fd.* -> file.*

1 files changed, 150 insertions, 0 deletions

diff --git a/file.c b/file.c
new file mode 100644
index 0000000..fd04383
--- /dev/null
+++ b/file.c
@@ -0,0 +1,150 @@
+#include "types.h"
+#include "stat.h"
+#include "param.h"
+#include "x86.h"
+#include "mmu.h"
+#include "proc.h"
+#include "defs.h"
+#include "file.h"
+#include "spinlock.h"
+#include "dev.h"
+#include "fs.h"
+#include "fsvar.h"
+
+struct spinlock fd_table_lock;
+struct devsw devsw[NDEV];
+
+struct file file[NFILE];
+
+void
+fd_init(void)
+{
+  initlock(&fd_table_lock, "fd_table");
+}
+
+// Allocate a file descriptor number for curproc.
+int
+fd_ualloc(void)
+{
+  int fd;
+  struct proc *p = curproc[cpu()];
+  for(fd = 0; fd < NOFILE; fd++)
+    if(p->ofile[fd] == 0)
+      return fd;
+  return -1;
+}
+
+// Allocate a file descriptor structure
+struct file*
+fd_alloc(void)
+{
+  int i;
+
+  acquire(&fd_table_lock);
+  for(i = 0; i < NFILE; i++){
+    if(file[i].type == FD_CLOSED){
+      file[i].type = FD_NONE;
+      file[i].ref = 1;
+      release(&fd_table_lock);
+      return file + i;
+    }
+  }
+  release(&fd_table_lock);
+  return 0;
+}
+
+// Write to file descriptor;
+// addr is a kernel address, pointing into some process's p->mem.
+int
+fd_write(struct file *fd, char *addr, int n)
+{
+  if(fd->writable == 0)
+    return -1;
+  if(fd->type == FD_PIPE){
+    return pipe_write(fd->pipe, addr, n);
+  } else if(fd->type == FD_FILE) {
+    ilock(fd->ip);
+    int r = writei(fd->ip, addr, fd->off, n);
+    if(r > 0) {
+      fd->off += r;
+    }
+    iunlock(fd->ip);
+    return r;
+  } else {
+    panic("fd_write");
+    return -1;
+  }
+}
+
+// Read from file descriptor.
+int
+fd_read(struct file *fd, char *addr, int n)
+{
+  if(fd->readable == 0)
+    return -1;
+  if(fd->type == FD_PIPE){
+    return pipe_read(fd->pipe, addr, n);
+  } else if(fd->type == FD_FILE){
+    ilock(fd->ip);
+    int cc = readi(fd->ip, addr, fd->off, n);
+    if(cc > 0)
+      fd->off += cc;
+    iunlock(fd->ip);
+    return cc;
+  } else {
+    panic("fd_read");
+    return -1;
+  }
+}
+
+// Close file descriptor.
+void
+fd_close(struct file *fd)
+{
+  acquire(&fd_table_lock);
+
+  if(fd->ref < 1 || fd->type == FD_CLOSED)
+    panic("fd_close");
+
+  if(--fd->ref == 0){
+    struct file dummy = *fd;
+
+    fd->ref = 0;
+    fd->type = FD_CLOSED;
+    release(&fd_table_lock);
+
+    if(dummy.type == FD_PIPE){
+      pipe_close(dummy.pipe, dummy.writable);
+    } else if(dummy.type == FD_FILE){
+      idecref(dummy.ip);
+    } else {
+      panic("fd_close");
+    }
+  } else {
+    release(&fd_table_lock);
+  }
+}
+
+// Get metadata about file descriptor.
+int
+fd_stat(struct file *fd, struct stat *st)
+{
+  if(fd->type == FD_FILE){
+    ilock(fd->ip);
+    stati(fd->ip, st);
+    iunlock(fd->ip);
+    return 0;
+  } else
+    return -1;
+}
+
+// Increment file descriptor reference count.
+void
+fd_incref(struct file *fd)
+{
+  acquire(&fd_table_lock);
+  if(fd->ref < 1 || fd->type == FD_CLOSED)
+    panic("fd_incref");
+  fd->ref++;
+  release(&fd_table_lock);
+}