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4c33415e4c
This is part of the interface to the kernel and some syscall wrappers depend on it so move it there. Reviewed by: kib, emaste, imp Pull Request: https://github.com/freebsd/freebsd-src/pull/908
106 lines
3.4 KiB
Groff
106 lines
3.4 KiB
Groff
.\"
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.\" Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 16, 2022
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.Dt ELF_AUX_INFO 3
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.Os
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.Sh NAME
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.Nm elf_aux_info
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.Nd extract data from the elf auxiliary vector of the current process
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/auxv.h
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.Ft int
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.Fn elf_aux_info "int aux" "void *buf" "int buflen"
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.Sh DESCRIPTION
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The
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.Fn elf_aux_info
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function retrieves the auxiliary info vector requested in
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.Va aux .
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The information is stored into the provided buffer if it will fit.
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The following values, defined in
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.In sys/elf_common.h
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can be requested (corresponding buffer sizes are specified in parenthesis):
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.Bl -tag -width AT_OSRELDATE
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.It AT_CANARY
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The canary value for SSP (arbitrary sized buffer, as many bytes are
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returned as it fits into it, rest is zeroed).
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.It AT_EXECPATH
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The path of executed program
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.Dv (MAXPATHLEN).
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This may not be present if the process was initialized by
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.Xr fexecve 2
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and the namecache no longer contains the file's name.
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.It AT_HWCAP
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CPU / hardware feature flags
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.Dv (sizeof(u_long)).
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.It AT_HWCAP2
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CPU / hardware feature flags
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.Dv (sizeof(u_long)).
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.It AT_NCPUS
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Number of CPUs
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.Dv (sizeof(int)).
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.It AT_OSRELDATE
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The
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.Dv OSRELDATE
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of the kernel or jail the program is running on
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.Dv (sizeof(int)).
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.It AT_PAGESIZES
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Vector of page sizes (arbitrary sized buffer, as many elements of the
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.Dv pagesizes
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array are returned as it fits).
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.It AT_PAGESZ
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Page size in bytes
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.Dv (sizeof(int)).
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.It AT_TIMEKEEP
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Pointer to VDSO timehands (for library internal use,
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.Dv sizeof(void *)).
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.It AT_USRSTACKBASE
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Top of the user stack for main thread.
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.It AT_USRSTACKLIM
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Limit for grow of the user stack for main thread.
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.El
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.Sh RETURN VALUES
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Returns zero on success, or an error number on failure.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EINVAL
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An unknown item was requested.
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.It Bq Er EINVAL
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The provided buffer was not the right size for the requested item.
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.It Bq Er ENOENT
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The requested item is not available.
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.El
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.Sh HISTORY
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The
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.Fn elf_aux_info
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function appeared in
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.Fx 12.0 .
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.Sh BUGS
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Only a small subset of available auxiliary info vector items are
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accessible with this function.
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Some items require a "right-sized" buffer while others just require a
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"big enough" buffer.
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