support: Add support_copy_file

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2020-11-26 16:59:44 +01:00
parent 05d38b3ef5
commit 603ae243f6
3 changed files with 49 additions and 0 deletions

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@ -46,6 +46,7 @@ libsupport-routines = \
support_capture_subprocess \
support_capture_subprocess_check \
support_chroot \
support_copy_file \
support_copy_file_range \
support_descriptor_supports_holes \
support_descriptors \

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@ -119,6 +119,11 @@ extern const char support_install_rootsbindir[];
/* Corresponds to the install's compiled locale directory. */
extern const char support_complocaledir_prefix[];
/* Copies the file at the path FROM to TO. If TO does not exist, it
is created. If TO is a regular file, it is truncated before
copying. The file mode is copied, but the permissions are not. */
extern void support_copy_file (const char *from, const char *to);
extern ssize_t support_copy_file_range (int, off64_t *, int, off64_t *,
size_t, unsigned int);

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@ -0,0 +1,43 @@
/* Copy a file from one path to another.
Copyright (C) 2020 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
<https://www.gnu.org/licenses/>. */
#include <fcntl.h>
#include <support/check.h>
#include <support/support.h>
#include <support/xunistd.h>
void
support_copy_file (const char *from, const char *to)
{
struct stat64 st;
xstat (from, &st);
int fd_from = xopen (from, O_RDONLY, 0);
mode_t mode = st.st_mode & 0777;
int fd_to = xopen (to, O_WRONLY | O_TRUNC | O_CREAT, mode);
ssize_t ret = support_copy_file_range (fd_from, NULL, fd_to, NULL,
st.st_size, 0);
if (ret < 0)
FAIL_EXIT1 ("copying from \"%s\" to \"%s\": %m", from, to);
if (ret != st.st_size)
FAIL_EXIT1 ("copying from \"%s\" to \"%s\": only %zd of %llu bytes copied",
from, to, ret, (unsigned long long int) st.st_size);
if (fchmod (fd_to, mode) < 0)
FAIL_EXIT1 ("fchmod on %s to 0%o: %m", to, mode);
xclose (fd_to);
xclose (fd_from);
}