1.\" $NetBSD: elf_errmsg.3,v 1.2 2014/03/09 16:58:04 christos Exp $ 2.\" 3.\" Copyright (c) 2006,2008 Joseph Koshy. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" This software is provided by Joseph Koshy ``as is'' and 15.\" any express or implied warranties, including, but not limited to, the 16.\" implied warranties of merchantability and fitness for a particular purpose 17.\" are disclaimed. in no event shall Joseph Koshy be liable 18.\" for any direct, indirect, incidental, special, exemplary, or consequential 19.\" damages (including, but not limited to, procurement of substitute goods 20.\" or services; loss of use, data, or profits; or business interruption) 21.\" however caused and on any theory of liability, whether in contract, strict 22.\" liability, or tort (including negligence or otherwise) arising in any way 23.\" out of the use of this software, even if advised of the possibility of 24.\" such damage. 25.\" 26.\" Id: elf_errmsg.3 189 2008-07-20 10:38:08Z jkoshy 27.\" 28.Dd June 11, 2006 29.Os 30.Dt ELF_ERRMSG 3 31.Sh NAME 32.Nm elf_errmsg , 33.Nm elf_errno 34.Nd ELF library error message handling 35.Sh LIBRARY 36.Lb libelf 37.Sh SYNOPSIS 38.In libelf.h 39.Ft int 40.Fn elf_errno "void" 41.Ft "const char *" 42.Fn elf_errmsg "int error" 43.Sh DESCRIPTION 44When an error occurs during an ELF library API call, the library 45encodes the error using an error number and stores the error number 46internally for retrieval by the application at a later point of time. 47Error numbers may contain an OS supplied error code in addition to 48an ELF API specific error code. 49An error number value of zero indicates no error. 50.Pp 51Function 52.Fn elf_errno 53is used to retrieve the last error recorded by the ELF library. 54Invoking this function has the side-effect of resetting the 55ELF library's recorded error number to zero. 56.Pp 57The function 58.Fn elf_errmsg 59returns a null-terminated string with a human readable 60description of the error specified in argument 61.Ar error . 62A zero value for argument 63.Ar error 64retrieves the most recent error encountered by the ELF 65library. 66An argument value of -1 behaves identically, except that 67it guarantees a non-NULL return from 68.Fn elf_errmsg . 69.Sh RETURN VALUES 70Function 71.Fn elf_errno 72returns a non-zero value encoding the last error encountered 73by the ELF library, or zero if no error was encountered. 74.Pp 75Function 76.Fn elf_errmsg 77returns a pointer to library local storage for non-zero values 78of argument 79.Ar error . 80With a zero argument, the function will return a NULL pointer if no 81error had been encountered by the library, or will return a pointer to 82library local storage containing an appropriate message otherwise. 83.Sh EXAMPLES 84Clearing the ELF library's recorded error number can be accomplished 85by invoking 86.Fn elf_errno 87and discarding its return value. 88.Bd -literal -offset indent 89/* clear error */ 90(void) elf_errno(); 91.Ed 92.Pp 93Retrieving a human-readable description of the current error number 94can be done with the following snippet: 95.Bd -literal -offset indent 96int err; 97const char *errmsg; 98\&... 99err = elf_errno(); 100if (err != 0) 101 errmsg = elf_errmsg(err); 102.Ed 103.Sh SEE ALSO 104.Xr elf 3 , 105.Xr gelf 3 106.Sh BUGS 107Function 108.Fn elf_errmsg 109is not localized. 110