elf_getscn(3) [netbsd man page]
ELF_GETSCN(3) BSD Library Functions Manual ELF_GETSCN(3) NAME
elf_getscn, elf_ndxscn, elf_newscn, elf_nextscn -- get/allocate section information for an ELF object LIBRARY
ELF Access Library (libelf, -lelf) SYNOPSIS
#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 are used to iterate through the sections associated with an ELF descriptor. Function elf_getscn() will return a section descriptor for the section at index index in the object denoted by ELF descriptor elf. An error will be signalled if the specified section does not exist. Function elf_ndxscn() returns the section table index associated with section descriptor scn. Function elf_newscn() creates a new section and appends it to the list of sections associated with descriptor elf. The library will automat- ically increment the e_shnum field of the ELF header associated with descriptor elf, and will set the ELF_F_DIRTY flag on the returned sec- tion descriptor. For ELF descriptors opened for writing, the ELF library will automatically create an empty section at index zero (SHN_UNDEF) on the first call to elf_newscn(). Function elf_nextscn() takes a section descriptor scn and returns a pointer to the section descriptor at the next higher index. Argument 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 elf_nextscn() will return a NULL pointer. RETURN VALUES
Functions elf_getscn(), elf_newscn() and elf_nextscn() return a valid pointer to a section descriptor if successful, or NULL if an error occurs. Function elf_ndxscn() returns a valid section table index if successful, or SHN_UNDEF if an error occurs. ERRORS
These functions may fail with the following errors: [ELF_E_ARGUMENT] Arguments elf or scn were NULL. [ELF_E_ARGUMENT] Argument index exceeded the current number of sections in the ELF object. [ELF_E_ARGUMENT] Argument elf was not a descriptor for an ELF file. [ELF_E_ARGUMENT] Section descriptor scn was not associated with ELF descriptor elf. [ELF_E_CLASS] Descriptor elf was of an unknown ELF class. [ELF_E_SECTION] Argument elf specified extended section numbering in the ELF header with the section header at index SHN_UNDEF not being of type SHT_NULL. SEE ALSO
elf(3), elf_flagdata(3), elf_flagscn(3), elf_getdata(3), elf_getshdr(3), gelf(3) BSD
October 22, 2007 BSD
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elf_getscn(3ELF) ELF Library Functions elf_getscn(3ELF) NAME
elf_getscn, elf_ndxscn, elf_newscn, elf_nextscn - get section information 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'' section has an index of 1. Although a program can get a section descriptor for the section whose index is 0 (SHN_UNDEF, the undefined sec- tion), 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_getshdr() to retrieve the newly created, ``clean'' section header. The new section descriptor will have no associated data (see elf_getdata(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 building 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 |Stable | +-----------------------------+-----------------------------+ |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 11 Jul 2001 elf_getscn(3ELF)