A filetable class

aaada9c3 · Silas Boyd-Wickizer · e4afcf9f · aaada9c3 · aaada9c3 · aaada9c3
--- a/include/filetable.hh
+++ b/include/filetable.hh
+#include "atomic.hh"
+class filetable {
+public:
+  filetable() : ref_(1) {
+    for(int fd = 0; fd < NOFILE; fd++)
+      ofile_[fd] = nullptr;
+  }
+  filetable(const filetable &f) : ref_(1) {
+    for(int fd = 0; fd < NOFILE; fd++) {
+      if (f.ofile_[fd])
+        ofile_[fd] = filedup(f.ofile_[fd]);
+      else
+        ofile_[fd] = nullptr;
+    }
+  }
+  ~filetable() {
+    for(int fd = 0; fd < NOFILE; fd++){
+      if (ofile_[fd]){
+        fileclose(ofile_[fd]);
+        ofile_[fd] = 0;
+      }
+    }
+  }
+  struct file *getfile(int fd) {
+    if (fd < 0 || fd >= NOFILE)
+      return nullptr;
+    return ofile_[fd];
+  }
+  int allocfd(struct file *f) {
+    for (int fd = 0; fd < NOFILE; fd++){
+      if (ofile_[fd] == nullptr){
+        ofile_[fd] = f;
+        return fd;
+      }
+    }
+    return -1;
+  }
+  void close(int fd) {
+    struct file *f = ofile_[fd];
+    ofile_[fd] = nullptr;
+    fileclose(f);
+  }
+  void decref() {
+    if (--ref_ == 0)
+      delete this;
+  }
+  void incref() {
+    ref_++;
+  }
+  NEW_DELETE_OPS(filetable)
+private:
+  struct file *ofile_[NOFILE];
+  std::atomic<u64> ref_;
+};
--- a/include/proc.hh
+++ b/include/proc.hh
@@ -3,6 +3,7 @@
 #include "spinlock.h"
 #include "atomic.hh"
 #include "cpputil.hh"
+#include "filetable.hh"
 // Saved registers for kernel context switches.
 // (also implicitly defined in swtch.S)
@@ -47,7 +48,7 @@ struct proc : public rcu_freed {
  struct trapframe *tf;        // Trap frame for current syscall
  struct context *context;     // swtch() here to run process
  int killed;                  // If non-zero, have been killed
-  struct file *ofile[NOFILE];  // Open files
+  filetable *ftable;
  struct inode *cwd;           // Current directory
  char name[16];               // Process name (debugging)
  u64 tsc;

--- a/kernel/async.cc
+++ b/kernel/async.cc
@@ -72,9 +72,9 @@ sys_async(int fd, size_t count, off_t off,
  msg = &ipcctl->msg[msgid];
  ubuf = (kshared+PGSIZE+(pageid*PGSIZE));
-  if(fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
+  if ((f = myproc()->ftable->getfile(fd)) == nullptr)
    return -1;
-  if(f->type != file::FD_INODE)
+  if (f->type != file::FD_INODE)
    return -1;
  f->ip->ref++;

--- a/kernel/proc.cc
+++ b/kernel/proc.cc
@@ -38,7 +38,7 @@ enum { sched_debug = 0 };
 proc::proc(int npid) :
  rcu_freed("proc"), vmap(0), brk(0), kstack(0),
  pid(npid), parent(0), tf(0), context(0), killed(0),
-  cwd(0), tsc(0), curcycles(0), cpuid(0), epoch(0),
+  ftable(0), cwd(0), tsc(0), curcycles(0), cpuid(0), epoch(0),
  on_runq(-1), cpu_pin(0), runq(0), oncv(0), cv_wakeup(0),
  user_fs_(0), state_(EMBRYO)
 {
@@ -48,7 +48,6 @@ proc::proc(int npid) :
  memset(&childq, 0, sizeof(childq));
  memset(&child_next, 0, sizeof(child_next));
-  memset(ofile, 0, sizeof(ofile));
  memset(&runqlink, 0, sizeof(runqlink));
  memset(&cv_waiters, 0, sizeof(cv_waiters));
  memset(&cv_sleep, 0, sizeof(cv_sleep));
@@ -122,19 +121,13 @@ void
 exit(void)
 {
  struct proc *p, *np;
-  int fd;
  int wakeupinit;
  if(myproc() == bootproc)
    panic("init exiting");
-  // Close all open files.
+  if (myproc()->ftable)
-  for(fd = 0; fd < NOFILE; fd++){
+    myproc()->ftable->decref();
-    if(myproc()->ofile[fd]){
-      fileclose(myproc()->ofile[fd]);
-      myproc()->ofile[fd] = 0;
-    }
-  }
  // Kernel threads might not have a cwd
  if (myproc()->cwd != nullptr) {
@@ -246,6 +239,9 @@ inituser(void)
  extern u64 _initcode_size;
  p = allocproc();
+  p->ftable = new filetable();
+  if (p->ftable == nullptr)
+    panic("userinit: new filetable");
  bootproc = p;
  if((p->vmap = new vmap()) == 0)
    panic("userinit: out of vmaps?");
@@ -432,7 +428,7 @@ procdumpall(void)
 int
 fork(int flags)
 {
-  int i, pid;
+  int pid;
  struct proc *np;
  int cow = 1;
@@ -464,9 +460,13 @@ fork(int flags)
  // Clear %eax so that fork returns 0 in the child.
  np->tf->rax = 0;
-  for(i = 0; i < NOFILE; i++)
+  np->ftable = new filetable(*myproc()->ftable);
-    if(myproc()->ofile[i])
+  if (np->ftable == nullptr) {
-      np->ofile[i] = filedup(myproc()->ofile[i]);
+    // XXX(sbw) leaking?
+    freeproc(np);
+    return -1;
+  }
  np->cwd = idup(myproc()->cwd);
  pid = np->pid;
  safestrcpy(np->name, myproc()->name, sizeof(myproc()->name));

--- a/kernel/sysfile.cc
+++ b/kernel/sysfile.cc
@@ -19,7 +19,7 @@ argfd(int fd, struct file **pf)
 {
  struct file *f;
-  if(fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
+  if((f = myproc()->ftable->getfile(fd)) == nullptr)
    return -1;
  if(pf)
    *pf = f;
@@ -31,15 +31,7 @@ argfd(int fd, struct file **pf)
 static int
 fdalloc(struct file *f)
 {
-  int fd;
+  return myproc()->ftable->allocfd(f);
-  for(fd = 0; fd < NOFILE; fd++){
-    if(myproc()->ofile[fd] == 0){
-      myproc()->ofile[fd] = f;
-      return fd;
-    }
-  }
-  return -1;
 }
 long
@@ -73,7 +65,7 @@ sys_pread(int fd, void *ubuf, size_t count, off_t offset)
  uptr i = (uptr)ubuf;
  int r;
-  if(fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
+  if ((f = myproc()->ftable->getfile(fd)) == nullptr)
    return -1;
  for(uptr va = PGROUNDDOWN(i); va < i+count; va = va + PGSIZE)
@@ -108,8 +100,7 @@ sys_close(int fd)
  if(argfd(fd, &f) < 0)
    return -1;
-  myproc()->ofile[fd] = 0;
+  myproc()->ftable->close(fd);
-  fileclose(f);
  return 0;
 }
@@ -296,7 +287,7 @@ sys_openat(int dirfd, const char *path, int omode)
  } else if (dirfd < 0 || dirfd >= NOFILE) {
    return -1;
  } else {
-    struct file *fdir = myproc()->ofile[dirfd];
+    struct file *fdir = myproc()->ftable->getfile(dirfd);
    if (fdir == nullptr || fdir->type != file::FD_INODE)
      return -1;
    cwd = fdir->ip;
@@ -424,8 +415,7 @@ sys_pipe(int *fd)
  fd0 = -1;
  if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){
    if(fd0 >= 0)
-      myproc()->ofile[fd0] = 0;
+      myproc()->ftable->close(fd0);
-    fileclose(rf);
    fileclose(wf);
    return -1;
  }
@@ -437,15 +427,14 @@ sys_pipe(int *fd)
 static void
 freesocket(int fd)
 {
-  fileclose(myproc()->ofile[fd]);
+  myproc()->ftable->close(fd);
-  myproc()->ofile[fd] = 0;  
 }
 static int
 getsocket(int fd, struct file **ret)
 {
  struct file *f;
-  if (fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
+  if ((f = myproc()->ftable->getfile(fd)) == nullptr)
    return -1;
  if (f->type != file::FD_SOCKET)
    return -1;
@@ -493,8 +482,7 @@ sys_socket(int domain, int type, int protocol)
  s = netsocket(domain, type, protocol);
  if (s < 0) {
-    myproc()->ofile[fd] = 0;
+    myproc()->ftable->close(fd);
-    fileclose(f);
    return s;
  }