Re: PATCH: relpath

[Jim Meyering]

Pádraig Brady wrote:
> On 12/12/2011 12:24 AM, Pádraig Brady wrote:
>> FYI I'm not forgetting about this.
>> This week I'll be travelling with work,
>> but I intend to tackle this early the following week.
>
> Sorry for the delay.
> Attached is the realpath implementation, which I think
> turned into a good cohesive set of functionality.
> It has this interface:

Thanks!
I noticed a couple nits.

> Usage: src/realpath [OPTION] FILE...
> Print the resolved absolute file name;
> all but the last component must exist
>
>   -e, --canonicalize-existing  all components of the path must exist
>   -m, --canonicalize-missing   no components of the path need exist
>   -L, --logical                resolve `..' components before symlinks
>   -P, --physical               resolve symlinks as encountered (default)
>   -q, --quiet                  suppress most error messages
>       --relative-to=FILE       print the resolved path relative to FILE
>       --relative-base=FILE     print absolute paths unless paths below FILE
>   -s, --strip                  don't expand symlinks
>   -z, --zero                   separate output with NUL rather than newline
>
>       --help     display this help and exit
>       --version  output version information and exit
>
> I was going to add a --readlink option to call readlink(3),
> but that's a separate function really, and since readlink(1)
> is widely available, I thought it better to not duplicate?
>
> I was going to add a --common-prefix mode, to print
> the common prefix of all supplied paths.
> We can do this in future anyway.
>
> Note this patch required this small update to gnulib:
> http://git.sv.gnu.org/gitweb/?p=gnulib.git;a=commit;h=8bcd0399
...

> Subject: [PATCH] readlink: A new program to print the resolved path

s/readlink: A/realpath: a/

> This program is compatible with other realpath(1)
> implementations, and also incorporates relpath like support,
> through the --relative options.  The relpath support
> was suggested by Peng Yu, who also provided an initial
> implemenation of that functionality.
>
> * AUTHORS: Add my name.
> * NEWS: Mention the new command.
> * README: Likewise.
> * doc/coreutils.texi (realpath invocation): Add realpath info.
> * man/Makefile.am (realpath.1): Add dependency.
> * man/realpath.x: New template.
> * man/.gitignore: Ignore generated man page.
> * po/POTFILES.in: Add src/realpath.c.
> * src/.gitignore: Exclude realpath.
> * src/Makefile.am (EXTRA_PROGRAMS): Add realpath.
> * src/realpath.c: New file.
> * scripts/git-hooks/commit-msg: Add realpath to the list of prefixes.
> * tests/Makefile.am (TESTS): Add misc/realpath.
> * tests/misc/realpath: New file.

"make check" failed with this:

  FAIL: misc/help-version (exit: 1)
  =================================
  ...
  + args=
  + env realpath
  realpath: missing operand
  Try `realpath --help' for more information.
  + echo FAIL: realpath
  FAIL: realpath
  + fail=1

The trivial patch is to tell this driver how to invoke the new program:

diff --git a/tests/misc/help-version b/tests/misc/help-version
index 0482209..ddb5b52 100755
--- a/tests/misc/help-version
+++ b/tests/misc/help-version
@@ -177,6 +177,7 @@ ln_setup () { args="$tmp_in ln-target"; }
 ginstall_setup () { args="$tmp_in $tmp_in2"; }
 mv_setup () { args="$tmp_in $tmp_in2"; }
 mkdir_setup () { args=$tmp_dir/subdir; }
+realpath_setup () { args=$tmp_in; }
 rmdir_setup () { args=$tmp_dir; }
 rm_setup () { args=$tmp_in; }
 shred_setup () { args=$tmp_in; }

-------------------------------------------------
Reading "info realpath", I saw this:

  `-s'
  `--strip'
       Do not resolve symbolic links.  Only resolve references to `/./',
       `/../' and extra `/' characters.

How about inserting "remove"?

       Do not resolve symbolic links.  Only resolve references to `/./',
       `/../' and remove extra `/' characters.

Also, if it's (as I assume) a text-only operation, never stat'ing
a named file, then say that:

  Unlike other modes of operation, with this one, realpath operates
  only on the file name, and does not touch any actual file.

-------------------------------------------------
Reading only the documentation for --relative-base=FILE,
I am not sure how it works:

`--relative-base=FILE'
     Ensure both the `--relative-to' and processed files are
     subdirectories of FILE, or otherwise output the absolute file name.
     Note this option honors the `-m' and `-e' options pertaining to
     file existence.

An example or two would help a lot.

I'll look through the rest later.