diff options
Diffstat (limited to 'REORG.TODO/sysdeps/posix/posix_fallocate64.c')
| -rw-r--r-- | REORG.TODO/sysdeps/posix/posix_fallocate64.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/posix/posix_fallocate64.c b/REORG.TODO/sysdeps/posix/posix_fallocate64.c new file mode 100644 index 0000000000..a637ebe0c6 --- /dev/null +++ b/REORG.TODO/sysdeps/posix/posix_fallocate64.c @@ -0,0 +1,142 @@ +/* Copyright (C) 2000-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdint.h> +#include <sys/fcntl.h> +#include <sys/stat.h> +#include <sys/statfs.h> + +/* Reserve storage for the data of the file associated with FD. This + emulation is far from perfect, but the kernel cannot do not much + better for network file systems, either. */ + +int +__posix_fallocate64_l64 (int fd, __off64_t offset, __off64_t len) +{ + struct stat64 st; + + if (offset < 0 || len < 0) + return EINVAL; + + /* Perform overflow check. The outer cast relies on a GCC + extension. */ + if ((__off64_t) ((uint64_t) offset + (uint64_t) len) < 0) + return EFBIG; + + /* pwrite64 below will not do the right thing in O_APPEND mode. */ + { + int flags = __fcntl (fd, F_GETFL, 0); + if (flags < 0 || (flags & O_APPEND) != 0) + return EBADF; + } + + /* We have to make sure that this is really a regular file. */ + if (__fxstat64 (_STAT_VER, fd, &st) != 0) + return EBADF; + if (S_ISFIFO (st.st_mode)) + return ESPIPE; + if (! S_ISREG (st.st_mode)) + return ENODEV; + + if (len == 0) + { + /* This is racy, but there is no good way to satisfy a + zero-length allocation request. */ + if (st.st_size < offset) + { + int ret = __ftruncate64 (fd, offset); + + if (ret != 0) + ret = errno; + return ret; + } + return 0; + } + + /* Minimize data transfer for network file systems, by issuing + single-byte write requests spaced by the file system block size. + (Most local file systems have fallocate support, so this fallback + code is not used there.) */ + + unsigned increment; + { + struct statfs64 f; + + if (__fstatfs64 (fd, &f) != 0) + return errno; + if (f.f_bsize == 0) + increment = 512; + else if (f.f_bsize < 4096) + increment = f.f_bsize; + else + /* NFS clients do not propagate the block size of the underlying + storage and may report a much larger value which would still + leave holes after the loop below, so we cap the increment at + 4096. */ + increment = 4096; + } + + /* Write a null byte to every block. This is racy; we currently + lack a better option. Compare-and-swap against a file mapping + might address local races, but requires interposition of a signal + handler to catch SIGBUS. */ + for (offset += (len - 1) % increment; len > 0; offset += increment) + { + len -= increment; + + if (offset < st.st_size) + { + unsigned char c; + ssize_t rsize = __libc_pread64 (fd, &c, 1, offset); + + if (rsize < 0) + return errno; + /* If there is a non-zero byte, the block must have been + allocated already. */ + else if (rsize == 1 && c != 0) + continue; + } + + if (__libc_pwrite64 (fd, "", 1, offset) != 1) + return errno; + } + + return 0; +} + +#undef __posix_fallocate64_l64 +#include <shlib-compat.h> +#include <bits/wordsize.h> + +#if __WORDSIZE == 32 && SHLIB_COMPAT(libc, GLIBC_2_2, GLIBC_2_3_3) + +int +attribute_compat_text_section +__posix_fallocate64_l32 (int fd, off64_t offset, size_t len) +{ + return __posix_fallocate64_l64 (fd, offset, len); +} + +versioned_symbol (libc, __posix_fallocate64_l64, posix_fallocate64, + GLIBC_2_3_3); +compat_symbol (libc, __posix_fallocate64_l32, posix_fallocate64, GLIBC_2_2); +#else +strong_alias (__posix_fallocate64_l64, posix_fallocate64); +#endif |