commit 9a512c978339fdb5d0712fe0746bfc881de6de56
author William A. Kennington III <wak@google.com> Fri Aug 12 15:15:55 2022 -0700
committer William A. Kennington III <wak@google.com> Tue Aug 16 13:04:33 2022 -0700
tree 9f245db9a42ebb3747f36780c2b196770cf56b2a
parent 42827deb280a4fbe22d044bf58831476415340ad

fd/line: Add line buffered reader

This gives us similar functionality to std::getline but on stdplus::Fd
instances. Also more predictable behavior around newlines at the end of
a file.

Change-Id: I19039c15fa02019e4ad767ca8a1996a8417fdd86
Signed-off-by: William A. Kennington III <wak@google.com>

test/fd/line.cpp

diff --git a/test/fd/line.cpp b/test/fd/line.cpp
new file mode 100644
index 0000000..8d9eb32
--- /dev/null
+++ b/test/fd/line.cpp
@@ -0,0 +1,98 @@
+#include <gtest/gtest.h>
+#include <stdplus/exception.hpp>
+#include <stdplus/fd/gmock.hpp>
+#include <stdplus/fd/line.hpp>
+#include <stdplus/fd/managed.hpp>
+#include <stdplus/fd/ops.hpp>
+#include <stdplus/raw.hpp>
+#include <stdplus/util/cexec.hpp>
+#include <string_view>
+#include <sys/mman.h>
+
+namespace stdplus
+{
+namespace fd
+{
+
+ManagedFd makeMemfd(std::string_view contents)
+{
+    auto fd = ManagedFd(CHECK_ERRNO(memfd_create("test", 0), "memfd_create"));
+    write(fd, contents);
+    lseek(fd, 0, Whence::Set);
+    return fd;
+}
+
+TEST(LineReader, Empty)
+{
+    auto fd = makeMemfd("");
+    LineReader reader(fd);
+    EXPECT_EQ("", *reader.readLine());
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+}
+
+TEST(LineReader, SingleLine)
+{
+    auto fd = makeMemfd("\n");
+    LineReader reader(fd);
+    EXPECT_EQ("", *reader.readLine());
+    EXPECT_EQ("", *reader.readLine());
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+}
+
+TEST(LineReader, SomeData)
+{
+    auto fd = makeMemfd("A\nbcd\n\ne");
+    LineReader reader(fd);
+    EXPECT_EQ("A", *reader.readLine());
+    EXPECT_EQ("bcd", *reader.readLine());
+    EXPECT_EQ("", *reader.readLine());
+    EXPECT_EQ("e", *reader.readLine());
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+}
+
+TEST(LineReader, LargerThanBuf)
+{
+    std::string big(LineReader::buf_size + 10, 'a');
+    auto fd = makeMemfd(std::string("alpha\n") + big + "\ndef");
+    LineReader reader(fd);
+    EXPECT_EQ("alpha", *reader.readLine());
+    EXPECT_EQ(big, *reader.readLine());
+    EXPECT_EQ("def", *reader.readLine());
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+}
+
+using testing::_;
+
+inline auto readSv(std::string_view s)
+{
+    return [s](std::span<std::byte> buf) {
+        memcpy(buf.data(), s.data(), s.size());
+        return buf.subspan(0, s.size());
+    };
+}
+
+TEST(LineReader, Nonblock)
+{
+    FdMock fd;
+    {
+        testing::InSequence seq;
+        EXPECT_CALL(fd, read(_)).WillOnce(readSv("alph"));
+        EXPECT_CALL(fd, read(_)).WillOnce(readSv({}));
+        EXPECT_CALL(fd, read(_)).WillOnce(readSv("a"));
+        EXPECT_CALL(fd, read(_))
+            .WillRepeatedly(testing::Throw(stdplus::exception::Eof("test")));
+    }
+
+    LineReader reader(fd);
+    EXPECT_EQ(nullptr, reader.readLine());
+    EXPECT_EQ("alpha", *reader.readLine());
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+    EXPECT_THROW(reader.readLine(), exception::Eof);
+}
+
+} // namespace fd
+} // namespace stdplus

test/meson.build

diff --git a/test/meson.build b/test/meson.build
index 4ebf17f..a0be742 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -33,6 +33,7 @@
     'fd/managed',
     'fd/intf',
     'fd/impl',
+    'fd/line',
     'fd/mmap',
     'fd/mock',
     'fd/ops',