Add a file reading utility function
Going to use this for parsing config protobufs.
Change-Id: I471030b31dcf0450d40566560b3ce7338e7a7d21
diff --git a/aos/common/util/BUILD b/aos/common/util/BUILD
index 4437ef6..b62e93c 100644
--- a/aos/common/util/BUILD
+++ b/aos/common/util/BUILD
@@ -220,3 +220,29 @@
'//aos/testing:test_logging',
],
)
+
+cc_library(
+ name = 'file',
+ hdrs = [
+ 'file.h',
+ ],
+ srcs = [
+ 'file.cc',
+ ],
+ deps = [
+ '//aos/common:scoped_fd',
+ ],
+)
+
+cc_test(
+ name = 'file_test',
+ srcs = [
+ 'file_test.cc',
+ ],
+ deps = [
+ ':file',
+ '//aos/testing:googletest',
+ '//aos/testing:test_logging',
+ ],
+ size = 'small',
+)
diff --git a/aos/common/util/file.cc b/aos/common/util/file.cc
new file mode 100644
index 0000000..4c859cf
--- /dev/null
+++ b/aos/common/util/file.cc
@@ -0,0 +1,28 @@
+#include "aos/common/util/file.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "aos/common/scoped_fd.h"
+
+namespace aos {
+namespace util {
+
+::std::string ReadFileToStringOrDie(const ::std::string &filename) {
+ ::std::string r;
+ ScopedFD fd(PCHECK(open(filename.c_str(), O_RDONLY)));
+ while (true) {
+ char buffer[1024];
+ const ssize_t result = read(fd.get(), buffer, sizeof(buffer));
+ if (result < 0) {
+ PLOG(FATAL, "reading from %s", filename.c_str());
+ } else if (result == 0) {
+ break;
+ }
+ r.append(buffer, result);
+ }
+ return r;
+}
+
+} // namespace util
+} // namespace aos
diff --git a/aos/common/util/file.h b/aos/common/util/file.h
new file mode 100644
index 0000000..a32d0a7
--- /dev/null
+++ b/aos/common/util/file.h
@@ -0,0 +1,16 @@
+#ifndef AOS_COMMON_UTIL_FILE_H_
+#define AOS_COMMON_UTIL_FILE_H_
+
+#include <string>
+
+namespace aos {
+namespace util {
+
+// Returns the complete contents of filename. LOG(FATAL)s if any errors are
+// encountered.
+::std::string ReadFileToStringOrDie(const ::std::string &filename);
+
+} // namespace util
+} // namespace aos
+
+#endif // AOS_COMMON_UTIL_FILE_H_
diff --git a/aos/common/util/file_test.cc b/aos/common/util/file_test.cc
new file mode 100644
index 0000000..12a4976
--- /dev/null
+++ b/aos/common/util/file_test.cc
@@ -0,0 +1,40 @@
+#include "aos/common/util/file.h"
+
+#include <stdlib.h>
+
+#include <string>
+
+#include "gtest/gtest.h"
+
+#include "aos/testing/test_logging.h"
+
+namespace aos {
+namespace util {
+namespace testing {
+
+class FileTest : public ::testing::Test {
+ protected:
+ FileTest() {
+ ::aos::testing::EnableTestLogging();
+ }
+};
+
+// Basic test of reading a normal file.
+TEST_F(FileTest, ReadNormalFile) {
+ const ::std::string tmpdir(getenv("TEST_TMPDIR"));
+ const ::std::string test_file = tmpdir + "/test_file";
+ ASSERT_EQ(0, system(("echo contents > " + test_file).c_str()));
+ EXPECT_EQ("contents\n", ReadFileToStringOrDie(test_file));
+}
+
+// Tests reading a file with 0 size, among other weird things.
+TEST_F(FileTest, ReadSpecialFile) {
+ const ::std::string stat = ReadFileToStringOrDie("/proc/self/stat");
+ EXPECT_EQ('\n', stat[stat.size() - 1]);
+ const ::std::string my_pid = ::std::to_string(getpid());
+ EXPECT_EQ(my_pid, stat.substr(0, my_pid.size()));
+}
+
+} // namespace testing
+} // namespace util
+} // namespace aos