/* Update data structures for changes and write them out.   Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2015 Red Hat, Inc.   This file is part of elfutils.   Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.    This file is free software; you can redistribute it and/or modify   it under the terms of either      * the GNU Lesser General Public License as published by the Free       Software Foundation; either version 3 of the License, or (at       your option) any later version    or      * the GNU General Public License as published by the Free       Software Foundation; either version 2 of the License, or (at       your option) any later version    or both in parallel, as here.    elfutils is distributed in the hope that it will be useful, but   WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   General Public License for more details.    You should have received copies of the GNU General Public License and   the GNU Lesser General Public License along with this program.  If   not, see <http://www.gnu.org/licenses/>.  */ #ifdef HAVE_CONFIG_H# include <config.h>#endif #include <libelf.h>#include <fcntl.h>#include <unistd.h>#include <sys/mman.h>#include <sys/stat.h> #include "libelfP.h"  static off_twrite_file (Elf *elf, off_t size, int change_bo, size_t shnum){  int class = elf->class;   /* Check the mode bits now, before modification might change them.  */  struct stat st;  if (unlikely (fstat (elf->fildes, &st) != 0))    {      __libelf_seterrno (ELF_E_WRITE_ERROR);      return -1;    }   /* Adjust the size in any case.  We do this even if we use `write'.     We cannot do this if this file is in an archive.  We also don't     do it *now* if we are shortening the file since this would     prevent programs to use the data of the file in generating the     new file.  We truncate the file later in this case.  */  if (elf->parent == NULL      && (elf->maximum_size == ~((size_t) 0)	  || (size_t) size > elf->maximum_size)      && unlikely (ftruncate (elf->fildes, size) != 0))    {      __libelf_seterrno (ELF_E_WRITE_ERROR);      return -1;    }   /* Try to map the file if this isn't done yet.  */  if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)    {      elf->map_address = mmap (NULL, size, PROT_READ | PROT_WRITE,			       MAP_SHARED, elf->fildes, 0);      if (unlikely (elf->map_address == MAP_FAILED))	elf->map_address = NULL;      else	elf->flags |= ELF_F_MMAPPED;    }   if (elf->map_address != NULL)    {#ifndef __APPLE__      /* When using mmap we want to make sure the file content is	 really there. Only using ftruncate might mean the file is	 extended, but space isn't allocated yet.  This might cause a	 SIGBUS once we write into the mmapped space and the disk is	 full.  In glibc posix_fallocate is required to extend the	 file and allocate enough space even if the underlying	 filesystem would normally return EOPNOTSUPP.  But other	 implementations might not work as expected.  And the glibc	 fallback case might fail (with unexpected errnos) in some cases.	 So we only report an error when the call fails and errno is	 ENOSPC. Otherwise we ignore the error and treat it as just hint.  */      if (elf->parent == NULL	  && (elf->maximum_size == ~((size_t) 0)	      || (size_t) size > elf->maximum_size)	  && unlikely (posix_fallocate (elf->fildes, 0, size) != 0))	if (errno == ENOSPC)	  {	    __libelf_seterrno (ELF_E_WRITE_ERROR);	    return -1;	  }#endif      /* The file is mmaped.  */      if ((class == ELFCLASS32	   ? __elf32_updatemmap (elf, change_bo, shnum)	   : __elf64_updatemmap (elf, change_bo, shnum)) != 0)	/* Some problem while writing.  */	size = -1;    }  else    {      /* The file is not mmaped.  */      if ((class == ELFCLASS32	   ? __elf32_updatefile (elf, change_bo, shnum)	   : __elf64_updatefile (elf, change_bo, shnum)) != 0)	/* Some problem while writing.  */	size = -1;    }   /* Reduce the file size if necessary.  */  if (size != -1      && elf->parent == NULL      && elf->maximum_size != ~((size_t) 0)      && (size_t) size < elf->maximum_size      && unlikely (ftruncate (elf->fildes, size) != 0))    {      __libelf_seterrno (ELF_E_WRITE_ERROR);      size = -1;    }   /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID     mode bits.  So make sure we restore them afterwards if they were set.     This is not atomic if someone else chmod's the file while we operate.  */  if (size != -1      && unlikely (st.st_mode & (S_ISUID | S_ISGID))      /* fchmod ignores the bits we cannot change.  */      && unlikely (fchmod (elf->fildes, st.st_mode) != 0))    {      __libelf_seterrno (ELF_E_WRITE_ERROR);      size = -1;    }   if (size != -1 && elf->parent == NULL)    elf->maximum_size = size;   return size;}  int64_telf_update (Elf *elf, Elf_Cmd cmd){  size_t shnum;  off_t size;  int change_bo = 0;   if (cmd != ELF_C_NULL      && cmd != ELF_C_WRITE      && unlikely (cmd != ELF_C_WRITE_MMAP))    {      __libelf_seterrno (ELF_E_INVALID_CMD);      return -1;    }   if (elf == NULL)    return -1;   if (elf->kind != ELF_K_ELF)    {      __libelf_seterrno (ELF_E_INVALID_HANDLE);      return -1;    }   rwlock_wrlock (elf->lock);   /* Make sure we have an ELF header.  */  if (elf->state.elf.ehdr == NULL)    {      __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);      size = -1;      goto out;    }   /* Determine the number of sections.  */  shnum = (elf->state.elf.scns_last->cnt == 0	   ? 0	   : 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt - 1].index);   /* Update the ELF descriptor.  First, place the program header.  It     will come right after the ELF header.  The count the size of all     sections and finally place the section table.  */  size = (elf->class == ELFCLASS32	  ? __elf32_updatenull_wrlock (elf, &change_bo, shnum)	  : __elf64_updatenull_wrlock (elf, &change_bo, shnum));  if (likely (size != -1)      /* See whether we actually have to write out the data.  */      && (cmd == ELF_C_WRITE || cmd == ELF_C_WRITE_MMAP))    {      if (elf->cmd != ELF_C_RDWR	  && elf->cmd != ELF_C_RDWR_MMAP	  && elf->cmd != ELF_C_WRITE	  && unlikely (elf->cmd != ELF_C_WRITE_MMAP))	{	  __libelf_seterrno (ELF_E_UPDATE_RO);	  size = -1;	}      else if (unlikely (elf->fildes == -1))	{	  /* We closed the file already.  */	  __libelf_seterrno (ELF_E_FD_DISABLED);	  size = -1;	}      else	size = write_file (elf, size, change_bo, shnum);    }  out:  rwlock_unlock (elf->lock);   return size;}