ClickHouse

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#include "ICommand.h"
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#include <Interpreters/Context.h>
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#include <IO/ReadBufferFromFile.h>
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#include <IO/WriteBufferFromFile.h>
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#include <IO/copyData.h>
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#include <Common/TerminalSize.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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    extern const int BAD_ARGUMENTS;
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}
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class CommandRead final : public ICommand
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{
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public:
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    CommandRead()
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    {
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        command_name = "read";
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        command_option_description.emplace(createOptionsDescription("Allowed options", getTerminalWidth()));
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        description = "Read a file from `FROM_PATH` to `TO_PATH`";
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        usage = "read [OPTION]... <FROM_PATH> [<TO_PATH>]";
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        command_option_description->add_options()
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            ("output", po::value<String>(), "file to which we are reading, defaults to `stdout`");
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    }
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    void processOptions(
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        Poco::Util::LayeredConfiguration & config,
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        po::variables_map & options) const override
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    {
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        if (options.count("output"))
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            config.setString("output", options["output"].as<String>());
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    }
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    void execute(
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        const std::vector<String> & command_arguments,
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       std::shared_ptr<DiskSelector> & disk_selector,
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        Poco::Util::LayeredConfiguration & config) override
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    {
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        if (command_arguments.size() != 1)
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        {
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            printHelpMessage();
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            throw DB::Exception(DB::ErrorCodes::BAD_ARGUMENTS, "Bad Arguments");
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        }
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        String disk_name = config.getString("disk", "default");
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        DiskPtr disk = disk_selector->get(disk_name);
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        String relative_path = validatePathAndGetAsRelative(command_arguments[0]);
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        String path_output = config.getString("output", "");
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        if (!path_output.empty())
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        {
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            String relative_path_output = validatePathAndGetAsRelative(path_output);
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            auto in = disk->readFile(relative_path);
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            auto out = disk->writeFile(relative_path_output);
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            copyData(*in, *out);
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            out->finalize();
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        }
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        else
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        {
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            auto in = disk->readFile(relative_path);
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            std::unique_ptr<WriteBufferFromFileBase> out = std::make_unique<WriteBufferFromFileDescriptor>(STDOUT_FILENO);
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            copyData(*in, *out);
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        }
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    }
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};
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}
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std::unique_ptr <DB::ICommand> makeCommandRead()
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{
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    return std::make_unique<DB::CommandRead>();
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}
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