This workaround is adapted from Coreutils.
* lib/copy-file-range.c [__linux__ && HAVE_COPY_FILE_RANGE]:
Include <sys/utsname.h>.
(copy_file_range): Use a stub to replace the copy_file_range of
Linux kernel versions 4.5 through 5.2.
* lib/unistd.in.h (copy_file_range):
* m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS):
* modules/copy-file-range (configure.ac):
* modules/unistd (unistd.h):
Support replacement of copy_file_range.
* m4/copy-file-range.m4 (gl_FUNC_COPY_FILE_RANGE):
Define HAVE_COPY_FILE_RANGE if the system has copy_file_range,
and on Linux check whether the system’s is known to work.
---
ChangeLog | 17 ++++++++++++
doc/glibc-functions/copy_file_range.texi | 5 ++++
lib/copy-file-range.c | 34 ++++++++++++++++++++++++
lib/unistd.in.h | 16 ++++++++++-
m4/copy-file-range.m4 | 25 ++++++++++++++++-
m4/unistd_h.m4 | 1 +
modules/copy-file-range | 4 ++-
modules/unistd | 1 +
8 files changed, 100 insertions(+), 3 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 93fe05770b..a900fec78d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2022-01-14 Paul Eggert <egg...@cs.ucla.edu>
+
+ copy-file-range: work around Linux kernel bug
+ This workaround is adapted from Coreutils.
+ * lib/copy-file-range.c [__linux__ && HAVE_COPY_FILE_RANGE]:
+ Include <sys/utsname.h>.
+ (copy_file_range): Use a stub to replace the copy_file_range of
+ Linux kernel versions 4.5 through 5.2.
+ * lib/unistd.in.h (copy_file_range):
+ * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS):
+ * modules/copy-file-range (configure.ac):
+ * modules/unistd (unistd.h):
+ Support replacement of copy_file_range.
+ * m4/copy-file-range.m4 (gl_FUNC_COPY_FILE_RANGE):
+ Define HAVE_COPY_FILE_RANGE if the system has copy_file_range,
+ and on Linux check whether the system’s is known to work.
+
2022-01-14 Bruno Haible <br...@clisp.org>
Avoid error "conditional LIBUNISTRING_COMPILE_... was never defined"
diff --git a/doc/glibc-functions/copy_file_range.texi
b/doc/glibc-functions/copy_file_range.texi
index baac6e1302..f10271c157 100644
--- a/doc/glibc-functions/copy_file_range.texi
+++ b/doc/glibc-functions/copy_file_range.texi
@@ -24,6 +24,11 @@ This function exists only on Linux and FreeBSD and is
therefore
missing on many non-glibc platforms:
glibc 2.26, macOS 11.1, FreeBSD 12.0, NetBSD 9.0, OpenBSD 6.7, Minix 3.1.8,
AIX 7.1, HP-UX 11.31, IRIX 6.5, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14,
Android 9.0.
But the replacement function is only a stub: It always fails with error ENOSYS.
+
+@item
+This function has many problems on Linux kernel versions before 5.3.
+On these kernel versions, the replacement function always fails with
+error ENOSYS.
@end itemize
Portability problems not fixed by Gnulib:
diff --git a/lib/copy-file-range.c b/lib/copy-file-range.c
index 96f1ec7c5e..1ec7f4de67 100644
--- a/lib/copy-file-range.c
+++ b/lib/copy-file-range.c
@@ -20,11 +20,45 @@
#include <errno.h>
+#if defined __linux__ && HAVE_COPY_FILE_RANGE
+# include <sys/utsname.h>
+#endif
+
ssize_t
copy_file_range (int infd, off_t *pinoff,
int outfd, off_t *poutoff,
size_t length, unsigned int flags)
{
+#undef copy_file_range
+
+#if defined __linux__ && HAVE_COPY_FILE_RANGE
+ /* The implementation of copy_file_range (which first appeared in
+ Linux kernel release 4.5) had many issues before release 5.3
+ <https://lwn.net/Articles/789527/>, so fail with ENOSYS for Linux
+ kernels 5.2 and earlier.
+
+ This workaround, and the configure-time check for Linux, can be
+ removed when such kernels (released March 2016 through September
+ 2019) are no longer a consideration. As of January 2021, the
+ furthest-future planned kernel EOL is December 2024 for kernel
+ release 4.19. */
+
+ static signed char ok;
+
+ if (! ok)
+ {
+ struct utsname name;
+ uname (&name);
+ char *p = name.release;
+ ok = ((p[1] != '.' || '5' < p[0]
+ || (p[0] == '5' && (p[3] != '.' || '2' < p[2])))
+ ? 1 : -1);
+ }
+
+ if (0 < ok)
+ return copy_file_range (infd, pinoff, outfd, poutoff, length, flags);
+#endif
+
/* There is little need to emulate copy_file_range with read+write,
since programs that use copy_file_range must fall back on
read+write anyway. */
diff --git a/lib/unistd.in.h b/lib/unistd.in.h
index 3386f0b0f7..57df09ecdf 100644
--- a/lib/unistd.in.h
+++ b/lib/unistd.in.h
@@ -415,16 +415,30 @@ _GL_CXXALIASWARN (close);
#if @GNULIB_COPY_FILE_RANGE@
-# if !@HAVE_COPY_FILE_RANGE@
+# if @REPLACE_COPY_FILE_RANGE@
+# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+# undef copy_file_range
+# define copy_file_range rpl_copy_file_range
+# endif
+_GL_FUNCDECL_RPL (copy_file_range, ssize_t, (int ifd, off_t *ipos,
+ int ofd, off_t *opos,
+ size_t len, unsigned flags));
+_GL_CXXALIAS_RPL (copy_file_range, ssize_t, (int ifd, off_t *ipos,
+ int ofd, off_t *opos,
+ size_t len, unsigned flags));
+# else
+# if !@HAVE_COPY_FILE_RANGE@
_GL_FUNCDECL_SYS (copy_file_range, ssize_t, (int ifd, off_t *ipos,
int ofd, off_t *opos,
size_t len, unsigned flags));
+# endif
_GL_CXXALIAS_SYS (copy_file_range, ssize_t, (int ifd, off_t *ipos,
int ofd, off_t *opos,
size_t len, unsigned flags));
# endif
_GL_CXXALIASWARN (copy_file_range);
#elif defined GNULIB_POSIXCHECK
+# undef copy_file_range
# if HAVE_RAW_DECL_COPY_FILE_RANGE
_GL_WARN_ON_USE (copy_file_range,
"copy_file_range is unportable - "
diff --git a/m4/copy-file-range.m4 b/m4/copy-file-range.m4
index 4c7ec4eaaf..1b8b9d8858 100644
--- a/m4/copy-file-range.m4
+++ b/m4/copy-file-range.m4
@@ -7,6 +7,7 @@ dnl with or without modifications, as long as this notice is
preserved.
AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+ AC_REQUIRE([AC_CANONICAL_HOST])
dnl Persuade glibc <unistd.h> to declare copy_file_range.
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
@@ -21,7 +22,7 @@ AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
[AC_LANG_PROGRAM(
[[#include <unistd.h>
]],
- [[ssize_t (*func) (int, off_t *, int, off_t, size_t, unsigned)
+ [[ssize_t (*func) (int, off_t *, int, off_t *, size_t, unsigned)
= copy_file_range;
return func (0, 0, 0, 0, 0, 0) & 127;
]])
@@ -32,5 +33,27 @@ AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
if test "$gl_cv_func_copy_file_range" != yes; then
HAVE_COPY_FILE_RANGE=0
+ else
+ AC_DEFINE([HAVE_COPY_FILE_RANGE], 1,
+ [Define to 1 if the function copy_file_range exists.])
+
+ case $host_os in
+ linux*)
+ AC_CACHE_CHECK([whether copy_file_range is known to work],
+ [gl_cv_copy_file_range_known_to_work],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <linux/version.h>
+ ]],
+ [[#if LINUX_VERSION_CODE < KERNEL_VERSION (5, 3, 0)
+ #error "copy_file_range is buggy"
+ #endif
+ ]])],
+ [gl_cv_copy_file_range_known_to_work=yes],
+ [gl_cv_copy_file_range_known_to_work=no])])
+ if test "$gl_cv_copy_file_range_known_to_work" = no; then
+ REPLACE_COPY_FILE_RANGE=1
+ fi;;
+ esac
fi
])
diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4
index f93f97a1bd..4c66ccc0a4 100644
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@@ -222,6 +222,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
REPLACE_ACCESS=0; AC_SUBST([REPLACE_ACCESS])
REPLACE_CHOWN=0; AC_SUBST([REPLACE_CHOWN])
REPLACE_CLOSE=0; AC_SUBST([REPLACE_CLOSE])
+ REPLACE_COPY_FILE_RANGE=0; AC_SUBST([REPLACE_COPY_FILE_RANGE])
REPLACE_DUP=0; AC_SUBST([REPLACE_DUP])
REPLACE_DUP2=0; AC_SUBST([REPLACE_DUP2])
REPLACE_EXECL=0; AC_SUBST([REPLACE_EXECL])
diff --git a/modules/copy-file-range b/modules/copy-file-range
index e2a4ffef46..4707f97561 100644
--- a/modules/copy-file-range
+++ b/modules/copy-file-range
@@ -11,7 +11,9 @@ unistd
configure.ac:
gl_FUNC_COPY_FILE_RANGE
-gl_CONDITIONAL([GL_COND_OBJ_COPY_FILE_RANGE], [test $HAVE_COPY_FILE_RANGE = 0])
+gl_CONDITIONAL([GL_COND_OBJ_COPY_FILE_RANGE],
+ [test $HAVE_COPY_FILE_RANGE = 0 ||
+ test $REPLACE_COPY_FILE_RANGE = 1])
gl_UNISTD_MODULE_INDICATOR([copy-file-range])
Makefile.am:
diff --git a/modules/unistd b/modules/unistd
index 326bae0e48..01da57e23a 100644
--- a/modules/unistd
+++ b/modules/unistd
@@ -176,6 +176,7 @@ unistd.h: unistd.in.h $(top_builddir)/config.status
$(CXXDEFS_H) $(ARG_NONNULL_H
sed -e 's|@''REPLACE_ACCESS''@|$(REPLACE_ACCESS)|g' \
-e 's|@''REPLACE_CHOWN''@|$(REPLACE_CHOWN)|g' \
-e 's|@''REPLACE_CLOSE''@|$(REPLACE_CLOSE)|g' \
+ -e 's|@''REPLACE_COPY_FILE_RANGE''@|$(REPLACE_COPY_FILE_RANGE)|g'
\
-e 's|@''REPLACE_DUP''@|$(REPLACE_DUP)|g' \
-e 's|@''REPLACE_DUP2''@|$(REPLACE_DUP2)|g' \
-e 's|@''REPLACE_EXECL''@|$(REPLACE_EXECL)|g' \
--
2.32.0
