LCOV - code coverage report
Current view: top level - libelf - elf_update.c (source / functions) Hit Total Coverage
Test: elfutils-0.189 Lines: 61 87 70.1 %
Date: 2023-08-28 19:26:08 Functions: 2 2 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 56 86 65.1 %

           Branch data     Line data    Source code
       1                 :            : /* Update data structures for changes and write them out.
       2                 :            :    Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2015 Red Hat, Inc.
       3                 :            :    This file is part of elfutils.
       4                 :            :    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
       5                 :            : 
       6                 :            :    This file is free software; you can redistribute it and/or modify
       7                 :            :    it under the terms of either
       8                 :            : 
       9                 :            :      * the GNU Lesser General Public License as published by the Free
      10                 :            :        Software Foundation; either version 3 of the License, or (at
      11                 :            :        your option) any later version
      12                 :            : 
      13                 :            :    or
      14                 :            : 
      15                 :            :      * the GNU General Public License as published by the Free
      16                 :            :        Software Foundation; either version 2 of the License, or (at
      17                 :            :        your option) any later version
      18                 :            : 
      19                 :            :    or both in parallel, as here.
      20                 :            : 
      21                 :            :    elfutils is distributed in the hope that it will be useful, but
      22                 :            :    WITHOUT ANY WARRANTY; without even the implied warranty of
      23                 :            :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      24                 :            :    General Public License for more details.
      25                 :            : 
      26                 :            :    You should have received copies of the GNU General Public License and
      27                 :            :    the GNU Lesser General Public License along with this program.  If
      28                 :            :    not, see <http://www.gnu.org/licenses/>.  */
      29                 :            : 
      30                 :            : #ifdef HAVE_CONFIG_H
      31                 :            : # include <config.h>
      32                 :            : #endif
      33                 :            : 
      34                 :            : #include <libelf.h>
      35                 :            : #include <fcntl.h>
      36                 :            : #include <sys/stat.h>
      37                 :            : 
      38                 :            : #include "libelfP.h"
      39                 :            : 
      40                 :            : 
      41                 :            : static int64_t
      42                 :        623 : write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
      43                 :            : {
      44                 :        623 :   int class = elf->class;
      45                 :            : 
      46                 :            :   /* Check the mode bits now, before modification might change them.  */
      47                 :        623 :   struct stat st;
      48         [ -  + ]:        623 :   if (unlikely (fstat (elf->fildes, &st) != 0))
      49                 :            :     {
      50                 :          0 :       __libelf_seterrno (ELF_E_WRITE_ERROR);
      51                 :          0 :       return -1;
      52                 :            :     }
      53                 :            : 
      54                 :            :   /* Adjust the size in any case.  We do this even if we use `write'.
      55                 :            :      We cannot do this if this file is in an archive.  We also don't
      56                 :            :      do it *now* if we are shortening the file since this would
      57                 :            :      prevent programs to use the data of the file in generating the
      58                 :            :      new file.  We truncate the file later in this case.  */
      59         [ +  - ]:        623 :   if (elf->parent == NULL
      60         [ +  - ]:        623 :       && (elf->maximum_size == ~((size_t) 0)
      61         [ +  + ]:        623 :           || (size_t) size > elf->maximum_size)
      62         [ -  + ]:        567 :       && unlikely (ftruncate (elf->fildes, size) != 0))
      63                 :            :     {
      64                 :          0 :       __libelf_seterrno (ELF_E_WRITE_ERROR);
      65                 :          0 :       return -1;
      66                 :            :     }
      67                 :            : 
      68                 :            :   /* Try to map the file if this isn't done yet.  */
      69   [ +  +  +  + ]:        623 :   if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)
      70                 :            :     {
      71                 :        125 :       elf->map_address = mmap (NULL, size, PROT_READ | PROT_WRITE,
      72                 :            :                                MAP_SHARED, elf->fildes, 0);
      73         [ -  + ]:        125 :       if (unlikely (elf->map_address == MAP_FAILED))
      74                 :          0 :         elf->map_address = NULL;
      75                 :            :       else
      76                 :        125 :         elf->flags |= ELF_F_MMAPPED;
      77                 :            :     }
      78                 :            : 
      79         [ +  + ]:        623 :   if (elf->map_address != NULL)
      80                 :            :     {
      81                 :            :       /* When using mmap we want to make sure the file content is
      82                 :            :          really there. Only using ftruncate might mean the file is
      83                 :            :          extended, but space isn't allocated yet.  This might cause a
      84                 :            :          SIGBUS once we write into the mmapped space and the disk is
      85                 :            :          full.  In glibc posix_fallocate is required to extend the
      86                 :            :          file and allocate enough space even if the underlying
      87                 :            :          filesystem would normally return EOPNOTSUPP.  But other
      88                 :            :          implementations might not work as expected.  And the glibc
      89                 :            :          fallback case might fail (with unexpected errnos) in some cases.
      90                 :            :          So we only report an error when the call fails and errno is
      91                 :            :          ENOSPC. Otherwise we ignore the error and treat it as just hint.  */
      92         [ +  - ]:        141 :       if (elf->parent == NULL
      93         [ +  - ]:        141 :           && (elf->maximum_size == ~((size_t) 0)
      94         [ +  + ]:        141 :               || (size_t) size > elf->maximum_size))
      95                 :            :         {
      96         [ -  + ]:        139 :           if (unlikely (posix_fallocate (elf->fildes, 0, size) != 0))
      97         [ #  # ]:          0 :             if (errno == ENOSPC)
      98                 :            :               {
      99                 :          0 :                 __libelf_seterrno (ELF_E_WRITE_ERROR);
     100                 :          0 :                 return -1;
     101                 :            :               }
     102                 :            : 
     103                 :            :           /* Extend the mmap address if needed.  */
     104         [ +  + ]:        139 :           if (elf->cmd == ELF_C_RDWR_MMAP
     105         [ +  - ]:         14 :               && (size_t) size > elf->maximum_size)
     106                 :            :             {
     107                 :            : #ifdef HAVE_MREMAP
     108         [ -  + ]:         14 :               if (mremap (elf->map_address, elf->maximum_size,
     109                 :            :                           size, 0) == MAP_FAILED)
     110                 :            : #endif
     111                 :            :                 {
     112                 :          0 :                   __libelf_seterrno (ELF_E_WRITE_ERROR);
     113                 :          0 :                   return -1;
     114                 :            :                 }
     115                 :         14 :               elf->maximum_size = size;
     116                 :            :             }
     117                 :            : 
     118                 :            :         }
     119                 :            : 
     120                 :            :       /* The file is mmaped.  */
     121         [ +  - ]:        141 :       if ((class == ELFCLASS32
     122                 :         66 :            ? __elf32_updatemmap (elf, change_bo, shnum)
     123         [ +  + ]:        207 :            : __elf64_updatemmap (elf, change_bo, shnum)) != 0)
     124                 :            :         /* Some problem while writing.  */
     125                 :            :         size = -1;
     126                 :            :     }
     127                 :            :   else
     128                 :            :     {
     129                 :            :       /* The file is not mmaped.  */
     130         [ -  + ]:        482 :       if ((class == ELFCLASS32
     131                 :        198 :            ? __elf32_updatefile (elf, change_bo, shnum)
     132         [ +  + ]:        680 :            : __elf64_updatefile (elf, change_bo, shnum)) != 0)
     133                 :            :         /* Some problem while writing.  */
     134                 :            :         size = -1;
     135                 :            :     }
     136                 :            : 
     137                 :            :   /* Reduce the file size if necessary.  */
     138         [ -  + ]:        623 :   if (size != -1
     139         [ +  - ]:        623 :       && elf->parent == NULL
     140         [ +  - ]:        623 :       && elf->maximum_size != ~((size_t) 0)
     141         [ +  + ]:        623 :       && (size_t) size < elf->maximum_size
     142         [ -  + ]:         40 :       && unlikely (ftruncate (elf->fildes, size) != 0))
     143                 :            :     {
     144                 :          0 :       __libelf_seterrno (ELF_E_WRITE_ERROR);
     145                 :          0 :       size = -1;
     146                 :            :     }
     147                 :            : 
     148                 :            :   /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID
     149                 :            :      mode bits.  So make sure we restore them afterwards if they were set.
     150                 :            :      This is not atomic if someone else chmod's the file while we operate.  */
     151         [ -  + ]:        623 :   if (size != -1
     152         [ -  + ]:        623 :       && unlikely (st.st_mode & (S_ISUID | S_ISGID))
     153                 :            :       /* fchmod ignores the bits we cannot change.  */
     154         [ #  # ]:          0 :       && unlikely (fchmod (elf->fildes, st.st_mode) != 0))
     155                 :            :     {
     156                 :          0 :       __libelf_seterrno (ELF_E_WRITE_ERROR);
     157                 :          0 :       size = -1;
     158                 :            :     }
     159                 :            : 
     160         [ -  + ]:        623 :   if (size != -1 && elf->parent == NULL)
     161                 :        623 :     elf->maximum_size = size;
     162                 :            : 
     163                 :            :   return size;
     164                 :            : }
     165                 :            : 
     166                 :            : 
     167                 :            : int64_t
     168                 :        691 : elf_update (Elf *elf, Elf_Cmd cmd)
     169                 :            : {
     170                 :        691 :   size_t shnum;
     171                 :        691 :   int64_t size;
     172                 :        691 :   int change_bo = 0;
     173                 :            : 
     174                 :        691 :   if (cmd != ELF_C_NULL
     175         [ +  + ]:        691 :       && cmd != ELF_C_WRITE
     176         [ -  + ]:          9 :       && unlikely (cmd != ELF_C_WRITE_MMAP))
     177                 :            :     {
     178                 :          0 :       __libelf_seterrno (ELF_E_INVALID_CMD);
     179                 :          0 :       return -1;
     180                 :            :     }
     181                 :            : 
     182         [ -  + ]:        691 :   if (elf == NULL)
     183                 :            :     return -1;
     184                 :            : 
     185         [ -  + ]:        691 :   if (elf->kind != ELF_K_ELF)
     186                 :            :     {
     187                 :          0 :       __libelf_seterrno (ELF_E_INVALID_HANDLE);
     188                 :          0 :       return -1;
     189                 :            :     }
     190                 :            : 
     191                 :        691 :   rwlock_wrlock (elf->lock);
     192                 :            : 
     193                 :            :   /* Make sure we have an ELF header.  */
     194         [ -  + ]:        691 :   if (elf->state.elf.ehdr == NULL)
     195                 :            :     {
     196                 :          0 :       __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
     197                 :          0 :       size = -1;
     198                 :          0 :       goto out;
     199                 :            :     }
     200                 :            : 
     201                 :            :   /* Determine the number of sections.  */
     202                 :       1382 :   shnum = (elf->state.elf.scns_last->cnt == 0
     203                 :            :            ? 0
     204         [ +  + ]:        691 :            : 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt - 1].index);
     205                 :            : 
     206                 :            :   /* Update the ELF descriptor.  First, place the program header.  It
     207                 :            :      will come right after the ELF header.  The count the size of all
     208                 :            :      sections and finally place the section table.  */
     209                 :       1382 :   size = (elf->class == ELFCLASS32
     210                 :        299 :           ? __elf32_updatenull_wrlock (elf, &change_bo, shnum)
     211         [ +  + ]:        691 :           : __elf64_updatenull_wrlock (elf, &change_bo, shnum));
     212         [ -  + ]:        691 :   if (likely (size != -1)
     213                 :            :       /* See whether we actually have to write out the data.  */
     214         [ +  + ]:        691 :       && (cmd == ELF_C_WRITE || cmd == ELF_C_WRITE_MMAP))
     215                 :            :     {
     216                 :        623 :       if (elf->cmd != ELF_C_RDWR
     217         [ +  + ]:        623 :           && elf->cmd != ELF_C_RDWR_MMAP
     218         [ +  + ]:        514 :           && elf->cmd != ELF_C_WRITE
     219         [ -  + ]:        125 :           && unlikely (elf->cmd != ELF_C_WRITE_MMAP))
     220                 :            :         {
     221                 :          0 :           __libelf_seterrno (ELF_E_UPDATE_RO);
     222                 :          0 :           size = -1;
     223                 :            :         }
     224         [ -  + ]:        623 :       else if (unlikely (elf->fildes == -1))
     225                 :            :         {
     226                 :            :           /* We closed the file already.  */
     227                 :          0 :           __libelf_seterrno (ELF_E_FD_DISABLED);
     228                 :          0 :           size = -1;
     229                 :            :         }
     230                 :            :       else
     231                 :        623 :         size = write_file (elf, size, change_bo, shnum);
     232                 :            :     }
     233                 :            : 
     234                 :         68 :  out:
     235                 :            :   rwlock_unlock (elf->lock);
     236                 :            : 
     237                 :            :   return size;
     238                 :            : }

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