more C89-fixes

going down to strict -ansi c89 is quite overkill (no 'inline',
and /* */-style comments).
But with these fixes, the code compiles with the stringent flags:
 -Wextra -Wold-style-definition -Wmissing-prototypes
 -Wmissing-declarations and -Wdeclaration-after-statement

Change-Id: I36222f8f505bcba3d9d1309ad98b5ccb04ec17e3

examples/cwebp.c

@@ -276,6 +276,7 @@ static int ReadJPEG(FILE* in_file, WebPPicture* const pic) {
 
 #ifdef WEBP_HAVE_PNG
 static void PNGAPI error_function(png_structp png, png_const_charp dummy) {
+  (void)dummy;  // remove variable-unused warning
   longjmp(png_jmpbuf(png), 1);
 }
 
@@ -284,9 +285,9 @@ static int ReadPNG(FILE* in_file, WebPPicture* const pic) {
   png_infop info;
   int color_type, bit_depth, interlaced;
   int num_passes;
-  int p, y;
+  int p;
   int ok = 0;
-  png_uint_32 width, height;
+  png_uint_32 width, height, y;
   int stride;
   uint8_t* rgb = NULL;
 
@@ -446,7 +447,7 @@ static void PrintValues(const int values[4]) {
   fprintf(stderr,"|\n");
 }
 
-void PrintExtraInfo(const WebPPicture* const pic, int short_output) {
+static void PrintExtraInfo(const WebPPicture* const pic, int short_output) {
   const WebPAuxStats* const stats = pic->stats;
   if (short_output) {
     fprintf(stderr, "%7d %2.2f\n", stats->coded_size, stats->PSNR[3]);
@@ -553,7 +554,7 @@ static int DumpPicture(const WebPPicture* const picture, const char* PGM_name) {
 
 //-----------------------------------------------------------------------------
 
-static void HelpShort() {
+static void HelpShort(void) {
   printf("Usage:\n\n");
   printf("   cwebp [options] -q quality input.png -o output.webp\n\n");
   printf("where quality is between 0 (poor) to 100 (very good).\n");
@@ -561,7 +562,7 @@ static void HelpShort() {
   printf("Try -longhelp for an exhaustive list of advanced options.\n");
 }
 
-static void HelpLong() {
+static void HelpLong(void) {
   printf("Usage:\n");
   printf(" cwebp [-preset <...>] [options] in_file [-o out_file]\n\n");
   printf("If input size (-s) for an image is not specified, "

examples/dwebp.c

@@ -117,6 +117,7 @@ static int WritePNG(const char* out_file_name, unsigned char* rgb, int stride,
 
 #elif defined(WEBP_HAVE_PNG)    // !WIN32
 static void PNGAPI error_function(png_structp png, png_const_charp dummy) {
+  (void)dummy;  // remove variable-unused warning
   longjmp(png_jmpbuf(png), 1);
 }
 
@@ -124,7 +125,7 @@ static int WritePNG(FILE* out_file, unsigned char* rgb, int stride,
                     png_uint_32 width, png_uint_32 height) {
   png_structp png;
   png_infop info;
-  int y;
+  png_uint_32 y;
 
   png = png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                 NULL, error_function, NULL);
@@ -203,7 +204,7 @@ typedef enum {
   PGM,
 } OutputFileFormat;
 
-static void help(const char *s) {
+static void Help(void) {
   printf("Usage: dwebp "
          "[in_file] [-h] [-v] [-ppm] [-pgm] [-version] [-o out_file]\n\n"
          "Decodes the WebP image file to PNG format [Default]\n"
@@ -227,7 +228,7 @@ int main(int argc, const char *argv[]) {
   int c;
   for (c = 1; c < argc; ++c) {
     if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
-      help(argv[0]);
+      Help();
       return 0;
     } else if (!strcmp(argv[c], "-o") && c < argc - 1) {
       out_file = argv[++c];
@@ -244,7 +245,7 @@ int main(int argc, const char *argv[]) {
       verbose = 1;
     } else if (argv[c][0] == '-') {
       printf("Unknown option '%s'\n", argv[c]);
-      help(argv[0]);
+      Help();
       return -1;
     } else {
       in_file = argv[c];
@@ -253,7 +254,7 @@ int main(int argc, const char *argv[]) {
 
   if (in_file == NULL) {
     printf("missing input file!!\n");
-    help(argv[0]);
+    Help();
     return -1;
   }
 

makefile.unix

@@ -31,7 +31,13 @@ endif
 # Uncomment for build for 32bit platform
 # Alternatively, you can just use the command
 # 'make -f makefile.unix EXTRA_FLAGS=-m32' to that effect.
-# EXTRA_FLAGS= -m32
+# EXTRA_FLAGS += -m32
+
+# Extra flags to emulate C89 strictness with the full ANSI
+EXTRA_FLAGS += -Wextra -Wold-style-definition
+EXTRA_FLAGS += -Wmissing-prototypes
+EXTRA_FLAGS += -Wmissing-declarations
+EXTRA_FLAGS += -Wdeclaration-after-statement
 
 #### Nothing should normally be changed below this line ####
 

src/dec/dsp.c

@@ -28,9 +28,11 @@ static int8_t sclip1[1020 + 1020 + 1];  // clips [-1020, 1020] to [-128, 127]
 static int8_t sclip2[112 + 112 + 1];    // clips [-112, 112] to [-16, 15]
 static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
 
-static int tables_ok = 0;
+// We declare this variable 'volatile' to prevent instruction reordering
+// and make sure it's set to true _last_ (so as to be thread-safe)
+static volatile int tables_ok = 0;
 
-void VP8DspInitTables() {
+void VP8DspInitTables(void) {
   if (!tables_ok) {
     int i;
     for (i = -255; i <= 255; ++i) {
@@ -685,7 +687,7 @@ void (*VP8SimpleHFilter16i)(uint8_t*, int, int) = SimpleHFilter16i;
 
 //-----------------------------------------------------------------------------
 
-void VP8DspInit() {
+void VP8DspInit(void) {
   // later we'll plug some SSE2 variant here
 }
 

src/dec/idec.c

@@ -496,10 +496,11 @@ static VP8StatusCode IDecCheckStatus(const WebPIDecoder* const idec) {
 
 VP8StatusCode WebPIAppend(WebPIDecoder* const idec, const uint8_t* data,
                           uint32_t data_size) {
+  VP8StatusCode status;
   if (idec == NULL || data == NULL) {
     return VP8_STATUS_INVALID_PARAM;
   }
-  const VP8StatusCode status = IDecCheckStatus(idec);
+  status = IDecCheckStatus(idec);
   if (status != VP8_STATUS_SUSPENDED) {
     return status;
   }
@@ -516,10 +517,11 @@ VP8StatusCode WebPIAppend(WebPIDecoder* const idec, const uint8_t* data,
 
 VP8StatusCode WebPIUpdate(WebPIDecoder* const idec, const uint8_t* data,
                           uint32_t data_size) {
+  VP8StatusCode status;
   if (idec == NULL || data == NULL) {
     return VP8_STATUS_INVALID_PARAM;
   }
-  const VP8StatusCode status = IDecCheckStatus(idec);
+  status = IDecCheckStatus(idec);
   if (status != VP8_STATUS_SUSPENDED) {
     return status;
   }
@@ -536,7 +538,7 @@ VP8StatusCode WebPIUpdate(WebPIDecoder* const idec, const uint8_t* data,
 
 //------------------------------------------------------------------------------
 
-uint8_t* WebPIDecGetRGB(const WebPIDecoder* idec, int *last_y,
+uint8_t* WebPIDecGetRGB(const WebPIDecoder* const idec, int *last_y,
                         int* width, int* height, int* stride) {
   if (!idec || !idec->dec_ || idec->params_.mode != MODE_RGB ||
       idec->state_ <= STATE_PARTS0) {
@@ -551,9 +553,9 @@ uint8_t* WebPIDecGetRGB(const WebPIDecoder* idec, int *last_y,
   return idec->params_.output;
 }
 
-uint8_t* WebPIDecGetYUV(const WebPIDecoder* idec, int *last_y, uint8_t** u,
-                        uint8_t** v, int* width, int* height, int *stride,
-                        int* uv_stride) {
+uint8_t* WebPIDecGetYUV(const WebPIDecoder* const idec, int *last_y,
+                        uint8_t** u, uint8_t** v, int* width, int* height,
+                        int *stride, int* uv_stride) {
   if (!idec || !idec->dec_ || idec->params_.mode != MODE_YUV ||
       idec->state_ <= STATE_PARTS0) {
     return NULL;

src/dec/vp8.c

@@ -18,7 +18,7 @@ extern "C" {
 
 //-----------------------------------------------------------------------------
 
-int WebPGetDecoderVersion() {
+int WebPGetDecoderVersion(void) {
   return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
 }
 
@@ -39,7 +39,7 @@ int VP8InitIoInternal(VP8Io* const io, int version) {
   return 1;
 }
 
-VP8Decoder* VP8New() {
+VP8Decoder* VP8New(void) {
   VP8Decoder* dec = (VP8Decoder*)calloc(1, sizeof(VP8Decoder));
   if (dec) {
     SetOk(dec);

src/dec/vp8i.h

@@ -289,8 +289,8 @@ extern VP8PredFunc VP8PredLuma16[NUM_B_DC_MODES];
 extern VP8PredFunc VP8PredChroma8[NUM_B_DC_MODES];
 extern VP8PredFunc VP8PredLuma4[NUM_BMODES];
 
-void VP8DspInit();        // must be called before anything using the above
-void VP8DspInitTables();  // needs to be called no matter what.
+void VP8DspInit(void);        // must be called before anything using the above
+void VP8DspInitTables(void);  // needs to be called no matter what.
 
 // simple filter (only for luma)
 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);

src/dec/webp.c

@@ -533,8 +533,9 @@ static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* data,
                        uint32_t data_size, int* width, int* height,
                        WebPDecParams* params_out) {
   uint8_t* output;
-  WebPDecParams params = { 0 };
+  WebPDecParams params;
 
+  memset(&params, 0, sizeof(params));
   params.mode = mode;
   if (!WebPInitDecParams(data, data_size, width, height, &params)) {
     return NULL;

src/dec/yuv.c

@@ -23,7 +23,7 @@ uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
 
 static int done = 0;
 
-void VP8YUVInit() {
+void VP8YUVInit(void) {
   int i;
   if (done) {
     return;

src/dec/yuv.h

@@ -57,7 +57,7 @@ inline static void VP8YuvToBgra(int y, int u, int v, uint8_t* const bgra) {
 }
 
 // Must be called before everything, to initialize the tables.
-void VP8YUVInit();
+void VP8YUVInit(void);
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }    // extern "C"

src/enc/Makefile.in

@@ -266,7 +266,7 @@ clean-noinstLTLIBRARIES:
 	  echo "rm -f \"$${dir}/so_locations\""; \
 	  rm -f "$${dir}/so_locations"; \
 	done
-libwebpencode.la: $(libwebpencode_la_OBJECTS) $(libwebpencode_la_DEPENDENCIES) 
+libwebpencode.la: $(libwebpencode_la_OBJECTS) $(libwebpencode_la_DEPENDENCIES)
 	$(libwebpencode_la_LINK)  $(libwebpencode_la_OBJECTS) $(libwebpencode_la_LIBADD) $(LIBS)
 
 mostlyclean-compile:

src/enc/dsp.c

@@ -21,9 +21,11 @@ extern "C" {
 
 static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
 
-static int tables_ok = 0;
+// We declare this variable 'volatile' to prevent instruction reordering
+// and make sure it's set to true _last_ (so as to be thread-safe)
+static volatile int tables_ok = 0;
 
-static void InitTables() {
+static void InitTables(void) {
   if (!tables_ok) {
     int i;
     for (i = -255; i <= 255 + 255; ++i) {
@@ -79,7 +81,7 @@ static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst) {
   }
 }
 
-void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
+static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
   int i;
   int tmp[16];
   for (i = 0; i < 4; ++i, src += BPS, ref += BPS) {
@@ -636,7 +638,7 @@ VP8BlockCopy VP8Copy16x16 = Copy16x16;
 
 //-----------------------------------------------------------------------------
 
-void VP8EncDspInit() {
+void VP8EncDspInit(void) {
   InitTables();
 }
 

src/enc/filter.c

@@ -25,7 +25,7 @@ static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
 
 static int tables_ok = 0;
 
-static void InitTables() {
+static void InitTables(void) {
   if (!tables_ok) {
     int i;
     for (i = -255; i <= 255; ++i) {

src/enc/iterator.c

@@ -270,7 +270,7 @@ int VP8IteratorNext(VP8EncIterator* const it,
 //-----------------------------------------------------------------------------
 // Helper function to set mode properties
 
-void VP8SetIntra16Mode(const VP8EncIterator* it, int mode) {
+void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode) {
   int y;
   uint8_t* preds = it->preds_;
   for (y = 0; y < 4; ++y) {

src/enc/picture.c

@@ -38,7 +38,7 @@ int WebPPictureAlloc(WebPPicture* const picture) {
     picture->y_stride = width;
     picture->uv_stride = uv_width;
     WebPPictureFree(picture);   // erase previous buffer
-    picture->y = (uint8_t*)malloc(total_size);
+    picture->y = (uint8_t*)malloc((size_t)total_size);
     if (picture->y == NULL) return 0;
     picture->u = picture->y + y_size;
     picture->v = picture->u + uv_size;
@@ -163,7 +163,7 @@ enum { YUV_FRAC = 16 };
 
 static inline int clip_uv(int v) {
    v = (v + (257 << (YUV_FRAC + 2 - 1))) >> (YUV_FRAC + 2);
-   return ((v & ~0xff) == 0) ? v : (v < 0) ? 0u : 255u;
+   return ((v & ~0xff) == 0) ? v : (v < 0) ? 0 : 255;
 }
 
 static inline int rgb_to_y(int r, int g, int b) {

src/enc/vp8enci.h

@@ -455,7 +455,7 @@ typedef enum {
 typedef int (*VP8CPUInfo)(CPUFeature feature);
 extern VP8CPUInfo CPUInfo;
 
-void VP8EncDspInit();   // must be called before using anything from the above.
+void VP8EncDspInit(void);   // must be called before using any of the above
 
   // in filter.c
 extern void VP8InitFilter(VP8EncIterator* const it);

src/enc/webpenc.c

@@ -29,7 +29,7 @@ extern "C" {
 
 //-----------------------------------------------------------------------------
 
-int WebPGetEncoderVersion() {
+int WebPGetEncoderVersion(void) {
   return (ENC_MAJ_VERSION << 16) | (ENC_MIN_VERSION << 8) | ENC_REV_VERSION;
 }
 
@@ -39,6 +39,10 @@ int WebPGetEncoderVersion() {
 
 static int DummyWriter(const uint8_t* data, size_t data_size,
                        const WebPPicture* const picture) {
+  // The following are to prevent 'unused variable' error message.
+  (void)data;
+  (void)data_size;
+  (void)picture;
   return 1;
 }
 

src/webp/decode.h

@@ -20,7 +20,7 @@ extern "C" {
 
 // Return the decoder's version number, packed in hexadecimal using 8bits for
 // each of major/minor/revision. E.g: v2.5.7 is 0x020507.
-int WebPGetDecoderVersion();
+int WebPGetDecoderVersion(void);
 
 // Retrieve basic header information: width, height.
 // This function will also validate the header and return 0 in
@@ -173,6 +173,8 @@ VP8StatusCode WebPIAppend(WebPIDecoder* const idec, const uint8_t* data,
 // A variant of the above function to be used when data buffer contains
 // partial data from the beginning. In this case data buffer is not copied
 // to the internal memory.
+// Note that the value of the 'data' pointer can change between calls to
+// WebPIUpdate, for instance when the data buffer is resized to fit larger data.
 VP8StatusCode WebPIUpdate(WebPIDecoder* const idec, const uint8_t* data,
                           uint32_t data_size);
 

src/webp/decode_vp8.h

@@ -83,13 +83,13 @@ struct VP8Io {
 };
 
 // Internal, version-checked, entry point
-extern int VP8InitIoInternal(VP8Io* const, int);
+int VP8InitIoInternal(VP8Io* const, int);
 
 // Main decoding object. This is an opaque structure.
 typedef struct VP8Decoder VP8Decoder;
 
 // Create a new decoder object.
-VP8Decoder* VP8New();
+VP8Decoder* VP8New(void);
 
 // Must be called to make sure 'io' is initialized properly.
 // Returns false in case of version mismatch. Upon such failure, no other

src/webp/encode.h

@@ -24,7 +24,7 @@ extern "C" {
 
 // Return the encoder's version number, packed in hexadecimal using 8bits for
 // each of major/minor/revision. E.g: v2.5.7 is 0x020507.
-int WebPGetEncoderVersion();
+int WebPGetEncoderVersion(void);
 
 //-----------------------------------------------------------------------------
 // One-stop-shop call! No questions asked: