAULT Bad address. The system encountered a hardware fault in attempting to use an argument of a system call; can also result from passing the wrong number of parameters to a system call. The reliable detection of this error is implementation dependent.

EFBIG File too large. The size of a file exceeded the maximum file size (for the file system) or ULIMIT was exceeded (see ulimit(2)), or a bad semaphore number in a semop() call (see semop(2)).

EHOSTDOWN Host is down. A socket operation encountered a dead host. Networking activity on the local host has not been initiated.

EHOSTUNREACH
No route to host. A socket operation was attempted to an unreachable host.

EIDRM Identifier Removed. This error is returned to processes that resume execution due to the removal of an identifier from the file system’s name space (see msgctl(2), semctl(2), and shmctl(2)).

EILSEQ Illegal byte sequence. A wide character code has been detected that does not correspond to a valid character, or a byte sequence does not form a valid wide character code.

EINPROGRESS Operation now in progress. An operation that takes a long time to complete was attempted on a non-blocking object (see ioctl(2) and fcntl(2)).

EINTR Interrupted system call. An asynchronous signal (such as interrupt or quit), which the user has elected to catch, occurred during a system call. If execution is resumed after processing the signal, it will appear as if the interrupted system call returned this error condition unless the system call is restarted (see sigvector(2)).

EINVAL Invalid argument. Some invalid argument (such as unmounting a device that is not currently mounted, mentioning an undefined signal in signal() or kill(), or reading or writing a file for which lseek() has generated a negative pointer). Also set by the math functions described in the (3M) entries of this manual.

EIO I/O error − some physical I/O error. This error may in some cases occur on a call following the one to which it actually applies.

EISCONN Socket is already connected. A connect() request was made on an already connected socket, or, a sendto() or sendmsg() request on a connected socket specified a destination other than the connected party.

EISDIR Is a directory. An attempt to open a directory for writing.

ELOOP Too many levels of symbolic links. A path name search involved more than MAXSYMLINKS symbolic links. MAXSYMLINKS is defined in <sys/param.h>.

EMFILE Too many open files. No process may have more than a system-defined number of file descriptors open at a time.

EMLINK Too many links. An attempt to make more than the maximum number of links to a file.

EMSGSIZE Message too long. The socket requires that the message be sent atomically, and the size of the message to be sent made this impossible.

ENAMETOOLONG
File name too long. A path specified exceeds the maximum path length for the system. The maximum path length is specified by PATH_MAX and is defined in <limits.h>. PATH_MAX is guaranteed to be at least 1023 bytes. This error is also generated if the length of a path name component exceeds NAME_MAX and the _POSIX_NO_TRUNC option is in effect for the specified path. Currently, _POSIX_NO_TRUNC is in effect only for HFS file systems configured to allow path name components up to 255 bytes long (see convertfs(1M)) and therefore only path names referring to such file systems can generate the error for this case. The values of NAME_MAX, PATH_MAX, and _POSIX_NO_TRUNC for a particular path name can be queried by using the pathconf() system call (see pathconf(2)).

ENETDOWN Network is down. A socket operation encountered a dead network.

ENETRESET Network dropped connection on reset. The host you were connected to crashed and rebooted.

ENETUNREACH Network is unreachable. A socket operation was attempted to an unreachable network.

ENFILE File table overflow. The system’s table of open files is full, and temporarily no more open()s can be accepted.

ENOBUFS No buffer space available. An operation on a socket was not performed because the system lacked sufficient buffer space.

ENODEV No such device. An attempt was made to apply an inappropriate system call to a device (such as read a write-only device).

ENOENT No such file or directory. This error occurs when a file name is specified and the file should exist but does not, or when one of the directories in a path name does not exist. It also occurs with msgget(), semget(), and shmget() when key does not refer to any object and the IPC_CREAT flag is not set.

ENOEXEC Exec format error. A request is made to execute a file which, although it has the appropriate permissions, does not start with a valid magic number (see a.out(4)), or the file is too small to have a valid executable file header.

ENOLCK System lock table is full. Too many files have file locks on them, or there are too many record locks on files, or there are too many instances of a reading or writing process sleeping until an enforcement mode lock clears. This error may also indicate system problems in handling a lock request on a remote NFS file. This error is also currently returned for all attempts to perform locking operations on a remote NFS file that has its locking enforcement mode bit set, since the stateless nature of NFS prevents maintaining the necessary lock information.

ENOMEM Not enough space. During a system call such as exec(), brk(), fork(), or sbrk(), a program asks for more space than the system is able to supply. This may not be a temporary condition; the maximum space size is a system parameter. The error can also occur if the arrangement of text, data, and stack segments requires too many segmentation registers, or if there is not enough swap space during a fork().

ENOMSG No message of desired type. An attempt was made to receive a message of a type that does not exist on the specified message queue; see msgop(2).

ENOPROTOOPT Protocol not available. A bad option was specified in a getsockopt() or setsockopt() call (see getsockopt(2)).

ENOSPC No space left on device. During a write() to an ordinary file, there is no free space left on the device; or no space in system table during msgget(), semget(), or semop() while SEM_UNDO flag is set.

ENOSYM Symbol does not exist in executable. The dynamic loader was unable to resolve a symbolic reference in a shared library during a call to one of the dynamic loader interface routines (see shl_load(3X). The program may be in an inconsistent state and should be terminated immediately.

ENOSYS Function is not available. The requested function or operation is not implemented or not configured in the system.

ENOTBLK Block device required. A non-block file was mentioned where a block device was required, such as in mount().

ENOTCONN Socket is not connected. A request to send or receive data was disallowed because the socket was not connected.

ENOTDIR Not a directory. A non-directory was specified where a directory is required, such as in a path prefix or as an argument to chdir().

ENOTEMPTY Directory not empty. An attempt was made to remove a non-empty directory.

ENOTSOCK Socket operation on non-socket. An operation was attempted on something that is not a socket.

ENOTTY Not a typewriter. The (ioctl()) command is inappropriate to the selected device type.

ENXIO No such device or address. I/O on a special file refers to a subdevice that does not exist, or is beyond the limits of the device. It can also occur when, for example, a tape drive is not on line or no disk pack is loaded on a drive.

EOPNOTSUPP Operation not supported. The requested operation on a socket or NFS file is either invalid or unsupported. For example, this might occur when an attempt to accept() a connection on a datagram socket fails.

EPERM Not owner. Typically, this error indicates an attempt to modify a file in some way forbidden except to its owner or the super-user, such as to change its mode. It is also returned for attempts by ordinary users to do things for which they need, but lack, a special privilege.

EPFNOSUPPORT
Protocol family not supported. The protocol family has not been configured into the system or no implementation for it exists. The socket is not connected.

EPIPE Broken pipe. Data has been written to a pipe for which the other (reading) end has been closed. This most often occurs when the reading process exits before the writing process. This condition also generates the signal SIGPIPE; the error is returned if the signal is ignored.

EPROTONOSUPPORT
Protocol not supported. The protocol has not been configured into the system or no implementation for it exists.

EPROTOTYPE Protocol wrong type for socket. A protocol was specified that does not support the semantics of the socket type requested. For example, ARPA Internet UDP protocol cannot be used with type SOCK_STREAM.

ERANGE Result too large. The value of a function in the math package (3M) is not representable within machine precision, or a semop() call would cause either a semaphore value or a semaphore adjust value to exceed it system-imposed maximum.

EROFS Read-only file system. An attempt to modify a file or directory was made on a device mounted read-only.

ESHUTDOWN Cannot send after socket shutdown. A request to send data was disallowed because the socket had already been shut down with a previous shutdown() call.

ESOCKTNOSUPPORT
Socket type not supported. The support for the socket type has not been configured into the system or no implementation for it exists.

ESPIPE Illegal seek. An lseek() was issued to a pipe.

ESRCH No such process. No process can be found corresponding to that specified by pid in kill(), rtprio(), or ptrace(), or the process is not accessible.

ETIMEDOUT Connection timed out. A connect() request failed because the connected party did not properly respond after a period of time (timeout period varies, depending on the communication protocol).

ETXTBSY Text file busy. An attempt to execute an executable file which is currently open for writing (or reading). Also, an attempt to open for writing an otherwise writable file which is currently open for execution.

EWOULDBLOCK
Operation would block. An operation which would cause a process to block was attempted on an object in non-blocking mode (see ioctl(2) and fcntl(2)).

EXDEV Cross-device link. A link to a file on another device was attempted.

DEPENDENCIES

The following NFS errors are also defined:

EREFUSED The same error as ECONNREFUSED. The external variable errno is defined as ECONNREFUSED for NFS compatibility.

EREMOTE Too many levels of remote in path. An attempt was made to remotely mount an NFS file system into a path which already has a remotely mounted NFS file system component.

ESTALE Stale NFS file handle. A client referenced an open file, but the file was previously deleted.

Series 700/800:
In the definition of error ENOMEM, the term “segmentation registers” is invalid.

STANDARDS CONFORMANCE

errno: AES, SVID2, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C