ELF Library Functions elf_getscn(3ELF)
NAME
elf_getscn, elf_ndxscn, elf_newscn, elf_nextscn - get sec-
tion informationSYNOPSIS
cc [ flag ... ] file ... -lelf [ library ... ]
#include
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 thesections associated with the ELF descriptor elf. If the pro-
gram is building a new file, it is responsible for creating the file's ELF header before creating sections; seeelf32_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'' section has an index of 1. Although a program can get a section descriptor for the section whoseindex 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 erroroccurs, 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 toelf_newscn() for an ELF descriptor with no existing sections
returns a descriptor for section 1. If an error occurs orelf is NULL, elf_newscn() returns a null pointer.
After creating a new section descriptor, the program can useelf32_getshdr() to retrieve the newly created, ``clean''
section header. The new section descriptor will have noassociated data (see elf_getdata(3ELF)). When creating a new
section in this way, the library updates the e_shnum member
SunOS 5.11 Last change: 11 Jul 2001 1
ELF Library Functions elf_getscn(3ELF)
of the ELF header and sets the ELF_F_DIRTY bit for the sec-
tion (see elf_flagdata(3ELF)). If the program is building a
new file, it is responsible for creating the file's ELFheader (see elf32_getehdr(3ELF)) before creating new sec-
tions.The elf_nextscn() function takes an existing section
descriptor, scn, and returns a section descriptor for thenext higher section. One may use a null scn to obtain a sec-
tion descriptor for the section whose index is 1 (skippingthe section whose index is SHN_UNDEF). If no further sec-
tions are present or an error occurs, elf_nextscn() returns
a null pointer.The elf_ndxscn() function takes an existing section descrip-
tor, scn, and returns its section table index. If scn isnull 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 attri-
butes:SunOS 5.11 Last change: 11 Jul 2001 2
ELF Library Functions elf_getscn(3ELF)
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
SEE ALSO
elf(3ELF), elf32_getehdr(3ELF), elf32_getshdr(3ELF),
elf_begin(3ELF), elf_flagdata(3ELF), elf_getdata(3ELF),
libelf(3LIB), attributes(5)SunOS 5.11 Last change: 11 Jul 2001 3