diff options
| -rw-r--r-- | libelf/ChangeLog | 5 | ||||
| -rw-r--r-- | libelf/elf_update.c | 16 |
2 files changed, 18 insertions, 3 deletions
diff --git a/libelf/ChangeLog b/libelf/ChangeLog index 2d10b83e..ed2ddd88 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2015-05-14 Mark Wielaard <[email protected]> + + * elf_update.c (write_file): Use posix_fallocate instead of + ftruncate to extend file if necessary. + 2015-05-13 Mark Wielaard <[email protected]> * elf32_updatenull.c (default_ehdr): If e_phnum is zero then set diff --git a/libelf/elf_update.c b/libelf/elf_update.c index 54c20f50..9e34c466 100644 --- a/libelf/elf_update.c +++ b/libelf/elf_update.c @@ -1,5 +1,5 @@ /* Update data structures for changes and write them out. - Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc. + Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2015 Red Hat, Inc. This file is part of elfutils. Contributed by Ulrich Drepper <[email protected]>, 1999. @@ -32,6 +32,7 @@ #endif #include <libelf.h> +#include <fcntl.h> #include <unistd.h> #include <sys/mman.h> #include <sys/stat.h> @@ -56,11 +57,19 @@ write_file (Elf *elf, off_t size, int change_bo, size_t shnum) 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. */ + new file. We truncate the file later in this case. + + Note we use posix_fallocate to make sure the file content is really + there. 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. Using fallocate might fail + on some file systems. posix_fallocate is required to extend the file + and allocate enough space even if the underlying filesystem would + normally return EOPNOTSUPP. */ if (elf->parent == NULL && (elf->maximum_size == ~((size_t) 0) || (size_t) size > elf->maximum_size) - && unlikely (ftruncate (elf->fildes, size) != 0)) + && unlikely (posix_fallocate (elf->fildes, 0, size) != 0)) { __libelf_seterrno (ELF_E_WRITE_ERROR); return -1; @@ -94,6 +103,7 @@ write_file (Elf *elf, off_t size, int change_bo, size_t shnum) size = -1; } + /* Reduce the file size if necessary. */ if (size != -1 && elf->parent == NULL && elf->maximum_size != ~((size_t) 0) |