freebsd-skq/contrib/elftoolchain/libelf/elf_getscn.3
Ed Maste ae500c1ff8 Update to ELF Tool Chain r3668
Highlights:
- Make sure that only TLS sections are sorted into TLS segment.
- Fixed multiple errors in "Section to Segment mapping".
- Man page updates
- ar improvements
- elfcopy: avoid filter_reloc uninitialized variable for rela
- elfcopy: avoid stripping relocations from static binaries
- readelf: avoid printing directory in front of absolute path
- readelf: add NT_FREEBSD_FEATURE_CTL FreeBSD note type
- test improvements

NOTES:

Some of these changes originated in FreeBSD and simply reduce diffs
between contrib and vendor.

ELF Tool Chain ar is not (currently) used in FreeBSD, and there are
improvements in both FreeBSD and ELF Tool Chain ar that are not in
the other.

Sponsored by:	The FreeBSD Foundation
2019-01-10 14:35:23 +00:00

156 lines
4.2 KiB
Groff

.\" Copyright (c) 2006-2008,2018 Joseph Koshy. All rights reserved.
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.\" $Id: elf_getscn.3 3639 2018-10-14 14:07:02Z jkoshy $
.\"
.Dd September 24, 2018
.Dt ELF_GETSCN 3
.Os
.Sh NAME
.Nm elf_getscn ,
.Nm elf_ndxscn ,
.Nm elf_newscn ,
.Nm elf_nextscn
.Nd get/allocate section information for an ELF object
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft "Elf_Scn *"
.Fn elf_getscn "Elf *elf" "size_t index"
.Ft size_t
.Fn elf_ndxscn "Elf_Scn *scn"
.Ft "Elf_Scn *"
.Fn elf_newscn "Elf *elf"
.Ft "Elf_Scn *"
.Fn elf_nextscn "Elf *elf" "Elf_Scn *scn"
.Sh DESCRIPTION
These functions are used to iterate through the sections associated
with an ELF descriptor.
.Pp
Function
.Fn elf_getscn
will return a section descriptor for the section at index
.Ar index
in the object denoted by ELF descriptor
.Ar elf .
An error will be signalled if the specified section does not
exist.
.Pp
Function
.Fn elf_ndxscn
returns the section table index associated with section descriptor
.Ar scn .
.Pp
Function
.Fn elf_newscn
creates a new section and appends it to the list of sections
associated with descriptor
.Ar elf .
The library will automatically increment the
.Va e_shnum
field of the ELF header associated with descriptor
.Ar elf ,
and will set the
.Dv ELF_F_DIRTY
flag on the returned section descriptor.
For ELF descriptors opened for writing, the ELF library will
automatically create an empty section at index zero
.Dv ( SHN_UNDEF )
on the first call to
.Fn elf_newscn .
.Pp
Function
.Fn elf_nextscn
takes a section descriptor
.Ar scn
and returns a pointer to the section descriptor at the next higher
index.
As a consequence,
.Fn elf_nextscn
will never return a pointer to the empty section at index zero
.Dv ( SHN_UNDEF ) .
Argument
.Ar scn
is allowed to be NULL, in which case this function will return a
pointer to the section descriptor at index 1.
If no further sections are present, function
.Fn elf_nextscn
will return a NULL pointer.
.Sh RETURN VALUES
Functions
.Fn elf_getscn ,
.Fn elf_newscn
and
.Fn elf_nextscn
return a valid pointer to a section descriptor if successful, or
NULL if an error occurs.
.Pp
Function
.Fn elf_ndxscn
returns a valid section table index if successful, or
.Dv SHN_UNDEF
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 elf
or
.Ar scn
were NULL.
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar index
exceeded the current number of sections in the ELF object.
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar elf
was not a descriptor for an ELF file.
.It Bq Er ELF_E_ARGUMENT
Section descriptor
.Ar scn
was not associated with ELF descriptor
.Ar elf .
.It Bq Er ELF_E_CLASS
Descriptor
.Ar elf
was of an unknown ELF class.
.It Bq Er ELF_E_SECTION
Argument
.Ar elf
specified extended section numbering in the ELF header with the section header at
index
.Dv SHN_UNDEF
not being of type
.Dv SHT_NULL .
.El
.Sh SEE ALSO
.Xr elf 3 ,
.Xr elf_flagdata 3 ,
.Xr elf_flagscn 3 ,
.Xr elf_getdata 3 ,
.Xr elf_getshdr 3 ,
.Xr gelf 3