vim-patch:3d7e567: runtime(netrw): simplify gx file handling

It did not work very well, at least on Debian 12, and I am not sure Git
Bash and WSL, for example, were taken care of as maintenance stalled.

The whole logic was somewhat convoluted with some parts repeatedly invoking
failed commands.

The file handling was outdated, for example, nowadays Netscape is rarely
used, and also opinionated, for example mainly Microsoft Paint and Gimp for
Image files.

Instead, let's use (xdg-)open and similar commands on other systems
which respects the user's preferences.

closes: vim/vim#15721

https://github.com/vim/vim/commit/3d7e567ea7392e43a90a6ffb3cd49b71a7b59d1a

Co-authored-by: Konfekt <Konfekt@users.noreply.github.com>
Co-authored-by: Luca Saccarola <96259932+saccarosium@users.noreply.github.com>

3 files changed, 195 insertions, 124 deletions

diff --git a/runtime/autoload/netrw.vim b/runtime/autoload/netrw.vim
index d5e3a77dd4..23440c085f 100644
--- a/runtime/autoload/netrw.vim
+++ b/runtime/autoload/netrw.vim
@@ -27,6 +27,7 @@
 "   2024 Sep 19 by Vim Project: mf-selection highlight uses wrong pattern (#15700)
 "   2024 Sep 21 by Vim Project: remove extraneous closing bracket (#15718)
 "   2024 Oct 21 by Vim Project: remove netrwFileHandlers (#15895)
+"   2024 Oct 27 by Vim Project: clean up gx mapping (#15721)
 "   }}}
 " Former Maintainer:	Charles E Campbell
 " GetLatestVimScripts: 1075 1 :AutoInstall: netrw.vim
@@ -533,7 +534,6 @@ if !exists("g:netrw_sort_sequence")
 endif
 call s:NetrwInit("g:netrw_special_syntax"   , 0)
 call s:NetrwInit("g:netrw_ssh_browse_reject", '^total\s\+\d\+$')
-call s:NetrwInit("g:netrw_suppress_gx_mesg",  1)
 call s:NetrwInit("g:netrw_use_noswf"        , 1)
 call s:NetrwInit("g:netrw_sizestyle"        ,"b")
 " Default values - t-w ---------- {{{3
@@ -5356,25 +5356,6 @@ fun! netrw#BrowseX(fname,remote)
 "  call Decho("fname<".fname.">",'~'.expand("<slnum>"))
 "  call Decho("exten<".exten."> "."netrwFileHandlers#NFH_".exten."():exists=".exists("*netrwFileHandlers#NFH_".exten),'~'.expand("<slnum>"))
 
-  " set up redirection (avoids browser messages)
-  " by default, g:netrw_suppress_gx_mesg is true
-  if g:netrw_suppress_gx_mesg
-   if &srr =~ "%s"
-    if has("win32")
-     let redir= substitute(&srr,"%s","nul","")
-    else
-     let redir= substitute(&srr,"%s","/dev/null","")
-    endif
-   elseif has("win32")
-    let redir= &srr . "nul"
-   else
-    let redir= &srr . "/dev/null"
-   endif
-  else
-   let redir= ""
-  endif
-"  call Decho("set up redirection: redir{".redir."} srr{".&srr."}",'~'.expand("<slnum>"))
-
   " extract any viewing options.  Assumes that they're set apart by spaces.
   if exists("g:netrw_browsex_viewer")
 "   call Decho("extract any viewing options from g:netrw_browsex_viewer<".g:netrw_browsex_viewer.">",'~'.expand("<slnum>"))
@@ -5397,86 +5378,14 @@ fun! netrw#BrowseX(fname,remote)
 "   call Decho("viewer<".viewer.">  viewopt<".viewopt.">",'~'.expand("<slnum>"))
   endif
 
-  " execute the file handler
-"  call Decho("execute the file handler (if any)",'~'.expand("<slnum>"))
   if exists("g:netrw_browsex_viewer") && executable(viewer)
 "   call Decho("(netrw#BrowseX) g:netrw_browsex_viewer<".g:netrw_browsex_viewer.">",'~'.expand("<slnum>"))
-   call s:NetrwExe("sil !".viewer." ".viewopt.s:ShellEscape(fname,1).redir)
-   let ret= v:shell_error
-
-  elseif has("win32")
-"   call Decho("(netrw#BrowseX) win".(has("win32")? "32" : "64"),'~'.expand("<slnum>"))
-   if executable("start")
-    call s:NetrwExe('sil! !start rundll32 url.dll,FileProtocolHandler '.s:ShellEscape(fname,1))
-   elseif executable("rundll32")
-    call s:NetrwExe('sil! !rundll32 url.dll,FileProtocolHandler '.s:ShellEscape(fname,1))
-   else
-    call netrw#ErrorMsg(s:WARNING,"rundll32 not on path",74)
-   endif
-   let ret= v:shell_error
-
-  elseif has("win32unix")
-   let winfname= 'c:\cygwin'.substitute(fname,'/','\\','g')
-"   call Decho("(netrw#BrowseX) cygwin: winfname<".s:ShellEscape(winfname,1).">",'~'.expand("<slnum>"))
-   if executable("start")
-"    call Decho("(netrw#BrowseX) win32unix+start",'~'.expand("<slnum>"))
-    call s:NetrwExe('sil !start rundll32 url.dll,FileProtocolHandler '.s:ShellEscape(winfname,1))
-   elseif executable("rundll32")
-"    call Decho("(netrw#BrowseX) win32unix+rundll32",'~'.expand("<slnum>"))
-    call s:NetrwExe('sil !rundll32 url.dll,FileProtocolHandler '.s:ShellEscape(winfname,1))
-   elseif executable("cygstart")
-"    call Decho("(netrw#BrowseX) win32unix+cygstart",'~'.expand("<slnum>"))
-    call s:NetrwExe('sil !cygstart '.s:ShellEscape(fname,1))
-   else
-    call netrw#ErrorMsg(s:WARNING,"rundll32 not on path",74)
-   endif
-   let ret= v:shell_error
-
-  elseif has("unix") && $DESKTOP_SESSION == "mate" && executable("atril")
-"   call Decho("(netrw#BrowseX) unix and atril",'~'.expand("<slnum>"))
-   if a:fname =~ '^https\=://'
-    " atril does not appear to understand how to handle html -- so use gvim to edit the document
-    let use_ctrlo= 0
-"    call Decho("fname<".fname.">")
-"    call Decho("a:fname<".a:fname.">")
-    call s:NetrwExe("sil! !gvim ".fname.' -c "keepj keepalt file '.fnameescape(a:fname).'"')
-
-   else
-    call s:NetrwExe("sil !atril ".s:ShellEscape(fname,1).redir)
-   endif
-   let ret= v:shell_error
-
-  elseif has("unix") && executable("kfmclient") && s:CheckIfKde()
-"   call Decho("(netrw#BrowseX) unix and kfmclient",'~'.expand("<slnum>"))
-   call s:NetrwExe("sil !kfmclient exec ".s:ShellEscape(fname,1)." ".redir)
-   let ret= v:shell_error
-
-  elseif has("unix") && executable("exo-open") && executable("xdg-open") && executable("setsid")
-"   call Decho("(netrw#BrowseX) unix, exo-open, xdg-open",'~'.expand("<slnum>"))
-   call s:NetrwExe("sil !setsid xdg-open ".s:ShellEscape(fname,1).redir.'&')
-   let ret= v:shell_error
-
-  elseif has("unix") && executable("xdg-open")
-"   call Decho("(netrw#BrowseX) unix and xdg-open",'~'.expand("<slnum>"))
-   call s:NetrwExe("sil !xdg-open ".s:ShellEscape(fname,1).redir.'&')
-   let ret= v:shell_error
-
-  elseif has("macunix") && executable("open")
-"   call Decho("(netrw#BrowseX) macunix and open",'~'.expand("<slnum>"))
-   call s:NetrwExe("sil !open ".s:ShellEscape(fname,1)." ".redir)
-   let ret= v:shell_error
+    exe 'Launch' viewer viewopt shellescape(fname, 1)
   else
-   call netrw#ErrorMsg(s:ERROR, "Couldn't find a program to open '".a:fname."'", 0)
-   let ret=0
-  endif
-
-  if ret
-   call netrw#ErrorMsg(s:ERROR, "Failed to open '".a:fname."'", 0)
+     " though shellescape(..., 1) is used in Open, it's insufficient
+     exe 'Open' escape(fname, '#%')
   endif
 
-  " restoring redraw! after external file handlers
-  redraw!
-
   " cleanup: remove temporary file,
   "          delete current buffer if success with handler,
   "          return to prior buffer (directory listing)
@@ -5513,12 +5422,37 @@ fun! netrw#GX()
   if &ft == "netrw"
    let fname= s:NetrwGetWord()
   else
-   let fname= expand((exists("g:netrw_gx")? g:netrw_gx : '<cfile>'))
+   let fname= exists("g:netrw_gx")? expand(g:netrw_gx) : s:GetURL()
   endif
 "  call Dret("netrw#GX <".fname.">")
   return fname
 endfun
 
+fun! s:GetURL() abort
+   let URL = ''
+   if exists('*Netrw_get_URL_' .. &filetype)
+      let URL = call('Netrw_get_URL_' .. &filetype, [])
+   endif
+   if !empty(URL) | return URL | endif
+  " URLs end in letter, digit or forward slash
+  let URL = matchstr(expand("<cWORD>"), '\<' .. g:netrw_regex_url .. '\ze[^A-Za-z0-9/]*$')
+  if !empty(URL) | return URL | endif
+
+  " Is it a file in the current work dir ...
+  let file = expand("<cfile>")
+  if filereadable(file) | return file | endif
+  " ... or in that of the current buffer?
+  let path = fnamemodify(expand('%'), ':p')
+  if isdirectory(path)
+    let dir = path
+  elseif filereadable(path)
+    let dir = fnamemodify(path, ':h')
+  endif
+  if exists('dir') && filereadable(dir..'/'..file) | return dir..'/'..file | endif
+
+  return ''
+endf
+
 " ---------------------------------------------------------------------
 " netrw#BrowseXVis: used by gx in visual mode to select a file for browsing {{{2
 fun! netrw#BrowseXVis()
@@ -6670,6 +6604,7 @@ fun! s:NetrwMaps(islocal)
    nnoremap <buffer> <silent> <nowait> U	:<c-u>call <SID>NetrwBookHistHandler(5,b:netrw_curdir)<cr>
    nnoremap <buffer> <silent> <nowait> v	:call <SID>NetrwSplit(2)<cr>
    nnoremap <buffer> <silent> <nowait> x	:<c-u>call netrw#BrowseX(<SID>NetrwBrowseChgDir(0,<SID>NetrwGetWord()),1)<cr>
+   nmap     <buffer>          <nowait> gx	x
    if !hasmapto('<Plug>NetrwHideEdit')
     nmap <buffer> <c-h> <Plug>NetrwHideEdit
    endif
@@ -12043,13 +11978,16 @@ endfun
 " s:NetrwExe: executes a string using "!" {{{2
 fun! s:NetrwExe(cmd)
 "  call Dfunc("s:NetrwExe(a:cmd<".a:cmd.">)")
-  if has("win32") && &shell !~? 'cmd\|pwsh\|powershell' && !g:netrw_cygwin
+  if has("win32")
 "    call Decho("using win32:",expand("<slnum>"))
     let savedShell=[&shell,&shellcmdflag,&shellxquote,&shellxescape,&shellquote,&shellpipe,&shellredir,&shellslash]
     set shell& shellcmdflag& shellxquote& shellxescape&
     set shellquote& shellpipe& shellredir& shellslash&
-    exe a:cmd
-    let [&shell,&shellcmdflag,&shellxquote,&shellxescape,&shellquote,&shellpipe,&shellredir,&shellslash] = savedShell
+    try
+     exe a:cmd
+    finally
+      let [&shell,&shellcmdflag,&shellxquote,&shellxescape,&shellquote,&shellpipe,&shellredir,&shellslash] = savedShell
+    endtry
   else
 "   call Decho("exe ".a:cmd,'~'.expand("<slnum>"))
    exe a:cmd
diff --git a/runtime/doc/pi_netrw.txt b/runtime/doc/pi_netrw.txt
index 7fc7d4140a..ed95cbb851 100644
--- a/runtime/doc/pi_netrw.txt
+++ b/runtime/doc/pi_netrw.txt
@@ -1465,42 +1465,93 @@ With either form of the command, netrw will first ask for confirmation
 that the removal is in fact what you want to do.  If netrw doesn't have
 permission to remove a file, it will issue an error message.
 
-						*netrw-gx*
+                                                *netrw-gx* *Open* *Launch*
 CUSTOMIZING BROWSING WITH A SPECIAL HANDLER	*netrw-x* *netrw-handler* {{{2
 
 Certain files, such as html, gif, jpeg, (word/office) doc, etc, files, are
 best seen with a special handler (ie. a tool provided with your computer's
-operating system).  Netrw allows one to invoke such special handlers by: >
+operating system).  Netrw allows one to invoke such special handlers by:
 
-	* when Exploring, hit the "x" key
-	* when editing, hit gx with the cursor atop the special filename
-<	  (latter not available if the |g:netrw_nogx| variable exists)
+        * hitting gx with the cursor atop the file path or alternatively x
+          in a netrw buffer; the former can be disabled by defining the
+          |g:netrw_nogx| variable
+        * when in command line, typing :Open <path>
 
-Netrw determines which special handler by the following method:
+One may also use visual mode (see |visual-start|) to select the text that the
+special handler will use.  Normally gx checks for a close-by URL or file name
+to pick up the text under the cursor; one may change what |expand()| uses via the
+|g:netrw_gx| variable (options include "<cword>", "<cWORD>").  Note that
+expand("<cfile>") depends on the |'isfname'| setting.  Alternatively, one may
+select the text to be used by gx by making a visual selection (see
+|visual-block|) and then pressing gx.
 
-  * if |g:netrw_browsex_viewer| exists, then it will be used to attempt to
-    view files.  Examples of useful settings (place into your <.vimrc>): >
+The selection function can be adapted for each filetype by adding a function
+Netrw_get_URL_<filetype>, where <filetype> is given by &filetype.
+The function should return the URL or file name to be used by gx, and will
+fall back to the default behavior if it returns an empty string.
+For example, special handlers for links Markdown and HTML are
+>
+" make gx work on concealed links regardless of exact cursor position
+function Netrw_get_URL_markdown()
+  " markdown URL such as [link text](http://ya.ru 'yandex search')
+  try
+    let save_view = winsaveview()
+    if searchpair('\[.\{-}\](', '', ')\zs', 'cbW', '', line('.')) > 0
+      return matchstr(getline('.')[col('.')-1:], '\[.\{-}\](\zs' .. g:netrw_regex_url .. '\ze\(\s\+.\{-}\)\?)')
+    endif
+  finally
+    call winrestview(save_view)
+    return ''
+  endtry
+endfunction
+
+function Netrw_get_URL_html()
+  " HTML URL such as <a href='http://www.python.org'>Python is here</a>
+  "                  <a href="http://www.python.org"/>
+  try
+    let save_view = winsaveview()
+    if searchpair('<a\s\+href=', '', '\%(</a>\|/>\)\zs', 'cbW', '', line('.')) > 0
+      return matchstr(getline('.')[col('.') - 1 : ],
+            \ 'href=["'.."'"..']\?\zs\S\{-}\ze["'.."'"..']\?/\?>')
+    endif
+  finally
+    call winrestview(save_view)
+    return ''
+  endtry
+endfunction
+<
 
-	:let g:netrw_browsex_viewer= "kfmclient exec"
-<   or >
-	:let g:netrw_browsex_viewer= "xdg-open"
+Other than a file path, the text under the cursor may be a URL.  Netrw uses
+by default the following regular expression to determine if the text under the
+cursor is a URL:
+>
+	g:netrw_regex_url = '\%(\%(http\|ftp\|irc\)s\?\|file\)://\S\{-}'
 <
+
+Netrw determines which special handler by the following method:
+
+  * if |g:netrw_browsex_viewer| exists, then it will be used to attempt to
+    view files.  Examples of useful settings (place into your <.vimrc>):
     If the viewer you wish to use does not support handling of a remote URL
     directory, set |g:netrw_browsex_support_remote| to 0.
-  * for Windows 32 or 64, the URL and FileProtocolHandler dlls are used.
-  * for Gnome (with gnome-open): gnome-open is used.
-  * for KDE (with kfmclient)   : kfmclient is used
-  * for Mac OS X               : open is used.
+  * otherwise:
 
-The gx mapping extends to all buffers; apply "gx" while atop a word and netrw
-will apply a special handler to it (like "x" works when in a netrw buffer).
-One may also use visual mode (see |visual-start|) to select the text that the
-special handler will use.  Normally gx uses expand("<cfile>") to pick up the
-text under the cursor; one may change what |expand()| uses via the
-|g:netrw_gx| variable (options include "<cword>", "<cWORD>").  Note that
-expand("<cfile>") depends on the |'isfname'| setting.  Alternatively, one may
-select the text to be used by gx by making a visual selection (see
-|visual-block|) and then pressing gx.
+    * for Windows			: explorer.exe is used
+    * for Mac OS X			: open is used.
+    * for Linux				: xdg-open is used.
+
+To open a file <filepath> by the appropriate handler, type
+
+	:Open <filepath>
+
+No escaping, neither for the shell, nor for Vim's command-line is needed.
+
+To launch a specific application <app> <args>, often <args> being <filepath>,
+
+	:Launch <app> <args>.
+
+Since <args> can be arbitrarily complex, in particular contain many file
+paths, the escaping is left to the user.
 
 Associated setting variables:
 	|g:netrw_gx|	control how gx picks up the text under the cursor
diff --git a/runtime/plugin/netrwPlugin.vim b/runtime/plugin/netrwPlugin.vim
index c70e6518ff..59fb7e727e 100644
--- a/runtime/plugin/netrwPlugin.vim
+++ b/runtime/plugin/netrwPlugin.vim
@@ -1,9 +1,10 @@
 " netrwPlugin.vim: Handles file transfer and remote directory listing across a network
 "            PLUGIN SECTION
 " Maintainer:	This runtime file is looking for a new maintainer.
-" Date:		Feb 09, 2021
+" Date:		Sep 09, 2021
 " Last Change:
 "   2024 May 08 by Vim Project: cleanup legacy Win9X checks
+"   2024 Oct 27 by Vim Project: cleanup gx mapping
 " Former Maintainer:   Charles E Campbell
 " GetLatestVimScripts: 1075 1 :AutoInstall: netrw.vim
 " Copyright:    Copyright (C) 1999-2021 Charles E. Campbell {{{1
@@ -31,6 +32,87 @@ set cpo&vim
 " ---------------------------------------------------------------------
 " Public Interface: {{{1
 
+" Commands Launch/URL {{{2
+" surpress output of command; use bang for GUI applications
+
+" set up redirection (avoids browser messages)
+" by default, g:netrw_suppress_gx_mesg is true
+if get(g:, ':netrw_suppress_gx_mesg', 1)
+  if &srr =~# "%s"
+    let s:redir = printf(&srr, has("win32") ? "nul" : "/dev/null")
+  else
+    let s:redir= &srr .. (has("win32") ? "nul" : "/dev/null")
+  endif
+else
+  let s:redir= ""
+endif
+
+if has('unix')
+  if has('win32unix')
+    " If cygstart provided, then assume Cygwin and use cygstart --hide; see man cygstart.
+    if executable('cygstart')
+      command -complete=shellcmd -nargs=1 -bang Launch
+          \ exe 'silent ! cygstart --hide' trim(<q-args>)  s:redir | redraw!
+    elseif !empty($MSYSTEM) && executable('start')
+      " MSYS2/Git Bash comes by default without cygstart; see
+      " https://www.msys2.org/wiki/How-does-MSYS2-differ-from-Cygwin
+      " Instead it provides /usr/bin/start script running `cmd.exe //c start`
+      " Adding "" //b` sets void title, hides cmd window and blocks path conversion
+      " of /b to \b\ " by MSYS2; see https://www.msys2.org/docs/filesystem-paths/
+      command -complete=shellcmd -nargs=1 -bang Launch
+            \ exe 'silent !start "" //b' trim(<q-args>)  s:redir | redraw!
+    else
+      " imitate /usr/bin/start script for other environments and hope for the best
+      command -complete=shellcmd -nargs=1 -bang Launch
+            \ exe 'silent !cmd //c start "" //b' trim(<q-args>)  s:redir | redraw!
+    endif
+  elseif exists('$WSL_DISTRO_NAME') " use cmd.exe to start GUI apps in WSL
+    command -complete=shellcmd -nargs=1 -bang Launch execute ':silent !'..
+          \ ((<q-args> =~? '\v<\f+\.(exe|com|bat|cmd)>') ?
+            \ 'cmd.exe /c start "" /b' trim(<q-args>) :
+            \ 'nohup ' trim(<q-args>) s:redir '&')
+          \ | redraw!
+  else
+    command -complete=shellcmd -nargs=1 -bang Launch
+        \ exe ':silent ! nohup' trim(<q-args>) s:redir '&' | redraw!
+  endif
+elseif has('win32')
+  command -complete=shellcmd -nargs=1 -bang Launch
+        \ exe 'silent !'.. (&shell =~? '\<cmd\.exe\>' ? '' : 'cmd.exe /c')
+        \ 'start /b ' trim(<q-args>) s:redir | redraw!
+endif
+if exists(':Launch') == 2
+  " Git Bash
+  if has('win32unix')
+      " start suffices
+      let s:cmd = ''
+  " Windows / WSL
+  elseif executable('explorer.exe')
+      let s:cmd = 'explorer.exe'
+  " Linux / BSD
+  elseif executable('xdg-open')
+      let s:cmd = 'xdg-open'
+  " MacOS
+  elseif executable('open')
+      let s:cmd = 'open'
+  else
+    s:cmd = ''
+  endif
+  function s:Open(cmd, file)
+    if empty(a:cmd) && !exists('g:netrw_browsex_viewer')
+      echoerr "No program to open this path found. See :help Open for more information."
+    else
+      Launch cmd shellescape(a:file, 1)
+    endif
+  endfunction
+  command -complete=file -nargs=1 Open call s:Open(s:cmd, <q-args>)
+endif
+
+if !exists('g:netrw_regex_url')
+  let g:netrw_regex_url = '\%(\%(http\|ftp\|irc\)s\?\|file\)://\S\{-}'
+endif
+
+" " }}}
 " Local Browsing Autocmds: {{{2
 augroup FileExplorer
  au!