201 lines
5.5 KiB
Groff
201 lines
5.5 KiB
Groff
.\" Copyright (c) 2006,2008,2010-2011 Joseph Koshy. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" This software is provided by Joseph Koshy ``as is'' and
|
|
.\" any express or implied warranties, including, but not limited to, the
|
|
.\" implied warranties of merchantability and fitness for a particular purpose
|
|
.\" are disclaimed. in no event shall Joseph Koshy be liable
|
|
.\" for any direct, indirect, incidental, special, exemplary, or consequential
|
|
.\" damages (including, but not limited to, procurement of substitute goods
|
|
.\" or services; loss of use, data, or profits; or business interruption)
|
|
.\" however caused and on any theory of liability, whether in contract, strict
|
|
.\" liability, or tort (including negligence or otherwise) arising in any way
|
|
.\" out of the use of this software, even if advised of the possibility of
|
|
.\" such damage.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd January 26, 2011
|
|
.Dt ELF_GETDATA 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm elf_getdata ,
|
|
.Nm elf_newdata ,
|
|
.Nm elf_rawdata
|
|
.Nd iterate through or allocate section data
|
|
.Sh LIBRARY
|
|
.Lb libelf
|
|
.Sh SYNOPSIS
|
|
.In libelf.h
|
|
.Ft "Elf_Data *"
|
|
.Fn elf_getdata "Elf_Scn *scn" "Elf_Data *data"
|
|
.Ft "Elf_Data *"
|
|
.Fn elf_newdata "Elf_Scn *scn"
|
|
.Ft "Elf_Data *"
|
|
.Fn elf_rawdata "Elf_Scn *scn" "Elf_Data *data"
|
|
.Sh DESCRIPTION
|
|
These functions are used to access and manipulate data descriptors
|
|
associated with section descriptors.
|
|
Data descriptors used by the ELF library are described in
|
|
.Xr elf 3 .
|
|
.Pp
|
|
Function
|
|
.Fn elf_getdata
|
|
will return the next data descriptor associated with section descriptor
|
|
.Ar scn .
|
|
The returned data descriptor will be setup to contain translated data.
|
|
Argument
|
|
.Ar data
|
|
may be NULL, in which case the function returns the first data descriptor
|
|
associated with section
|
|
.Ar scn .
|
|
If argument
|
|
.Ar data
|
|
is not NULL, it must be a pointer to a data descriptor associated with
|
|
section descriptor
|
|
.Ar scn ,
|
|
and function
|
|
.Fn elf_getdata
|
|
will return a pointer to the next data descriptor for the section,
|
|
or NULL when the end of the section's descriptor list is reached.
|
|
.Pp
|
|
Function
|
|
.Fn elf_newdata
|
|
will allocate a new data descriptor and append it to the list of data
|
|
descriptors associated with section descriptor
|
|
.Ar scn .
|
|
The new data descriptor will be initialized as follows:
|
|
.Bl -tag -width "d_version" -compact -offset indent
|
|
.It Va d_align
|
|
Set to 1.
|
|
.It Va d_buf
|
|
Initialized to NULL.
|
|
.It Va d_off
|
|
Set to (off_t) -1.
|
|
This field is under application control if the
|
|
.Dv ELF_F_LAYOUT
|
|
flag was set on the ELF descriptor.
|
|
.It Va d_size
|
|
Set to zero.
|
|
.It Va d_type
|
|
Initialized to
|
|
.Dv ELF_T_BYTE .
|
|
.It Va d_version
|
|
Set to the current working version of the library, as set by
|
|
.Xr elf_version 3 .
|
|
.El
|
|
The application must set these values as appropriate before
|
|
calling
|
|
.Xr elf_update 3 .
|
|
Section
|
|
.Ar scn
|
|
must be associated with an ELF file opened for writing.
|
|
If the application has not requested full control of layout by
|
|
setting the
|
|
.Dv ELF_F_LAYOUT
|
|
flag on descriptor
|
|
.Ar elf ,
|
|
then the data referenced by the returned descriptor will be positioned
|
|
after the existing content of the section, honoring the file alignment
|
|
specified in member
|
|
.Va d_align .
|
|
On successful completion of a call to
|
|
.Fn elf_newdata ,
|
|
the ELF library will mark the section
|
|
.Ar scn
|
|
as
|
|
.Dq dirty .
|
|
.Pp
|
|
Function
|
|
.Fn elf_rawdata
|
|
is used to step through the data descriptors associated with
|
|
section
|
|
.Ar scn .
|
|
In contrast to function
|
|
.Fn elf_getdata ,
|
|
this function returns untranslated data.
|
|
If argument
|
|
.Ar data
|
|
is NULL, the first data descriptor associated with section
|
|
.Ar scn
|
|
is returned.
|
|
If argument
|
|
.Ar data
|
|
is not NULL, is must be a data descriptor associated with
|
|
section
|
|
.Ar scn ,
|
|
and function
|
|
.Fn elf_rawdata
|
|
will return the next data descriptor in the list, or NULL
|
|
if no further descriptors are present.
|
|
Function
|
|
.Fn elf_rawdata
|
|
always returns
|
|
.Vt Elf_Data
|
|
structures of type
|
|
.Dv ELF_T_BYTE .
|
|
.Ss Special handling of zero-sized and SHT_NOBITS sections
|
|
For sections of type
|
|
.Dv SHT_NOBITS,
|
|
and for zero-sized sections,
|
|
the functions
|
|
.Fn elf_getdata
|
|
and
|
|
.Fn elf_rawdata
|
|
return a pointer to a valid
|
|
.Vt Elf_Data
|
|
structure that has its
|
|
.Va d_buf
|
|
member set to NULL and its
|
|
.Va d_size
|
|
member set to the size of the section.
|
|
.Pp
|
|
If an application wishes to create a section of type
|
|
.Dv SHT_NOBITS ,
|
|
it should add a data buffer to the section using function
|
|
.Fn elf_newdata .
|
|
It should then set the
|
|
.Va d_buf
|
|
and
|
|
.Va d_size
|
|
members of the returned
|
|
.Vt Elf_Data
|
|
structure to NULL and the desired size of the section respectively.
|
|
.Sh RETURN VALUES
|
|
These functions return a valid pointer to a data descriptor if successful, or
|
|
NULL if an error occurs.
|
|
.Sh ERRORS
|
|
These functions may fail with the following errors:
|
|
.Bl -tag -width "[ELF_E_RESOURCE]"
|
|
.It Bq Er ELF_E_ARGUMENT
|
|
Arguments
|
|
.Ar scn
|
|
was NULL.
|
|
.It Bq Er ELF_E_ARGUMENT
|
|
Data descriptor
|
|
.Ar data
|
|
was not associated with section descriptor
|
|
.Ar scn .
|
|
.It Bq Er ELF_E_RESOURCE
|
|
An out of memory condition was detected.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr elf 3 ,
|
|
.Xr elf_flagdata 3 ,
|
|
.Xr elf_flagscn 3 ,
|
|
.Xr elf_getscn 3 ,
|
|
.Xr elf_getshdr 3 ,
|
|
.Xr elf_newscn 3 ,
|
|
.Xr elf_rawfile 3 ,
|
|
.Xr elf_update 3 ,
|
|
.Xr elf_version 3 ,
|
|
.Xr gelf 3
|