base: refactor process class (specifically FdMap and friends)

This patch extends the previous patch's alterations around fd_map.  It cleans
up some of the uglier code in the process file and replaces it with a more
concise C++11 version.  As part of the changes, the FdMap class is pulled out
of the Process class and receives its own file.

8 files changed, 359 insertions, 287 deletions

diff --git a/src/sim/SConscript b/src/sim/SConscript
index 400d595e3..0b3a35915 100644
--- a/src/sim/SConscript
+++ b/src/sim/SConscript
@@ -72,6 +72,7 @@ if env['TARGET_ISA'] != 'null':
     SimObject('Process.py')
     Source('faults.cc')
     Source('process.cc')
+    Source('fd_entry.cc')
     Source('pseudo_inst.cc')
     Source('syscall_emul.cc')
 
diff --git a/src/sim/fd_entry.cc b/src/sim/fd_entry.cc
new file mode 100644
index 000000000..72975a7a6
--- /dev/null
+++ b/src/sim/fd_entry.cc
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2015 Advanced Micro Devices, Inc.
+ * Copyright (c) 2001-2005 The Regents of The University of Michigan
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ *          Steve Reinhardt
+ */
+
+#include "base/misc.hh"
+#include "fd_entry.hh"
+
+using namespace std;
+
+void
+FDEntry::serialize(CheckpointOut &cp) const
+{
+    SERIALIZE_SCALAR(fd);
+    if (fd != -1) {
+        SERIALIZE_SCALAR(mode);
+        SERIALIZE_SCALAR(flags);
+        SERIALIZE_SCALAR(isPipe);
+        SERIALIZE_SCALAR(readPipeSource);
+        SERIALIZE_SCALAR(fileOffset);
+        SERIALIZE_SCALAR(filename);
+    }
+    if (driver)
+        warn("EmulatedDriver objects do not currently support checkpoints");
+}
+
+void
+FDEntry::unserialize(CheckpointIn &cp)
+{
+    UNSERIALIZE_SCALAR(fd);
+    if (fd != -1) {
+        UNSERIALIZE_SCALAR(mode);
+        UNSERIALIZE_SCALAR(flags);
+        UNSERIALIZE_SCALAR(isPipe);
+        UNSERIALIZE_SCALAR(readPipeSource);
+        UNSERIALIZE_SCALAR(fileOffset);
+        UNSERIALIZE_SCALAR(filename);
+    }
+    driver = NULL;
+}
+
+bool
+FDEntry::isFree()
+{
+    return (fd == -1 && driver == NULL);
+}
+
+void
+FDEntry::set(int sim_fd, const string name, int flags, int mode, bool pipe)
+{
+    fd = sim_fd;
+    filename = name;
+    this->flags = flags;
+    this->mode = mode;
+    isPipe = pipe;
+    fileOffset = 0;
+    readPipeSource = 0;
+    driver = NULL;
+}
+
+void
+FDEntry::reset()
+{
+    set(-1, "", 0, 0, false);
+}
diff --git a/src/sim/fd_entry.hh b/src/sim/fd_entry.hh
new file mode 100644
index 000000000..e0fd0b0a2
--- /dev/null
+++ b/src/sim/fd_entry.hh
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2015 Advanced Micro Devices, Inc.
+ * Copyright (c) 2001-2005 The Regents of The University of Michigan
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ *          Steve Reinhardt
+ */
+
+#ifndef __FD_ENTRY_HH__
+#define __FD_ENTRY_HH__
+
+#include <ostream>
+#include <string>
+
+#include "sim/emul_driver.hh"
+
+/**
+ * FDEntry is used to manage a single file descriptor mapping and metadata
+ * for processes.
+ * Note that the fields are all declared publicly since system calls have a
+ * habit of only needing to access a single field at a time and accessor
+ * methods seem like overkill.
+ */
+class FDEntry : public Serializable
+{
+  public:
+    /**
+     * Constructor contains default values
+     * The file descriptor is free.
+     */
+    FDEntry()
+        : fd(-1), mode(0), flags(0), isPipe(false), readPipeSource(0),
+          fileOffset(0), filename(""), driver(NULL)
+    { }
+
+    void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+    void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
+
+    /**
+     * Check if the target file descriptor is in use.
+     * @return value denoting if target file descriptor already used
+     */
+    bool isFree();
+
+    /**
+     * Fill in members for this file descriptor entry.
+     * @param sim_fd host file descriptor
+     * @param name filename string
+     * @param flags current flags of the file descriptor
+     * @param mode current mode of the file descriptor
+     * @param pipe denotes whether the file descriptor belongs to a pipe
+     */
+    void set(int sim_fd, const std::string name, int flags, int mode,
+             bool pipe);
+
+    /** Reset members to their default values. */
+    void reset();
+
+    int fd;
+    int mode;
+    int flags;
+    bool isPipe;
+    int readPipeSource;
+    uint64_t fileOffset;
+    std::string filename;
+    EmulatedDriver *driver;
+};
+
+#endif // __FD_ENTRY_HH__
diff --git a/src/sim/process.cc b/src/sim/process.cc
index 8aca849a6..f27b70853 100644
--- a/src/sim/process.cc
+++ b/src/sim/process.cc
@@ -47,6 +47,7 @@
 #include <unistd.h>
 
 #include <cstdio>
+#include <map>
 #include <string>
 
 #include "base/loader/object_file.hh"
@@ -103,6 +104,27 @@ AuxVector<IntType>::AuxVector(IntType type, IntType val)
 template struct AuxVector<uint32_t>;
 template struct AuxVector<uint64_t>;
 
+static int
+openFile(const string& filename, int flags, mode_t mode)
+{
+    int sim_fd = open(filename.c_str(), flags, mode);
+    if (sim_fd != -1)
+        return sim_fd;
+    fatal("Unable to open %s with mode %O", filename, mode);
+}
+
+static int
+openInputFile(const string &filename)
+{
+    return openFile(filename, O_RDONLY, 0);
+}
+
+static int
+openOutputFile(const string &filename)
+{
+    return openFile(filename, O_WRONLY | O_CREAT | O_TRUNC, 0664);
+}
+
 Process::Process(ProcessParams * params)
     : SimObject(params), system(params->system),
       brk_point(0), stack_base(0), stack_size(0), stack_min(0),
@@ -116,70 +138,48 @@ Process::Process(ProcessParams * params)
         static_cast<PageTableBase *>(new FuncPageTable(name(), M5_pid)) ),
       initVirtMem(system->getSystemPort(), this,
                   SETranslatingPortProxy::Always),
-      fd_map(new FdMap[NUM_FDS])
+      fd_array(make_shared<array<FDEntry, NUM_FDS>>()),
+      imap {{"",       -1},
+            {"cin",    STDIN_FILENO},
+            {"stdin",  STDIN_FILENO}},
+      oemap{{"",       -1},
+            {"cout",   STDOUT_FILENO},
+            {"stdout", STDOUT_FILENO},
+            {"cerr",   STDERR_FILENO},
+            {"stderr", STDERR_FILENO}}
 {
-    string in = params->input;
-    string out = params->output;
-    string err = params->errout;
-
-    // initialize file descriptors to default: same as simulator
-    int stdin_fd, stdout_fd, stderr_fd;
-
-    if (in == "stdin" || in == "cin")
-        stdin_fd = STDIN_FILENO;
-    else if (in == "None")
-        stdin_fd = -1;
+    int sim_fd;
+    std::map<string,int>::iterator it;
+
+    // Search through the input options and set fd if match is found;
+    // otherwise, open an input file and seek to location.
+    FDEntry *fde_stdin = get_fd_entry(STDIN_FILENO);
+    if ((it = imap.find(params->input)) != imap.end())
+        sim_fd = it->second;
     else
-        stdin_fd = Process::openInputFile(in);
-
-    if (out == "stdout" || out == "cout")
-        stdout_fd = STDOUT_FILENO;
-    else if (out == "stderr" || out == "cerr")
-        stdout_fd = STDERR_FILENO;
-    else if (out == "None")
-        stdout_fd = -1;
+        sim_fd = openInputFile(params->input);
+    fde_stdin->set(sim_fd, params->input, O_RDONLY, -1, false);
+
+    // Search through the output/error options and set fd if match is found;
+    // otherwise, open an output file and seek to location.
+    FDEntry *fde_stdout = get_fd_entry(STDOUT_FILENO);
+    if ((it = oemap.find(params->output)) != oemap.end())
+        sim_fd = it->second;
     else
-        stdout_fd = Process::openOutputFile(out);
-
-    if (err == "stdout" || err == "cout")
-        stderr_fd = STDOUT_FILENO;
-    else if (err == "stderr" || err == "cerr")
-        stderr_fd = STDERR_FILENO;
-    else if (err == "None")
-        stderr_fd = -1;
-    else if (err == out)
-        stderr_fd = stdout_fd;
+        sim_fd = openOutputFile(params->output);
+    fde_stdout->set(sim_fd, params->output, O_WRONLY | O_CREAT | O_TRUNC,
+                    0664, false);
+
+    FDEntry *fde_stderr = get_fd_entry(STDERR_FILENO);
+    if (params->output == params->errout)
+        // Reuse the same file descriptor if these match.
+        sim_fd = fde_stdout->fd;
+    else if ((it = oemap.find(params->errout)) != oemap.end())
+        sim_fd = it->second;
     else
-        stderr_fd = Process::openOutputFile(err);
-
-    // initialize first 3 fds (stdin, stdout, stderr)
-    Process::FdMap *fdo = &fd_map[STDIN_FILENO];
-    fdo->fd = stdin_fd;
-    fdo->filename = in;
-    fdo->flags = O_RDONLY;
-    fdo->mode = -1;
-    fdo->fileOffset = 0;
-
-    fdo =  &fd_map[STDOUT_FILENO];
-    fdo->fd = stdout_fd;
-    fdo->filename = out;
-    fdo->flags =  O_WRONLY | O_CREAT | O_TRUNC;
-    fdo->mode = 0774;
-    fdo->fileOffset = 0;
-
-    fdo = &fd_map[STDERR_FILENO];
-    fdo->fd = stderr_fd;
-    fdo->filename = err;
-    fdo->flags = O_WRONLY;
-    fdo->mode = -1;
-    fdo->fileOffset = 0;
-
-
-    // mark remaining fds as free
-    for (int i = 3; i < NUM_FDS; ++i) {
-        fdo = &fd_map[i];
-        fdo->fd = -1;
-    }
+        sim_fd = openOutputFile(params->errout);
+    fde_stderr->set(sim_fd, params->errout, O_WRONLY | O_CREAT | O_TRUNC,
+                    0664, false);
 
     mmap_start = mmap_end = 0;
     nxm_start = nxm_end = 0;
@@ -198,37 +198,10 @@ Process::regStats()
         ;
 }
 
-//
-// static helper functions
-//
-
-int
-Process::openInputFile(const string &filename)
-{
-    int fd = open(filename.c_str(), O_RDONLY);
-
-    if (fd == -1) {
-        perror(NULL);
-        cerr << "unable to open \"" << filename << "\" for reading\n";
-        fatal("can't open input file");
-    }
-
-    return fd;
-}
-
-
-int
-Process::openOutputFile(const string &filename)
+void
+Process::inheritFdArray(Process *p)
 {
-    int fd = open(filename.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0664);
-
-    if (fd == -1) {
-        perror(NULL);
-        cerr << "unable to open \"" << filename << "\" for writing\n";
-        fatal("can't open output file");
-    }
-
-    return fd;
+    fd_array = p->fd_array;
 }
 
 ThreadContext *
@@ -268,64 +241,48 @@ int
 Process::alloc_fd(int sim_fd, const string& filename, int flags, int mode,
                   bool pipe)
 {
-    // in case open() returns an error, don't allocate a new fd
     if (sim_fd == -1)
         return -1;
 
-    // find first free target fd
-    for (int free_fd = 0; free_fd < NUM_FDS; ++free_fd) {
-        Process::FdMap *fdo = &fd_map[free_fd];
-        if (fdo->fd == -1 && fdo->driver == NULL) {
-            fdo->fd = sim_fd;
-            fdo->filename = filename;
-            fdo->mode = mode;
-            fdo->fileOffset = 0;
-            fdo->flags = flags;
-            fdo->isPipe = pipe;
-            fdo->readPipeSource = 0;
+    for (int free_fd = 0; free_fd < fd_array->size(); free_fd++) {
+        FDEntry *fde = get_fd_entry(free_fd);
+        if (fde->isFree()) {
+            fde->set(sim_fd, filename, flags, mode, pipe);
             return free_fd;
         }
     }
 
-    panic("Process::alloc_fd: out of file descriptors!");
+    fatal("Out of target file descriptors");
 }
 
 void
-Process::free_fdmap_entry(int tgt_fd)
+Process::reset_fd_entry(int tgt_fd)
 {
-    Process::FdMap *fdo = &fd_map[tgt_fd];
-    assert(fd_map[tgt_fd].fd > -1);
-
-    fdo->fd = -1;
-    fdo->filename = "NULL";
-    fdo->mode = 0;
-    fdo->fileOffset = 0;
-    fdo->flags = 0;
-    fdo->isPipe = false;
-    fdo->readPipeSource = 0;
-    fdo->driver = NULL;
+    FDEntry *fde = get_fd_entry(tgt_fd);
+    assert(fde->fd > -1);
+
+    fde->reset();
 }
 
 int
 Process::sim_fd(int tgt_fd)
 {
-    FdMap *obj = sim_fd_obj(tgt_fd);
-    return obj ? obj->fd : -1;
+    FDEntry *entry = get_fd_entry(tgt_fd);
+    return entry ? entry->fd : -1;
 }
 
-Process::FdMap *
-Process::sim_fd_obj(int tgt_fd)
+FDEntry *
+Process::get_fd_entry(int tgt_fd)
 {
-    if (tgt_fd < 0 || tgt_fd >= NUM_FDS)
-        return NULL;
-    return &fd_map[tgt_fd];
+    assert(0 <= tgt_fd && tgt_fd < fd_array->size());
+    return &(*fd_array)[tgt_fd];
 }
 
 int
 Process::tgt_fd(int sim_fd)
 {
-    for (int index = 0; index < NUM_FDS; ++index)
-        if (fd_map[index].fd == sim_fd)
+    for (int index = 0; index < fd_array->size(); index++)
+        if ((*fd_array)[index].fd == sim_fd)
             return index;
     return -1;
 }
@@ -363,98 +320,70 @@ Process::fixupStackFault(Addr vaddr)
     return false;
 }
 
-// find all offsets for currently open files and save them
 void
 Process::fix_file_offsets()
 {
-    Process::FdMap *fdo_stdin = &fd_map[STDIN_FILENO];
-    Process::FdMap *fdo_stdout = &fd_map[STDOUT_FILENO];
-    Process::FdMap *fdo_stderr = &fd_map[STDERR_FILENO];
-    string in = fdo_stdin->filename;
-    string out = fdo_stdout->filename;
-    string err = fdo_stderr->filename;
-
-    // initialize file descriptors to default: same as simulator
-    int stdin_fd, stdout_fd, stderr_fd;
-
-    if (in == "stdin" || in == "cin")
-        stdin_fd = STDIN_FILENO;
-    else if (in == "NULL")
-        stdin_fd = -1;
-    else {
-        // open standard in and seek to the right location
-        stdin_fd = Process::openInputFile(in);
-        if (lseek(stdin_fd, fdo_stdin->fileOffset, SEEK_SET) < 0)
-            panic("Unable to seek to correct location in file: %s", in);
+    auto seek = [] (FDEntry *fde)
+    {
+        if (lseek(fde->fd, fde->fileOffset, SEEK_SET) < 0)
+            fatal("Unable to see to location in %s", fde->filename);
+    };
+
+    std::map<string,int>::iterator it;
+
+    // Search through the input options and set fd if match is found;
+    // otherwise, open an input file and seek to location.
+    FDEntry *fde_stdin = get_fd_entry(STDIN_FILENO);
+    if ((it = imap.find(fde_stdin->filename)) != imap.end()) {
+        fde_stdin->fd = it->second;
+    } else {
+        fde_stdin->fd = openInputFile(fde_stdin->filename);
+        seek(fde_stdin);
     }
 
-    if (out == "stdout" || out == "cout")
-        stdout_fd = STDOUT_FILENO;
-    else if (out == "stderr" || out == "cerr")
-        stdout_fd = STDERR_FILENO;
-    else if (out == "NULL")
-        stdout_fd = -1;
-    else {
-        stdout_fd = Process::openOutputFile(out);
-        if (lseek(stdout_fd, fdo_stdout->fileOffset, SEEK_SET) < 0)
-            panic("Unable to seek to correct location in file: %s", out);
+    // Search through the output/error options and set fd if match is found;
+    // otherwise, open an output file and seek to location.
+    FDEntry *fde_stdout = get_fd_entry(STDOUT_FILENO);
+    if ((it = oemap.find(fde_stdout->filename)) != oemap.end()) {
+        fde_stdout->fd = it->second;
+    } else {
+        fde_stdout->fd = openOutputFile(fde_stdout->filename);
+        seek(fde_stdout);
     }
 
-    if (err == "stdout" || err == "cout")
-        stderr_fd = STDOUT_FILENO;
-    else if (err == "stderr" || err == "cerr")
-        stderr_fd = STDERR_FILENO;
-    else if (err == "NULL")
-        stderr_fd = -1;
-    else if (err == out)
-        stderr_fd = stdout_fd;
-    else {
-        stderr_fd = Process::openOutputFile(err);
-        if (lseek(stderr_fd, fdo_stderr->fileOffset, SEEK_SET) < 0)
-            panic("Unable to seek to correct location in file: %s", err);
+    FDEntry *fde_stderr = get_fd_entry(STDERR_FILENO);
+    if (fde_stdout->filename == fde_stderr->filename) {
+        // Reuse the same file descriptor if these match.
+        fde_stderr->fd = fde_stdout->fd;
+    } else if ((it = oemap.find(fde_stderr->filename)) != oemap.end()) {
+        fde_stderr->fd = it->second;
+    } else {
+        fde_stderr->fd = openOutputFile(fde_stderr->filename);
+        seek(fde_stderr);
     }
 
-    fdo_stdin->fd = stdin_fd;
-    fdo_stdout->fd = stdout_fd;
-    fdo_stderr->fd = stderr_fd;
-
-
-    for (int free_fd = 3; free_fd < NUM_FDS; ++free_fd) {
-        Process::FdMap *fdo = &fd_map[free_fd];
-        if (fdo->fd != -1) {
-            if (fdo->isPipe){
-                if (fdo->filename == "PIPE-WRITE")
-                    continue;
-                else {
-                    assert (fdo->filename == "PIPE-READ");
-                    //create a new pipe
-                    int fds[2];
-                    int pipe_retval = pipe(fds);
-
-                    if (pipe_retval < 0) {
-                        // error
-                        panic("Unable to create new pipe.");
-                    }
-                    fdo->fd = fds[0]; //set read pipe
-                    Process::FdMap *fdo_write = &fd_map[fdo->readPipeSource];
-                    if (fdo_write->filename != "PIPE-WRITE")
-                        panic ("Couldn't find write end of the pipe");
-
-                    fdo_write->fd = fds[1];//set write pipe
-               }
-            } else {
-                //Open file
-                int fd = open(fdo->filename.c_str(), fdo->flags, fdo->mode);
-
-                if (fd == -1)
-                    panic("Unable to open file: %s", fdo->filename);
-                fdo->fd = fd;
-
-                //Seek to correct location before checkpoint
-                if (lseek(fd, fdo->fileOffset, SEEK_SET) < 0)
-                    panic("Unable to seek to correct location in file: %s",
-                          fdo->filename);
-            }
+    for (int tgt_fd = 3; tgt_fd < fd_array->size(); tgt_fd++) {
+        FDEntry *fde = get_fd_entry(tgt_fd);
+        if (fde->fd == -1)
+            continue;
+
+        if (fde->isPipe) {
+            if (fde->filename == "PIPE-WRITE")
+                continue;
+            assert(fde->filename == "PIPE-READ");
+
+            int fds[2];
+            if (pipe(fds) < 0)
+                fatal("Unable to create new pipe");
+
+            fde->fd = fds[0];
+
+            FDEntry *fde_write = get_fd_entry(fde->readPipeSource);
+            assert(fde_write->filename == "PIPE-WRITE");
+            fde_write->fd = fds[1];
+        } else {
+            fde->fd = openFile(fde->filename.c_str(), fde->flags, fde->mode);
+            seek(fde);
         }
     }
 }
@@ -462,44 +391,18 @@ Process::fix_file_offsets()
 void
 Process::find_file_offsets()
 {
-    for (int free_fd = 0; free_fd < NUM_FDS; ++free_fd) {
-        Process::FdMap *fdo = &fd_map[free_fd];
-        if (fdo->fd != -1) {
-            fdo->fileOffset = lseek(fdo->fd, 0, SEEK_CUR);
-        } else {
-            fdo->filename = "NULL";
-            fdo->fileOffset = 0;
-        }
+    for (auto& fde : *fd_array) {
+        if (fde.fd != -1)
+            fde.fileOffset = lseek(fde.fd, 0, SEEK_CUR);
     }
 }
 
 void
 Process::setReadPipeSource(int read_pipe_fd, int source_fd)
 {
-    Process::FdMap *fdo = &fd_map[read_pipe_fd];
-    fdo->readPipeSource = source_fd;
-}
-
-void
-Process::FdMap::serialize(CheckpointOut &cp) const
-{
-    SERIALIZE_SCALAR(fd);
-    SERIALIZE_SCALAR(isPipe);
-    SERIALIZE_SCALAR(filename);
-    SERIALIZE_SCALAR(flags);
-    SERIALIZE_SCALAR(readPipeSource);
-    SERIALIZE_SCALAR(fileOffset);
-}
-
-void
-Process::FdMap::unserialize(CheckpointIn &cp)
-{
-    UNSERIALIZE_SCALAR(fd);
-    UNSERIALIZE_SCALAR(isPipe);
-    UNSERIALIZE_SCALAR(filename);
-    UNSERIALIZE_SCALAR(flags);
-    UNSERIALIZE_SCALAR(readPipeSource);
-    UNSERIALIZE_SCALAR(fileOffset);
+    FDEntry *fde = get_fd_entry(read_pipe_fd);
+    assert(source_fd >= -1);
+    fde->readPipeSource = source_fd;
 }
 
 void
@@ -515,8 +418,8 @@ Process::serialize(CheckpointOut &cp) const
     SERIALIZE_SCALAR(nxm_start);
     SERIALIZE_SCALAR(nxm_end);
     pTable->serialize(cp);
-    for (int x = 0; x < NUM_FDS; x++) {
-        fd_map[x].serializeSection(cp, csprintf("FdMap%d", x));
+    for (int x = 0; x < fd_array->size(); x++) {
+        (*fd_array)[x].serializeSection(cp, csprintf("FDEntry%d", x));
     }
     SERIALIZE_SCALAR(M5_pid);
 
@@ -535,14 +438,15 @@ Process::unserialize(CheckpointIn &cp)
     UNSERIALIZE_SCALAR(nxm_start);
     UNSERIALIZE_SCALAR(nxm_end);
     pTable->unserialize(cp);
-    for (int x = 0; x < NUM_FDS; x++) {
-        fd_map[x].unserializeSection(cp, csprintf("FdMap%d", x));
+    for (int x = 0; x < fd_array->size(); x++) {
+        FDEntry *fde = get_fd_entry(x);
+        fde->unserializeSection(cp, csprintf("FDEntry%d", x));
     }
     fix_file_offsets();
     UNSERIALIZE_OPT_SCALAR(M5_pid);
     // The above returns a bool so that you could do something if you don't
     // find the param in the checkpoint if you wanted to, like set a default
-    // but in this case we'll just stick with the instantianted value if not
+    // but in this case we'll just stick with the instantiated value if not
     // found.
 }
 
diff --git a/src/sim/process.hh b/src/sim/process.hh
index fe41a35e4..2de83565c 100644
--- a/src/sim/process.hh
+++ b/src/sim/process.hh
@@ -33,6 +33,7 @@
 #ifndef __PROCESS_HH__
 #define __PROCESS_HH__
 
+#include <array>
 #include <string>
 #include <vector>
 
@@ -41,6 +42,7 @@
 #include "base/types.hh"
 #include "config/the_isa.hh"
 #include "mem/se_translating_port_proxy.hh"
+#include "sim/fd_entry.hh"
 #include "sim/sim_object.hh"
 #include "sim/syscallreturn.hh"
 
@@ -135,27 +137,6 @@ class Process : public SimObject
 
     PageTableBase* pTable;
 
-    class FdMap : public Serializable
-    {
-      public:
-        int fd;
-        std::string filename;
-        int mode;
-        int flags;
-        bool isPipe;
-        int readPipeSource;
-        uint64_t fileOffset;
-        EmulatedDriver *driver;
-
-        FdMap()
-            : fd(-1), filename("NULL"), mode(0), flags(0),
-              isPipe(false), readPipeSource(0), fileOffset(0), driver(NULL)
-        { }
-
-        void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
-        void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
-    };
-
   protected:
     /// Memory proxy for initialization (image loading)
     SETranslatingPortProxy initVirtMem;
@@ -164,12 +145,15 @@ class Process : public SimObject
     static const int NUM_FDS = 1024;
 
     // File descriptor remapping support.
-    FdMap *fd_map;
+    std::shared_ptr<std::array<FDEntry, NUM_FDS>> fd_array;
+
+    // Standard file descriptor options for initialization and checkpoints.
+    std::map<std::string, int> imap;
+    std::map<std::string, int> oemap;
 
   public:
-    // static helper functions to generate file descriptors for constructor
-    static int openInputFile(const std::string &filename);
-    static int openOutputFile(const std::string &filename);
+    // inherit file descriptor map from another process (necessary for clone)
+    void inheritFdArray(Process *p);
 
     // override of virtual SimObject method: register statistics
     virtual void regStats();
@@ -192,13 +176,13 @@ class Process : public SimObject
                  bool pipe);
 
     // disassociate target fd with simulator fd and cleanup subsidiary fields
-    void free_fdmap_entry(int tgt_fd);
+    void reset_fd_entry(int tgt_fd);
 
     // look up simulator fd for given target fd
     int sim_fd(int tgt_fd);
 
-    // look up simulator fd_map object for a given target fd
-    FdMap *sim_fd_obj(int tgt_fd);
+    // look up fd entry for a given target fd
+    FDEntry *get_fd_entry(int tgt_fd);
 
     // look up target fd for given host fd
     // Assumes a 1:1 mapping between target file descriptor and host file
diff --git a/src/sim/serialize.hh b/src/sim/serialize.hh
index ea2bd2928..a0be62db5 100644
--- a/src/sim/serialize.hh
+++ b/src/sim/serialize.hh
@@ -76,7 +76,7 @@ typedef std::ostream CheckpointOut;
  * SimObject shouldn't cause the version number to increase, only changes to
  * existing objects such as serializing/unserializing more state, changing sizes
  * of serialized arrays, etc. */
-static const uint64_t gem5CheckpointVersion = 0x000000000000000e;
+static const uint64_t gem5CheckpointVersion = 0x000000000000000f;
 
 template <class T>
 void paramOut(CheckpointOut &cp, const std::string &name, const T &param);
diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc
index 00506125e..4f1cd2a75 100644
--- a/src/sim/syscall_emul.cc
+++ b/src/sim/syscall_emul.cc
@@ -216,7 +216,7 @@ closeFunc(SyscallDesc *desc, int num, LiveProcess *p, ThreadContext *tc)
     if (sim_fd > 2)
         status = close(sim_fd);
     if (status >= 0)
-        p->free_fdmap_entry(target_fd);
+        p->reset_fd_entry(target_fd);
     return status;
 }
 
@@ -597,11 +597,11 @@ dupFunc(SyscallDesc *desc, int num, LiveProcess *process, ThreadContext *tc)
     if (sim_fd < 0)
         return -EBADF;
 
-    Process::FdMap *fdo = process->sim_fd_obj(tgt_fd);
+    FDEntry *fde = process->get_fd_entry(tgt_fd);
 
     int result = dup(sim_fd);
     return (result == -1) ? -errno :
-        process->alloc_fd(result, fdo->filename, fdo->flags, fdo->mode, false);
+        process->alloc_fd(result, fde->filename, fde->flags, fde->mode, false);
 }
 
 
diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh
index 07b910727..b942cb601 100644
--- a/src/sim/syscall_emul.hh
+++ b/src/sim/syscall_emul.hh
@@ -553,20 +553,20 @@ ioctlFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
           ThreadContext *tc)
 {
     int index = 0;
-    int fd = process->getSyscallArg(tc, index);
+    int tgt_fd = process->getSyscallArg(tc, index);
     unsigned req = process->getSyscallArg(tc, index);
 
-    DPRINTF(SyscallVerbose, "ioctl(%d, 0x%x, ...)\n", fd, req);
+    DPRINTF(SyscallVerbose, "ioctl(%d, 0x%x, ...)\n", tgt_fd, req);
 
-    Process::FdMap *fdObj = process->sim_fd_obj(fd);
+    FDEntry *fde = process->get_fd_entry(tgt_fd);
 
-    if (fdObj == NULL) {
+    if (fde == NULL) {
         // doesn't map to any simulator fd: not a valid target fd
         return -EBADF;
     }
 
-    if (fdObj->driver != NULL) {
-        return fdObj->driver->ioctl(process, tc, req);
+    if (fde->driver != NULL) {
+        return fde->driver->ioctl(process, tc, req);
     }
 
     if (OS::isTtyReq(req)) {
@@ -574,7 +574,7 @@ ioctlFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     }
 
     warn("Unsupported ioctl call: ioctl(%d, 0x%x, ...) @ \n",
-         fd, req, tc->pcState());
+         tgt_fd, req, tc->pcState());
     return -ENOTTY;
 }
 
@@ -1235,18 +1235,18 @@ mmapFunc(SyscallDesc *desc, int num, LiveProcess *p, ThreadContext *tc)
         warn("mmap length argument %#x is unreasonably large.\n", length);
 
     if (!(flags & OS::TGT_MAP_ANONYMOUS)) {
-        Process::FdMap *fd_map = p->sim_fd_obj(tgt_fd);
-        if (!fd_map || fd_map->fd < 0) {
+        FDEntry *fde = p->get_fd_entry(tgt_fd);
+        if (!fde || fde->fd < 0) {
             warn("mmap failing: target fd %d is not valid\n", tgt_fd);
             return -EBADF;
         }
 
-        if (fd_map->filename != "/dev/zero") {
+        if (fde->filename != "/dev/zero") {
             // This is very likely broken, but leave a warning here
             // (rather than panic) in case /dev/zero is known by
             // another name on some platform
             warn("allowing mmap of file %s; mmap not supported on files"
-                 " other than /dev/zero\n", fd_map->filename);
+                 " other than /dev/zero\n", fde->filename);
         }
     }