Squashed 'third_party/elfutils/' content from commit 555e15e
Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libelf/elf_update.c b/libelf/elf_update.c
new file mode 100644
index 0000000..8ce0782
--- /dev/null
+++ b/libelf/elf_update.c
@@ -0,0 +1,222 @@
+/* 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_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)
+ {
+ 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)
+ {
+ /* 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;
+ }
+
+ /* 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;
+}
+
+
+off_t
+elf_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;
+}