[PATCH] lineedit: support empty PATH entries in tab completion

[Denys Vlasenko]

Applied, thank you!

On Thu, Feb 18, 2021 at 10:50 AM Ron Yorston <rmy at pobox.com> wrote:
>
> Zero-length path prefixes can be specified in PATH as a leading or
> trailing colon or two adjacent colons.  POSIX says that the use of
> zero-length prefixes to refer to the current directory is a legacy
> feature.  Nonetheless the shells in BusyBox respect this feature,
> as does 'which'.
>
> Tab-completion of executables using PATH should support this too.
>
> function                                             old     new   delta
> complete_cmd_dir_file                                934     931      -3
> ------------------------------------------------------------------------------
> (add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-3)               Total: -3 bytes
>
> Signed-off-by: Ron Yorston <rmy at pobox.com>
> ---
>  libbb/lineedit.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/libbb/lineedit.c b/libbb/lineedit.c
> index 367396b91..b0adcf140 100644
> --- a/libbb/lineedit.c
> +++ b/libbb/lineedit.c
> @@ -769,8 +769,6 @@ static unsigned path_parse(char ***p)
>                 if (!tmp)
>                         break;
>                 tmp++;
> -               if (*tmp == '\0')
> -                       break;  /* :<empty> */
>                 npth++;
>         }
>
> @@ -782,8 +780,6 @@ static unsigned path_parse(char ***p)
>                 if (!tmp)
>                         break;
>                 *tmp++ = '\0'; /* ':' -> '\0' */
> -               if (*tmp == '\0')
> -                       break; /* :<empty> */
>                 res[npth++] = tmp;
>         }
>         /* special case: "match subdirectories of the current directory" */
> @@ -854,6 +850,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
>                 struct dirent *next;
>                 struct stat st;
>                 char *found;
> +               const char *lpath;
>
>                 if (paths[i] == NULL) { /* path_parse()'s last component? */
>                         /* in PATH completion, current dir's subdir names
> @@ -863,7 +860,8 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
>                         paths[i] = (char *)".";
>                 }
>
> -               dir = opendir(paths[i]);
> +               lpath = *paths[i] ? paths[i] : ".";
> +               dir = opendir(lpath);
>                 if (!dir)
>                         continue; /* don't print an error */
>
> @@ -878,7 +876,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
>                         if (strncmp(basecmd, name_found, baselen) != 0)
>                                 continue; /* no */
>
> -                       found = concat_path_file(paths[i], name_found);
> +                       found = concat_path_file(lpath, name_found);
>                         /* NB: stat() first so that we see is it a directory;
>                          * but if that fails, use lstat() so that
>                          * we still match dangling links */
> --
> 2.29.2
>
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