+2010-05-05 Peter O'Gorman <pogma@thewrittenword.com>
+
+ New module pwrite.
+ * lib/unistd.in.h (pwrite): New declaration.
+ * lib/pwrite.c: New file, from glibc with modifications.
+ * m4/pwrite.m4: New file.
+ * m4/unistd_h.m4 (gl_UNISTD_H): Test whether pwrite is declared.
+ (gl_UNISTD_H_DEFAULTS): Initialize GNULIB_PWRITE, HAVE_PWRITE,
+ REPLACE_PWRITE.
+ * modules/pwrite: New file.
+ * modules/unistd (Makefile.am): Substitute GNULIB_PWRITE, HAVE_PWRITE,
+ REPLACE_PWRITE.
+ * tests/test-unistd-c++.cc: Check GNULIB_NAMESPACE::pwrite.
+ * doc/posix-functions/pwrite.texi: Mention the new module.
+
2010-05-05 Peter O'Gorman <pogma@thewrittenword.com>
pread: Update documentation.
POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/pwrite.html}
-Gnulib module: ---
+Gnulib module: pwrite
Portability problems fixed by Gnulib:
@itemize
+@item
+This function is missing on some platforms:
+HP-UX 10, mingw, BeOS.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
-@item
-This function is missing on some platforms:
-mingw, BeOS.
@end itemize
--- /dev/null
+/* Write block to given position in file without changing file pointer.
+ POSIX version.
+ Copyright (C) 1997, 1998, 1999, 2002 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <unistd.h>
+
+#include <errno.h>
+
+#define __libc_lseek(f,o,w) lseek (f, o, w)
+#define __set_errno(Val) errno = (Val)
+#define __libc_write(f,b,n) write (f, b, n)
+
+/* Note: This implementation of pwrite is not multithread-safe. */
+
+ssize_t
+pwrite (int fd, const void *buf, size_t nbyte, off_t offset)
+{
+ /* Since we must not change the file pointer preserve the value so that
+ we can restore it later. */
+ int save_errno;
+ ssize_t result;
+ off_t old_offset = __libc_lseek (fd, 0, SEEK_CUR);
+ if (old_offset == (off_t) -1)
+ return -1;
+
+ /* Set to wanted position. */
+ if (__libc_lseek (fd, offset, SEEK_SET) == (off_t) -1)
+ return -1;
+
+ /* Write out the data. */
+ result = __libc_write (fd, buf, nbyte);
+
+ /* Now we have to restore the position. If this fails we have to
+ return this as an error. But if the writing also failed we
+ return this error. */
+ save_errno = errno;
+ if (__libc_lseek (fd, old_offset, SEEK_SET) == (off_t) -1)
+ {
+ if (result == -1)
+ __set_errno (save_errno);
+ return -1;
+ }
+ __set_errno (save_errno);
+
+ return result;
+}
#endif
#if (@GNULIB_WRITE@ || @GNULIB_READLINK@ || @GNULIB_READLINKAT@ \
- || @GNULIB_PREAD@ || defined GNULIB_POSIXCHECK)
+ || @GNULIB_PREAD@ || @GNULIB_PWRITE@ || defined GNULIB_POSIXCHECK)
/* Get ssize_t. */
# include <sys/types.h>
#endif
#endif
+#if @GNULIB_PWRITE@
+/* Write at most BUFSIZE bytes from BUF into FD, starting at OFFSET.
+ Return the number of bytes written if successful, otherwise
+ set errno and return -1. 0 indicates nothing written. See the
+ POSIX:2001 specification
+ <http://www.opengroup.org/susv3xsh/pwrite.html>. */
+# if @REPLACE_PWRITE@
+# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+# define pwrite rpl_pwrite
+# endif
+_GL_FUNCDECL_RPL (pwrite, ssize_t,
+ (int fd, const void *buf, size_t bufsize, off_t offset)
+ _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (pwrite, ssize_t,
+ (int fd, const void *buf, size_t bufsize, off_t offset));
+# else
+# if !@HAVE_PWRITE@
+_GL_FUNCDECL_SYS (pwrite, ssize_t,
+ (int fd, const void *buf, size_t bufsize, off_t offset)
+ _GL_ARG_NONNULL ((2)));
+# endif
+_GL_CXXALIAS_SYS (pwrite, ssize_t,
+ (int fd, const void *buf, size_t bufsize, off_t offset));
+# endif
+_GL_CXXALIASWARN (pwrite);
+#elif defined GNULIB_POSIXCHECK
+# undef pwrite
+# if HAVE_RAW_DECL_PWRITE
+_GL_WARN_ON_USE (pwrite, "pwrite is unportable - "
+ "use gnulib module pwrite for portability");
+# endif
+#endif
+
+
#if @GNULIB_READLINK@
/* Read the contents of the symbolic link FILE and place the first BUFSIZE
bytes of it into BUF. Return the number of bytes placed into BUF if
--- /dev/null
+# pwrite.m4 serial 1
+dnl Copyright (C) 2010 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_PWRITE],
+[
+ AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+ dnl Persuade glibc <unistd.h> to declare pwrite().
+ AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+ AC_CHECK_FUNCS_ONCE([pwrite])
+ if test $ac_cv_func_pwrite = no; then
+ HAVE_PWRITE=0
+ AC_LIBOBJ([pwrite])
+ fi
+])
]], [chown dup2 dup3 environ euidaccess faccessat fchdir fchownat
fsync ftruncate getcwd getdomainname getdtablesize getgroups
gethostname getlogin getlogin_r getpagesize getusershell setusershell
- endusershell lchown link linkat lseek pipe2 pread readlink readlinkat
- rmdir sleep symlink symlinkat ttyname_r unlink unlinkat usleep])
+ endusershell lchown link linkat lseek pipe2 pread pwrite readlink
+ readlinkat rmdir sleep symlink symlinkat ttyname_r unlink unlinkat
+ usleep])
])
AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
GNULIB_LSEEK=0; AC_SUBST([GNULIB_LSEEK])
GNULIB_PIPE2=0; AC_SUBST([GNULIB_PIPE2])
GNULIB_PREAD=0; AC_SUBST([GNULIB_PREAD])
+ GNULIB_PWRITE=0; AC_SUBST([GNULIB_PWRITE])
GNULIB_READLINK=0; AC_SUBST([GNULIB_READLINK])
GNULIB_READLINKAT=0; AC_SUBST([GNULIB_READLINKAT])
GNULIB_RMDIR=0; AC_SUBST([GNULIB_RMDIR])
HAVE_LINKAT=1; AC_SUBST([HAVE_LINKAT])
HAVE_PIPE2=1; AC_SUBST([HAVE_PIPE2])
HAVE_PREAD=1; AC_SUBST([HAVE_PREAD])
+ HAVE_PWRITE=1; AC_SUBST([HAVE_PWRITE])
HAVE_READLINK=1; AC_SUBST([HAVE_READLINK])
HAVE_READLINKAT=1; AC_SUBST([HAVE_READLINKAT])
HAVE_SLEEP=1; AC_SUBST([HAVE_SLEEP])
REPLACE_LINKAT=0; AC_SUBST([REPLACE_LINKAT])
REPLACE_LSEEK=0; AC_SUBST([REPLACE_LSEEK])
REPLACE_PREAD=0; AC_SUBST([REPLACE_PREAD])
+ REPLACE_PWRITE=0; AC_SUBST([REPLACE_PWRITE])
REPLACE_READLINK=0; AC_SUBST([REPLACE_READLINK])
REPLACE_RMDIR=0; AC_SUBST([REPLACE_RMDIR])
REPLACE_SLEEP=0; AC_SUBST([REPLACE_SLEEP])
--- /dev/null
+Description:
+pwrite() function: write without changing file offset
+
+Files:
+lib/pwrite.c
+m4/pwrite.m4
+
+Depends-on:
+lseek
+unistd
+
+configure.ac:
+gl_FUNC_PWRITE
+gl_UNISTD_MODULE_INDICATOR([pwrite])
+
+Makefile.am:
+
+Include:
+<unistd.h>
+
+License:
+LGPLv2+
+
+Maintainer:
+Peter O'Gorman
-e 's|@''GNULIB_LSEEK''@|$(GNULIB_LSEEK)|g' \
-e 's|@''GNULIB_PIPE2''@|$(GNULIB_PIPE2)|g' \
-e 's|@''GNULIB_PREAD''@|$(GNULIB_PREAD)|g' \
+ -e 's|@''GNULIB_PWRITE''@|$(GNULIB_PWRITE)|g' \
-e 's|@''GNULIB_READLINK''@|$(GNULIB_READLINK)|g' \
-e 's|@''GNULIB_READLINKAT''@|$(GNULIB_READLINKAT)|g' \
-e 's|@''GNULIB_RMDIR''@|$(GNULIB_RMDIR)|g' \
-e 's|@''HAVE_LINKAT''@|$(HAVE_LINKAT)|g' \
-e 's|@''HAVE_PIPE2''@|$(HAVE_PIPE2)|g' \
-e 's|@''HAVE_PREAD''@|$(HAVE_PREAD)|g' \
+ -e 's|@''HAVE_PWRITE''@|$(HAVE_PWRITE)|g' \
-e 's|@''HAVE_READLINK''@|$(HAVE_READLINK)|g' \
-e 's|@''HAVE_READLINKAT''@|$(HAVE_READLINKAT)|g' \
-e 's|@''HAVE_SLEEP''@|$(HAVE_SLEEP)|g' \
-e 's|@''REPLACE_LINKAT''@|$(REPLACE_LINKAT)|g' \
-e 's|@''REPLACE_LSEEK''@|$(REPLACE_LSEEK)|g' \
-e 's|@''REPLACE_PREAD''@|$(REPLACE_PREAD)|g' \
+ -e 's|@''REPLACE_PWRITE''@|$(REPLACE_PWRITE)|g' \
-e 's|@''REPLACE_READLINK''@|$(REPLACE_READLINK)|g' \
-e 's|@''REPLACE_RMDIR''@|$(REPLACE_RMDIR)|g' \
-e 's|@''REPLACE_SLEEP''@|$(REPLACE_SLEEP)|g' \
(int, void *, size_t, off_t));
#endif
+#if GNULIB_TEST_PWRITE
+SIGNATURE_CHECK (GNULIB_NAMESPACE::pwrite, ssize_t,
+ (int, const void *, size_t, off_t));
+#endif
+
#if GNULIB_TEST_READLINK
SIGNATURE_CHECK (GNULIB_NAMESPACE::readlink, ssize_t,
(const char *, char *, size_t));
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