/*
 * Copyright 2004-2009, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Distributed under the terms of the MIT License.
 */


#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <list>
#include <stack>
#include <string>
#include <string.h>
#include <vector>

#include "gensyscalls_common.h"

#include "arch_gensyscalls.h"
        // for the alignment type macros (only for the type names)

#ifndef SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE
#define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE SYSCALL_PARAMETER_ALIGNMENT_TYPE
#endif


// macro trickery to create a string literal
#define MAKE_STRING(x)  #x
#define EVAL_MACRO(macro, x) macro(x)


const char* kUsage =
        "Usage: gensyscallinfos <header> <syscall infos> <syscall types sizes>\n"
        "\n"
        "Given the (preprocessed) header file that defines the syscall prototypes "
                "the\n"
        "command generates a source file consisting of syscall infos, which is "
                "needed\n"
        "to build gensyscalls, which in turn generates the assembly syscall\n"
        "definitions and code for the kernelland syscall dispatcher.\n"
        "\n"
        "  <header>               - Input: The preprocessed header file with the\n"
        "                           syscall prototypes.\n"
        "  <syscall infos>        - Output: The syscall infos source file needed "
                "to\n"
        "                           build gensyscalls.\n"
        "  <syscall types sizes>  - Output: A source file that will by another "
                "build\n"
        "                           step turned into a header file included by\n"
        "                           <syscall infos>.\n";


static void
print_usage(bool error)
{
        fputs(kUsage, (error ? stderr : stdout));
}


struct Type {
        Type(const char* type) : type(type) {}
        Type(const string& type) : type(type) {}

        string type;
};


struct NamedType : Type {
        NamedType(const char* type, const char* name)
                : Type(type), name(name) {}
        NamedType(const string& type, const string& name)
                : Type(type), name(name) {}

        string name;
};


class Function {
public:
        Function() : fReturnType("") {}

        void SetName(const string& name)
        {
                fName = name;
        }

        const string& GetName() const
        {
                return fName;
        }

        void AddParameter(const NamedType& type)
        {
                fParameters.push_back(type);
        }

        int CountParameters() const
        {
                return fParameters.size();
        }

        const NamedType& ParameterAt(int index) const
        {
                return fParameters[index];
        }

        void SetReturnType(const Type& type)
        {
                fReturnType = type;
        }

        const Type& GetReturnType() const
        {
                return fReturnType;
        }

protected:
        string                          fName;
        vector<NamedType>       fParameters;
        Type                            fReturnType;
};


class Syscall : public Function {
public:
        string GetKernelName() const
        {
                int baseIndex = 0;
                if (fName.find("_kern_") == 0)
                        baseIndex = strlen("_kern_");
                else if (fName.find("sys_") == 0)
                        baseIndex = strlen("sys_");
                string kernelName("_user_");
                kernelName.append(string(fName, baseIndex));
                return kernelName;
        }
};


class Tokenizer {
public:
        Tokenizer(istream& input)
                : fInput(input),
                  fHasCurrent(false)
        {
        }

        string GetCurrentToken()
        {
                if (!fHasCurrent)
                        throw Exception("GetCurrentToken(): No current token!");
                return fTokens.front();
        }

        string GetNextToken()
        {
                return GetNextToken(NULL);
        }

        string GetNextToken(stack<string>& skippedTokens)
        {
                return GetNextToken(&skippedTokens);
        }

        string GetNextToken(stack<string>* skippedTokens)
        {
                if (fHasCurrent) {
                        fTokens.pop_front();
                        fHasCurrent = false;
                }
                while (fTokens.empty())
                        _ReadLine();
                fHasCurrent = true;
                if (skippedTokens)
                        skippedTokens->push(fTokens.front());
                return fTokens.front();
        }

        void ExpectToken(const string& expectedToken)
        {
                string token = GetCurrentToken();
                if (expectedToken != token) {
                        throw ParseException(string("Unexpected token `") + token
                                + "'. Expected was `" + expectedToken + "'.");
                }
        }

        void ExpectNextToken(const string& expectedToken)
        {
                GetNextToken();
                ExpectToken(expectedToken);
        }

        bool CheckToken(const string& expectedToken)
        {
                string token = GetCurrentToken();
                return (expectedToken == token);
        }

        bool CheckNextToken(const string& expectedToken)
        {
                GetNextToken();
                bool result = CheckToken(expectedToken);
                if (!result)
                        PutCurrentToken();
                return result;
        }

        void PutCurrentToken()
        {
                if (!fHasCurrent)
                        throw Exception("GetCurrentToken(): No current token!");
                fHasCurrent = false;
        }

        void PutToken(string token)
        {
                if (fHasCurrent) {
                        fTokens.pop_front();
                        fHasCurrent = false;
                }
                fTokens.push_front(token);
        }

        void PutTokens(stack<string>& tokens)
        {
                if (fHasCurrent) {
                        fTokens.pop_front();
                        fHasCurrent = false;
                }
                while (!tokens.empty()) {
                        fTokens.push_front(tokens.top());
                        tokens.pop();
                }
        }

private:
        void _ReadLine()
        {
                // read the line
                char buffer[10240];
                if (!fInput.getline(buffer, sizeof(buffer)))
                        throw EOFException("Unexpected end of input.");
                // parse it
                vector<string> line;
                int len = strlen(buffer);
                int tokenStart = 0;
                for (int i = 0; i < len; i++) {
                        char c = buffer[i];
                        if (isspace(c)) {
                                if (tokenStart < i)
                                        line.push_back(string(buffer + tokenStart, buffer + i));
                                tokenStart = i + 1;
                                continue;
                        }
                        switch (buffer[i]) {
                                case '#':
                                case '(':
                                case ')':
                                case '*':
                                case '&':
                                case '[':
                                case ']':
                                case ';':
                                case ',':
                                        if (tokenStart < i) {
                                                line.push_back(string(buffer + tokenStart,
                                                                                                 buffer + i));
                                        }
                                        line.push_back(string(buffer + i, buffer + i + 1));
                                        tokenStart = i + 1;
                                        break;
                        }
                }
                if (tokenStart < len)
                        line.push_back(string(buffer + tokenStart, buffer + len));
                // drop the line, if it starts with "# <number>", as those are
                // directions from the pre-processor to the compiler
                if (line.size() >= 2) {
                        if (line[0] == "#" && isdigit(line[1][0]))
                                return;
                }
                for (int i = 0; i < (int)line.size(); i++)
                        fTokens.push_back(line[i]);
        }

private:
        istream&                fInput;
        list<string>    fTokens;
        bool                    fHasCurrent;
};


class Main {
public:

        int Run(int argc, char** argv)
        {
                // parse parameters
                if (argc >= 2
                        && (string(argv[1]) == "-h" || string(argv[1]) == "--help")) {
                        print_usage(false);
                        return 0;
                }
                if (argc != 4) {
                        print_usage(true);
                        return 1;
                }
                _ParseSyscalls(argv[1]);
                _WriteSyscallInfoFile(argv[2]);
                _WriteSyscallTypeSizes(argv[3]);
                return 0;
        }

private:
        void _ParseSyscalls(const char* filename)
        {
                // open the input file
                ifstream file(filename, ifstream::in);
                if (!file.is_open())
                        throw IOException(string("Failed to open `") + filename + "'.");
                // parse the syscalls
                Tokenizer tokenizer(file);
                // find "#pragma syscalls begin"
                while (true) {
                        while (tokenizer.GetNextToken() != "#");
                        stack<string> skippedTokens;
                        if (tokenizer.GetNextToken(skippedTokens) == "pragma"
                                && tokenizer.GetNextToken(skippedTokens) == "syscalls"
                                && tokenizer.GetNextToken(skippedTokens) == "begin") {
                                break;
                        }
                        tokenizer.PutTokens(skippedTokens);
                }
                // parse the functions
                while (!tokenizer.CheckNextToken("#")) {
                        Syscall syscall;
                        _ParseSyscall(tokenizer, syscall);
                        fSyscalls.push_back(syscall);
                }
                // expect "pragma syscalls end"
                tokenizer.ExpectNextToken("pragma");
                tokenizer.ExpectNextToken("syscalls");
                tokenizer.ExpectNextToken("end");
        }

        void _WriteSyscallInfoFile(const char* filename)
        {
                // open the syscall info file
                ofstream file(filename, ofstream::out | ofstream::trunc);
                if (!file.is_open())
                        throw IOException(string("Failed to open `") + filename + "'.");

                // write preamble
                file << "#include \"gensyscalls.h\"" << endl;
                file << "#include \"syscall_types_sizes.h\"" << endl;
                file << endl;

                file << "const char* const kReturnTypeAlignmentType = \""
                        EVAL_MACRO(MAKE_STRING, SYSCALL_RETURN_TYPE_ALIGNMENT_TYPE)
                        << "\";" << endl;
                file << "const char* const kParameterAlignmentType = \""
                        EVAL_MACRO(MAKE_STRING, SYSCALL_PARAMETER_ALIGNMENT_TYPE)
                        << "\";" << endl;
                file << "const char* const kLongParameterAlignmentType = \""
                        EVAL_MACRO(MAKE_STRING, SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE)
                        << "\";" << endl;
                file << "const int kReturnTypeAlignmentSize = "
                        "SYSCALL_RETURN_TYPE_ALIGNMENT_SIZE;" << endl;
                file << "const int kParameterAlignmentSize = "
                        "SYSCALL_PARAMETER_ALIGNMENT_SIZE;" << endl;
                file << "const int kLongParameterAlignmentSize = "
                        "SYSCALL_LONG_PARAMETER_ALIGNMENT_SIZE;" << endl;
                file << endl;

                file << "SyscallVector* create_syscall_vector() {" << endl;
                file << "\tSyscallVector* syscallVector = SyscallVector::Create();"
                        << endl;
                file << "\tSyscall* syscall;" << endl;

                // syscalls
                for (int i = 0; i < (int)fSyscalls.size(); i++) {
                        const Syscall& syscall = fSyscalls[i];

                        // syscall = syscallVector->CreateSyscall("syscallName",
                        //      "syscallKernelName");
                        file << "\tsyscall = syscallVector->CreateSyscall(\""
                                << syscall.GetName() << "\", \""
                                << syscall.GetKernelName() << "\");" << endl;

                        const Type& returnType = syscall.GetReturnType();

                        // syscall->SetReturnType<(SYSCALL_RETURN_TYPE_SIZE_<i>,
                        //              "returnType");
                        file << "\tsyscall->SetReturnType("
                                << "SYSCALL_RETURN_TYPE_SIZE_" << i << ", \""
                                << returnType.type << "\");" << endl;

                        // parameters
                        int paramCount = syscall.CountParameters();
                        for (int k = 0; k < paramCount; k++) {
                                const NamedType& param = syscall.ParameterAt(k);
                                // syscall->AddParameter(SYSCALL_PARAMETER_SIZE_<i>_<k>,
                                //              "parameterTypeName", "parameterName");
                                file << "\tsyscall->AddParameter("
                                        << "SYSCALL_PARAMETER_SIZE_" << i << "_" << k
                                        << ", \"" << param.type << "\", \"" << param.name << "\");"
                                        << endl;
                        }
                        file << endl;
                }

                // postamble
                file << "\treturn syscallVector;" << endl;
                file << "}" << endl;
        }

        void _WriteSyscallTypeSizes(const char* filename)
        {
                // open the syscall info file
                ofstream file(filename, ofstream::out | ofstream::trunc);
                if (!file.is_open())
                        throw IOException(string("Failed to open `") + filename + "'.");

                // write preamble
                file << "#include <computed_asm_macros.h>" << endl;
                file << "#include <syscalls.h>" << endl;
                file << endl;
                file << "#include \"arch_gensyscalls.h\"" << endl;
                file << endl;
                file << "#ifndef SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE" << endl;
                file << "#define SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE SYSCALL_PARAMETER_ALIGNMENT_TYPE"
                        << endl;
                file << "#endif" << endl;
                file << "void dummy() {" << endl;

                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_RETURN_TYPE_ALIGNMENT_SIZE, "
                        "sizeof(SYSCALL_RETURN_TYPE_ALIGNMENT_TYPE));" << endl;
                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_PARAMETER_ALIGNMENT_SIZE, "
                        "sizeof(SYSCALL_PARAMETER_ALIGNMENT_TYPE));" << endl;
                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_LONG_PARAMETER_ALIGNMENT_SIZE, "
                        "sizeof(SYSCALL_LONG_PARAMETER_ALIGNMENT_TYPE));" << endl;
                file << endl;

                // syscalls
                for (int i = 0; i < (int)fSyscalls.size(); i++) {
                        const Syscall& syscall = fSyscalls[i];
                        const Type& returnType = syscall.GetReturnType();

                        if (returnType.type == "void") {
                                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_RETURN_TYPE_SIZE_"
                                        << i << ", 0);" << endl;
                        } else {
                                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_RETURN_TYPE_SIZE_"
                                        << i << ", sizeof(" << returnType.type << "));" << endl;
                        }

                        // parameters
                        int paramCount = syscall.CountParameters();
                        for (int k = 0; k < paramCount; k++) {
                                const NamedType& param = syscall.ParameterAt(k);
                                file << "DEFINE_COMPUTED_ASM_MACRO(SYSCALL_PARAMETER_SIZE_" << i
                                        << "_" << k << ", sizeof(" << param.type << "));" << endl;
                        }
                        file << endl;
                }

                // postamble
                file << "}" << endl;
        }

        void _ParseSyscall(Tokenizer& tokenizer, Syscall& syscall)
        {
                // get return type and function name
                vector<string> returnType;
                while (tokenizer.GetNextToken() != "(") {
                        string token = tokenizer.GetCurrentToken();
                        // strip leading "extern"
                        if (!returnType.empty() || token != "extern")
                                returnType.push_back(token);
                }
                if (returnType.size() < 2) {
                        throw ParseException("Error while parsing function "
                                "return type.");
                }
                syscall.SetName(returnType[returnType.size() - 1]);
                returnType.pop_back();
                string returnTypeString(returnType[0]);
                for (int i = 1; i < (int)returnType.size(); i++) {
                        returnTypeString += " ";
                        returnTypeString += returnType[i];
                }
                syscall.SetReturnType(returnTypeString);
                // get arguments
                if (!tokenizer.CheckNextToken(")")) {
                        _ParseParameter(tokenizer, syscall);
                        while (!tokenizer.CheckNextToken(")")) {
                                tokenizer.ExpectNextToken(",");
                                _ParseParameter(tokenizer, syscall);
                        }
                }
                tokenizer.ExpectNextToken(";");
        }

        void _ParseParameter(Tokenizer& tokenizer, Syscall& syscall)
        {
                vector<string> type;
                while (tokenizer.GetNextToken() != ")"
                        && tokenizer.GetCurrentToken() != ",") {
                        string token = tokenizer.GetCurrentToken();
                        type.push_back(token);
                        if (token == "(") {
                                // This must be a function pointer. We deal with that in a
                                // separate method.
                                _ParseFunctionPointerParameter(tokenizer, syscall, type);
                                return;
                        }
                }
                tokenizer.PutCurrentToken();
                if (type.size() < 2) {
                        if (type.size() == 1 && type[0] == "void") {
                                // that's OK
                                return;
                        }
                        throw ParseException("Error while parsing function parameter.");
                }

                // last component is the parameter name
                string typeName = type.back();
                type.pop_back();

                string typeString(type[0]);
                for (int i = 1; i < (int)type.size(); i++) {
                        typeString += " ";
                        typeString += type[i];
                }
                syscall.AddParameter(NamedType(typeString, typeName));
        }

        void _ParseFunctionPointerParameter(Tokenizer& tokenizer, Syscall& syscall,
                vector<string>& type)
        {
                // When this method is entered, the return type and the opening
                // parenthesis must already be parse and stored in the supplied type
                // vector.
                if (type.size() < 2) {
                        throw ParseException("Error parsing function parameter. "
                                "No return type.");
                }
                // read all the "*"s there are
                while (tokenizer.CheckNextToken("*"))
                        type.push_back("*");
                // now comes the parameter name, if specified -- skip it
                string typeName;
                if (!tokenizer.CheckNextToken(")")) {
                        typeName = tokenizer.GetNextToken();
                        tokenizer.ExpectNextToken(")");
                } else {
                        throw ParseException("Error while parsing function parameter. "
                                "No parameter name.");
                }
                type.push_back(")");
                // the function parameters
                tokenizer.ExpectNextToken("(");
                type.push_back("(");
                while (!tokenizer.CheckNextToken(")"))
                        type.push_back(tokenizer.GetNextToken());
                type.push_back(")");
                // compose the type string and add it to the syscall parameters
                string typeString(type[0]);
                for (int i = 1; i < (int)type.size(); i++) {
                        typeString += " ";
                        typeString += type[i];
                }
                syscall.AddParameter(NamedType(typeString, typeName));
        }

private:
        vector<Syscall> fSyscalls;
};


int
main(int argc, char** argv)
{
        try {
                return Main().Run(argc, argv);
        } catch (const Exception& exception) {
                fprintf(stderr, "%s\n", exception.what());
                return 1;
        }
}