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One of the best-kept secrets of libast/ksh93 is that the code includes support for case-insensitive file name generation (a.k.a. pathname expansion, a.k.a. globbing) as well as case-insensitive file name completion on interactive shells, depending on whether the file system is case-insensitive or not. This is transparently determined for each directory, so a path pattern that spans multiple file systems can be part case-sensitive and part case- insensitive. In more precise terms, each slash-separated path name component pattern P is treated as ~(i:P) if its parent directory exists on a case-insensitive file system. I recently discovered this while dealing with <https://github.com/ksh93/ksh/issues/223>. However, that support is dead code on almost all current systems. It depends on pathconf(2) having a _PC_PATH_ATTRIBUTES selector. The 'c' attribute is supposedly returned if the given directory is on a case insensitive file system. There are other attributes as well (at least 'l', see src/lib/libcmd/rm.c). However, I have been unable to find any system, current or otherwise, that has _PC_PATH_ATTRIBUTES. Google and mailing list searches yield no relevant results at all. If anyone knows of such a system, please add a comment to this commit on GitHub, or email me. An exception is Cygwin/Windows, on which the "c" attribute was simply hardcoded, so globbing/completion is always case- insensitive. As of Windows 10, that is wrong, as it added the possibility to mount case-sensitive file systems. On the other hand, this was never activated on the Mac, even though macOS has always used a case-insensitive file like Windows. But, being UNIX, it can also mount case-sensitive file systems. Finally, Linux added the possibility to create individual case- insensitive ext4 directories fairly recently, in version 5.2. https://www.collabora.com/news-and-blog/blog/2020/08/27/using-the-linux-kernel-case-insensitive-feature-in-ext4/ So, since this functionality latently exists in the code base, and three popular OSs now have relevant file system support, we might as well make it usable on those systems. It's a nice idea, as it intuitively makes sense for globbing and completion behaviour to auto-adapt to file system case insensitivity on a per-directory basis. No other shell does this, so it's a nice selling point, too. However, the way it is coded, this is activated unconditionally on supported systems. That is not a good idea. It will surprise users. Since globbing is used with commands like 'rm', we do not want surprises. So this commit makes it conditional upon a new shell option called 'globcasedetect'. This option is only compiled into ksh on systems where we can actually detect FS case insensitivity. To implement this, libast needs some public API additions first. *** libast changes *** src/lib/libast/features/lib: - Add probes for the linux/fs.h and sys/ioctl.h headers. Linux needs these to use ioctl(2) in pathicase(3) (see below). src/lib/libast/path/pathicase.c, src/lib/libast/include/ast.h, src/lib/libast/man/path.3, src/lib/libast/Mamfile: - Add new pathicase(3) public API function. This uses whatever OS-specific method it can detect at compile time to determine if a particular path is on a case-insensitive file system. If no method is available, it only sets errno to ENOSYS and returns -1. Currently known to work on: macOS, Cygwin, Linux 5.2+, QNX 7.0+. - On systems (if any) that have the mysterious _PC_PATH_ATTRIBUTES selector for pathconf(2), call astconf(3) and check for the 'c' attribute to determine case insensitivity. This should preserve compatibility with any such system. src/lib/libast/port/astconf.c: - dynamic[]: As case-insensitive globbing is now optional on all systems, do not set the 'c' attribute by default on _WINIX (Cygwin/Windows) systems. - format(): On systems that do not have _PC_PATH_ATTRIBUTES, call pathicase(3) to determine the value for the "c" (case insensitive) attribute only. This is for compatibility as it is more efficient to call pathicase(3) directly. src/lib/libast/misc/glob.c, src/lib/libast/include/glob.h: - Add new GLOB_DCASE public API flag to glob(3). This is like GLOB_ICASE (case-insensitive matching) except it only makes the match case-insensitive if the file system for the current pathname component is determined to be case-insensitive. - gl_attr(): For efficiency, call pathicase(3) directly instead of via astconf(3). - glob_dir(): Only call gl_attr() to determine file system case insensitivity if the GLOB_DCASE flag was passed. This makes case insensitive globbing optional on all systems. - glob(): The options bitmask needs to be widened to fit the new GLOB_DCASE option. Define this centrally in a new GLOB_FLAGMASK macro so it is easy to change it along with GLOB_MAGIC (which uses the remaining bits for a sanity check bit pattern). src/lib/libast/path/pathexists.c: - For efficiency, call pathicase(3) directly instead of via astconf(3). *** ksh changes *** src/cmd/ksh93/features/options, src/cmd/ksh93/SHOPT.sh: - Add new SHOPT_GLOBCASEDET compile-time option. Set it to probe (empty) by default so that the shell option is compiled in on supported systems only, which is determined by new iffe feature test that checks if pathicase(3) returns an ENOSYS error. src/cmd/ksh93/data/options.c, src/cmd/ksh93/include/shell.h: - Add -o globcasedetect shell option if compiling with SHOPT_GLOBCASEDET. src/cmd/ksh93/sh/expand.c: path_expand(): - Pass the new GLOB_DCASE flag to glob(3) if the globcasedetect/SH_GLOBCASEDET shell option is set. src/cmd/ksh93/edit/completion.c: - While file listing/completion is based on globbing and automatically becomes case-insensitive when globbing does, it needs some additional handling to make a string comparison case-insensitive in corresponding cases. Otherwise, partial completions may be deleted from the command line upon pressing tab. This code was already in ksh 93u+ and just needs to be made conditional upon SHOPT_GLOBCASEDET and globcasedetect. - For efficiency, call pathicase(3) directly instead of via astconf(3). src/cmd/ksh93/sh.1: - Document the new globcasedetect shell option. |
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| completion.c | ||
| edit.c | ||
| emacs.c | ||
| hexpand.c | ||
| history.c | ||
| vi.c | ||