/* $NetBSD: libelf_open.c,v 1.5 2024/03/03 17:37:34 christos Exp $ */
/*-
* Copyright (c) 2006,2008-2011 Joseph Koshy
* 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, 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.
*/
#if HAVE_NBTOOL_CONFIG_H
# include "nbtool_config.h"
#endif
#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <errno.h>
#include <libelf.h>
#include <stdlib.h>
#include <unistd.h>
#include "_libelf.h"
#if ELFTC_HAVE_MMAP
#include <sys/mman.h>
#endif
__RCSID("$NetBSD: libelf_open.c,v 1.5 2024/03/03 17:37:34 christos Exp $");
ELFTC_VCSID("Id: libelf_open.c 3977 2022-05-01 06:45:34Z jkoshy");
#define _LIBELF_INITSIZE (64*1024)
/*
* Read from a device file, pipe or socket.
*/
static void *
_libelf_read_special_file(int fd, size_t *fsz)
{
ssize_t readsz;
size_t bufsz, datasz;
unsigned char *buf, *t;
datasz = 0;
readsz = 0;
bufsz = _LIBELF_INITSIZE;
if ((buf = malloc(bufsz)) == NULL)
goto resourceerror;
/*
* Read data from the file descriptor till we reach EOF, or
* till an error is encountered.
*/
do {
/* Check if we need to expand the data buffer. */
if (datasz == bufsz) {
bufsz *= 2;
if ((t = realloc(buf, bufsz)) == NULL)
goto resourceerror;
buf = t;
}
do {
assert(bufsz - datasz > 0);
t = buf + datasz;
if ((readsz = read(fd, t, bufsz - datasz)) <= 0)
break;
datasz += (size_t) readsz;
} while (datasz < bufsz);
} while (readsz > 0);
if (readsz < 0) {
LIBELF_SET_ERROR(IO, errno);
goto error;
}
assert(readsz == 0);
/*
* Free up extra buffer space.
*/
if (bufsz > datasz) {
if (datasz > 0) {
if ((t = realloc(buf, datasz)) == NULL)
goto resourceerror;
buf = t;
} else { /* Zero bytes read. */
LIBELF_SET_ERROR(ARGUMENT, 0);
free(buf);
buf = NULL;
}
}
*fsz = datasz;
return (buf);
resourceerror:
LIBELF_SET_ERROR(RESOURCE, 0);
error:
if (buf != NULL)
free(buf);
return (NULL);
}
/*
* Read the contents of the file referenced by the file descriptor
* 'fd'.
*/
Elf *
_libelf_open_object(int fd, Elf_Cmd c, int reporterror)
{
Elf *e;
void *m;
mode_t mode;
size_t fsize;
struct stat sb;
unsigned int flags;
assert(c == ELF_C_READ || c == ELF_C_RDWR || c == ELF_C_WRITE);
if (fstat(fd, &sb) < 0) {
LIBELF_SET_ERROR(IO, errno);
return (NULL);
}
mode = sb.st_mode;
fsize = (size_t) sb.st_size;
/*
* Reject unsupported file types.
*/
if (!S_ISREG(mode) && !S_ISCHR(mode) && !S_ISFIFO(mode) &&
!S_ISSOCK(mode)) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
/*
* For ELF_C_WRITE mode, allocate and return a descriptor.
*/
if (c == ELF_C_WRITE) {
if ((e = _libelf_allocate_elf()) != NULL) {
_libelf_init_elf(e, ELF_K_ELF);
e->e_byteorder = LIBELF_PRIVATE(byteorder);
e->e_fd = fd;
e->e_cmd = c;
if (!S_ISREG(mode))
e->e_flags |= LIBELF_F_SPECIAL_FILE;
}
return (e);
}
/*
* ELF_C_READ and ELF_C_RDWR mode.
*/
m = NULL;
flags = 0;
if (S_ISREG(mode)) {
/*
* Reject zero length files.
*/
if (fsize == 0) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
#if ELFTC_HAVE_MMAP
/*
* Always map regular files in with 'PROT_READ'
* permissions.
*
* For objects opened in ELF_C_RDWR mode, when
* elf_update(3) is called, we remove this mapping,
* write file data out using write(2), and map the new
* contents back.
*/
m = mmap(NULL, fsize, PROT_READ, MAP_PRIVATE, fd, (off_t) 0);
if (m == MAP_FAILED)
m = NULL;
else
flags = LIBELF_F_RAWFILE_MMAP;
#endif
/*
* Fallback to a read() if the call to mmap() failed,
* or if mmap() is not available.
*/
if (m == NULL) {
if ((m = malloc(fsize)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
if (read(fd, m, fsize) != (ssize_t) fsize) {
LIBELF_SET_ERROR(IO, errno);
free(m);
return (NULL);
}
flags = LIBELF_F_RAWFILE_MALLOC;
}
} else if ((m = _libelf_read_special_file(fd, &fsize)) != NULL)
flags = LIBELF_F_RAWFILE_MALLOC | LIBELF_F_SPECIAL_FILE;
else
return (NULL);
if ((e = _libelf_memory(m, fsize, reporterror)) == NULL) {
assert((flags & LIBELF_F_RAWFILE_MALLOC) ||
(flags & LIBELF_F_RAWFILE_MMAP));
if (flags & LIBELF_F_RAWFILE_MALLOC)
free(m);
#if ELFTC_HAVE_MMAP
else
(void) munmap(m, fsize);
#endif
return (NULL);
}
/* ar(1) archives aren't supported in RDWR mode. */
if (c == ELF_C_RDWR && e->e_kind == ELF_K_AR) {
(void) elf_end(e);
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
e->e_flags |= flags;
e->e_fd = fd;
e->e_cmd = c;
return (e);
}
