dist/src/readelf.c

/*	$NetBSD: readelf.c,v 1.8 2014/06/13 02:08:06 christos Exp $	*/
/*
 * Copyright (c) Christos Zoulas 2003.
 * All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include "file.h"

#ifndef lint
#if 0
FILE_RCSID("@(#)$File: readelf.c,v 1.103 2014/05/02 02:25:10 christos Exp $")
#else
__RCSID("$NetBSD: readelf.c,v 1.8 2014/06/13 02:08:06 christos Exp $");
#endif
#endif

#ifdef BUILTIN_ELF
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "readelf.h"
#include "magic.h"

#ifdef	ELFCORE
private int dophn_core(struct magic_set *, int, int, int, off_t, int, size_t,
    off_t, int *);
#endif
private int dophn_exec(struct magic_set *, int, int, int, off_t, int, size_t,
    off_t, int *, int);
private int doshn(struct magic_set *, int, int, int, off_t, int, size_t,
    off_t, int *, int, int);
private size_t donote(struct magic_set *, void *, size_t, size_t, int,
    int, size_t, int *);

#define	ELF_ALIGN(a)	((((a) + align - 1) / align) * align)

#define isquote(c) (strchr("'\"`", (c)) != NULL)

private uint16_t getu16(int, uint16_t);
private uint32_t getu32(int, uint32_t);
private uint64_t getu64(int, uint64_t);

private uint16_t
getu16(int swap, uint16_t value)
{
	union {
		uint16_t ui;
		char c[2];
	} retval, tmpval;

	if (swap) {
		tmpval.ui = value;

		retval.c[0] = tmpval.c[1];
		retval.c[1] = tmpval.c[0];

		return retval.ui;
	} else
		return value;
}

private uint32_t
getu32(int swap, uint32_t value)
{
	union {
		uint32_t ui;
		char c[4];
	} retval, tmpval;

	if (swap) {
		tmpval.ui = value;

		retval.c[0] = tmpval.c[3];
		retval.c[1] = tmpval.c[2];
		retval.c[2] = tmpval.c[1];
		retval.c[3] = tmpval.c[0];

		return retval.ui;
	} else
		return value;
}

private uint64_t
getu64(int swap, uint64_t value)
{
	union {
		uint64_t ui;
		char c[8];
	} retval, tmpval;

	if (swap) {
		tmpval.ui = value;

		retval.c[0] = tmpval.c[7];
		retval.c[1] = tmpval.c[6];
		retval.c[2] = tmpval.c[5];
		retval.c[3] = tmpval.c[4];
		retval.c[4] = tmpval.c[3];
		retval.c[5] = tmpval.c[2];
		retval.c[6] = tmpval.c[1];
		retval.c[7] = tmpval.c[0];

		return retval.ui;
	} else
		return value;
}

#define elf_getu16(swap, value) getu16(swap, value)
#define elf_getu32(swap, value) getu32(swap, value)
#define elf_getu64(swap, value) getu64(swap, value)

#define xsh_addr	(clazz == ELFCLASS32			\
			 ? (void *)&sh32			\
			 : (void *)&sh64)
#define xsh_sizeof	(clazz == ELFCLASS32			\
			 ? sizeof(sh32)				\
			 : sizeof(sh64))
#define xsh_size	(size_t)(clazz == ELFCLASS32		\
			 ? elf_getu32(swap, sh32.sh_size)	\
			 : elf_getu64(swap, sh64.sh_size))
#define xsh_offset	(off_t)(clazz == ELFCLASS32		\
			 ? elf_getu32(swap, sh32.sh_offset)	\
			 : elf_getu64(swap, sh64.sh_offset))
#define xsh_type	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, sh32.sh_type)	\
			 : elf_getu32(swap, sh64.sh_type))
#define xsh_name    	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, sh32.sh_name)	\
			 : elf_getu32(swap, sh64.sh_name))
#define xph_addr	(clazz == ELFCLASS32			\
			 ? (void *) &ph32			\
			 : (void *) &ph64)
#define xph_sizeof	(clazz == ELFCLASS32			\
			 ? sizeof(ph32)				\
			 : sizeof(ph64))
#define xph_type	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, ph32.p_type)	\
			 : elf_getu32(swap, ph64.p_type))
#define xph_offset	(off_t)(clazz == ELFCLASS32		\
			 ? elf_getu32(swap, ph32.p_offset)	\
			 : elf_getu64(swap, ph64.p_offset))
#define xph_align	(size_t)((clazz == ELFCLASS32		\
			 ? (off_t) (ph32.p_align ? 		\
			    elf_getu32(swap, ph32.p_align) : 4) \
			 : (off_t) (ph64.p_align ?		\
			    elf_getu64(swap, ph64.p_align) : 4)))
#define xph_filesz	(size_t)((clazz == ELFCLASS32		\
			 ? elf_getu32(swap, ph32.p_filesz)	\
			 : elf_getu64(swap, ph64.p_filesz)))
#define xnh_addr	(clazz == ELFCLASS32			\
			 ? (void *)&nh32			\
			 : (void *)&nh64)
#define xph_memsz	(size_t)((clazz == ELFCLASS32		\
			 ? elf_getu32(swap, ph32.p_memsz)	\
			 : elf_getu64(swap, ph64.p_memsz)))
#define xnh_sizeof	(clazz == ELFCLASS32			\
			 ? sizeof nh32				\
			 : sizeof nh64)
#define xnh_type	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, nh32.n_type)	\
			 : elf_getu32(swap, nh64.n_type))
#define xnh_namesz	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, nh32.n_namesz)	\
			 : elf_getu32(swap, nh64.n_namesz))
#define xnh_descsz	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, nh32.n_descsz)	\
			 : elf_getu32(swap, nh64.n_descsz))
#define prpsoffsets(i)	(clazz == ELFCLASS32			\
			 ? prpsoffsets32[i]			\
			 : prpsoffsets64[i])
#define xcap_addr	(clazz == ELFCLASS32			\
			 ? (void *)&cap32			\
			 : (void *)&cap64)
#define xcap_sizeof	(clazz == ELFCLASS32			\
			 ? sizeof cap32				\
			 : sizeof cap64)
#define xcap_tag	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, cap32.c_tag)	\
			 : elf_getu64(swap, cap64.c_tag))
#define xcap_val	(clazz == ELFCLASS32			\
			 ? elf_getu32(swap, cap32.c_un.c_val)	\
			 : elf_getu64(swap, cap64.c_un.c_val))

#ifdef ELFCORE
/*
 * Try larger offsets first to avoid false matches
 * from earlier data that happen to look like strings.
 */
static const size_t	prpsoffsets32[] = {
#ifdef USE_NT_PSINFO
	104,		/* SunOS 5.x (command line) */
	88,		/* SunOS 5.x (short name) */
#endif /* USE_NT_PSINFO */

	100,		/* SunOS 5.x (command line) */
	84,		/* SunOS 5.x (short name) */

	44,		/* Linux (command line) */
	28,		/* Linux 2.0.36 (short name) */

	8,		/* FreeBSD */
};

static const size_t	prpsoffsets64[] = {
#ifdef USE_NT_PSINFO
	152,		/* SunOS 5.x (command line) */
	136,		/* SunOS 5.x (short name) */
#endif /* USE_NT_PSINFO */

	136,		/* SunOS 5.x, 64-bit (command line) */
	120,		/* SunOS 5.x, 64-bit (short name) */

	56,		/* Linux (command line) */
	40,             /* Linux (tested on core from 2.4.x, short name) */

	16,		/* FreeBSD, 64-bit */
};

#define	NOFFSETS32	(sizeof prpsoffsets32 / sizeof prpsoffsets32[0])
#define NOFFSETS64	(sizeof prpsoffsets64 / sizeof prpsoffsets64[0])

#define NOFFSETS	(clazz == ELFCLASS32 ? NOFFSETS32 : NOFFSETS64)

/*
 * Look through the program headers of an executable image, searching
 * for a PT_NOTE section of type NT_PRPSINFO, with a name "CORE" or
 * "FreeBSD"; if one is found, try looking in various places in its
 * contents for a 16-character string containing only printable
 * characters - if found, that string should be the name of the program
 * that dropped core.  Note: right after that 16-character string is,
 * at least in SunOS 5.x (and possibly other SVR4-flavored systems) and
 * Linux, a longer string (80 characters, in 5.x, probably other
 * SVR4-flavored systems, and Linux) containing the start of the
 * command line for that program.
 *
 * SunOS 5.x core files contain two PT_NOTE sections, with the types
 * NT_PRPSINFO (old) and NT_PSINFO (new).  These structs contain the
 * same info about the command name and command line, so it probably
 * isn't worthwhile to look for NT_PSINFO, but the offsets are provided
 * above (see USE_NT_PSINFO), in case we ever decide to do so.  The
 * NT_PRPSINFO and NT_PSINFO sections are always in order and adjacent;
 * the SunOS 5.x file command relies on this (and prefers the latter).
 *
 * The signal number probably appears in a section of type NT_PRSTATUS,
 * but that's also rather OS-dependent, in ways that are harder to
 * dissect with heuristics, so I'm not bothering with the signal number.
 * (I suppose the signal number could be of interest in situations where
 * you don't have the binary of the program that dropped core; if you
 * *do* have that binary, the debugger will probably tell you what
 * signal it was.)
 */

#define	OS_STYLE_SVR4		0
#define	OS_STYLE_FREEBSD	1
#define	OS_STYLE_NETBSD		2

private const char os_style_names[][8] = {
	"SVR4",
	"FreeBSD",
	"NetBSD",
};

#define FLAGS_DID_CORE		0x01
#define FLAGS_DID_NOTE		0x02
#define FLAGS_DID_BUILD_ID	0x04
#define FLAGS_DID_CORE_STYLE	0x08
#define FLAGS_IS_CORE		0x10

private int
dophn_core(struct magic_set *ms, int clazz, int swap, int fd, off_t off,
    int num, size_t size, off_t fsize, int *flags)
{
	Elf32_Phdr ph32;
	Elf64_Phdr ph64;
	size_t offset, len;
	unsigned char nbuf[BUFSIZ];
	ssize_t bufsize;

	if (size != xph_sizeof) {
		if (file_printf(ms, ", corrupted program header size") == -1)
			return -1;
		return 0;
	}

	/*
	 * Loop through all the program headers.
	 */
	for ( ; num; num--) {
		if (pread(fd, xph_addr, xph_sizeof, off) == -1) {
			file_badread(ms);
			return -1;
		}
		off += size;

		if (xph_offset > fsize) {
			/* Perhaps warn here */
			continue;
		}

		if (xph_type != PT_NOTE)
			continue;

		/*
		 * This is a PT_NOTE section; loop through all the notes
		 * in the section.
		 */
		len = xph_filesz < sizeof(nbuf) ? xph_filesz : sizeof(nbuf);
		if ((bufsize = pread(fd, nbuf, len, xph_offset)) == -1) {
			file_badread(ms);
			return -1;
		}
		offset = 0;
		for (;;) {
			if (offset >= (size_t)bufsize)
				break;
			offset = donote(ms, nbuf, offset, (size_t)bufsize,
			    clazz, swap, 4, flags);
			if (offset == 0)
				break;

		}
	}
	return 0;
}
#endif

static void
do_note_netbsd_version(struct magic_set *ms, int swap, void *v)
{
	uint32_t desc;
	(void)memcpy(&desc, v, sizeof(desc));
	desc = elf_getu32(swap, desc);

	if (file_printf(ms, ", for NetBSD") == -1)
		return;
	/*
	 * The version number used to be stuck as 199905, and was thus
	 * basically content-free.  Newer versions of NetBSD have fixed
	 * this and now use the encoding of __NetBSD_Version__:
	 *
	 *	MMmmrrpp00
	 *
	 * M = major version
	 * m = minor version
	 * r = release ["",A-Z,Z[A-Z] but numeric]
	 * p = patchlevel
	 */
	if (desc > 100000000U) {
		uint32_t ver_patch = (desc / 100) % 100;
		uint32_t ver_rel = (desc / 10000) % 100;
		uint32_t ver_min = (desc / 1000000) % 100;
		uint32_t ver_maj = desc / 100000000;

		if (file_printf(ms, " %u.%u", ver_maj, ver_min) == -1)
			return;
		if (ver_rel == 0 && ver_patch != 0) {
			if (file_printf(ms, ".%u", ver_patch) == -1)
				return;
		} else if (ver_rel != 0) {
			while (ver_rel > 26) {
				if (file_printf(ms, "Z") == -1)
					return;
				ver_rel -= 26;
			}
			if (file_printf(ms, "%c", 'A' + ver_rel - 1)
			    == -1)
				return;
		}
	}
}

static void
do_note_freebsd_version(struct magic_set *ms, int swap, void *v)
{
	uint32_t desc;

	(void)memcpy(&desc, v, sizeof(desc));
	desc = elf_getu32(swap, desc);
	if (file_printf(ms, ", for FreeBSD") == -1)
		return;

	/*
	 * Contents is __FreeBSD_version, whose relation to OS
	 * versions is defined by a huge table in the Porter's
	 * Handbook.  This is the general scheme:
	 *
	 * Releases:
	 * 	Mmp000 (before 4.10)
	 * 	Mmi0p0 (before 5.0)
	 * 	Mmm0p0
	 *
	 * Development branches:
	 * 	Mmpxxx (before 4.6)
	 * 	Mmp1xx (before 4.10)
	 * 	Mmi1xx (before 5.0)
	 * 	M000xx (pre-M.0)
	 * 	Mmm1xx
	 *
	 * M = major version
	 * m = minor version
	 * i = minor version increment (491000 -> 4.10)
	 * p = patchlevel
	 * x = revision
	 *
	 * The first release of FreeBSD to use ELF by default
	 * was version 3.0.
	 */
	if (desc == 460002) {
		if (file_printf(ms, " 4.6.2") == -1)
			return;
	} else if (desc < 460100) {
		if (file_printf(ms, " %d.%d", desc / 100000,
		    desc / 10000 % 10) == -1)
			return;
		if (desc / 1000 % 10 > 0)
			if (file_printf(ms, ".%d", desc / 1000 % 10) == -1)
				return;
		if ((desc % 1000 > 0) || (desc % 100000 == 0))
			if (file_printf(ms, " (%d)", desc) == -1)
				return;
	} else if (desc < 500000) {
		if (file_printf(ms, " %d.%d", desc / 100000,
		    desc / 10000 % 10 + desc / 1000 % 10) == -1)
			return;
		if (desc / 100 % 10 > 0) {
			if (file_printf(ms, " (%d)", desc) == -1)
				return;
		} else if (desc / 10 % 10 > 0) {
			if (file_printf(ms, ".%d", desc / 10 % 10) == -1)
				return;
		}
	} else {
		if (file_printf(ms, " %d.%d", desc / 100000,
		    desc / 1000 % 100) == -1)
			return;
		if ((desc / 100 % 10 > 0) ||
		    (desc % 100000 / 100 == 0)) {
			if (file_printf(ms, " (%d)", desc) == -1)
				return;
		} else if (desc / 10 % 10 > 0) {
			if (file_printf(ms, ".%d", desc / 10 % 10) == -1)
				return;
		}
	}
}

private size_t
donote(struct magic_set *ms, void *vbuf, size_t offset, size_t size,
    int clazz, int swap, size_t align, int *flags)
{
	Elf32_Nhdr nh32 = { 0 };
	Elf64_Nhdr nh64 = { 0 };
	size_t noff, doff;
#ifdef ELFCORE
	int os_style = -1;
#endif
	uint32_t namesz, descsz;
	unsigned char *nbuf = CAST(unsigned char *, vbuf);

	(void)memcpy(xnh_addr, &nbuf[offset], xnh_sizeof);
	offset += xnh_sizeof;

	namesz = xnh_namesz;
	descsz = xnh_descsz;
	if ((namesz == 0) && (descsz == 0)) {
		/*
		 * We're out of note headers.
		 */
		return (offset >= size) ? offset : size;
	}

	if (namesz & 0x80000000) {
	    (void)file_printf(ms, ", bad note name size 0x%lx",
		(unsigned long)namesz);
	    return offset;
	}

	if (descsz & 0x80000000) {
	    (void)file_printf(ms, ", bad note description size 0x%lx",
		(unsigned long)descsz);
	    return offset;
	}


	noff = offset;
	doff = ELF_ALIGN(offset + namesz);

	if (offset + namesz > size) {
		/*
		 * We're past the end of the buffer.
		 */
		return doff;
	}

	offset = ELF_ALIGN(doff + descsz);
	if (doff + descsz > size) {
		/*
		 * We're past the end of the buffer.
		 */
		return (offset >= size) ? offset : size;
	}

	if ((*flags & (FLAGS_DID_NOTE|FLAGS_DID_BUILD_ID)) ==
	    (FLAGS_DID_NOTE|FLAGS_DID_BUILD_ID))
		goto core;

	if (namesz == 5 && strcmp((char *)&nbuf[noff], "SuSE") == 0 &&
	    xnh_type == NT_GNU_VERSION && descsz == 2) {
	    file_printf(ms, ", for SuSE %d.%d", nbuf[doff], nbuf[doff + 1]);
	}
	if (namesz == 4 && strcmp((char *)&nbuf[noff], "GNU") == 0 &&
	    xnh_type == NT_GNU_VERSION && descsz == 16) {
		uint32_t desc[4];
		(void)memcpy(desc, &nbuf[doff], sizeof(desc));

		if (file_printf(ms, ", for GNU/") == -1)
			return size;
		switch (elf_getu32(swap, desc[0])) {
		case GNU_OS_LINUX:
			if (file_printf(ms, "Linux") == -1)
				return size;
			break;
		case GNU_OS_HURD:
			if (file_printf(ms, "Hurd") == -1)
				return size;
			break;
		case GNU_OS_SOLARIS:
			if (file_printf(ms, "Solaris") == -1)
				return size;
			break;
		case GNU_OS_KFREEBSD:
			if (file_printf(ms, "kFreeBSD") == -1)
				return size;
			break;
		case GNU_OS_KNETBSD:
			if (file_printf(ms, "kNetBSD") == -1)
				return size;
			break;
		default:
			if (file_printf(ms, "<unknown>") == -1)
				return size;
		}
		if (file_printf(ms, " %d.%d.%d", elf_getu32(swap, desc[1]),
		    elf_getu32(swap, desc[2]), elf_getu32(swap, desc[3])) == -1)
			return size;
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 4 && strcmp((char *)&nbuf[noff], "GNU") == 0 &&
	    xnh_type == NT_GNU_BUILD_ID && (descsz == 16 || descsz == 20)) {
	    uint8_t desc[20];
	    uint32_t i;
	    if (file_printf(ms, ", BuildID[%s]=", descsz == 16 ? "md5/uuid" :
		"sha1") == -1)
		    return size;
	    (void)memcpy(desc, &nbuf[doff], descsz);
	    for (i = 0; i < descsz; i++)
		if (file_printf(ms, "%02x", desc[i]) == -1)
		    return size;
	    *flags |= FLAGS_DID_BUILD_ID;
	}

	if (namesz == 4 && strcmp((char *)&nbuf[noff], "PaX") == 0 &&
	    xnh_type == NT_NETBSD_PAX && descsz == 4) {
		static const char *pax[] = {
		    "+mprotect",
		    "-mprotect",
		    "+segvguard",
		    "-segvguard",
		    "+ASLR",
		    "-ASLR",
		};
		uint32_t desc;
		size_t i;
		int did = 0;

		(void)memcpy(&desc, &nbuf[doff], sizeof(desc));
		desc = elf_getu32(swap, desc);

		if (desc && file_printf(ms, ", PaX: ") == -1)
			return size;

		for (i = 0; i < __arraycount(pax); i++) {
			if (((1 << i) & desc) == 0)
				continue;
			if (file_printf(ms, "%s%s", did++ ? "," : "",
			    pax[i]) == -1)
				return size;
		}
	}

	if (namesz == 7 && strcmp((char *)&nbuf[noff], "NetBSD") == 0) {
		switch (xnh_type) {
		case NT_NETBSD_VERSION:
			if (descsz == 4) {
				do_note_netbsd_version(ms, swap, &nbuf[doff]);
				*flags |= FLAGS_DID_NOTE;
				return size;
			}
			break;
		case NT_NETBSD_MARCH:
			if (file_printf(ms, ", compiled for: %.*s", (int)descsz,
			    (const char *)&nbuf[doff]) == -1)
				return size;
			break;
		case NT_NETBSD_CMODEL:
			if (file_printf(ms, ", compiler model: %.*s",
			    (int)descsz, (const char *)&nbuf[doff]) == -1)
				return size;
			break;
		default:
			if (file_printf(ms, ", note=%u", xnh_type) == -1)
				return size;
			break;
		}
		return size;
	}

	if (namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0) {
	    	if (xnh_type == NT_FREEBSD_VERSION && descsz == 4) {
			do_note_freebsd_version(ms, swap, &nbuf[doff]);
			*flags |= FLAGS_DID_NOTE;
			return size;
		}
	}

	if (namesz == 8 && strcmp((char *)&nbuf[noff], "OpenBSD") == 0 &&
	    xnh_type == NT_OPENBSD_VERSION && descsz == 4) {
		if (file_printf(ms, ", for OpenBSD") == -1)
			return size;
		/* Content of note is always 0 */
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

	if (namesz == 10 && strcmp((char *)&nbuf[noff], "DragonFly") == 0 &&
	    xnh_type == NT_DRAGONFLY_VERSION && descsz == 4) {
		uint32_t desc;
		if (file_printf(ms, ", for DragonFly") == -1)
			return size;
		(void)memcpy(&desc, &nbuf[doff], sizeof(desc));
		desc = elf_getu32(swap, desc);
		if (file_printf(ms, " %d.%d.%d", desc / 100000,
		    desc / 10000 % 10, desc % 10000) == -1)
			return size;
		*flags |= FLAGS_DID_NOTE;
		return size;
	}

core:
	/*
	 * Sigh.  The 2.0.36 kernel in Debian 2.1, at
	 * least, doesn't correctly implement name
	 * sections, in core dumps, as specified by
	 * the "Program Linking" section of "UNIX(R) System
	 * V Release 4 Programmer's Guide: ANSI C and
	 * Programming Support Tools", because my copy
	 * clearly says "The first 'namesz' bytes in 'name'
	 * contain a *null-terminated* [emphasis mine]
	 * character representation of the entry's owner
	 * or originator", but the 2.0.36 kernel code
	 * doesn't include the terminating null in the
	 * name....
	 */
	if ((namesz == 4 && strncmp((char *)&nbuf[noff], "CORE", 4) == 0) ||
	    (namesz == 5 && strcmp((char *)&nbuf[noff], "CORE") == 0)) {
		os_style = OS_STYLE_SVR4;
	}

	if ((namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0)) {
		os_style = OS_STYLE_FREEBSD;
	}

	if ((namesz >= 11 && strncmp((char *)&nbuf[noff], "NetBSD-CORE", 11)
	    == 0)) {
		os_style = OS_STYLE_NETBSD;
	}

#ifdef ELFCORE
	if ((*flags & FLAGS_DID_CORE) != 0)
		return size;

	if (os_style != -1 && (*flags & FLAGS_DID_CORE_STYLE) == 0) {
		if (file_printf(ms, ", %s-style", os_style_names[os_style])
		    == -1)
			return size;
		*flags |= FLAGS_DID_CORE_STYLE;
	}

	switch (os_style) {
	case OS_STYLE_NETBSD:
		if (xnh_type == NT_NETBSD_CORE_PROCINFO) {
			uint32_t signo;
			/*
			 * Extract the program name.  It is at
			 * offset 0x7c, and is up to 32-bytes,
			 * including the terminating NUL.
			 */
			if (file_printf(ms, ", from '%.31s'",
			    &nbuf[doff + 0x7c]) == -1)
				return size;

			/*
			 * Extract the signal number.  It is at
			 * offset 0x08.
			 */
			(void)memcpy(&signo, &nbuf[doff + 0x08],
			    sizeof(signo));
			if (file_printf(ms, " (signal %u)",
			    elf_getu32(swap, signo)) == -1)
				return size;
			*flags |= FLAGS_DID_CORE;
			return size;
		}
		break;

	default:
		if (xnh_type == NT_PRPSINFO && *flags & FLAGS_IS_CORE) {
			size_t i, j;
			unsigned char c;
			/*
			 * Extract the program name.  We assume
			 * it to be 16 characters (that's what it
			 * is in SunOS 5.x and Linux).
			 *
			 * Unfortunately, it's at a different offset
			 * in various OSes, so try multiple offsets.
			 * If the characters aren't all printable,
			 * reject it.
			 */
			for (i = 0; i < NOFFSETS; i++) {
				unsigned char *cname, *cp;
				size_t reloffset = prpsoffsets(i);
				size_t noffset = doff + reloffset;
				size_t k;
				for (j = 0; j < 16; j++, noffset++,
				    reloffset++) {
					/*
					 * Make sure we're not past
					 * the end of the buffer; if
					 * we are, just give up.
					 */
					if (noffset >= size)
						goto tryanother;

					/*
					 * Make sure we're not past
					 * the end of the contents;
					 * if we are, this obviously
					 * isn't the right offset.
					 */
					if (reloffset >= descsz)
						goto tryanother;

					c = nbuf[noffset];
					if (c == '\0') {
						/*
						 * A '\0' at the
						 * beginning is
						 * obviously wrong.
						 * Any other '\0'
						 * means we're done.
						 */
						if (j == 0)
							goto tryanother;
						else
							break;
					} else {
						/*
						 * A nonprintable
						 * character is also
						 * wrong.
						 */
						if (!isprint(c) || isquote(c))
							goto tryanother;
					}
				}
				/*
				 * Well, that worked.
				 */

				/*
				 * Try next offsets, in case this match is
				 * in the middle of a string.
				 */
				for (k = i + 1 ; k < NOFFSETS ; k++) {
					size_t no;
					int adjust = 1;
					if (prpsoffsets(k) >= prpsoffsets(i))
						continue;
					for (no = doff + prpsoffsets(k);
					     no < doff + prpsoffsets(i); no++)
						adjust = adjust
						         && isprint(nbuf[no]);
					if (adjust)
						i = k;
				}

				cname = (unsigned char *)
				    &nbuf[doff + prpsoffsets(i)];
				for (cp = cname; *cp && isprint(*cp); cp++)
					continue;
				/*
				 * Linux apparently appends a space at the end
				 * of the command line: remove it.
				 */
				while (cp > cname && isspace(cp[-1]))
					cp--;
				if (file_printf(ms, ", from '%.*s'",
				    (int)(cp - cname), cname) == -1)
					return size;
				*flags |= FLAGS_DID_CORE;
				return size;

			tryanother:
				;
			}
		}
		break;
	}
#endif
	return offset;
}

/* SunOS 5.x hardware capability descriptions */
typedef struct cap_desc {
	uint64_t cd_mask;
	const char *cd_name;
} cap_desc_t;

static const cap_desc_t cap_desc_sparc[] = {
	{ AV_SPARC_MUL32,		"MUL32" },
	{ AV_SPARC_DIV32,		"DIV32" },
	{ AV_SPARC_FSMULD,		"FSMULD" },
	{ AV_SPARC_V8PLUS,		"V8PLUS" },
	{ AV_SPARC_POPC,		"POPC" },
	{ AV_SPARC_VIS,			"VIS" },
	{ AV_SPARC_VIS2,		"VIS2" },
	{ AV_SPARC_ASI_BLK_INIT,	"ASI_BLK_INIT" },
	{ AV_SPARC_FMAF,		"FMAF" },
	{ AV_SPARC_FJFMAU,		"FJFMAU" },
	{ AV_SPARC_IMA,			"IMA" },
	{ 0, NULL }
};

static const cap_desc_t cap_desc_386[] = {
	{ AV_386_FPU,			"FPU" },
	{ AV_386_TSC,			"TSC" },
	{ AV_386_CX8,			"CX8" },
	{ AV_386_SEP,			"SEP" },
	{ AV_386_AMD_SYSC,		"AMD_SYSC" },
	{ AV_386_CMOV,			"CMOV" },
	{ AV_386_MMX,			"MMX" },
	{ AV_386_AMD_MMX,		"AMD_MMX" },
	{ AV_386_AMD_3DNow,		"AMD_3DNow" },
	{ AV_386_AMD_3DNowx,		"AMD_3DNowx" },
	{ AV_386_FXSR,			"FXSR" },
	{ AV_386_SSE,			"SSE" },
	{ AV_386_SSE2,			"SSE2" },
	{ AV_386_PAUSE,			"PAUSE" },
	{ AV_386_SSE3,			"SSE3" },
	{ AV_386_MON,			"MON" },
	{ AV_386_CX16,			"CX16" },
	{ AV_386_AHF,			"AHF" },
	{ AV_386_TSCP,			"TSCP" },
	{ AV_386_AMD_SSE4A,		"AMD_SSE4A" },
	{ AV_386_POPCNT,		"POPCNT" },
	{ AV_386_AMD_LZCNT,		"AMD_LZCNT" },
	{ AV_386_SSSE3,			"SSSE3" },
	{ AV_386_SSE4_1,		"SSE4.1" },
	{ AV_386_SSE4_2,		"SSE4.2" },
	{ 0, NULL }
};

private int
doshn(struct magic_set *ms, int clazz, int swap, int fd, off_t off, int num,
    size_t size, off_t fsize, int *flags, int mach, int strtab)
{
	Elf32_Shdr sh32;
	Elf64_Shdr sh64;
	int stripped = 1;
	void *nbuf;
	off_t noff, coff, name_off;
	uint64_t cap_hw1 = 0;	/* SunOS 5.x hardware capabilites */
	uint64_t cap_sf1 = 0;	/* SunOS 5.x software capabilites */
	char name[50];

	if (size != xsh_sizeof) {
		if (file_printf(ms, ", corrupted section header size") == -1)
			return -1;
		return 0;
	}

	/* Read offset of name section to be able to read section names later */
	if (pread(fd, xsh_addr, xsh_sizeof, off + size * strtab) == -1) {
		file_badread(ms);
		return -1;
	}
	name_off = xsh_offset;

	for ( ; num; num--) {
		/* Read the name of this section. */
		if (pread(fd, name, sizeof(name), name_off + xsh_name) == -1) {
			file_badread(ms);
			return -1;
		}
		name[sizeof(name) - 1] = '\0';
		if (strcmp(name, ".debug_info") == 0)
			stripped = 0;

		if (pread(fd, xsh_addr, xsh_sizeof, off) == -1) {
			file_badread(ms);
			return -1;
		}
		off += size;

		/* Things we can determine before we seek */
		switch (xsh_type) {
		case SHT_SYMTAB:
#if 0
		case SHT_DYNSYM:
#endif
			stripped = 0;
			break;
		default:
			if (xsh_offset > fsize) {
				/* Perhaps warn here */
				continue;
			}
			break;
		}

		/* Things we can determine when we seek */
		switch (xsh_type) {
		case SHT_NOTE:
			if ((nbuf = malloc(xsh_size)) == NULL) {
				file_error(ms, errno, "Cannot allocate memory"
				    " for note");
				return -1;
			}
			if (pread(fd, nbuf, xsh_size, xsh_offset) == -1) {
				file_badread(ms);
				free(nbuf);
				return -1;
			}

			noff = 0;
			for (;;) {
				if (noff >= (off_t)xsh_size)
					break;
				noff = donote(ms, nbuf, (size_t)noff,
				    xsh_size, clazz, swap, 4, flags);
				if (noff == 0)
					break;
			}
			free(nbuf);
			break;
		case SHT_SUNW_cap:
			switch (mach) {
			case EM_SPARC:
			case EM_SPARCV9:
			case EM_IA_64:
			case EM_386:
			case EM_AMD64:
				break;
			default:
				goto skip;
			}

			if (lseek(fd, xsh_offset, SEEK_SET) == (off_t)-1) {
				file_badseek(ms);
				return -1;
			}
			coff = 0;
			for (;;) {
				Elf32_Cap cap32;
				Elf64_Cap cap64;
				char cbuf[/*CONSTCOND*/
				    MAX(sizeof cap32, sizeof cap64)];
				if ((coff += xcap_sizeof) > (off_t)xsh_size)
					break;
				if (read(fd, cbuf, (size_t)xcap_sizeof) !=
				    (ssize_t)xcap_sizeof) {
					file_badread(ms);
					return -1;
				}
				if (cbuf[0] == 'A') {
#ifdef notyet
					char *p = cbuf + 1;
					uint32_t len, tag;
					memcpy(&len, p, sizeof(len));
					p += 4;
					len = getu32(swap, len);
					if (memcmp("gnu", p, 3) != 0) {
					    if (file_printf(ms,
						", unknown capability %.3s", p)
						== -1)
						return -1;
					    break;
					}
					p += strlen(p) + 1;
					tag = *p++;
					memcpy(&len, p, sizeof(len));
					p += 4;
					len = getu32(swap, len);
					if (tag != 1) {
					    if (file_printf(ms, ", unknown gnu"
						" capability tag %d", tag)
						== -1)
						return -1;
					    break;
					}
					// gnu attributes
#endif
					break;
				}
				(void)memcpy(xcap_addr, cbuf, xcap_sizeof);
				switch (xcap_tag) {
				case CA_SUNW_NULL:
					break;
				case CA_SUNW_HW_1:
					cap_hw1 |= xcap_val;
					break;
				case CA_SUNW_SF_1:
					cap_sf1 |= xcap_val;
					break;
				default:
					if (file_printf(ms,
					    ", with unknown capability "
					    "0x%" INT64_T_FORMAT "x = 0x%"
					    INT64_T_FORMAT "x",
					    (unsigned long long)xcap_tag,
					    (unsigned long long)xcap_val) == -1)
						return -1;
					break;
				}
			}
			/*FALLTHROUGH*/
		skip:
		default:
			break;
		}
	}

	if (file_printf(ms, ", %sstripped", stripped ? "" : "not ") == -1)
		return -1;
	if (cap_hw1) {
		const cap_desc_t *cdp;
		switch (mach) {
		case EM_SPARC:
		case EM_SPARC32PLUS:
		case EM_SPARCV9:
			cdp = cap_desc_sparc;
			break;
		case EM_386:
		case EM_IA_64:
		case EM_AMD64:
			cdp = cap_desc_386;
			break;
		default:
			cdp = NULL;
			break;
		}
		if (file_printf(ms, ", uses") == -1)
			return -1;
		if (cdp) {
			while (cdp->cd_name) {
				if (cap_hw1 & cdp->cd_mask) {
					if (file_printf(ms,
					    " %s", cdp->cd_name) == -1)
						return -1;
					cap_hw1 &= ~cdp->cd_mask;
				}
				++cdp;
			}
			if (cap_hw1)
				if (file_printf(ms,
				    " unknown hardware capability 0x%"
				    INT64_T_FORMAT "x",
				    (unsigned long long)cap_hw1) == -1)
					return -1;
		} else {
			if (file_printf(ms,
			    " hardware capability 0x%" INT64_T_FORMAT "x",
			    (unsigned long long)cap_hw1) == -1)
				return -1;
		}
	}
	if (cap_sf1) {
		if (cap_sf1 & SF1_SUNW_FPUSED) {
			if (file_printf(ms,
			    (cap_sf1 & SF1_SUNW_FPKNWN)
			    ? ", uses frame pointer"
			    : ", not known to use frame pointer") == -1)
				return -1;
		}
		cap_sf1 &= ~SF1_SUNW_MASK;
		if (cap_sf1)
			if (file_printf(ms,
			    ", with unknown software capability 0x%"
			    INT64_T_FORMAT "x",
			    (unsigned long long)cap_sf1) == -1)
				return -1;
	}
	return 0;
}

/*
 * Look through the program headers of an executable image, searching
 * for a PT_INTERP section; if one is found, it's dynamically linked,
 * otherwise it's statically linked.
 */
private int
dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,
    int num, size_t size, off_t fsize, int *flags, int sh_num)
{
	Elf32_Phdr ph32;
	Elf64_Phdr ph64;
	const char *linking_style = "statically";
	const char *shared_libraries = "";
	unsigned char nbuf[BUFSIZ];
	ssize_t bufsize;
	size_t offset, align, len;

	if (size != xph_sizeof) {
		if (file_printf(ms, ", corrupted program header size") == -1)
			return -1;
		return 0;
	}

  	for ( ; num; num--) {
		if (pread(fd, xph_addr, xph_sizeof, off) == -1) {
			file_badread(ms);
			return -1;
		}

		off += size;

		/* Things we can determine before we seek */
		switch (xph_type) {
		case PT_DYNAMIC:
			linking_style = "dynamically";
			break;
		case PT_INTERP:
			shared_libraries = " (uses shared libs)";
			break;
		default:
			if (xph_offset > fsize) {
				/* Maybe warn here? */
				continue;
			}
			break;
		}

		/* Things we can determine when we seek */
		switch (xph_type) {
		case PT_NOTE:
			if ((align = xph_align) & 0x80000000UL) {
				if (file_printf(ms,
				    ", invalid note alignment 0x%lx",
				    (unsigned long)align) == -1)
					return -1;
				align = 4;
			}
			if (sh_num)
				break;
			/*
			 * This is a PT_NOTE section; loop through all the notes
			 * in the section.
			 */
			len = xph_filesz < sizeof(nbuf) ? xph_filesz
			    : sizeof(nbuf);
			bufsize = pread(fd, nbuf, len, xph_offset);
			if (bufsize == -1) {
				file_badread(ms);
				return -1;
			}
			offset = 0;
			for (;;) {
				if (offset >= (size_t)bufsize)
					break;
				offset = donote(ms, nbuf, offset,
				    (size_t)bufsize, clazz, swap, align,
				    flags);
				if (offset == 0)
					break;
			}
			break;
		default:
			break;
		}
	}
	if (file_printf(ms, ", %s linked%s", linking_style, shared_libraries)
	    == -1)
	    return -1;
	return 0;
}


protected int
file_tryelf(struct magic_set *ms, int fd, const unsigned char *buf,
    size_t nbytes)
{
	union {
		int32_t l;
		char c[sizeof (int32_t)];
	} u;
	int clazz;
	int swap;
	struct stat st;
	off_t fsize;
	int flags = 0;
	Elf32_Ehdr elf32hdr;
	Elf64_Ehdr elf64hdr;
	uint16_t type;

	if (ms->flags & (MAGIC_MIME|MAGIC_APPLE))
		return 0;
	/*
	 * ELF executables have multiple section headers in arbitrary
	 * file locations and thus file(1) cannot determine it from easily.
	 * Instead we traverse thru all section headers until a symbol table
	 * one is found or else the binary is stripped.
	 * Return immediately if it's not ELF (so we avoid pipe2file unless needed).
	 */
	if (buf[EI_MAG0] != ELFMAG0
	    || (buf[EI_MAG1] != ELFMAG1 && buf[EI_MAG1] != OLFMAG1)
	    || buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3)
		return 0;

	/*
	 * If we cannot seek, it must be a pipe, socket or fifo.
	 */
	if((lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) && (errno == ESPIPE))
		fd = file_pipe2file(ms, fd, buf, nbytes);

	if (fstat(fd, &st) == -1) {
  		file_badread(ms);
		return -1;
	}
	fsize = st.st_size;

	clazz = buf[EI_CLASS];

	switch (clazz) {
	case ELFCLASS32:
#undef elf_getu
#define elf_getu(a, b)	elf_getu32(a, b)
#undef elfhdr
#define elfhdr elf32hdr
#include "elfclass.h"
	case ELFCLASS64:
#undef elf_getu
#define elf_getu(a, b)	elf_getu64(a, b)
#undef elfhdr
#define elfhdr elf64hdr
#include "elfclass.h"
	default:
	    if (file_printf(ms, ", unknown class %d", clazz) == -1)
		    return -1;
	    break;
	}
	return 0;
}
#endif