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(posix_fallocate): If len == 0, call ftruncate if offset is bigger than current size. Make sure the file is offset + len bytes long if that is more than current size. Don't overwrite previous content of the file.

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This commit is contained in:
Ulrich Drepper 2005-05-03 15:07:47 +00:00
parent ccaee9ce5d
commit fe80efd5f6
2 changed files with 66 additions and 20 deletions
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43
sysdeps/posix/posix_fallocate.c
View File

@ -1,4 +1,4 @@
/* Copyright (C) 2000, 2003 Free Software Foundation, Inc.
/* Copyright (C) 2000, 2003, 2005 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
@ -29,9 +29,8 @@ posix_fallocate (int fd, __off_t offset, __off_t len)
{
struct stat64 st;
struct statfs f;
size_t step;
/* `off_t´ is a signed type. Therefore we can determine whether
/* `off_t' is a signed type. Therefore we can determine whether
OFFSET + LEN is too large if it is a negative value. */
if (offset < 0 || len < 0)
return EINVAL;
@ -47,24 +46,48 @@ posix_fallocate (int fd, __off_t offset, __off_t len)
if (! S_ISREG (st.st_mode))
return ENODEV;
if (len == 0)
{
if (st.st_size < offset)
{
int ret = __ftruncate (fd, offset);
if (ret != 0)
ret = errno;
return ret;
}
return 0;
}
/* We have to know the block size of the filesystem to get at least some
sort of performance. */
if (__fstatfs (fd, &f) != 0)
return errno;
/* Align OFFSET to block size and adjust LEN. */
step = (offset + f.f_bsize - 1) % ~f.f_bsize;
offset += step;
/* Try to play safe. */
if (f.f_bsize == 0)
f.f_bsize = 512;
/* Write something to every block. */
while (len > step)
for (offset += (len - 1) % f.f_bsize; len > 0; offset += f.f_bsize)
{
len -= step;
len -= f.f_bsize;
if (offset < st.st_size)
{
unsigned char c;
ssize_t rsize = __pread (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 (__pwrite (fd, "", 1, offset) != 1)
return errno;
offset += step;
}
return 0;

43
sysdeps/posix/posix_fallocate64.c
View File

@ -1,4 +1,4 @@
/* Copyright (C) 2000, 2003, 2004 Free Software Foundation, Inc.
/* Copyright (C) 2000, 2003, 2004, 2005 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
@ -29,9 +29,8 @@ __posix_fallocate64_l64 (int fd, __off64_t offset, __off64_t len)
{
struct stat64 st;
struct statfs64 f;
size_t step;
/* `off64_t´ is a signed type. Therefore we can determine whether
/* `off64_t' is a signed type. Therefore we can determine whether
OFFSET + LEN is too large if it is a negative value. */
if (offset < 0 || len < 0)
return EINVAL;
@ -47,24 +46,48 @@ __posix_fallocate64_l64 (int fd, __off64_t offset, __off64_t len)
if (! S_ISREG (st.st_mode))
return ENODEV;
if (len == 0)
{
if (st.st_size < offset)
{
int ret = __ftruncate64 (fd, offset);
if (ret != 0)
ret = errno;
return ret;
}
return 0;
}
/* We have to know the block size of the filesystem to get at least some
sort of performance. */
if (__fstatfs64 (fd, &f) != 0)
return errno;
/* Align OFFSET to block size and adjust LEN. */
step = (offset + f.f_bsize - 1) % ~f.f_bsize;
offset += step;
/* Try to play safe. */
if (f.f_bsize == 0)
f.f_bsize = 512;
/* Write something to every block. */
while (len > step)
for (offset += (len - 1) % f.f_bsize; len > 0; offset += f.f_bsize)
{
len -= step;
len -= f.f_bsize;
if (offset < st.st_size)
{
unsigned char c;
ssize_t rsize = __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 (__pwrite64 (fd, "", 1, offset) != 1)
return errno;
offset += step;
}
return 0;