syscall_emul: [patch 10/22] refactor fdentry and add fdarray class

Several large changes happen in this patch.

The FDEntry class is rewritten so that file descriptors now correspond to
types: 'File' which is normal file-backed file with the file open on the
host machine, 'Pipe' which is a pipe that has been opened on the host machine,
and 'Device' which does not have an open file on the host yet acts as a pseudo
device with which to issue ioctls. Other types which might be added in the
future are directory entries and sockets (off the top of my head).

The FDArray class was create to hold most of the file descriptor handling
that was stuffed into the Process class. It uses shared pointers and
the std::array type to hold the FDEntries mentioned above.

The changes to these two classes needed to be propagated out to the rest
of the code so there were quite a few changes for that. Also, comments were
added where I thought they were needed to help others and extend our
DOxygen coverage.

1 files changed, 27 insertions, 249 deletions

diff --git a/src/sim/process.cc b/src/sim/process.cc
index 9510fd71d..4c44f4086 100644
--- a/src/sim/process.cc
+++ b/src/sim/process.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 Advanced Micro Devices, Inc.
+ * Copyright (c) 2014-2016 Advanced Micro Devices, Inc.
  * Copyright (c) 2012 ARM Limited
  * All rights reserved
  *
@@ -41,6 +41,7 @@
  * Authors: Nathan Binkert
  *          Steve Reinhardt
  *          Ali Saidi
+ *          Brandon Potter
  */
 
 #include "sim/process.hh"
@@ -63,6 +64,8 @@
 #include "mem/se_translating_port_proxy.hh"
 #include "params/Process.hh"
 #include "sim/emul_driver.hh"
+#include "sim/fd_array.hh"
+#include "sim/fd_entry.hh"
 #include "sim/syscall_desc.hh"
 #include "sim/system.hh"
 
@@ -90,27 +93,6 @@
 using namespace std;
 using namespace TheISA;
 
-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, ObjectFile * obj_file)
     : SimObject(params), system(params->system),
       brk_point(0), stack_base(0), stack_size(0), stack_min(0),
@@ -124,58 +106,16 @@ Process::Process(ProcessParams * params, ObjectFile * obj_file)
         static_cast<PageTableBase *>(new FuncPageTable(name(), params->pid))),
       initVirtMem(system->getSystemPort(), this,
                   SETranslatingPortProxy::Always),
-      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}},
       objFile(obj_file),
       argv(params->cmd), envp(params->env), cwd(params->cwd),
       executable(params->executable),
       _uid(params->uid), _euid(params->euid),
       _gid(params->gid), _egid(params->egid),
       _pid(params->pid), _ppid(params->ppid),
-      drivers(params->drivers)
+      drivers(params->drivers),
+      fds(make_shared<FDArray>(params->input, params->output, params->errout))
 {
-    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 = getFDEntry(STDIN_FILENO);
-    if ((it = imap.find(params->input)) != imap.end())
-        sim_fd = it->second;
-    else
-        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 = getFDEntry(STDOUT_FILENO);
-    if ((it = oemap.find(params->output)) != oemap.end())
-        sim_fd = it->second;
-    else
-        sim_fd = openOutputFile(params->output);
-    fde_stdout->set(sim_fd, params->output, O_WRONLY | O_CREAT | O_TRUNC,
-                    0664, false);
-
-    FDEntry *fde_stderr = getFDEntry(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
-        sim_fd = openOutputFile(params->errout);
-    fde_stderr->set(sim_fd, params->errout, O_WRONLY | O_CREAT | O_TRUNC,
-                    0664, false);
-
     mmap_end = 0;
-    // other parameters will be initialized when the program is loaded
 
     // load up symbols, if any... these may be used for debugging or
     // profiling.
@@ -204,12 +144,6 @@ Process::regStats()
         ;
 }
 
-void
-Process::inheritFDArray(Process *p)
-{
-    fd_array = p->fd_array;
-}
-
 ThreadContext *
 Process::findFreeContext()
 {
@@ -239,57 +173,10 @@ Process::initState()
 DrainState
 Process::drain()
 {
-    findFileOffsets();
+    fds->updateFileOffsets();
     return DrainState::Drained;
 }
 
-int
-Process::allocFD(int sim_fd, const string& filename, int flags, int mode,
-                 bool pipe)
-{
-    for (int free_fd = 0; free_fd < fd_array->size(); free_fd++) {
-        FDEntry *fde = getFDEntry(free_fd);
-        if (fde->isFree()) {
-            fde->set(sim_fd, filename, flags, mode, pipe);
-            return free_fd;
-        }
-    }
-
-    fatal("Out of target file descriptors");
-}
-
-void
-Process::resetFDEntry(int tgt_fd)
-{
-    FDEntry *fde = getFDEntry(tgt_fd);
-    assert(fde->fd > -1);
-
-    fde->reset();
-}
-
-int
-Process::getSimFD(int tgt_fd)
-{
-    FDEntry *entry = getFDEntry(tgt_fd);
-    return entry ? entry->fd : -1;
-}
-
-FDEntry *
-Process::getFDEntry(int tgt_fd)
-{
-    assert(0 <= tgt_fd && tgt_fd < fd_array->size());
-    return &(*fd_array)[tgt_fd];
-}
-
-int
-Process::getTgtFD(int sim_fd)
-{
-    for (int index = 0; index < fd_array->size(); index++)
-        if ((*fd_array)[index].fd == sim_fd)
-            return index;
-    return -1;
-}
-
 void
 Process::allocateMem(Addr vaddr, int64_t size, bool clobber)
 {
@@ -325,127 +212,6 @@ Process::fixupStackFault(Addr vaddr)
 }
 
 void
-Process::fixFileOffsets()
-{
-    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 = getFDEntry(STDIN_FILENO);
-
-    // Check if user has specified a different input file, and if so, use it
-    // instead of the file specified in the checkpoint. This also resets the
-    // file offset from the checkpointed value
-    string new_in = ((ProcessParams*)params())->input;
-    if (new_in != fde_stdin->filename) {
-        warn("Using new input file (%s) rather than checkpointed (%s)\n",
-             new_in, fde_stdin->filename);
-        fde_stdin->filename = new_in;
-        fde_stdin->fileOffset = 0;
-    }
-
-    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);
-    }
-
-    // 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 = getFDEntry(STDOUT_FILENO);
-
-    // Check if user has specified a different output file, and if so, use it
-    // instead of the file specified in the checkpoint. This also resets the
-    // file offset from the checkpointed value
-    string new_out = ((ProcessParams*)params())->output;
-    if (new_out != fde_stdout->filename) {
-        warn("Using new output file (%s) rather than checkpointed (%s)\n",
-             new_out, fde_stdout->filename);
-        fde_stdout->filename = new_out;
-        fde_stdout->fileOffset = 0;
-    }
-
-    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);
-    }
-
-    FDEntry *fde_stderr = getFDEntry(STDERR_FILENO);
-
-    // Check if user has specified a different error file, and if so, use it
-    // instead of the file specified in the checkpoint. This also resets the
-    // file offset from the checkpointed value
-    string new_err = ((ProcessParams*)params())->errout;
-    if (new_err != fde_stderr->filename) {
-        warn("Using new error file (%s) rather than checkpointed (%s)\n",
-             new_err, fde_stderr->filename);
-        fde_stderr->filename = new_err;
-        fde_stderr->fileOffset = 0;
-    }
-
-    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);
-    }
-
-    for (int tgt_fd = 3; tgt_fd < fd_array->size(); tgt_fd++) {
-        FDEntry *fde = getFDEntry(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 = getFDEntry(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);
-        }
-    }
-}
-
-void
-Process::findFileOffsets()
-{
-    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)
-{
-    FDEntry *fde = getFDEntry(read_pipe_fd);
-    assert(source_fd >= -1);
-    fde->readPipeSource = source_fd;
-}
-
-void
 Process::serialize(CheckpointOut &cp) const
 {
     SERIALIZE_SCALAR(brk_point);
@@ -455,9 +221,16 @@ Process::serialize(CheckpointOut &cp) const
     SERIALIZE_SCALAR(next_thread_stack_base);
     SERIALIZE_SCALAR(mmap_end);
     pTable->serialize(cp);
-    for (int x = 0; x < fd_array->size(); x++) {
-        (*fd_array)[x].serializeSection(cp, csprintf("FDEntry%d", x));
-    }
+    /**
+     * Checkpoints for file descriptors currently do not work. Need to
+     * come back and fix them at a later date.
+     */
+
+    warn("Checkpoints for file descriptors currently do not work.");
+#if 0
+    for (int x = 0; x < fds->getSize(); x++)
+        (*fds)[x].serializeSection(cp, csprintf("FDEntry%d", x));
+#endif
 
 }
 
@@ -471,11 +244,16 @@ Process::unserialize(CheckpointIn &cp)
     UNSERIALIZE_SCALAR(next_thread_stack_base);
     UNSERIALIZE_SCALAR(mmap_end);
     pTable->unserialize(cp);
-    for (int x = 0; x < fd_array->size(); x++) {
-        FDEntry *fde = getFDEntry(x);
-        fde->unserializeSection(cp, csprintf("FDEntry%d", x));
-    }
-    fixFileOffsets();
+    /**
+     * Checkpoints for file descriptors currently do not work. Need to
+     * come back and fix them at a later date.
+     */
+    warn("Checkpoints for file descriptors currently do not work.");
+#if 0
+    for (int x = 0; x < fds->getSize(); x++)
+        (*fds)[x]->unserializeSection(cp, csprintf("FDEntry%d", x));
+    fds->restoreFileOffsets();
+#endif
     // 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 instantiated value if not