2014-01-15 08:43:20 +00:00
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/*-
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* Copyright (c) 2006,2008-2011 Joseph Koshy
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* All rights reserved.
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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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* 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 AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include <errno.h>
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#include <libelf.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "_libelf.h"
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#if ELFTC_HAVE_MMAP
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#include <sys/mman.h>
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#endif
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2014-12-22 20:32:23 +00:00
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ELFTC_VCSID("$Id: libelf_open.c 3007 2014-03-22 08:10:14Z jkoshy $");
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2014-01-15 08:43:20 +00:00
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#define _LIBELF_INITSIZE (64*1024)
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/*
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* Read from a device file, pipe or socket.
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*/
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static void *
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_libelf_read_special_file(int fd, size_t *fsz)
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{
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ssize_t readsz;
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size_t bufsz, datasz;
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unsigned char *buf, *t;
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datasz = 0;
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readsz = 0;
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bufsz = _LIBELF_INITSIZE;
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if ((buf = malloc(bufsz)) == NULL)
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goto resourceerror;
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/*
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* Read data from the file descriptor till we reach EOF, or
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* till an error is encountered.
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*/
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do {
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/* Check if we need to expand the data buffer. */
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if (datasz == bufsz) {
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bufsz *= 2;
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if ((t = realloc(buf, bufsz)) == NULL)
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goto resourceerror;
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buf = t;
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}
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do {
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2014-12-22 20:32:23 +00:00
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assert(bufsz - datasz > 0);
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2014-01-15 08:43:20 +00:00
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t = buf + datasz;
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2014-12-22 20:32:23 +00:00
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if ((readsz = read(fd, t, bufsz - datasz)) <= 0)
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2014-01-15 08:43:20 +00:00
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break;
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2014-12-22 20:32:23 +00:00
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datasz += (size_t) readsz;
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2014-01-15 08:43:20 +00:00
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} while (datasz < bufsz);
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} while (readsz > 0);
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if (readsz < 0) {
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LIBELF_SET_ERROR(IO, errno);
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goto error;
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}
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assert(readsz == 0);
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/*
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* Free up extra buffer space.
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*/
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if (bufsz > datasz) {
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if (datasz > 0) {
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if ((t = realloc(buf, datasz)) == NULL)
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goto resourceerror;
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buf = t;
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} else { /* Zero bytes read. */
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LIBELF_SET_ERROR(ARGUMENT, 0);
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free(buf);
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buf = NULL;
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}
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}
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*fsz = datasz;
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return (buf);
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resourceerror:
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LIBELF_SET_ERROR(RESOURCE, 0);
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error:
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if (buf != NULL)
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free(buf);
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return (NULL);
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}
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/*
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* Read the contents of the file referenced by the file descriptor
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* 'fd'.
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*/
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Elf *
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_libelf_open_object(int fd, Elf_Cmd c, int reporterror)
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{
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Elf *e;
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void *m;
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mode_t mode;
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size_t fsize;
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struct stat sb;
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unsigned int flags;
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assert(c == ELF_C_READ || c == ELF_C_RDWR || c == ELF_C_WRITE);
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if (fstat(fd, &sb) < 0) {
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LIBELF_SET_ERROR(IO, errno);
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return (NULL);
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}
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mode = sb.st_mode;
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fsize = (size_t) sb.st_size;
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/*
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* Reject unsupported file types.
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*/
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if (!S_ISREG(mode) && !S_ISCHR(mode) && !S_ISFIFO(mode) &&
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!S_ISSOCK(mode)) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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/*
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* For ELF_C_WRITE mode, allocate and return a descriptor.
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*/
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if (c == ELF_C_WRITE) {
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if ((e = _libelf_allocate_elf()) != NULL) {
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_libelf_init_elf(e, ELF_K_ELF);
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e->e_byteorder = LIBELF_PRIVATE(byteorder);
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e->e_fd = fd;
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e->e_cmd = c;
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if (!S_ISREG(mode))
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e->e_flags |= LIBELF_F_SPECIAL_FILE;
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}
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return (e);
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}
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/*
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* ELF_C_READ and ELF_C_RDWR mode.
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*/
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m = NULL;
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flags = 0;
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if (S_ISREG(mode)) {
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/*
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* Reject zero length files.
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*/
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if (fsize == 0) {
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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#if ELFTC_HAVE_MMAP
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/*
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* Always map regular files in with 'PROT_READ'
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* permissions.
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*
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* For objects opened in ELF_C_RDWR mode, when
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* elf_update(3) is called, we remove this mapping,
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* write file data out using write(2), and map the new
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* contents back.
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*/
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m = mmap(NULL, fsize, PROT_READ, MAP_PRIVATE, fd, (off_t) 0);
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if (m == MAP_FAILED)
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m = NULL;
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else
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flags = LIBELF_F_RAWFILE_MMAP;
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#endif
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/*
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* Fallback to a read() if the call to mmap() failed,
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* or if mmap() is not available.
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*/
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if (m == NULL) {
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if ((m = malloc(fsize)) == NULL) {
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LIBELF_SET_ERROR(RESOURCE, 0);
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return (NULL);
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}
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if (read(fd, m, fsize) != (ssize_t) fsize) {
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LIBELF_SET_ERROR(IO, errno);
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free(m);
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return (NULL);
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}
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flags = LIBELF_F_RAWFILE_MALLOC;
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}
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} else if ((m = _libelf_read_special_file(fd, &fsize)) != NULL)
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flags = LIBELF_F_RAWFILE_MALLOC | LIBELF_F_SPECIAL_FILE;
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else
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return (NULL);
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if ((e = _libelf_memory(m, fsize, reporterror)) == NULL) {
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assert((flags & LIBELF_F_RAWFILE_MALLOC) ||
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(flags & LIBELF_F_RAWFILE_MMAP));
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if (flags & LIBELF_F_RAWFILE_MALLOC)
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free(m);
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#if ELFTC_HAVE_MMAP
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else
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(void) munmap(m, fsize);
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#endif
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return (NULL);
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}
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/* ar(1) archives aren't supported in RDWR mode. */
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if (c == ELF_C_RDWR && e->e_kind == ELF_K_AR) {
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(void) elf_end(e);
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LIBELF_SET_ERROR(ARGUMENT, 0);
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return (NULL);
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}
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e->e_flags |= flags;
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e->e_fd = fd;
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e->e_cmd = c;
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return (e);
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}
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