HP-UX Reference (11i v3 07/02) - 3 Library Functions A-M (vol 6)

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elf_cntl(3E) elf_cntl(3E)

NAME

elf_cntl - control a ﬁle descriptor

SYNOPSIS

cc [ﬂag... ] ﬁle...

-lelf [library] ...

#include <libelf.h>

int elf_cntl(Elf *elf, Elf_Cmd cmd);

DESCRIPTION

elf_cntl instructs the library to modify its behavior with respect to an ELF descriptor, elf.As

elf_begin(3E) describes, an ELF descriptor can have multiple activations, and multiple ELF descriptors may

share a single ﬁle descriptor. Generally,

elf_cntl

commands apply to all activations of elf. Moreover, if

the ELF descriptor is associated with an archive ﬁle, descriptors for members within the archive will also

be affected as described below. Unless stated otherwise, operations on archive members do not affect the

descriptor for the containing archive.

The cmd argument tells what actions to take and may have the following values.

ELF_C_FDDONE This value tells the library not to use the ﬁle descriptor associated with elf.Aprogram

should use this command when it has requested all the information it cares to use and

wishes to avoid the overhead of reading the rest of the ﬁle. The memory for all com-

pleted operations remains valid, but later ﬁle operations, such as the initial

elf_getdata for a section, will fail if the data is not in memory already.

ELF_C_FDREAD This command is similar to ELF_C_FDDONE , except it forces the library to read the

rest of the ﬁle. A program should use this command when it must close the ﬁle descrip-

tor but has not yet read everything it needs from the ﬁle. After elf_cntl completes

the

ELF_C_FDREAD command, future operations, such as elf_getdata , will use

the memory version of the ﬁle without needing to use the ﬁle descriptor.

If elf_cntl succeeds, it returns zero. Otherwise, elf was null or an error occurred, and the function

returns -1.

Note

If the program wishes to use the ‘‘raw’’ operations (see

elf_rawdata , described in elf_getdata(3E), and

elf_rawﬁle(3E)) after disabling the ﬁle descriptor with

ELF_C_FDDONE or ELF_C_FDREAD , it must exe-

cute the raw operations explicitly beforehand. Otherwise, the raw ﬁle operations will fail. Calling

elf_rawfile makes the entire image available, thus supporting subsequent elf_rawdata calls.