Add <error.h>.

Bug: https://code.google.com/p/android/issues/detail?id=79170
Change-Id: Id91765fac45124545e2674a5b2c814707c1a448b
diff --git a/libc/Android.mk b/libc/Android.mk
index 71ddbd3..522d514 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -112,6 +112,7 @@
     bionic/epoll_pwait.cpp \
     bionic/epoll_wait.cpp \
     bionic/__errno.cpp \
+    bionic/error.cpp \
     bionic/eventfd_read.cpp \
     bionic/eventfd_write.cpp \
     bionic/ffs.cpp \
diff --git a/libc/bionic/error.cpp b/libc/bionic/error.cpp
new file mode 100644
index 0000000..9f4d0ee
--- /dev/null
+++ b/libc/bionic/error.cpp
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <error.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+unsigned int error_message_count = 0;
+void (*error_print_progname)(void) = NULL;
+int error_one_per_line = 0;
+
+static void __error_head() {
+  ++error_message_count;
+
+  if (error_print_progname != NULL) {
+    error_print_progname();
+  } else {
+    fflush(stdout);
+    fprintf(stderr, "%s:", getprogname());
+  }
+}
+
+static void __error_tail(int status, int error) {
+  if (error != 0) {
+    fprintf(stderr, ": %s", strerror(error));
+  }
+
+  putc('\n', stderr);
+  fflush(stderr);
+
+  if (status != 0) {
+    exit(status);
+  }
+}
+
+void error(int status, int error, const char* fmt, ...) {
+  __error_head();
+  putc(' ', stderr);
+
+  va_list ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+
+  __error_tail(status, error);
+}
+
+void error_at_line(int status, int error, const char* file, unsigned int line, const char* fmt, ...) {
+  if (error_one_per_line) {
+    static const char* last_file;
+    static unsigned int last_line;
+    if (last_line == line && last_file != NULL && strcmp(last_file, file) == 0) {
+      return;
+    }
+    last_file = file;
+    last_line = line;
+  }
+
+  __error_head();
+  fprintf(stderr, "%s:%d: ", file, line);
+
+  va_list ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+
+  __error_tail(status, error);
+}
diff --git a/libc/include/error.h b/libc/include/error.h
new file mode 100644
index 0000000..dd12884
--- /dev/null
+++ b/libc/include/error.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _ERROR_H
+#define _ERROR_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+void error(int, int, const char*, ...) __printflike(3, 4);
+void error_at_line(int, int, const char*, unsigned int, const char*, ...) __printflike(5, 6);
+
+extern void (*error_print_progname)(void);
+extern unsigned int error_message_count;
+extern int error_one_per_line;
+
+__END_DECLS
+
+#endif
diff --git a/tests/Android.mk b/tests/Android.mk
index 87c330b..9304d46 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -57,6 +57,7 @@
     complex_test.cpp \
     ctype_test.cpp \
     dirent_test.cpp \
+    error_test.cpp \
     eventfd_test.cpp \
     fcntl_test.cpp \
     fenv_test.cpp \
diff --git a/tests/error_test.cpp b/tests/error_test.cpp
new file mode 100644
index 0000000..5fee16f
--- /dev/null
+++ b/tests/error_test.cpp
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <gtest/gtest.h>
+
+#include <error.h>
+
+#include "BionicDeathTest.h"
+
+static size_t g_test_error_print_progname_invocation_count;
+
+static void test_error_print_progname() {
+  ++g_test_error_print_progname_invocation_count;
+}
+
+TEST(error, smoke) {
+  error_message_count = 0;
+  error(0, 0, "oops");
+  ASSERT_EQ(1U, error_message_count);
+  error(0, ENOENT, "couldn't open file '%s'", "blah");
+  ASSERT_EQ(2U, error_message_count);
+
+  error_print_progname = test_error_print_progname;
+  g_test_error_print_progname_invocation_count = 0;
+  error(0, 0, "oops");
+  ASSERT_EQ(1U, g_test_error_print_progname_invocation_count);
+
+  error_at_line(0, 0, "blah.c", 123, "hello %s", "world");
+
+  error_print_progname = NULL;
+}
+
+TEST(error_DeathTest, error_exit) {
+  ASSERT_EXIT(error(22, 0, "x%c", 'y'), ::testing::ExitedWithCode(22), "xy");
+}
+
+TEST(error_DeathTest, error_exit_with_errno) {
+  ASSERT_EXIT(error(22, EBADF, "x%c", 'y'), ::testing::ExitedWithCode(22), ": xy: Bad file descriptor");
+}
+
+TEST(error_DeathTest, error_at_line_exit) {
+  ASSERT_EXIT(error_at_line(22, 0, "a.c", 123, "x%c", 'y'), ::testing::ExitedWithCode(22), ":a.c:123: xy");
+}
+
+TEST(error_DeathTest, error_at_line_exit_with_errno) {
+  ASSERT_EXIT(error_at_line(22, EBADF, "a.c", 123, "x%c", 'y'), ::testing::ExitedWithCode(22), ":a.c:123: xy: Bad file descriptor");
+}