annotate checker/plugincandidates.h @ 24:24b1d94440f5

Debug output improvements, and make the checker actually attempt to call the descriptor function for known plugin types

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
/*
    Copyright (c) 2016 Queen Mary, University of London

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    obtaining a copy of this software and associated documentation
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*/

#ifndef PLUGIN_CANDIDATES_H
#define PLUGIN_CANDIDATES_H

#include <string>
#include <vector>
#include <map>

/**
 * Class to identify and list candidate shared-library files possibly
 * containing plugins. Uses a separate process (the "helper", whose
 * executable name must be provided at construction) to test-load each
 * library in order to winnow out any that fail to load or crash on
 * load.
 *
 * Requires C++11 and the Qt5 QtCore library.
 */
class PluginCandidates
{
    typedef std::vector<std::string> stringlist;

public:
    /** Construct a PluginCandidates scanner that uses the given
     *  executable as its load check helper.
     */
    PluginCandidates(std::string helperExecutableName);

    struct LogCallback {
        virtual ~LogCallback() { }

        /// implementation is responsible for adding \n and flushing output
        virtual void log(std::string) = 0;
    };
    
    /** Set a callback to be called for log output.
     */
    void setLogCallback(LogCallback *cb);

    /** Scan the libraries found in the given plugin path (i.e. list
     *  of plugin directories), checking that the given descriptor
     *  symbol can be looked up in each. Store the results
     *  internally, associated with the given (arbitrary) tag, for
     *  later querying using getCandidateLibrariesFor() and
     *  getFailedLibrariesFor().
     *
     *  Not thread-safe.
     */
    void scan(std::string tag,
              stringlist pluginPath,
              std::string descriptorSymbolName);

    /** Return list of plugin library paths that were checked
     *  successfully during the scan for the given tag.
     */
    stringlist getCandidateLibrariesFor(std::string tag) const;

    struct FailureRec {
        std::string library;
        std::string message;
    };

    /** Return list of failure reports arising from the prior scan for
     *  the given tag. 
     */
    std::vector<FailureRec> getFailedLibrariesFor(std::string tag) const;

private:
    std::string m_helper;
    std::map<std::string, stringlist> m_candidates;
    std::map<std::string, std::vector<FailureRec> > m_failures;
    LogCallback *m_logCallback;

    stringlist getLibrariesInPath(stringlist path);
    stringlist runHelper(stringlist libraries, std::string descriptor);
    void recordResult(std::string tag, stringlist results);
    void log(std::string);
};

#endif