Re: [PATCH] findprog: Support searching in a specified path string

[Paul Smith]

I don't know if people would prefer to actually define two real
functions one of which just invokes the other, rather than use a
preprocessor macro to forward the old one to the new one.

I'm fine with it either way.


On Fri, 2019-09-06 at 19:10 -0400, Paul Smith wrote:
> find_prog_in_path() always uses the PATH value in the current
> environment.  It can be very useful to search for programs on
> a path without having to modify the environment first.
> 
> Provide find_in_path_str() which takes a path string to search.
> If the path passed in is NULL, fall back to searching in the
> environment's PATH value.
> 
> * lib/findprog.h (find_prog_in_path_str): Added.
> (find_prog_in_path): Turn into a macro invoking the new function.
> * lib/findprog.c (find_prog_in_path): Rename, add the extra
> argument "in_path", and only look up PATH if it's NULL.
> ---
>  lib/findprog.c | 12 +++++++-----
>  lib/findprog.h | 10 +++++++++-
>  2 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/findprog.c b/lib/findprog.c
> index 89fbe5fdf..94c938306 100644
> --- a/lib/findprog.c
> +++ b/lib/findprog.c
> @@ -36,7 +36,7 @@
>  
>  
>  const char *
> -find_in_path (const char *progname)
> +find_in_path_str (const char *progname, const char *in_path)
>  {
>  #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined 
> __DJGPP__
>    /* Native Windows, Cygwin, OS/2, DOS */
> @@ -54,17 +54,19 @@ find_in_path (const char *progname)
>         the current directory.  PATH is not used.  */
>      return progname;
>  
> -  path = getenv ("PATH");
> -  if (path == NULL || *path == '\0')
> +  if (in_path == NULL)
> +    in_path = getenv ("PATH");
> +
> +  if (in_path == NULL || *in_path == '\0')
>      /* If PATH is not set, the default search path is implementation
>         dependent.  */
>      return progname;
>  
>    /* Make a copy, to prepare for destructive modifications.  */
>  # if !IN_FINDPROG_LGPL
> -  path = xstrdup (path);
> +  path = xstrdup (in_path);
>  # else
> -  path = strdup (path);
> +  path = strdup (in_path);
>    if (path == NULL)
>      /* Out of memory.  */
>      return progname;
> diff --git a/lib/findprog.h b/lib/findprog.h
> index a354f67f7..5af3f1a90 100644
> --- a/lib/findprog.h
> +++ b/lib/findprog.h
> @@ -29,7 +29,15 @@ extern "C" {
>     Because of the latter case, callers should use execlp/execvp, not
>     execl/execv on the returned pathname.
>     The returned string is freshly malloc()ed if it is != PROGNAME.  */
> -extern const char *find_in_path (const char *progname);
> +#define find_in_path(_p) find_in_path_str(_p, 0)
> +
> +
> +/* Look up a program in the provided path.
> +   Behaves the same as find_in_path() but looks in the provided path string
> +   rather than in the PATH environment variable.  If path is null then use
> +   the PATH environment variable.
> +   The returned string is freshly malloc()ed if it is != PROGNAME.  */
> +extern const char *find_in_path_str (const char *progname, const char *path);
>  
>  
>  #ifdef __cplusplus