[NaCl SDK] Fix broken printf format strings in the nacl_io_demo.

We use custom printf functions for nacl_io_demo, which were not being checked
for passing the correct arguments.

This CL adds a printf format checking attribute to those functions, as well as dbgprintf in nacl_io.

BUG=363096
R=sbc@chromium.org

Review URL: https://codereview.chromium.org/239543014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@264562 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 27 insertions, 10 deletions

diff --git a/native_client_sdk/src/examples/demo/nacl_io/handlers.c b/native_client_sdk/src/examples/demo/nacl_io/handlers.c
index d615eda..ae40d2d 100644
--- a/native_client_sdk/src/examples/demo/nacl_io/handlers.c
+++ b/native_client_sdk/src/examples/demo/nacl_io/handlers.c
@@ -379,11 +379,11 @@ int HandleFseek(int num_params, char** params, char** output) {
   offset = ftell(file);
   if (offset < 0) {
     *output = PrintfToNewString(
-        "fseek succeeded, but ftell returned error %d.", offset);
+        "fseek succeeded, but ftell returned error %ld.", offset);
     return 4;
   }
 
-  *output = PrintfToNewString("fseek\1%s\1%d", file_index_string, offset);
+  *output = PrintfToNewString("fseek\1%s\1%ld", file_index_string, offset);
   return 0;
 }
 
@@ -507,7 +507,7 @@ int HandleStat(int num_params, char** params, char** output) {
     return 2;
   }
 
-  *output = PrintfToNewString("stat\1%s\1%d", filename, buf.st_size);
+  *output = PrintfToNewString("stat\1%s\1%lld", filename, buf.st_size);
   return 0;
 }
 
@@ -601,8 +601,8 @@ int HandleReaddir(int num_params, char** params, char** output) {
 
   entry = readdir(dir);
   if (entry != NULL) {
-    *output = PrintfToNewString("readdir\1%s\1%d\1%s", dir_index_string,
-                                entry->d_ino, entry->d_name);
+    *output = PrintfToNewString(
+        "readdir\1%s\1%lld\1%s", dir_index_string, entry->d_ino, entry->d_name);
   } else {
     *output = PrintfToNewString("readdir\1%s\1\1", dir_index_string);
   }
diff --git a/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.c b/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.c
index 76eea39..66b2591 100644
--- a/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.c
+++ b/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.c
@@ -349,7 +349,7 @@ static void Messaging_HandleMessage(PP_Instance instance,
   if (!EnqueueMessage(strdup(buffer))) {
     struct PP_Var var;
     var = PrintfToVar(
-        "Warning: dropped message \"%s\" because the queue was full.", message);
+        "Warning: dropped message \"%s\" because the queue was full.", buffer);
     ppb_messaging_interface->PostMessage(g_instance, var);
   }
 }
diff --git a/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.h b/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.h
index 6eccb5e..b507110 100644
--- a/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.h
+++ b/native_client_sdk/src/examples/demo/nacl_io/nacl_io_demo.h
@@ -7,11 +7,12 @@
 
 #include <stdarg.h>
 #include "ppapi/c/pp_var.h"
+#include "sdk_util/macros.h"  // for PRINTF_LIKE
 
 struct PP_Var CStrToVar(const char* str);
-char* VprintfToNewString(const char* format, va_list args);
-char* PrintfToNewString(const char* format, ...);
-struct PP_Var PrintfToVar(const char* format, ...);
+char* VprintfToNewString(const char* format, va_list args) PRINTF_LIKE(1, 0);
+char* PrintfToNewString(const char* format, ...) PRINTF_LIKE(1, 2);
+struct PP_Var PrintfToVar(const char* format, ...) PRINTF_LIKE(1, 2);
 uint32_t VarToCStr(struct PP_Var var, char* buffer, uint32_t length);
 
 #endif /* NACL_IO_DEMO_H_ */
diff --git a/native_client_sdk/src/libraries/nacl_io/dbgprint.h b/native_client_sdk/src/libraries/nacl_io/dbgprint.h
index 305fea5..91fcf58 100644
--- a/native_client_sdk/src/libraries/nacl_io/dbgprint.h
+++ b/native_client_sdk/src/libraries/nacl_io/dbgprint.h
@@ -9,7 +9,7 @@
 
 EXTERN_C_BEGIN
 
-void dbgprintf(const char* format, ...);
+void dbgprintf(const char* format, ...) PRINTF_LIKE(1, 2);
 
 EXTERN_C_END
 
diff --git a/native_client_sdk/src/libraries/sdk_util/macros.h b/native_client_sdk/src/libraries/sdk_util/macros.h
index e2e5400..b1bc75e 100644
--- a/native_client_sdk/src/libraries/sdk_util/macros.h
+++ b/native_client_sdk/src/libraries/sdk_util/macros.h
@@ -46,4 +46,20 @@
     force_link_##x = 1; \
   }
 
+/**
+ * Macro to error out when a printf-like function is passed incorrect arguments.
+ *
+ * Use like this:
+ * void foo(const char* fmt, ...) PRINTF_LIKE(1, 2);
+ *
+ * The first argument is the location of the fmt string (1-based).
+ * The second argument is the location of the first argument to validate (also
+ *   1-based, but can be zero if the function uses a va_list, like vprintf.)
+ */
+#if defined(__GNUC__)
+#define PRINTF_LIKE(a, b) __attribute__ ((format(printf, a, b)))
+#else
+#define PRINTF_LIKE(a, b)
+#endif
+
 #endif  /* LIBRARIES_SDK_UTIL_MACROS_H_ */