tools_common.h: add VPX_TOOLS_FORMAT_PRINTF

and use it to set the format attribute for printf like functions. this
allows the examples to be built with -Wformat-nonliteral without
producing warnings.

Bug: webm:1744
Change-Id: I26b4c41c9a42790053b1ae0e4a678af8f2cd1d82
Fixed: webm:1744

10 files changed, 59 insertions, 40 deletions

diff --git a/configure b/configure
index da631a45e..e3babbe82 100755
--- a/configure
+++ b/configure
@@ -621,6 +621,7 @@ process_toolchain() {
         check_add_cflags -Wdeclaration-after-statement
         check_add_cflags -Wdisabled-optimization
         check_add_cflags -Wfloat-conversion
+        check_add_cflags -Wformat=2
         check_add_cflags -Wparentheses-equality
         check_add_cflags -Wpointer-arith
         check_add_cflags -Wtype-limits
diff --git a/examples/svc_encodeframe.c b/examples/svc_encodeframe.c
index a73ee8ed6..08bda0e5c 100644
--- a/examples/svc_encodeframe.c
+++ b/examples/svc_encodeframe.c
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #define VPX_DISABLE_CTRL_TYPECHECKS 1
+#include "../tools_common.h"
 #include "./vpx_config.h"
 #include "./svc_context.h"
 #include "vpx/vp8cx.h"
@@ -95,8 +96,9 @@ static const SvcInternal_t *get_const_svc_internal(const SvcContext *svc_ctx) {
   return (const SvcInternal_t *)svc_ctx->internal;
 }
 
-static int svc_log(SvcContext *svc_ctx, SVC_LOG_LEVEL level, const char *fmt,
-                   ...) {
+static VPX_TOOLS_FORMAT_PRINTF(3, 4) int svc_log(SvcContext *svc_ctx,
+                                                 SVC_LOG_LEVEL level,
+                                                 const char *fmt, ...) {
   char buf[512];
   int retval = 0;
   va_list ap;
@@ -264,7 +266,7 @@ static vpx_codec_err_t parse_options(SvcContext *svc_ctx, const char *options) {
   if (alt_ref_enabled > REF_FRAMES - svc_ctx->spatial_layers) {
     svc_log(svc_ctx, SVC_LOG_ERROR,
             "svc: auto alt ref: Maxinum %d(REF_FRAMES - layers) layers could"
-            "enabled auto alt reference frame, but % layers are enabled\n",
+            "enabled auto alt reference frame, but %d layers are enabled\n",
             REF_FRAMES - svc_ctx->spatial_layers, alt_ref_enabled);
     res = VPX_CODEC_INVALID_PARAM;
   }
@@ -456,10 +458,11 @@ vpx_codec_err_t vpx_svc_init(SvcContext *svc_ctx, vpx_codec_ctx_t *codec_ctx,
     svc_ctx->temporal_layers = VPX_TS_MAX_LAYERS;
 
   if (svc_ctx->temporal_layers * svc_ctx->spatial_layers > VPX_MAX_LAYERS) {
-    svc_log(svc_ctx, SVC_LOG_ERROR,
-            "spatial layers * temporal layers exceeds the maximum number of "
-            "allowed layers of %d\n",
-            svc_ctx->spatial_layers * svc_ctx->temporal_layers, VPX_MAX_LAYERS);
+    svc_log(
+        svc_ctx, SVC_LOG_ERROR,
+        "spatial layers * temporal layers (%d) exceeds the maximum number of "
+        "allowed layers of %d\n",
+        svc_ctx->spatial_layers * svc_ctx->temporal_layers, VPX_MAX_LAYERS);
     return VPX_CODEC_INVALID_PARAM;
   }
   res = assign_layer_bitrates(svc_ctx, enc_cfg);
diff --git a/examples/twopass_encoder.c b/examples/twopass_encoder.c
index 3d950b2c4..07ba37dfd 100644
--- a/examples/twopass_encoder.c
+++ b/examples/twopass_encoder.c
@@ -221,7 +221,7 @@ int main(int argc, char **argv) {
     die("Invalid frame size: %dx%d", w, h);
 
   if (!vpx_img_alloc(&raw, VPX_IMG_FMT_I420, w, h, 1))
-    die("Failed to allocate image", w, h);
+    die("Failed to allocate image (%dx%d)", w, h);
 
   printf("Using %s\n", vpx_codec_iface_name(encoder->codec_interface()));
 
diff --git a/examples/vp8_multi_resolution_encoder.c b/examples/vp8_multi_resolution_encoder.c
index e72f8a019..62d96de55 100644
--- a/examples/vp8_multi_resolution_encoder.c
+++ b/examples/vp8_multi_resolution_encoder.c
@@ -352,7 +352,7 @@ int main(int argc, char **argv) {
   framerate = (int)strtol(argv[3], NULL, 0);
 
   if (width < 16 || width % 2 || height < 16 || height % 2)
-    die("Invalid resolution: %ldx%ld", width, height);
+    die("Invalid resolution: %dx%d", width, height);
 
   /* Open input video file for encoding */
   if (!(infile = fopen(argv[4], "rb")))
@@ -380,7 +380,7 @@ int main(int argc, char **argv) {
         (int)strtol(argv[2 * NUM_ENCODERS + 5 + i], NULL, 0);
     if (num_temporal_layers[i] < 1 || num_temporal_layers[i] > 3)
       die("Invalid temporal layers: %d, Must be 1, 2, or 3. \n",
-          num_temporal_layers);
+          num_temporal_layers[i]);
   }
 
   /* Open file to write out each spatially downsampled input stream. */
@@ -468,7 +468,7 @@ int main(int argc, char **argv) {
   /* Allocate image for each encoder */
   for (i = 0; i < NUM_ENCODERS; i++)
     if (!vpx_img_alloc(&raw[i], VPX_IMG_FMT_I420, cfg[i].g_w, cfg[i].g_h, 32))
-      die("Failed to allocate image", cfg[i].g_w, cfg[i].g_h);
+      die("Failed to allocate image (%dx%d)", cfg[i].g_w, cfg[i].g_h);
 
   if (raw[0].stride[VPX_PLANE_Y] == (int)raw[0].d_w)
     read_frame_p = mulres_read_frame;
diff --git a/examples/vpx_temporal_svc_encoder.c b/examples/vpx_temporal_svc_encoder.c
index ad3e79c71..47f30751e 100644
--- a/examples/vpx_temporal_svc_encoder.c
+++ b/examples/vpx_temporal_svc_encoder.c
@@ -687,14 +687,14 @@ int main(int argc, char **argv) {
             &raw,
             bit_depth == VPX_BITS_8 ? VPX_IMG_FMT_I420 : VPX_IMG_FMT_I42016,
             width, height, 32)) {
-      die("Failed to allocate image", width, height);
+      die("Failed to allocate image (%dx%d)", width, height);
     }
   }
 #else
   // Y4M reader has its own allocation.
   if (input_ctx.file_type != FILE_TYPE_Y4M) {
     if (!vpx_img_alloc(&raw, VPX_IMG_FMT_I420, width, height, 32)) {
-      die("Failed to allocate image", width, height);
+      die("Failed to allocate image (%dx%d)", width, height);
     }
   }
 #endif  // CONFIG_VP9_HIGHBITDEPTH
diff --git a/rate_hist.c b/rate_hist.c
index 6cf8ce7bb..d10e754fe 100644
--- a/rate_hist.c
+++ b/rate_hist.c
@@ -193,7 +193,7 @@ static int merge_hist_buckets(struct hist_bucket *bucket, int max_buckets,
 
 static void show_histogram(const struct hist_bucket *bucket, int buckets,
                            int total, int scale) {
-  const char *pat1, *pat2;
+  int width1, width2;
   int i;
 
   assert(bucket != NULL);
@@ -201,32 +201,32 @@ static void show_histogram(const struct hist_bucket *bucket, int buckets,
   switch ((int)(log(bucket[buckets - 1].high) / log(10)) + 1) {
     case 1:
     case 2:
-      pat1 = "%4d %2s: ";
-      pat2 = "%4d-%2d: ";
+      width1 = 4;
+      width2 = 2;
       break;
     case 3:
-      pat1 = "%5d %3s: ";
-      pat2 = "%5d-%3d: ";
+      width1 = 5;
+      width2 = 3;
       break;
     case 4:
-      pat1 = "%6d %4s: ";
-      pat2 = "%6d-%4d: ";
+      width1 = 6;
+      width2 = 4;
       break;
     case 5:
-      pat1 = "%7d %5s: ";
-      pat2 = "%7d-%5d: ";
+      width1 = 7;
+      width2 = 5;
       break;
     case 6:
-      pat1 = "%8d %6s: ";
-      pat2 = "%8d-%6d: ";
+      width1 = 8;
+      width2 = 6;
       break;
     case 7:
-      pat1 = "%9d %7s: ";
-      pat2 = "%9d-%7d: ";
+      width1 = 9;
+      width2 = 7;
       break;
     default:
-      pat1 = "%12d %10s: ";
-      pat2 = "%12d-%10d: ";
+      width1 = 12;
+      width2 = 10;
       break;
   }
 
@@ -241,9 +241,10 @@ static void show_histogram(const struct hist_bucket *bucket, int buckets,
     assert(len <= HIST_BAR_MAX);
 
     if (bucket[i].low == bucket[i].high)
-      fprintf(stderr, pat1, bucket[i].low, "");
+      fprintf(stderr, "%*d %*s: ", width1, bucket[i].low, width2, "");
     else
-      fprintf(stderr, pat2, bucket[i].low, bucket[i].high);
+      fprintf(stderr, "%*d-%*d: ", width1, bucket[i].low, width2,
+              bucket[i].high);
 
     for (j = 0; j < HIST_BAR_MAX; j++) fprintf(stderr, j < len ? "=" : " ");
     fprintf(stderr, "\t%5d (%6.2f%%)\n", bucket[i].count, pct);
diff --git a/tools_common.h b/tools_common.h
index 4e8851fc1..b9cfb9cc8 100644
--- a/tools_common.h
+++ b/tools_common.h
@@ -116,12 +116,24 @@ extern "C" {
 #define VPX_NO_RETURN
 #endif
 
+// Tells the compiler to perform `printf` format string checking if the
+// compiler supports it; see the 'format' attribute in
+// <https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>.
+#define VPX_TOOLS_FORMAT_PRINTF(string_index, first_to_check)
+#if defined(__has_attribute)
+#if __has_attribute(format)
+#undef VPX_TOOLS_FORMAT_PRINTF
+#define VPX_TOOLS_FORMAT_PRINTF(string_index, first_to_check) \
+  __attribute__((__format__(__printf__, string_index, first_to_check)))
+#endif
+#endif
+
 /* Sets a stdio stream into binary mode */
 FILE *set_binary_mode(FILE *stream);
 
-VPX_NO_RETURN void die(const char *fmt, ...);
-VPX_NO_RETURN void fatal(const char *fmt, ...);
-void warn(const char *fmt, ...);
+VPX_NO_RETURN void die(const char *fmt, ...) VPX_TOOLS_FORMAT_PRINTF(1, 2);
+VPX_NO_RETURN void fatal(const char *fmt, ...) VPX_TOOLS_FORMAT_PRINTF(1, 2);
+void warn(const char *fmt, ...) VPX_TOOLS_FORMAT_PRINTF(1, 2);
 
 VPX_NO_RETURN void die_codec(vpx_codec_ctx_t *ctx, const char *s);
 
diff --git a/vpxenc.c b/vpxenc.c
index a0122ef80..b64b6cf44 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -58,8 +58,8 @@ static size_t wrap_fwrite(const void *ptr, size_t size, size_t nmemb,
 
 static const char *exec_name;
 
-static void warn_or_exit_on_errorv(vpx_codec_ctx_t *ctx, int fatal,
-                                   const char *s, va_list ap) {
+static VPX_TOOLS_FORMAT_PRINTF(3, 0) void warn_or_exit_on_errorv(
+    vpx_codec_ctx_t *ctx, int fatal, const char *s, va_list ap) {
   if (ctx->err) {
     const char *detail = vpx_codec_error_detail(ctx);
 
@@ -72,7 +72,9 @@ static void warn_or_exit_on_errorv(vpx_codec_ctx_t *ctx, int fatal,
   }
 }
 
-static void ctx_exit_on_error(vpx_codec_ctx_t *ctx, const char *s, ...) {
+static VPX_TOOLS_FORMAT_PRINTF(2,
+                               3) void ctx_exit_on_error(vpx_codec_ctx_t *ctx,
+                                                         const char *s, ...) {
   va_list ap;
 
   va_start(ap, s);
@@ -80,8 +82,8 @@ static void ctx_exit_on_error(vpx_codec_ctx_t *ctx, const char *s, ...) {
   va_end(ap);
 }
 
-static void warn_or_exit_on_error(vpx_codec_ctx_t *ctx, int fatal,
-                                  const char *s, ...) {
+static VPX_TOOLS_FORMAT_PRINTF(3, 4) void warn_or_exit_on_error(
+    vpx_codec_ctx_t *ctx, int fatal, const char *s, ...) {
   va_list ap;
 
   va_start(ap, s);
diff --git a/vpxstats.c b/vpxstats.c
index 142e367bb..c0dd14e45 100644
--- a/vpxstats.c
+++ b/vpxstats.c
@@ -41,7 +41,7 @@ int stats_open_file(stats_io_t *stats, const char *fpf, int pass) {
     stats->buf.buf = malloc(stats->buf_alloc_sz);
 
     if (!stats->buf.buf)
-      fatal("Failed to allocate first-pass stats buffer (%lu bytes)",
+      fatal("Failed to allocate first-pass stats buffer (%u bytes)",
             (unsigned int)stats->buf_alloc_sz);
 
     nbytes = fread(stats->buf.buf, 1, stats->buf.sz, stats->file);
diff --git a/warnings.c b/warnings.c
index a80da527f..3e6e70253 100644
--- a/warnings.c
+++ b/warnings.c
@@ -98,7 +98,7 @@ void check_encoder_config(int disable_prompt,
   /* Count and print warnings. */
   for (warning = warning_list.warning_node; warning != NULL;
        warning = warning->next_warning, ++num_warnings) {
-    warn(warning->warning_string);
+    warn("%s", warning->warning_string);
   }
 
   free_warning_list(&warning_list);