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Diffstat (limited to 'man3/errno.3')
| -rw-r--r-- | man3/errno.3 | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/man3/errno.3 b/man3/errno.3 new file mode 100644 index 000000000..52ab4b8e3 --- /dev/null +++ b/man3/errno.3 @@ -0,0 +1,335 @@ +.\" Copyright (c) 1996 Andries Brouwer (aeb@cwi.nl) +.\" +.\" This is free documentation; you can redistribute it and/or +.\" modify it under the terms of the GNU General Public License as +.\" published by the Free Software Foundation; either version 2 of +.\" the License, or (at your option) any later version. +.\" +.\" The GNU General Public License's references to "object code" +.\" and "executables" are to be interpreted as the output of any +.\" document formatting or typesetting system, including +.\" intermediate and printed output. +.\" +.\" This manual is distributed in the hope that it will be useful, +.\" but WITHOUT ANY WARRANTY; without even the implied warranty of +.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.\" GNU General Public License for more details. +.\" +.\" You should have received a copy of the GNU General Public +.\" License along with this manual; if not, write to the Free +.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, +.\" USA. +.\" +.\" 5 Oct 2002, Modified by Michael Kerrisk <mtk16@ext.canterbury.ac.nz> +.\" Updated for POSIX 1003.1 2001 +.\" +.TH ERRNO 3 2002-10-05 "" "Library functions" +.SH NAME +errno \- number of last error +.SH SYNOPSIS +.B #include <errno.h> +.sp +.BI "extern int " errno ; +.SH DESCRIPTION +The integer +.B errno +is set by system calls (and some library functions) to indicate +what went wrong. Its value is significant only when the call +returned an error (usually \-1), and a library function that does succeed +is allowed to change +.BR errno . + +Sometimes, when \-1 is also a legal return value one has to zero +.B errno +before the call in order to detect possible errors. + +\fBerrno\fR is defined by the ISO C standard to be a modifiable lvalue +of type \fBint\fR, and must not be explicitly declared; \fBerrno\fR +may be a macro. \fBerrno\fR is thread-local; setting it in one thread +does not affect its value in any other thread. + +Valid error numbers are all non-zero; \fBerrno\fR is never set to zero +by any library function. All the error names specified by POSIX.1 +must have distinct values. + +.\" FIXME EILSEQ is in C99. +POSIX.1 (2001 edition) lists the following symbolic error names. Of +these, \fBEDOM\fR and \fBERANGE\fR are in the ISO C standard. ISO C +Amendment 1 defines the additional error number \fBEILSEQ\fR for +coding errors in multibyte or wide characters. + +.TP +.B E2BIG +Arg list too long +.TP +.B EACCES +Permission denied +.TP +.B EADDRINUSE +Address in use +.TP +.B EADDRNOTAVAIL +Address not available +.TP +.B EAFNOSUPPORT +Address family not supported +.TP +.B EAGAIN +Resource temporarily unavailable +.TP +.B EALREADY +Connection already in progress +.TP +.B EBADF +Bad file descriptor +.TP +.B EBADMSG +Bad message +.TP +.B EBUSY +Resource busy +.TP +.B ECANCELED +Operation canceled +.TP +.B ECHILD +No child processes +.TP +.B ECONNABORTED +Connection aborted +.TP +.B ECONNREFUSED +Connection refused +.TP +.B ECONNRESET +Connection reset +.TP +.B EDEADLK +Resource deadlock avoided +.TP +.B EDESTADDRREQ +Destination address required +.TP +.B EDOM +Domain error +.TP +.B EDQUOT +Reserved +.TP +.B EEXIST +File exists +.TP +.B EFAULT +Bad address +.TP +.B EFBIG +File too large +.TP +.B EHOSTUNREACH +Host is unreachable +.TP +.B EIDRM +Identifier removed +.TP +.B EILSEQ +Illegal byte sequence +.TP +.B EINPROGRESS +Operation in progress +.TP +.B EINTR +Interrupted function call +.TP +.B EINVAL +Invalid argument +.TP +.B EIO +Input/output error +.TP +.B EISCONN +Socket is connected +.TP +.B EISDIR +Is a directory +.TP +.B ELOOP +Too many levels of symbolic links +.TP +.B EMFILE +Too many open files +.TP +.B EMLINK +Too many links +.TP +.B EMSGSIZE +Inappropriate message buffer length +.TP +.B EMULTIHOP +Reserved +.TP +.B ENAMETOOLONG +Filename too long +.TP +.B ENETDOWN +Network is down +.TP +.B ENETRESET +Connection aborted by network +.TP +.B ENETUNREACH +Network unreachable +.TP +.B ENFILE +Too many open files in system +.TP +.B ENOBUFS +No buffer space available +.\" ENODATA is part of XSR option +.TP +.B ENODATA +No message is available on the STREAM head read queue +.TP +.B ENODEV +No such device +.TP +.B ENOENT +No such file or directory +.TP +.B ENOEXEC +Exec format error +.TP +.B ENOLCK +No locks available +.TP +.B ENOLINK +Reserved +.TP +.B ENOMEM +Not enough space +.TP +.B ENOMSG +No message of the desired type +.TP +.B ENOPROTOOPT +Protocol not available +.TP +.B ENOSPC +No space left on device +.\" ENOSR is part of XSR option +.TP +.B ENOSR +No STREAM resources +.\" ENOSTR is part of XSR option +.TP +.B ENOSTR +Not a STREAM +.TP +.B ENOSYS +Function not implemented +.TP +.B ENOTCONN +The socket is not connected +.TP +.B ENOTDIR +Not a directory +.TP +.B ENOTEMPTY +Directory not empty +.TP +.B ENOTSOCK +Not a socket +.TP +.B ENOTSUP +Not supported +.TP +.B ENOTTY +Inappropriate I/O control operation +.TP +.B ENXIO +No such device or address +.TP +.B EOPNOTSUPP +Operation not supported on socket +.TP +.B EOVERFLOW +Value too large to be stored in data type +.TP +.B EPERM +Operation not permitted +.TP +.B EPIPE +Broken pipe +.TP +.B EPROTO +Protocol error +.TP +.B EPROTONOSUPPORT +Protocol not supported +.TP +.B EPROTOTYPE +Protocol wrong type for socket +.TP +.B ERANGE +Result too large +.TP +.B EROFS +Read-only file system +.TP +.B ESPIPE +Invalid seek +.TP +.B ESRCH +No such process +.TP +.B ESTALE +Reserved +.\" ETIME is part of XSR option +.TP +.B ETIME +STREAM ioctl() timeout +.TP +.B ETIMEDOUT +Operation timed out +.TP +.B ETXTBSY +Test file busy +.TP +.B EWOULDBLOCK +Operation would block (may be same value as +.BR EAGAIN ) +.TP +.B EXDEV +Improper link +.SH NOTE +A common mistake is to do +.RS +.nf + +if (somecall() == -1) { + printf("somecall() failed\en"); + if (errno == ...) { ... } +} + +.fi +.RE +where +.I errno +no longer needs to have the value it had upon return from +.IR somecall() . +If the value of +.I errno +should be preserved across a library call, it must be saved: +.RS +.nf + +if (somecall() == -1) { + int errsv = errno; + printf("somecall() failed\en"); + if (errsv == ...) { ... } +} + +.fi +.RE +.SH "SEE ALSO" +.BR perror (3), +.BR strerror (3) |