• Paul Eggert's avatar
    Use fdopendir, fstatat and readlinkat, for efficiency. · 8654f9d7
    Paul Eggert authored
    On my host, this speeds up directory-files-and-attributes by a
    factor of 3, when applied to Emacs's src directory.
    These functions are standardized by POSIX and are common these
    days; fall back on a (slower) gnulib implementation if the host
    is too old to supply them.
    * .bzrignore: Add lib/dirent.h.
    * lib/Makefile.am (libgnu_a_SOURCES): Add openat-die.c, save-cwd.c.
    * lib/careadlinkat.c, lib/careadlinkat.h: Merge from gnulib,
    incorporating: 2013-01-29 careadlinkat: do not provide careadlinkatcwd.
    * lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
    * lib/dirent.in.h, lib/fdopendir.c, lib/fstatat.c, lib/openat-priv.h:
    * lib/openat-proc.c, lib/openat.h, m4/dirent_h.m4, m4/fdopendir.m4:
    * m4/fstatat.m4: New files, from gnulib.
    * lib/openat-die.c, lib/save-cwd.c, lib/save-cwd.h: New files.
    These last three are specific to Emacs and are not copied from gnulib.
    They are simpler than the gnulib versions and are tuned for Emacs.
    * admin/merge-gnulib (GNULIB_MODULES): Add fdopendir, fstatat, readlinkat.
    (GNULIB_TOOL_FLAGS): Do not avoid at-internal, openat-h.
    Avoid dup, open, opendir.
    * nt/inc/sys/stat.h (fstatat):
    * nt/inc/unistd.h (readlinkat): New decls.
    * src/conf_post.h (GNULIB_SUPPORT_ONLY_AT_FDCWD): Remove.
    * src/dired.c: Include <fcntl.h>.
    (open_directory): New function, which uses open and fdopendir
    rather than opendir.  DOS_NT platforms still use opendir, though.
    (directory_files_internal, file_name_completion): Use it.
    (file_attributes): New function, with most of the old Ffile_attributes.
    (directory_files_internal, Ffile_attributes): Use it.
    (file_attributes, file_name_completion_stat): First arg is now fd,
    not dir name.  All uses changed.  Use fstatat rather than lstat +
    stat.
    (file_attributes): Use emacs_readlinkat rather than Ffile_symlink_p.
    * src/fileio.c: Include <allocator.h>, <careadlinkat.h>.
    (emacs_readlinkat): New function, with much of the old
    Ffile_symlink_p, but with an fd argument for speed.
    It uses readlinkat rather than careadlinkatcwd, so that it
    need not assume the working directory.
    (Ffile_symlink_p): Use it.
    * src/filelock.c (current_lock_owner): Use emacs_readlinkat
    rather than emacs_readlink.
    * src/lisp.h (emacs_readlinkat): New decl.
    (READLINK_BUFSIZE, emacs_readlink): Remove.
    * src/sysdep.c: Do not include <allocator.h>, <careadlinkat.h>.
    (emacs_norealloc_allocator, emacs_readlink): Remove.
    This stuff is moved to fileio.c.
    * src/w32.c (fstatat, readlinkat): New functions.
    (careadlinkat): Don't check that fd == AT_FDCWD.
    (careadlinkatcwd): Remove; no longer needed.
    
    Fixes: debbugs:13539
    8654f9d7
fstatat.c 4.35 KB