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While AT_NO_AUTOMOUNT is similar in function to the Hurd's O_NOTRANS, there are significant enough differences in semantics: 1. AT_NO_AUTOMOUNT has no effect on already established mounts, whereas O_NOTRANS causes the lookup to ignore both passive and active translators. A better approximation of the AT_NO_AUTOMOUNT behavior would be to honor active translators, but avoid starting passive ones; like what the file_name_lookup_carefully () routine from sutils/clookup.c in the Hurd source tree does. 2. On GNU/Hurd, translators are used much more pervasively than mounts on "traditional" Unix systems: among other things, translators underlie features like symlinks, device nodes, and sockets. And while on a "traditional" Unix system, the mountpoint and the root of the mounted tree may look similar enough for many purposes (they're both directories, for one thing), the Hurd allows for any combination of the two node types, and indeed it is common to have e.g. a device node "mounted" on top of a regular file node on the underlying filesystem. Ignoring the translator and stat'ing the underlying node is therefore likely to return very different results from what you'd get if you stat the translator's root node. In practice, mapping AT_NO_AUTOMOUNT to O_NOTRANS was breaking GNU Coreutils, including stat(1) and ls(1): $ stat /dev/hd0s1 File: /dev/hd0s1 Size: 0 Blocks: 8 IO Block: 8192 regular empty file Device: 0,8 Inode: 32866 Links: 1 This was also breaking GNOME's glib, where a g_local_file_stat () call that is supposed to stat () a file through a symlink uses AT_NO_AUTOMOUNT, which gets mapped to O_NOTRANS, which then causes the stat () call to stat symlink itself like lstat () would, rather then the file it points to, which is what the logic expects to happen. This reverts most of 13710e7e6af6c8965cc9a63a0660cb4ce1966557 "hurd: Add support for AT_NO_AUTOMOUNT". Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu and x86_64-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arc*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 loongarch64-*-linux-gnu Hardware floating point, LE only. m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu or1k-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv32-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.