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.Dd April 25, 2019
.Dt ELF_AUX_INFO 3
.Os
.Sh NAME
.Nm elf_aux_info
.Nd extract data from the elf auxiliary vector of the current process
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/auxv.h
.Ft int
.Fn elf_aux_info "int aux" "void *buf" "int buflen"
.Sh DESCRIPTION
The
.Fn elf_aux_info
function retrieves the auxiliary info vector requested in
.Va aux .
The information is stored into the provided buffer if it will fit.
The following values, defined in
.In sys/elf_common.h
can be requested:
.Bl -tag -width AT_OSRELDATE
.It AT_CANARY
The canary value for SSP.
.It AT_HWCAP
CPU / hardware feature flags.
.It AT_HWCAP2
CPU / hardware feature flags.
.It AT_NCPUS
Number of CPUs.
.It AT_OSRELDATE
Kernel OSRELDATE.
.It AT_PAGESIZES
Vector of page sizes.
.It AT_PAGESZ
Page size in bytes.
.It AT_TIMEKEEP
Pointer to VDSO timehands (for library internal use).
.El
.Sh RETURN VALUES
Returns zero on success, or an error number on failure.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EINVAL
An unknown item was requested.
.It Bq Er EINVAL
The provided buffer was not the right size for the requested item.
.It Bq Er ENOENT
The requested item is not available.
.El
.Sh HISTORY
The
.Fn elf_aux_info
function appeared in
.Fx 12.0 .
.Sh BUGS
Only a small subset of available auxiliary info vector items are
accessible with this function.
Some items require a "right-sized" buffer while others just require a
"big enough" buffer.