>
>
> spice-bitmap-utils.c has a lot of calls to fwrite() that don't check the
> return value. On RHEL 6 these cause compilation errors due to -Werror:
>
> spice-bitmap-utils.c:147: error: ignoring return value of 'fwrite',
> declared with attribute warn_unused_result
>
> What should be done about that?
> * One option would be to remove -Werror but that would be really
> heavy handed.
>
> * I have not found a way to disable just that one warning. But if
> others have more luck that could be an option.
>
> * The best solution would be to not ignore the return values but that
> means adding a lot of error-handling code. Does anyone want to take
> this on?
>
> * Otherwise the usual way to trick the compiler is to rewrite the code
> as
> (void)(func(...)+1)
> It's really ugly so it is generally further hidden in a macro.
> This would yield a patch somewhat like this:
>
>
> diff --git a/server/spice-bitmap-utils.c b/server/spice-bitmap-utils.c
> index 8d6e7c6..3cc8b35 100644
> --- a/server/spice-bitmap-utils.c
> +++ b/server/spice-bitmap-utils.c
> @@ -30,6 +30,8 @@
> #define GRADUAL_HIGH_RGB24_TH -0.03
> #define GRADUAL_HIGH_RGB16_TH 0
>
> +#define IGNORE(x) ((void)(x+1))
> +
> // setting a more permissive threshold for stream identification in order
> // not to miss streams that were artificially scaled on the guest (e.g.,
> full screen view
> // in window media player 12). see red_stream_add_frame
> @@ -141,7 +143,7 @@ static void dump_palette(FILE *f, SpicePalette* plt)
> {
> int i;
> for (i = 0; i < plt->num_ents; i++) {
> - fwrite(plt->ents + i, sizeof(uint32_t), 1, f);
> + IGNORE(fwrite(plt->ents + i, sizeof(uint32_t), 1, f));
> }
> }
>
> @@ -150,11 +152,11 @@ static void dump_line(FILE *f, uint8_t* line, uint16_t
> n_pixel_bits, int width,
> int i;
> int copy_bytes_size = SPICE_ALIGN(n_pixel_bits * width, 8) / 8;
>
> - fwrite(line, 1, copy_bytes_size, f);
> + IGNORE(fwrite(line, 1, copy_bytes_size, f));
> if (row_size > copy_bytes_size) {
> // each line should be 4 bytes aligned
> for (i = copy_bytes_size; i < row_size; i++) {
> - fprintf(f, "%c", 0);
> + IGNORE(fprintf(f, "%c", 0));
> }
> }
> }
> @@ -235,36 +237,36 @@ void dump_bitmap(SpiceBitmap *bitmap)
> }
>
> /* writing the bmp v3 header */
> - fprintf(f, "BM");
> - fwrite(&file_size, sizeof(file_size), 1, f);
> + IGNORE(fprintf(f, "BM"));
> + IGNORE(fwrite(&file_size, sizeof(file_size), 1, f));
> tmp_u16 = alpha ? 1 : 0;
> - fwrite(&tmp_u16, sizeof(tmp_u16), 1, f); // reserved for application
> + IGNORE(fwrite(&tmp_u16, sizeof(tmp_u16), 1, f)); // reserved for
> application
> tmp_u16 = 0;
> - fwrite(&tmp_u16, sizeof(tmp_u16), 1, f);
> - fwrite(&bitmap_data_offset, sizeof(bitmap_data_offset), 1, f);
> + IGNORE(fwrite(&tmp_u16, sizeof(tmp_u16), 1, f));
> + IGNORE(fwrite(&bitmap_data_offset, sizeof(bitmap_data_offset), 1, f));
> tmp_u32 = header_size - 14;
> - fwrite(&tmp_u32, sizeof(tmp_u32), 1, f); // sub header size
> + IGNORE(fwrite(&tmp_u32, sizeof(tmp_u32), 1, f)); // sub header size
> tmp_32 = bitmap->x;
> - fwrite(&tmp_32, sizeof(tmp_32), 1, f);
> + IGNORE(fwrite(&tmp_32, sizeof(tmp_32), 1, f));
> tmp_32 = bitmap->y;
> - fwrite(&tmp_32, sizeof(tmp_32), 1, f);
> + IGNORE(fwrite(&tmp_32, sizeof(tmp_32), 1, f));
>
> tmp_u16 = 1;
> - fwrite(&tmp_u16, sizeof(tmp_u16), 1, f); // color plane
> - fwrite(&n_pixel_bits, sizeof(n_pixel_bits), 1, f); // pixel depth
> + IGNORE(fwrite(&tmp_u16, sizeof(tmp_u16), 1, f)); // color plane
> + IGNORE(fwrite(&n_pixel_bits, sizeof(n_pixel_bits), 1, f)); // pixel
> depth
>
> tmp_u32 = 0;
> - fwrite(&tmp_u32, sizeof(tmp_u32), 1, f); // compression method
> + IGNORE(fwrite(&tmp_u32, sizeof(tmp_u32), 1, f)); // compression method
>
> tmp_u32 = 0; //file_size - bitmap_data_offset;
> - fwrite(&tmp_u32, sizeof(tmp_u32), 1, f); // image size
> + IGNORE(fwrite(&tmp_u32, sizeof(tmp_u32), 1, f)); // image size
> tmp_32 = 0;
> - fwrite(&tmp_32, sizeof(tmp_32), 1, f);
> - fwrite(&tmp_32, sizeof(tmp_32), 1, f);
> + IGNORE(fwrite(&tmp_32, sizeof(tmp_32), 1, f));
> + IGNORE(fwrite(&tmp_32, sizeof(tmp_32), 1, f));
> tmp_u32 = (!plt) ? 0 : plt->num_ents; // plt entries
> - fwrite(&tmp_u32, sizeof(tmp_u32), 1, f);
> + IGNORE(fwrite(&tmp_u32, sizeof(tmp_u32), 1, f));
> tmp_u32 = 0;
> - fwrite(&tmp_u32, sizeof(tmp_u32), 1, f);
> + IGNORE(fwrite(&tmp_u32, sizeof(tmp_u32), 1, f));
>
> if (plt) {
> dump_palette(f, plt);
Your ignore suggestion with a trick:
diff --git a/server/spice-bitmap-utils.c b/server/spice-bitmap-utils.c
index 8d6e7c6..42c6608 100644
--- a/server/spice-bitmap-utils.c
+++ b/server/spice-bitmap-utils.c
@@ -137,6 +137,15 @@ int spice_bitmap_from_surface_type(uint32_t surface_format)
#define RAM_PATH "/tmp/tmpfs"
+static inline void fwrite_noerr(const void *ptr, size_t size, size_t nmemb,
+ FILE *f)
+{
+ (void)(fwrite(ptr, size, nmemb, f)+1);
+}
+
+#undef fwrite
+#define fwrite(a,b,c,d) fwrite_noerr(a,b,c,d)
+
static void dump_palette(FILE *f, SpicePalette* plt)
{
int i;
@@ -147,17 +156,14 @@ static void dump_palette(FILE *f, SpicePalette* plt)
static void dump_line(FILE *f, uint8_t* line, uint16_t n_pixel_bits, int width, int row_size)
{
- int i;
+ static char zeroes[4] = { 0 };
int copy_bytes_size = SPICE_ALIGN(n_pixel_bits * width, 8) / 8;
fwrite(line, 1, copy_bytes_size, f);
- if (row_size > copy_bytes_size) {
- // each line should be 4 bytes aligned
- for (i = copy_bytes_size; i < row_size; i++) {
- fprintf(f, "%c", 0);
- }
- }
+ // each line should be 4 bytes aligned
+ fwrite(zeroes, 1, row_size - copy_bytes_size, f);
}
+
void dump_bitmap(SpiceBitmap *bitmap)
{
static uint32_t file_id = 0;
@@ -235,7 +241,7 @@ void dump_bitmap(SpiceBitmap *bitmap)
}
/* writing the bmp v3 header */
- fprintf(f, "BM");
+ fwrite("BM", 2, 1, f);
fwrite(&file_size, sizeof(file_size), 1, f);
tmp_u16 = alpha ? 1 : 0;
fwrite(&tmp_u16, sizeof(tmp_u16), 1, f); // reserved for application
Frediano
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