Prefix error messages with program name.

It make it easier while debugging to know who is reporting the error:
Ninja itself or one of the command called by Ninja during the build
process or one of the generator which called Ninja.

3 files changed, 23 insertions, 10 deletions

diff --git a/src/ninja.cc b/src/ninja.cc
index c113bfb..35d25e0 100644
--- a/src/ninja.cc
+++ b/src/ninja.cc
@@ -34,6 +34,7 @@
 #include "graph.h"
 #include "graphviz.h"
 #include "parsers.h"
+#include "util.h"
 
 option options[] = {
   { "help", no_argument, NULL, 'h' },
@@ -164,7 +165,7 @@ int main(int argc, char** argv) {
     }
   }
   if (optind >= argc) {
-    fprintf(stderr, "expected target to build\n");
+    Error("expected target to build");
     usage(config);
     return 1;
   }
@@ -182,7 +183,7 @@ int main(int argc, char** argv) {
   ManifestParser parser(&state, &file_reader);
   string err;
   if (!parser.Load(input_file, &err)) {
-    fprintf(stderr, "error loading '%s': %s\n", input_file, err.c_str());
+    Error("loading '%s': %s", input_file, err.c_str());
     return 1;
   }
 
@@ -193,7 +194,7 @@ int main(int argc, char** argv) {
       return CmdQuery(&state, argc, argv);
     if (tool == "browse")
       return CmdBrowse(&state, argc, argv);
-    fprintf(stderr, "unknown tool '%s'\n", tool.c_str());
+    Error("unknown tool '%s'", tool.c_str());
   }
 
   BuildLog build_log;
@@ -205,21 +206,21 @@ int main(int argc, char** argv) {
   string log_path = kLogPath;
   if (!build_dir.empty()) {
     if (mkdir(build_dir.c_str(), 0777) < 0 && errno != EEXIST) {
-      fprintf(stderr, "Error creating build directory %s: %s\n",
-              build_dir.c_str(), strerror(errno));
+      Error("creating build directory %s: %s",
+            build_dir.c_str(), strerror(errno));
       return 1;
     }
     log_path = build_dir + "/" + kLogPath;
   }
 
   if (!build_log.Load(log_path.c_str(), &err)) {
-    fprintf(stderr, "error loading build log %s: %s\n",
-            log_path.c_str(), err.c_str());
+    Error("loading build log %s: %s",
+          log_path.c_str(), err.c_str());
     return 1;
   }
 
   if (!build_log.OpenForWrite(log_path.c_str(), &err)) {
-    fprintf(stderr, "error opening build log: %s\n", err.c_str());
+    Error("opening build log: %s", err.c_str());
     return 1;
   }
 
@@ -227,7 +228,7 @@ int main(int argc, char** argv) {
   for (int i = 0; i < argc; ++i) {
     if (!builder.AddTarget(argv[i], &err)) {
       if (!err.empty()) {
-        fprintf(stderr, "%s\n", err.c_str());
+        Error("%s", err.c_str());
         return 1;
       } else {
         // Added a target that is already up-to-date; not really
diff --git a/src/util.cc b/src/util.cc
index 1968702..a2e080f 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -20,10 +20,19 @@
 
 void Fatal(const char* msg, ...) {
   va_list ap;
-  fprintf(stderr, "FATAL: ");
+  fprintf(stderr, "ninja: FATAL: ");
   va_start(ap, msg);
   vfprintf(stderr, msg, ap);
   va_end(ap);
   fprintf(stderr, "\n");
   exit(1);
 }
+
+void Error(const char* msg, ...) {
+  va_list ap;
+  fprintf(stderr, "ninja: error: ");
+  va_start(ap, msg);
+  vfprintf(stderr, msg, ap);
+  va_end(ap);
+  fprintf(stderr, "\n");
+}
diff --git a/src/util.h b/src/util.h
index 188528c..e697b92 100644
--- a/src/util.h
+++ b/src/util.h
@@ -19,3 +19,6 @@ void DumpBacktrace(int skip_frames);
 
 // Log a fatal message, dump a backtrace, and exit.
 void Fatal(const char* msg, ...);
+
+// Log an error message.
+void Error(const char* msg, ...);