elf_getscn(3ELF) ELF Library Functions elf_getscn(3ELF)NAME
elf_getscn, elf_ndxscn, elf_newscn, elf_nextscn - get section informa‐
tion
SYNOPSIS
cc [ flag ... ] file ... -lelf [ library ... ]
#include <libelf.h>
Elf_Scn *elf_getscn(Elf *elf, size_t index);
size_t elf_ndxscn(Elf_Scn *scn);
Elf_Scn *elf_newscn(Elf *elf);
Elf_Scn *elf_nextscn(Elf *elf, Elf_Scn *scn);
DESCRIPTION
These functions provide indexed and sequential access to the sections
associated with the ELF descriptor elf. If the program is building a
new file, it is responsible for creating the file's ELF header before
creating sections; see elf32_getehdr(3ELF).
The elf_getscn() function returns a section descriptor, given an index
into the file's section header table. Note that the first ``real'' sec‐
tion has an index of 1. Although a program can get a section descriptor
for the section whose index is 0 (SHN_UNDEF, the undefined section),
the section has no data and the section header is ``empty'' (though
present). If the specified section does not exist, an error occurs, or
elf is NULL, elf_getscn() returns a null pointer.
The elf_newscn() function creates a new section and appends it to the
list for elf. Because the SHN_UNDEF section is required and not
``interesting'' to applications, the library creates it automatically.
Thus the first call to elf_newscn() for an ELF descriptor with no
existing sections returns a descriptor for section 1. If an error
occurs or elf is NULL, elf_newscn() returns a null pointer.
After creating a new section descriptor, the program can use elf32_get‐
shdr() to retrieve the newly created, ``clean'' section header. The new
section descriptor will have no associated data (see elf_get‐
data(3ELF)). When creating a new section in this way, the library
updates the e_shnum member of the ELF header and sets the ELF_F_DIRTY
bit for the section (see elf_flagdata(3ELF)). If the program is build‐
ing a new file, it is responsible for creating the file's ELF header
(see elf32_getehdr(3ELF)) before creating new sections.
The elf_nextscn() function takes an existing section descriptor, scn,
and returns a section descriptor for the next higher section. One may
use a null scn to obtain a section descriptor for the section whose
index is 1 (skipping the section whose index is SHN_UNDEF). If no fur‐
ther sections are present or an error occurs, elf_nextscn() returns a
null pointer.
The elf_ndxscn() function takes an existing section descriptor, scn,
and returns its section table index. If scn is null or an error occurs,
elf_ndxscn() returns SHN_UNDEF.
EXAMPLES
Example 1 A sample of calling elf_getscn() function.
An example of sequential access appears below. Each pass through the
loop processes the next section in the file; the loop terminates when
all sections have been processed.
scn = 0;
while ((scn = elf_nextscn(elf, scn)) != 0)
{
/* process section */
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOelf(3ELF), elf32_getehdr(3ELF), elf32_getshdr(3ELF), elf_begin(3ELF),
elf_flagdata(3ELF), elf_getdata(3ELF), libelf(3LIB), attributes(5)SunOS 5.10 11 Jul 2001 elf_getscn(3ELF)
