gpg: Improve the photo image viewer selection.

* g10/exec.c (w32_system): Add "!ShellExecute" special.
* g10/photoid.c (get_default_photo_command): Use the new ShellExecute
under Windows and fallbac to 'display' and 'xdg-open' in the Unix
case.
(show_photos): Flush stdout so that the output is shown before the
image pops up.
--

For Unix this basically syncs the code with what we have in gpg 1.4.
Note that xdg-open may not be used when running as root which we
support here.

For Windows we now use ShellExecute as this seems to be preferred over
"cmd /c start"; however this does not solve the actual problem we had
in the bug report.  To solve that problem we resort to a wait
parameter which defaults to 400ms.  This works on my Windows-10
virtualized test box.  If we can figure out which simple viewers are
commonly installed on Windows we should enhance this patch to test for
them.

GnuPG-bug-id: 4334
Signed-off-by: Werner Koch <[email protected]>

1 files changed, 13 insertions, 3 deletions

diff --git a/g10/photoid.c b/g10/photoid.c
index bcea64fbf..f9720d329 100644
--- a/g10/photoid.c
+++ b/g10/photoid.c
@@ -262,7 +262,8 @@ char *image_type_to_string(byte type,int style)
 }
 
 #if !defined(FIXED_PHOTO_VIEWER) && !defined(DISABLE_PHOTO_VIEWER)
-static const char *get_default_photo_command(void)
+static const char *
+get_default_photo_command(void)
 {
 #if defined(_WIN32)
   OSVERSIONINFO osvi;
@@ -274,14 +275,21 @@ static const char *get_default_photo_command(void)
   if(osvi.dwPlatformId==VER_PLATFORM_WIN32_WINDOWS)
     return "start /w %i";
   else
-    return "cmd /c start /w %i";
+    return "!ShellExecute 400 %i";
 #elif defined(__APPLE__)
   /* OS X.  This really needs more than just __APPLE__. */
   return "open %I";
 #elif defined(__riscos__)
   return "Filer_Run %I";
 #else
-  return "xloadimage -fork -quiet -title 'KeyID 0x%k' stdin";
+  if (!path_access ("xloadimage", X_OK))
+    return "xloadimage -fork -quiet -title 'KeyID 0x%k' stdin";
+  else if (!path_access ("display",X_OK))
+    return "display -title 'KeyID 0x%k' %i";
+  else if (getuid () && !path_access ("xdg-open", X_OK))
+    return "xdg-open %i";
+  else
+    return "/bin/true";
 #endif
 }
 #endif
@@ -312,6 +320,8 @@ show_photos (ctrl_t ctrl, const struct user_attribute *attrs, int count,
   if (pk)
     keyid_from_pk (pk, kid);
 
+  es_fflush (es_stdout);
+
   for(i=0;i<count;i++)
     if(attrs[i].type==ATTRIB_IMAGE &&
        parse_image_header(&attrs[i],&args.imagetype,&len))