diff options
Diffstat (limited to 'libelf')
| -rw-r--r-- | libelf/ChangeLog | 5 | ||||
| -rw-r--r-- | libelf/elf_update.c | 36 |
2 files changed, 28 insertions, 13 deletions
diff --git a/libelf/ChangeLog b/libelf/ChangeLog index b1d1ecdf..af2438b4 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2015-10-05 Mark Wielaard <mjw@redhat.com> + + * elf_update.c (write_file): Only use posix_fallocate when using + mmap. Only report failure when errno is ENOSPC. + 2015-10-09 Josh Stone <jistone@redhat.com> * libelfP.h (struct Elf): Replace off64_t with off_t. diff --git a/libelf/elf_update.c b/libelf/elf_update.c index 00f7a010..c635eb32 100644 --- a/libelf/elf_update.c +++ b/libelf/elf_update.c @@ -57,22 +57,11 @@ 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. - - Note we use posix_fallocate 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. 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. Note that we do also need to ftruncate - in case the maximum_size isn't known and the file needs to be shorter - because posix_fallocate can only extend. */ + 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) - && unlikely (posix_fallocate (elf->fildes, 0, size) != 0)) + && unlikely (ftruncate (elf->fildes, size) != 0)) { __libelf_seterrno (ELF_E_WRITE_ERROR); return -1; @@ -89,6 +78,27 @@ write_file (Elf *elf, off_t size, int change_bo, size_t shnum) 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) |