cpp: add PrintWarning() function to errors.h

It provides a single and clean way to output warning messages,
and replaces the fprintf(stderr, "Warning: ...\n") or
fprintf(stderr, "WARNING: ...\n") calls.

Change-Id: I2f8a8f659085b9e57a08b5208a8b8f683a7cd72c
PiperOrigin-RevId: 155386233

src/main/cpp/blaze.cc

@@ -70,6 +70,7 @@
 
 using blaze_util::die;
 using blaze_util::pdie;
+using blaze_util::PrintWarning;
 
 namespace blaze {
 
@@ -641,13 +642,13 @@ static void StartStandalone(const WorkspaceLayout *workspace_layout,
   if (!command_arguments.empty() && command == "shutdown") {
     string product = globals->options->product_name;
     blaze_util::ToLower(&product);
-    fprintf(stderr,
-            "WARNING: Running command \"shutdown\" in batch mode.  Batch mode "
-            "is triggered\nwhen not running %s within a workspace. If you "
-            "intend to shutdown an\nexisting %s server, run \"%s "
-            "shutdown\" from the directory where\nit was started.\n",
-            globals->options->product_name.c_str(),
-            globals->options->product_name.c_str(), product.c_str());
+    PrintWarning(
+        "Running command \"shutdown\" in batch mode.  Batch mode "
+        "is triggered\nwhen not running %s within a workspace. If you "
+        "intend to shutdown an\nexisting %s server, run \"%s "
+        "shutdown\" from the directory where\nit was started.",
+        globals->options->product_name.c_str(),
+        globals->options->product_name.c_str(), product.c_str());
   }
   vector<string> jvm_args_vector = GetArgumentArray();
   if (command != "") {
@@ -1042,10 +1043,10 @@ static void KillRunningServerIfDifferentStartupOptions(BlazeServer *server) {
   // mortal coil.
   if (ServerNeedsToBeKilled(arguments, GetArgumentArray())) {
     globals->restart_reason = NEW_OPTIONS;
-    fprintf(stderr,
-            "WARNING: Running %s server needs to be killed, because the "
-            "startup options are different.\n",
-            globals->options->product_name.c_str());
+    PrintWarning(
+        "Running %s server needs to be killed, because the "
+        "startup options are different.",
+        globals->options->product_name.c_str());
     server->KillRunningServer();
   }
 }
@@ -1233,7 +1234,7 @@ static void ComputeBaseDirectories(const WorkspaceLayout *workspace_layout,
 
 static void CheckEnvironment() {
   if (!blaze::GetEnv("http_proxy").empty()) {
-    fprintf(stderr, "Warning: ignoring http_proxy in environment.\n");
+    PrintWarning("ignoring http_proxy in environment.");
     blaze::UnsetEnv("http_proxy");
   }
 
@@ -1242,18 +1243,18 @@ static void CheckEnvironment() {
     // specified, the JVM fails to create threads.  See thread_stack_regtest.
     // This is also provoked by LD_LIBRARY_PATH=/usr/lib/debug,
     // or anything else that causes the JVM to use LinuxThreads.
-    fprintf(stderr, "Warning: ignoring LD_ASSUME_KERNEL in environment.\n");
+    PrintWarning("ignoring LD_ASSUME_KERNEL in environment.");
     blaze::UnsetEnv("LD_ASSUME_KERNEL");
   }
 
   if (!blaze::GetEnv("LD_PRELOAD").empty()) {
-    fprintf(stderr, "Warning: ignoring LD_PRELOAD in environment.\n");
+    PrintWarning("ignoring LD_PRELOAD in environment.");
     blaze::UnsetEnv("LD_PRELOAD");
   }
 
   if (!blaze::GetEnv("_JAVA_OPTIONS").empty()) {
     // This would override --host_jvm_args
-    fprintf(stderr, "Warning: ignoring _JAVA_OPTIONS in environment.\n");
+    PrintWarning("ignoring _JAVA_OPTIONS in environment.");
     blaze::UnsetEnv("_JAVA_OPTIONS");
   }
 

src/main/cpp/blaze_util_freebsd.cc

@@ -39,6 +39,7 @@ namespace blaze {
 
 using blaze_util::die;
 using blaze_util::pdie;
+using blaze_util::PrintWarning;
 using std::string;
 
 string GetOutputRoot() {
@@ -57,17 +58,16 @@ string GetOutputRoot() {
 void WarnFilesystemType(const string &output_base) {
   struct statfs buf = {};
   if (statfs(output_base.c_str(), &buf) < 0) {
-    fprintf(stderr,
-            "WARNING: couldn't get file system type information for '%s': %s\n",
-            output_base.c_str(), strerror(errno));
+    PrintWaring("couldn't get file system type information for '%s': %s",
+                output_base.c_str(), strerror(errno));
     return;
   }
 
   if (strcmp(buf.f_fstypename, "nfs") == 0) {
-    fprintf(stderr,
-            "WARNING: Output base '%s' is on NFS. This may lead "
-            "to surprising failures and undetermined behavior.\n",
-            output_base.c_str());
+    PrintWarning(
+        "Output base '%s' is on NFS. This may lead "
+        "to surprising failures and undetermined behavior.",
+        output_base.c_str());
   }
 }
 

src/main/cpp/blaze_util_linux.cc

@@ -38,6 +38,7 @@ namespace blaze {
 
 using blaze_util::die;
 using blaze_util::pdie;
+using blaze_util::PrintWarning;
 using std::string;
 using std::vector;
 
@@ -67,16 +68,16 @@ string GetOutputRoot() {
 void WarnFilesystemType(const string& output_base) {
   struct statfs buf = {};
   if (statfs(output_base.c_str(), &buf) < 0) {
-    fprintf(stderr,
-            "WARNING: couldn't get file system type information for '%s': %s\n",
-            output_base.c_str(), strerror(errno));
+    PrintWarning("couldn't get file system type information for '%s': %s",
+                 output_base.c_str(), strerror(errno));
     return;
   }
 
   if (buf.f_type == NFS_SUPER_MAGIC) {
-    fprintf(stderr, "WARNING: Output base '%s' is on NFS. This may lead "
-            "to surprising failures and undetermined behavior.\n",
-            output_base.c_str());
+    PrintWarning(
+        "Output base '%s' is on NFS. This may lead "
+        "to surprising failures and undetermined behavior.",
+        output_base.c_str());
   }
 }
 

src/main/cpp/util/errors.cc

@@ -51,4 +51,14 @@ void PrintError(const char *format, ...) {
   fprintf(stderr, ": %s\n", errormsg);
 }
 
+void PrintWarning(const char *format, ...) {
+  va_list args;
+
+  va_start(args, format);
+  fputs("WARNING: ", stderr);
+  vfprintf(stderr, format, args);
+  fputc('\n', stderr);
+  va_end(args);
+}
+
 }  // namespace blaze_util

src/main/cpp/util/errors.h

@@ -30,6 +30,7 @@ void die(const int exit_status, const char *format, ...) ATTRIBUTE_NORETURN
 void pdie(const int exit_status, const char *format, ...) ATTRIBUTE_NORETURN
     PRINTF_ATTRIBUTE(2, 3);
 void PrintError(const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
+void PrintWarning(const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
 
 // Returns the last error as a platform-specific error message.
 // The string will also contain the platform-specific error code itself