strerror---convert error number to string

Synopsis

#include <string.h>
char *strerror(int errnum);

Description
strerror converts the error number errnum into a string. The value of errnum is usually a copy of errno. If errnum is not a known error number, the result points to an empty string.

This implementation of strerror prints out the following strings for each of the values defined in `errno.h':

E2BIG

Arg list too long

EACCES

Permission denied

EADV

Advertise error

EAGAIN

No more processes

EBADF

Bad file number

EBADMSG

Bad message

EBUSY

Device or resource busy

ECHILD

No children

ECOMM

Communication error

EDEADLK

Deadlock

EEXIST

File exists

EDOM

Math argument

EFAULT

Bad address

EFBIG

File too large

EIDRM

Identifier removed

EINTR

Interrupted system call

EINVAL

Invalid argument

EIO

I/O error

EISDIR

Is a directory

ELIBACC

Cannot access a needed shared library

ELIBBAD

Accessing a corrupted shared library

ELIBEXEC

Cannot exec a shared library directly

ELIBMAX

Attempting to link in more shared libraries than system limit

ELIBSCN

.lib section in a.out corrupted

EMFILE

Too many open files

EMLINK

Too many links

EMULTIHOP

Multihop attempted

ENAMETOOLONG

File or path name too long

ENFILE

Too many open files in system

ENODEV

No such device

ENOENT

No such file or directory

ENOEXEC

Exec format error

ENOLCK

No lock

ENOLINK

Virtual circuit is gone

ENOMEM

Not enough space

ENOMSG

No message of desired type

ENONET

Machine is not on the network

ENOPKG

No package

ENOSPC

No space left on device

ENOSR

No stream resources

ENOSTR

Not a stream

ENOSYS

Function not implemented

ENOTBLK

Block device required

ENOTDIR

Not a directory

ENOTEMPTY

Directory not empty

ENOTTY

Not a character device

ENXIO

No such device or address

EPERM

Not owner

EPIPE

Broken pipe

EPROTO

Protocol error

ERANGE

Result too large

EREMOTE

Resource is remote

EROFS

Read-only file system

ESPIPE

Illegal seek

ESRCH

No such process

ESRMNT

Srmount error

ETIME

Stream ioctl timeout

ETXTBSY

Text file busy

EXDEV

Cross-device link

Returns
This function returns a pointer to a string. Your application must not modify that string.

Portability
ANSI C requires strerror, but does not specify the strings used for each error number.

Although this implementation of strerror is reentrant, ANSI C declares that subsequent calls to strerror may overwrite the result string; therefore portable code cannot depend on the reentrancy of this subroutine.

This implementation of strerror provides for user-defined extensibility. errno.h defines __ELASTERROR, which can be used as a base for user-defined error values. If the user supplies a routine named _user_strerror, and errnum passed to strerror does not match any of the supported values, _user_strerror is called with errnum as its argument.

_user_strerror takes one argument of type int, and returns a character pointer. If errnum is unknown to _user_strerror, _user_strerror returns NULL. The default _user_strerror returns NULL for all input values.

strerror requires no supporting OS subroutines.

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