2006-11-11 17:16:35 +00:00
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.\" Copyright (c) 2006 Joseph Koshy. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" This software is provided by Joseph Koshy ``as is'' and
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.\" any express or implied warranties, including, but not limited to, the
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.\" implied warranties of merchantability and fitness for a particular purpose
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.\" are disclaimed. in no event shall Joseph Koshy be liable
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.\" for any direct, indirect, incidental, special, exemplary, or consequential
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.\" damages (including, but not limited to, procurement of substitute goods
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.\" or services; loss of use, data, or profits; or business interruption)
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.\" however caused and on any theory of liability, whether in contract, strict
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.\" liability, or tort (including negligence or otherwise) arising in any way
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.\" out of the use of this software, even if advised of the possibility of
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.\" such damage.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 11, 2006
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.Os
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2006-11-13 09:46:16 +00:00
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.Dt ELF_ERRMSG 3
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2006-11-11 17:16:35 +00:00
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.Sh NAME
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.Nm elf_errmsg ,
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.Nm elf_errno
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.Nd ELF library error message handling
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.Sh LIBRARY
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.Lb libelf
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.Sh SYNOPSIS
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.In libelf.h
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.Ft int
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.Fn elf_errno "void"
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.Ft "const char *"
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.Fn elf_errmsg "int error"
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.Sh DESCRIPTION
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When an error occurs during an ELF library API call, the library
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encodes the error using an error number and stores the error number
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internally for retrieval by the application at a later point of time.
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Error numbers may contain an OS supplied error code in addition to
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an ELF API specific error code.
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An error number value of zero indicates no error.
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.Pp
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Function
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.Fn elf_errno
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is used to retrieve the last error recorded by the ELF library.
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Invoking this function has the side-effect of resetting the
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ELF library's recorded error number to zero.
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.Pp
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The function
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.Fn elf_errmsg
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returns a null-terminated string with a human readable
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description of the error specified in argument
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.Ar error .
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A zero value for argument
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.Ar error
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retrieves the most recent error encountered by the ELF
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library.
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An argument value of -1 behaves identically, except that
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it guarantees a non-NULL return from
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.Fn elf_errmsg .
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.Sh RETURN VALUES
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Function
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.Fn elf_errno
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returns a non-zero value encoding the last error encountered
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by the ELF library, or zero if no error was encountered.
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.Pp
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Function
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.Fn elf_errmsg
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returns a pointer to library local storage for non-zero values
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of argument
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.Ar error .
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With a zero argument, the function will return a NULL pointer if no
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error had been encountered by the library, or will return a pointer to
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library local storage containing an appropriate message otherwise.
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.Sh EXAMPLES
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Clearing the ELF library's recorded error number can be accomplished
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by invoking
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.Fn elf_errno
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and discarding its return value.
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.Bd -literal -offset indent
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/* clear error */
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(void) elf_errno();
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.Ed
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.Pp
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Retrieving a human-readable description of the current error number
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can be done with the following snippet:
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.Bd -literal -offset indent
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int err;
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const char *errmsg;
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\&...
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err = elf_errno();
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if (err != 0)
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errmsg = elf_errmsg(err);
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.Ed
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.Sh SEE ALSO
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.Xr elf 3 ,
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.Xr gelf 3
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.Sh BUGS
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Function
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.Fn elf_errmsg
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is not localized.
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