Add log file option

readme.md

@@ -175,6 +175,7 @@ usage: ashuffle [-h] [-n] [-v] [[-e PATTERN ...] ...] [-o NUMBER]
 
 Optional Arguments:
    -h,-?,--help      Display this help message.
+   --by-album        Same as '--group-by album date'.
    -e,--exclude      Specify things to remove from shuffle (think
                      blacklist). A PATTERN should follow the exclude
                      flag.
@@ -186,13 +187,13 @@ Optional Arguments:
                      filename to retrive URI's from standard in. This
                      can be used to pipe song URI's from another program
                      into ashuffle.
-   --by-album        Same as '--group-by album date'.
    -g,--group-by     Shuffle songs grouped by the given tags. For
                      example 'album' could be used as the tag, and an
                      entire album's worth of songs would be queued
                      instead of one song at a time.
    --host            Specify a hostname or IP address to connect to.
                      Defaults to `localhost`.
+   --log-file        Path to write log output to. Defaults to stderr.
    -n,--no-check     When reading URIs from a file, don't check to
                      ensure that the URIs match the given exclude rules.
                      This option is most helpful when shuffling songs

src/args.cc

@@ -28,6 +28,7 @@ constexpr char kHelpMessage[] =
     "\n"
     "Optional Arguments:\n"
     "   -h,-?,--help      Display this help message.\n"
+    "   --by-album        Same as '--group-by album date'.\n"
     "   -e,--exclude      Specify things to remove from shuffle (think\n"
     "                     blacklist). A PATTERN should follow the exclude\n"
     "                     flag.\n"
@@ -39,13 +40,13 @@ constexpr char kHelpMessage[] =
     "                     filename to retrive URI's from standard in. This\n"
     "                     can be used to pipe song URI's from another program\n"
     "                     into ashuffle.\n"
-    "   --by-album        Same as '--group-by album date'.\n"
     "   -g,--group-by     Shuffle songs grouped by the given tags. For\n"
     "                     example 'album' could be used as the tag, and an\n"
     "                     entire album's worth of songs would be queued\n"
     "                     instead of one song at a time.\n"
     "   --host            Specify a hostname or IP address to connect to.\n"
     "                     Defaults to `localhost`.\n"
+    "   --log-file        Path to write log output to. Defaults to stderr.\n"
     "   -n,--no-check     When reading URIs from a file, don't check to\n"
     "                     ensure that the URIs match the given exclude rules.\n"
     "                     This option is most helpful when shuffling songs\n"
@@ -111,6 +112,7 @@ class Parser {
         kGroup,        // (generic) Expecting tag for group.
         kGroupBegin,   // Expecting first tag for group.
         kHost,         // Expecting hostname
+        kLogFile,      // Expecting file path to log file.
         kNone,         // (generic) Default state, and initial state.
         kPort,         // Expecting port
         kQueue,        // Expecting --only value
@@ -413,6 +415,9 @@ std::variant<Parser::State, ParseError> Parser::ConsumeInternal(
         if (arg == "--exclude-from") {
             return kExcludeFile;
         }
+        if (arg == "--log-file") {
+            return kLogFile;
+        }
     }
     switch (state_) {
         case kExcludeFile:
@@ -434,6 +439,11 @@ std::variant<Parser::State, ParseError> Parser::ConsumeInternal(
         case kHost:
             opts_.host = arg;
             return kNone;
+        case kLogFile: {
+            std::string filepath(arg);
+            opts_.InternalTakeLog(std::make_unique<std::ofstream>(filepath));
+            return kNone;
+        }
         case kPort:
             if (!absl::SimpleAtoi(arg, &opts_.port)) {
                 return ParseError(

src/args.h

@@ -35,6 +35,7 @@ class Options {
     std::vector<Rule> ruleset;
     unsigned queue_only = 0;
     std::istream *file_in = nullptr;
+    std::ostream *log_file = nullptr;
     bool check_uris = true;
     unsigned queue_buffer = 0;
     std::optional<std::string> host = {};
@@ -89,12 +90,21 @@ class Options {
         owned_file_ = std::move(is);
     };
 
+    // Same as InternalTakeIstream but for the log file ostream.
+    void InternalTakeLog(std::unique_ptr<std::ostream> &&os) {
+        log_file = os.get();
+        owned_log_file_ = std::move(os);
+    }
+
    private:
     // The owned_file is set if this Options class owns the file_in ptr.
     // The file_in ptr is only *sometimes* owned. For example, the file_in ptr
     // may point to std::cin, which has static lifetime, and is not owned by
     // this object.
     std::unique_ptr<std::istream> owned_file_;
+
+    // Same as above.
+    std::unique_ptr<std::ostream> owned_log_file_;
 };
 
 // Print the help message on the given output stream, and return the input

src/main.cc

@@ -88,7 +88,12 @@ int main(int argc, const char* argv[]) {
         exit(EXIT_FAILURE);
     }
 
-    log::SetOutput(std::cerr);
+    if (options.log_file == nullptr) {
+        // By default, log to stderr.
+        log::SetOutput(std::cerr);
+    } else {
+        log::SetOutput(*options.log_file);
+    }
 
     bool disable_reconnect = false;
     std::function<std::string()> pass_f = [&disable_reconnect] {

t/args_test.cc

@@ -10,6 +10,7 @@
 #include <mpd/tag.h>
 
 #include "args.h"
+#include "gmock/gmock.h"
 #include "rule.h"
 
 #include "t/helper.h"
@@ -40,6 +41,7 @@ TEST(ParseTest, Empty) {
     EXPECT_TRUE(opts.ruleset.empty()) << "there should be no rules by default";
     EXPECT_EQ(opts.queue_only, 0U);
     EXPECT_THAT(opts.file_in, IsNull());
+    EXPECT_THAT(opts.log_file, IsNull());
     EXPECT_TRUE(opts.check_uris);
     EXPECT_EQ(opts.queue_buffer, 0U);
     EXPECT_EQ(opts.host, std::nullopt);
@@ -96,6 +98,7 @@ TEST(ParseTest, Long) {
             "--only", "5",
             "--no-check",
             "--file", "/dev/zero",
+            "--log-file", "/dev/null",
             "--exclude", "artist", "test artist", "artist", "another one",
             "--queue-buffer", "10",
             "--host", "foo",
@@ -113,6 +116,7 @@ TEST(ParseTest, Long) {
     EXPECT_EQ(opts.ruleset.size(), 1U);
     EXPECT_EQ(opts.queue_only, 5U);
     EXPECT_THAT(opts.file_in, NotNull());
+    EXPECT_THAT(opts.log_file, NotNull());
     EXPECT_FALSE(opts.check_uris);
     EXPECT_EQ(opts.queue_buffer, 10U);
     EXPECT_EQ(opts.host, "foo");