1.\"	$NetBSD: elf_getscn.3,v 1.2 2014/03/09 16:58:04 christos Exp $
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3.\" Copyright (c) 2006-2008 Joseph Koshy.  All rights reserved.
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26.\" Id: elf_getscn.3 189 2008-07-20 10:38:08Z jkoshy
27.\"
28.Dd October 22, 2007
29.Os
30.Dt ELF_GETSCN 3
31.Sh NAME
32.Nm elf_getscn ,
33.Nm elf_ndxscn ,
34.Nm elf_newscn ,
35.Nm elf_nextscn
36.Nd get/allocate section information for an ELF object
37.Sh LIBRARY
38.Lb libelf
39.Sh SYNOPSIS
40.In libelf.h
41.Ft "Elf_Scn *"
42.Fn elf_getscn "Elf *elf" "size_t index"
43.Ft size_t
44.Fn elf_ndxscn "Elf_Scn *scn"
45.Ft "Elf_Scn *"
46.Fn elf_newscn "Elf *elf"
47.Ft "Elf_Scn *"
48.Fn elf_nextscn "Elf *elf" "Elf_Scn *scn"
49.Sh DESCRIPTION
50These functions are used to iterate through the sections associated
51with an ELF descriptor.
52.Pp
53Function
54.Fn elf_getscn
55will return a section descriptor for the section at index
56.Ar index
57in the object denoted by ELF descriptor
58.Ar elf .
59An error will be signalled if the specified section does not
60exist.
61.Pp
62Function
63.Fn elf_ndxscn
64returns the section table index associated with section descriptor
65.Ar scn .
66.Pp
67Function
68.Fn elf_newscn
69creates a new section and appends it to the list of sections
70associated with descriptor
71.Ar elf .
72The library will automatically increment the
73.Va e_shnum
74field of the ELF header associated with descriptor
75.Ar elf ,
76and will set the
77.Dv ELF_F_DIRTY
78flag on the returned section descriptor.
79For ELF descriptors opened for writing, the ELF library will
80automatically create an empty section at index zero
81.Dv ( SHN_UNDEF )
82on the first call to
83.Fn elf_newscn .
84.Pp
85Function
86.Fn elf_nextscn
87takes a section descriptor
88.Ar scn
89and returns a pointer to the section descriptor at the next higher
90index.
91Argument
92.Ar scn
93is allowed to be NULL, in which case this function will return a
94pointer to the section descriptor at index 1.
95If no further sections are present, function
96.Fn elf_nextscn
97will return a NULL pointer.
98.Sh RETURN VALUES
99Functions
100.Fn elf_getscn ,
101.Fn elf_newscn
102and
103.Fn elf_nextscn
104return a valid pointer to a section descriptor if successful, or
105NULL if an error occurs.
106.Pp
107Function
108.Fn elf_ndxscn
109returns a valid section table index if successful, or
110.Dv SHN_UNDEF
111if an error occurs.
112.Sh ERRORS
113These functions may fail with the following errors:
114.Bl -tag -width "[ELF_E_RESOURCE]"
115.It Bq Er ELF_E_ARGUMENT
116Arguments
117.Ar elf
118or
119.Ar scn
120were NULL.
121.It Bq Er ELF_E_ARGUMENT
122Argument
123.Ar index
124exceeded the current number of sections in the ELF object.
125.It Bq Er ELF_E_ARGUMENT
126Argument
127.Ar elf
128was not a descriptor for an ELF file.
129.It Bq Er ELF_E_ARGUMENT
130Section descriptor
131.Ar scn
132was not associated with ELF descriptor
133.Ar elf .
134.It Bq Er ELF_E_CLASS
135Descriptor
136.Ar elf
137was of an unknown ELF class.
138.It Bq Er ELF_E_SECTION
139Argument
140.Ar elf
141specified extended section numbering in the ELF header with the section header at
142index
143.Dv SHN_UNDEF
144not being of type
145.Dv SHT_NULL .
146.El
147.Sh SEE ALSO
148.Xr elf 3 ,
149.Xr elf_flagdata 3 ,
150.Xr elf_flagscn 3 ,
151.Xr elf_getdata 3 ,
152.Xr elf_getshdr 3 ,
153.Xr gelf 3
154