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package com.oracle.graal.python.builtins.modules;

import static com.oracle.graal.python.runtime.exception.PythonErrorType.RuntimeError;
import static com.oracle.graal.python.runtime.exception.PythonErrorType.TypeError;
import static com.oracle.graal.python.runtime.exception.PythonErrorType.ValueError;

import java.util.Arrays;
import java.util.List;

import com.oracle.graal.python.annotations.ArgumentClinic;
import com.oracle.graal.python.annotations.ArgumentClinic.ClinicConversion;
import com.oracle.graal.python.annotations.ClinicConverterFactory;
import com.oracle.graal.python.builtins.Builtin;
import com.oracle.graal.python.builtins.CoreFunctions;
import com.oracle.graal.python.builtins.PythonBuiltins;
import com.oracle.graal.python.builtins.modules.PosixModuleBuiltins.ObjectToOpaquePathNode;
import com.oracle.graal.python.builtins.modules.PosixSubprocessModuleBuiltinsClinicProviders.NewForkExecNodeClinicProviderGen;
import com.oracle.graal.python.builtins.modules.PosixSubprocessModuleBuiltinsFactory.EnvConversionNodeGen;
import com.oracle.graal.python.builtins.modules.PosixSubprocessModuleBuiltinsFactory.ProcessArgsConversionNodeGen;
import com.oracle.graal.python.builtins.objects.PNone;
import com.oracle.graal.python.builtins.objects.bytes.BytesNodes.ToBytesNode;
import com.oracle.graal.python.builtins.objects.common.SequenceNodes.GetSequenceStorageNode;
import com.oracle.graal.python.builtins.objects.common.SequenceStorageNodes.GetItemNode;
import com.oracle.graal.python.builtins.objects.common.SequenceStorageNodes.LenNode;
import com.oracle.graal.python.builtins.objects.exception.OSErrorEnum;
import com.oracle.graal.python.builtins.objects.tuple.PTuple;
import com.oracle.graal.python.lib.PyObjectGetItem;
import com.oracle.graal.python.lib.PyObjectSizeNode;
import com.oracle.graal.python.nodes.ErrorMessages;
import com.oracle.graal.python.nodes.PGuards;
import com.oracle.graal.python.nodes.builtins.ListNodes.FastConstructListNode;
import com.oracle.graal.python.nodes.function.PythonBuiltinBaseNode;
import com.oracle.graal.python.nodes.function.builtins.PythonClinicBuiltinNode;
import com.oracle.graal.python.nodes.function.builtins.clinic.ArgumentCastNode.ArgumentCastNodeWithRaise;
import com.oracle.graal.python.nodes.function.builtins.clinic.ArgumentClinicProvider;
import com.oracle.graal.python.nodes.object.IsBuiltinClassProfile;
import com.oracle.graal.python.nodes.util.CannotCastException;
import com.oracle.graal.python.nodes.util.CastToJavaIntExactNode;
import com.oracle.graal.python.runtime.GilNode;
import com.oracle.graal.python.runtime.PosixSupportLibrary;
import com.oracle.graal.python.runtime.PosixSupportLibrary.PosixException;
import com.oracle.graal.python.runtime.PythonOptions;
import com.oracle.graal.python.runtime.exception.PException;
import com.oracle.graal.python.runtime.sequence.PSequence;
import com.oracle.graal.python.runtime.sequence.storage.SequenceStorage;
import com.oracle.graal.python.util.PythonUtils;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.GenerateNodeFactory;
import com.oracle.truffle.api.dsl.NodeFactory;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.library.CachedLibrary;

@CoreFunctions(defineModule = "_posixsubprocess")
public class PosixSubprocessModuleBuiltins extends PythonBuiltins {
    @Override
    protected List<? extends NodeFactory<? extends PythonBuiltinBaseNode>> getNodeFactories() {
        return PosixSubprocessModuleBuiltinsFactory.getFactories();
    }

    /**
     * Helper converter which iterates the argv argument and converts each element to the opaque
     * path representation used by {@link PosixSupportLibrary}.
     */
    abstract static class ProcessArgsConversionNode extends ArgumentCastNodeWithRaise {
        @Specialization
        static Object[] doNone(@SuppressWarnings("unused") PNone processArgs) {
            // CPython passes NULL to execve() in this case. man execve explicitly discourages this,
            // but says that on Linux it is equivalent to an empty array.
            return new Object[0];
        }

        @Specialization
        Object[] doSequence(VirtualFrame frame, Object processArgs,
                        @Cached FastConstructListNode fastConstructListNode,
                        @Cached GetSequenceStorageNode getSequenceStorageNode,
                        @Cached IsBuiltinClassProfile isBuiltinClassProfile,
                        @Cached ObjectToOpaquePathNode objectToOpaquePathNode,
                        @Cached LenNode lenNode,
                        @Cached("createNotNormalized()") GetItemNode getItemNode) {
            PSequence argsSequence;
            try {
                argsSequence = fastConstructListNode.execute(frame, processArgs);
            } catch (PException e) {
                e.expect(TypeError, isBuiltinClassProfile);
                throw raise(TypeError, ErrorMessages.S_MUST_BE_S, "argv", "a tuple");
            }

            SequenceStorage argsStorage = getSequenceStorageNode.execute(argsSequence);
            int len = lenNode.execute(argsStorage);
            Object[] argsArray = new Object[len];
            for (int i = 0; i < len; ++i) {
                SequenceStorage newStorage = getSequenceStorageNode.execute(argsSequence);
                if (newStorage != argsStorage || lenNode.execute(newStorage) != len) {
                    // TODO write a test for this
                    throw raise(RuntimeError, ErrorMessages.ARGS_CHANGED_DURING_ITERATION);
                }
                Object o = getItemNode.execute(frame, argsStorage, i);
                argsArray[i] = objectToOpaquePathNode.execute(frame, o, false);
            }
            return argsArray;
        }

        @ClinicConverterFactory
        static ProcessArgsConversionNode create() {
            return ProcessArgsConversionNodeGen.create();
        }
    }

    abstract static class EnvConversionNode extends ArgumentCastNodeWithRaise {
        @Specialization
        static Object doNone(@SuppressWarnings("unused") PNone env) {
            return null;
        }

        @Specialization(guards = "!isPNone(env)")
        Object doSequence(VirtualFrame frame, Object env,
                        @Cached PyObjectSizeNode sizeNode,
                        @Cached ToBytesNode toBytesNode,
                        @Cached PyObjectGetItem getItem,
                        @CachedLibrary("getContext().getPosixSupport()") PosixSupportLibrary posixLib) {
            // TODO unlike CPython, this accepts a dict (if the keys are integers (0, 1, ..., len-1)
            int length = sizeNode.execute(frame, env);
            Object[] result = new Object[length];
            for (int i = 0; i < length; ++i) {
                Object o = getItem.execute(frame, env, i);
                byte[] bytes = toBytesNode.execute(frame, o);
                Object o1 = posixLib.createPathFromBytes(getContext().getPosixSupport(), bytes);
                if (o1 == null) {
                    throw raise(ValueError, ErrorMessages.EMBEDDED_NULL_BYTE);
                }
                result[i] = o1;
            }
            return result;
        }

        @ClinicConverterFactory
        static EnvConversionNode create() {
            return EnvConversionNodeGen.create();
        }
    }

    @Builtin(name = "fork_exec", minNumOfPositionalArgs = 17, parameterNames = {"args", "executable_list", "close_fds",
                    "fds_to_keep", "cwd", "env", "p2cread", "p2cwrite", "c2pread", "c2pwrite", "errread", "errwrite",
                    "errpipe_read", "errpipe_write", "restore_signals", "call_setsid", "preexec_fn"})
    @ArgumentClinic(name = "args", conversionClass = ProcessArgsConversionNode.class)
    @ArgumentClinic(name = "close_fds", conversion = ClinicConversion.Boolean)
    @ArgumentClinic(name = "env", conversionClass = EnvConversionNode.class)
    @ArgumentClinic(name = "p2cread", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "p2cwrite", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "c2pread", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "c2pwrite", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "errread", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "errwrite", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "errpipe_read", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "errpipe_write", conversion = ClinicConversion.Int)
    @ArgumentClinic(name = "restore_signals", conversion = ClinicConversion.IntToBoolean)
    @ArgumentClinic(name = "call_setsid", conversion = ClinicConversion.IntToBoolean)
    @GenerateNodeFactory
    abstract static class NewForkExecNode extends PythonClinicBuiltinNode {

        @Override
        protected ArgumentClinicProvider getArgumentClinic() {
            return NewForkExecNodeClinicProviderGen.INSTANCE;
        }

        @TruffleBoundary
        private static byte[] fsEncode(String s) {
            // This is needed for the special case when someone uses sys.executable in call to
            // POpen, which converts it to bytes using os.fsencode
            // TODO Implement fsencode
            return s.getBytes();
        }

        private Object createPathFromBytes(byte[] bytes, PosixSupportLibrary posixLib) {
            Object o = posixLib.createPathFromBytes(getPosixSupport(), bytes);
            if (o == null) {
                // TODO reconsider the contract of PosixSupportLibrary#createPathFromBytes w.r.t.
                // embedded null checks (we need to review that anyway since PosixSupportLibrary
                // cannot do Python-specific fsencode)
                throw raise(ValueError, ErrorMessages.EMBEDDED_NULL_BYTE);
            }
            return o;
        }

        @Specialization(guards = "errPipeValid(closeFds, errPipeWrite)")
        int forkExec(VirtualFrame frame, Object[] args, Object executableList, boolean closeFds,
                        PTuple fdsToKeepTuple, Object cwdObj, Object env,
                        int stdinRead, int stdinWrite, int stdoutRead, int stdoutWrite,
                        int stderrRead, int stderrWrite, int errPipeRead, int errPipeWrite,
                        boolean restoreSignals, boolean callSetsid, @SuppressWarnings("unused") PNone preexecFn,
                        @CachedLibrary("getPosixSupport()") PosixSupportLibrary posixLib,
                        @Cached LenNode lenNode,
                        @Cached("createNotNormalized()") GetItemNode tupleGetItem,
                        @Cached PyObjectGetItem getItem,
                        @Cached CastToJavaIntExactNode castToIntNode,
                        @Cached ObjectToOpaquePathNode objectToOpaquePathNode,
                        @Cached PyObjectSizeNode sizeNode,
                        @Cached GilNode gil,
                        @Cached ToBytesNode toBytesNode) {

            Object[] processArgs = args;
            int[] fdsToKeep = convertFdSequence(frame, fdsToKeepTuple, lenNode, tupleGetItem, castToIntNode);
            Object cwd = PGuards.isPNone(cwdObj) ? null : objectToOpaquePathNode.execute(frame, cwdObj, false);

            byte[] sysExecutable = fsEncode(getContext().getOption(PythonOptions.Executable));
            // TODO unlike CPython, this accepts a dict (if the keys are integers (0, 1, ..., len-1)
            int length = sizeNode.execute(frame, executableList);
            Object[] executables = new Object[length];
            for (int i = 0; i < length; ++i) {
                byte[] bytes = toBytesNode.execute(frame, getItem.execute(frame, executableList, i));
                if (Arrays.equals(bytes, sysExecutable)) {
                    if (length != 1) {
                        throw raise(ValueError, ErrorMessages.UNSUPPORTED_USE_OF_SYS_EXECUTABLE);
                    }
                    String[] additionalArgs = PythonOptions.getExecutableList(getContext());
                    Object[] extendedArgs = new Object[additionalArgs.length + (processArgs.length == 0 ? 0 : processArgs.length - 1)];
                    for (int j = 0; j < additionalArgs.length; ++j) {
                        extendedArgs[j] = createPathFromBytes(fsEncode(additionalArgs[j]), posixLib);
                    }
                    if (processArgs.length > 1) {
                        PythonUtils.arraycopy(processArgs, 1, extendedArgs, additionalArgs.length, processArgs.length - 1);
                    }
                    processArgs = extendedArgs;
                    executables[i] = extendedArgs[0];
                } else {
                    executables[i] = createPathFromBytes(bytes, posixLib);
                }
            }

            gil.release(true);
            try {
                return posixLib.forkExec(getPosixSupport(), executables, processArgs, cwd, env == null ? null : (Object[]) env, stdinRead, stdinWrite, stdoutRead, stdoutWrite, stderrRead, stderrWrite,
                                errPipeRead, errPipeWrite, closeFds, restoreSignals, callSetsid, fdsToKeep);
            } catch (PosixException e) {
                gil.acquire();
                throw raiseOSErrorFromPosixException(frame, e);
            } catch (SecurityException e) {
                gil.acquire();
                throw raiseOSError(frame, OSErrorEnum.EPERM);
            } finally {
                gil.acquire();
            }
        }

        @Specialization(guards = "!isPTuple(fdsToKeep)")
        @SuppressWarnings("unused")
        int fdsToKeepNotATuple(VirtualFrame frame, Object processArgs, Object executableList, boolean closeFds,
                        Object fdsToKeep, Object cwd, Object env,
                        int stdinRead, int stdinWrite, int stdoutRead, int stdoutWrite,
                        int stderrRead, int stderrWrite, int errPipeRead, int errPipeWrite,
                        boolean restoreSignals, boolean callSetsid, Object preexecFn) {
            throw raise(TypeError, ErrorMessages.ARG_D_MUST_BE_S_NOT_P, "fork_exec()", 4, "tuple", fdsToKeep);
        }

        @Specialization(guards = "!isPNone(preexecFn)")
        @SuppressWarnings("unused")
        int preexecFn(VirtualFrame frame, Object processArgs, Object executableList, boolean closeFds,
                        PTuple fdsToKeep, Object cwd, Object env,
                        int stdinRead, int stdinWrite, int stdoutRead, int stdoutWrite,
                        int stderrRead, int stderrWrite, int errPipeRead, int errPipeWrite,
                        boolean restoreSignals, boolean callSetsid, Object preexecFn) {
            throw raise(RuntimeError, ErrorMessages.S_NOT_SUPPORTED, "preexec_fn");
        }

        @Specialization(guards = "!errPipeValid(closeFds, errPipeWrite)")
        @SuppressWarnings("unused")
        int errPipePrecondition(VirtualFrame frame, Object processArgs, Object executableList, boolean closeFds,
                        PTuple fdsToKeep, Object cwd, Object env,
                        int stdinRead, int stdinWrite, int stdoutRead, int stdoutWrite,
                        int stderrRead, int stderrWrite, int errPipeRead, int errPipeWrite,
                        boolean restoreSignals, boolean callSetsid, PNone preexecFn) {
            throw raise(ValueError, ErrorMessages.S_MUST_BE_S, "errpipe_write", ">= 3");
        }

        protected static boolean errPipeValid(boolean closeFds, int errPipeWrite) {
            return !(closeFds && errPipeWrite < 3);
        }

        /**
         * Checks that the tuple contains only valid fds (positive integers fitting into an int) in
         * ascending order.
         */
        private int[] convertFdSequence(VirtualFrame frame, PTuple fdSequence, LenNode lenNode, GetItemNode getItemNode, CastToJavaIntExactNode castToIntNode) {
            SequenceStorage storage = fdSequence.getSequenceStorage();
            int len = lenNode.execute(storage);
            int[] fds = new int[len];
            int prevFd = -1;
            for (int i = 0; i < len; ++i) {
                try {
                    int fd = castToIntNode.execute(getItemNode.execute(frame, storage, i));
                    if (fd > prevFd) {
                        prevFd = fds[i] = fd;
                        continue;
                    }
                } catch (PException | CannotCastException e) {
                    // 'handled' by raise() below
                }
                throw raise(ValueError, ErrorMessages.BAD_VALUES_IN_FDS_TO_KEEP);
            }
            return fds;
        }

    }
}
