diff options
Diffstat (limited to 'src/libelf/elf_update.c')
| -rw-r--r-- | src/libelf/elf_update.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/src/libelf/elf_update.c b/src/libelf/elf_update.c new file mode 100644 index 00000000..5daece40 --- /dev/null +++ b/src/libelf/elf_update.c @@ -0,0 +1,224 @@ +/* Update data structures for changes and write them out. + Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc. + This file is part of Red Hat elfutils. + Contributed by Ulrich Drepper <drepper@redhat.com>, 1999. + + Red Hat elfutils is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by the + Free Software Foundation; version 2 of the License. + + Red Hat 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 a copy of the GNU General Public License along + with Red Hat elfutils; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. + + In addition, as a special exception, Red Hat, Inc. gives You the + additional right to link the code of Red Hat elfutils with code licensed + under any Open Source Initiative certified open source license + (http://www.opensource.org/licenses/index.php) which requires the + distribution of source code with any binary distribution and to + distribute linked combinations of the two. Non-GPL Code permitted under + this exception must only link to the code of Red Hat elfutils through + those well defined interfaces identified in the file named EXCEPTION + found in the source code files (the "Approved Interfaces"). The files + of Non-GPL Code may instantiate templates or use macros or inline + functions from the Approved Interfaces without causing the resulting + work to be covered by the GNU General Public License. Only Red Hat, + Inc. may make changes or additions to the list of Approved Interfaces. + Red Hat's grant of this exception is conditioned upon your not adding + any new exceptions. If you wish to add a new Approved Interface or + exception, please contact Red Hat. You must obey the GNU General Public + License in all respects for all of the Red Hat elfutils code and other + code used in conjunction with Red Hat elfutils except the Non-GPL Code + covered by this exception. If you modify this file, you may extend this + exception to your version of the file, but you are not obligated to do + so. If you do not wish to provide this exception without modification, + you must delete this exception statement from your version and license + this file solely under the GPL without exception. + + Red Hat elfutils is an included package of the Open Invention Network. + An included package of the Open Invention Network is a package for which + Open Invention Network licensees cross-license their patents. No patent + license is granted, either expressly or impliedly, by designation as an + included package. Should you wish to participate in the Open Invention + Network licensing program, please visit www.openinventionnetwork.com + <http://www.openinventionnetwork.com>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <libelf.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/stat.h> + +#include "libelfP.h" + + +static off_t +write_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) + { +#if _MUDFLAP + /* Mudflap doesn't grok that our mmap'd data is ok. */ +#else + 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; +#endif + } + + if (elf->map_address != NULL) + { + /* 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; + } + + 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; +} + + +off_t +elf_update (elf, cmd) + 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; +} |