[Spice-devel] [vdagent-win PATCH 12/13] Factor out an utility function to read strings from registry

[Frediano Ziglio]

> 
> On Mon, May 28, 2018 at 09:58:05AM +0100, Frediano Ziglio wrote:
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> >  vdagent/display_setting.cpp | 97 +++++++++++++++++++++----------------
> >  1 file changed, 54 insertions(+), 43 deletions(-)
> > 
> > diff --git a/vdagent/display_setting.cpp b/vdagent/display_setting.cpp
> > index 5585bb5..cdc42c7 100644
> > --- a/vdagent/display_setting.cpp
> > +++ b/vdagent/display_setting.cpp
> > @@ -282,30 +282,70 @@ bool DisplaySetting::disable_wallpaper()
> >      }
> >  }
> >  
> > -bool DisplaySetting::reload_wallpaper(HKEY desktop_reg_key)
> > +template <typename T>
> > +static bool RegReadString(HKEY key, const T *name, T *buffer, size_t
> > buffer_len)
> >  {
> > -    TCHAR wallpaper_path[MAX_PATH + 1];
> > -    DWORD value_size = sizeof(wallpaper_path) - sizeof(wallpaper_path[0]);
> > +    static_assert(sizeof(T) == sizeof(char) || sizeof(T) ==
> > sizeof(WCHAR));
> > +    DWORD value_size = buffer_len * sizeof(buffer[0]);
> >      DWORD value_type;
> >      LONG status;
> > -    TCHAR cur_wallpaper[MAX_PATH + 1];
> >  
> > -    vd_printf("");
> > -    status = RegQueryValueEx(desktop_reg_key, TEXT("Wallpaper"), NULL,
> > -                             &value_type, (LPBYTE)wallpaper_path,
> > &value_size);
> > +    if (sizeof(T) == sizeof(char)) {
> > +        status = RegQueryValueExA(key, (const char*) name, NULL,
> > +                                  &value_type, (LPBYTE)buffer,
> > &value_size);
> > +    } else {
> > +        status = RegQueryValueExW(key, (LPCWSTR) name, NULL,
> > +                                  &value_type, (LPBYTE)buffer,
> > &value_size);
> > +    }
> 
> I think switching win_anim_value/smooth_value to TCHAR/_tcscmp would
> allow to use RegQueryValueEx in all cases and make this helper a bit
> simpler?
> 

Does not work with templates, the _tcs macros (and also RegQueryValueEx)
are replaced with a single instance.

> Christophe
> 
> > +    if (status == ERROR_SUCCESS && value_type == REG_SZ) {
> > +        // assure NUL-terminated
> > +        value_size /= sizeof(buffer[0]);
> > +        if (value_size == buffer_len) {
> > +            // full buffer but not terminated?
> > +            if (buffer[value_size-1] != '\0') {
> > +                status = ERROR_MORE_DATA;
> > +            }
> > +        } else {
> > +            // append a NUL. If there's already a NUL character this
> > +            // new one will be ignored
> > +            buffer[value_size] = '\0';
> > +        }
> > +    }
> >      if (status != ERROR_SUCCESS) {
> > -        vd_printf("RegQueryValueEx(Wallpaper) : fail %ld", status);
> > +        if (sizeof(T) == sizeof(char)) {
> > +            vd_printf("RegQueryValueEx(%s) : fail %ld", (const char*)
> > name, status);
> > +        } else {
> > +            vd_printf("RegQueryValueEx(%ls) : fail %ld", (LPCWSTR) name,
> > status);
> > +        }
> >          return false;
> >      }
> >  
> >      if (value_type != REG_SZ) {
> > -        vd_printf("bad wallpaper value type %lu (expected REG_SZ)",
> > value_type);
> > +        if (sizeof(T) == sizeof(char)) {
> > +            vd_printf("bad %s value type %lu (expected REG_SZ)", (const
> > char*) name, value_type);
> > +        } else {
> > +            vd_printf("bad %ls value type %lu (expected REG_SZ)",
> > (LPCWSTR) name, value_type);
> > +        }
> >          return false;
> >      }
> >  
> > -    value_size /= sizeof(wallpaper_path[0]);
> > -    if (!value_size || wallpaper_path[value_size - 1] != '\0') {
> > -        wallpaper_path[value_size] = '\0';
> > +    return true;
> > +}
> > +
> > +template <typename T, size_t N>
> > +static inline bool RegReadString(HKEY key, const T *name, T (&buffer)[N])
> > +{
> > +    return RegReadString(key, name, buffer, N);
> > +}
> > +
> > +bool DisplaySetting::reload_wallpaper(HKEY desktop_reg_key)
> > +{
> > +    TCHAR wallpaper_path[MAX_PATH + 1];
> > +    TCHAR cur_wallpaper[MAX_PATH + 1];
> > +
> > +    vd_printf("");
> > +    if (!RegReadString(desktop_reg_key, TEXT("Wallpaper"),
> > wallpaper_path)) {
> > +        return false;
> >      }
> >  
> >      if (SystemParametersInfo(SPI_GETDESKWALLPAPER,
> >      SPICE_N_ELEMENTS(cur_wallpaper), cur_wallpaper, 0)) {
> > @@ -340,28 +380,13 @@ bool DisplaySetting::disable_font_smoothing()
> >  bool DisplaySetting::reload_font_smoothing(HKEY desktop_reg_key)
> >  {
> >      CHAR smooth_value[4+1];
> > -    DWORD value_size = sizeof(smooth_value)-1;
> > -    DWORD value_type;
> > -    LONG status;
> >      BOOL cur_font_smooth;
> >  
> >      vd_printf("");
> > -    status = RegQueryValueExA(desktop_reg_key, "FontSmoothing", NULL,
> > -                              &value_type, (LPBYTE)smooth_value,
> > &value_size);
> > -    if (status != ERROR_SUCCESS) {
> > -        vd_printf("RegQueryValueEx(FontSmoothing) : fail %ld", status);
> > -        return false;
> > -    }
> > -
> > -    if (value_type != REG_SZ) {
> > -        vd_printf("bad font smoothing value type %lu (expected REG_SZ)",
> > value_type);
> > +    if (!RegReadString(desktop_reg_key, "FontSmoothing", smooth_value)) {
> >          return false;
> >      }
> >  
> > -    if (!value_size || smooth_value[value_size - 1] != '\0') {
> > -        smooth_value[value_size] = '\0';
> > -    }
> > -
> >      if (strcmp(smooth_value, "0") == 0) {
> >          vd_printf("font smoothing is disabled in registry. do nothing");
> >          return true;
> > @@ -413,8 +438,6 @@ bool DisplaySetting::reload_win_animation(HKEY
> > desktop_reg_key)
> >  {
> >      HKEY win_metrics_hkey;
> >      CHAR win_anim_value[4+1];
> > -    DWORD value_size = sizeof(win_anim_value)-1;
> > -    DWORD value_type;
> >      LONG status;
> >      ANIMATIONINFO active_win_animation;
> >  
> > @@ -427,25 +450,13 @@ bool DisplaySetting::reload_win_animation(HKEY
> > desktop_reg_key)
> >          return false;
> >      }
> >  
> > -    status = RegQueryValueExA(win_metrics_hkey, "MinAnimate", NULL,
> > -                              &value_type, (LPBYTE)win_anim_value,
> > &value_size);
> > -    if (status != ERROR_SUCCESS) {
> > -        vd_printf("RegQueryValueEx(MinAnimate) : fail %ld", status);
> > +    if (!RegReadString(win_metrics_hkey, "MinAnimate", win_anim_value)) {
> >          RegCloseKey(win_metrics_hkey);
> >          return false;
> >      }
> >  
> >      RegCloseKey(win_metrics_hkey);
> >  
> > -    if (value_type != REG_SZ) {
> > -        vd_printf("bad MinAnimate value type %lu (expected REG_SZ)",
> > value_type);
> > -        return false;
> > -    }
> > -
> > -    if (!value_size || win_anim_value[value_size - 1] != '\0') {
> > -        win_anim_value[value_size] = '\0';
> > -    }
> > -
> >      if (!strcmp(win_anim_value, "0")) {
> >          vd_printf("window animation is disabled in registry. do nothing");
> >          return true;

Frediano