A pread user test, fix a XXX

1934d0a3 · Silas Boyd-Wickizer · 41352a11 · 1934d0a3 · 1934d0a3
--- a/sysfile.cc
+++ b/sysfile.cc
@@ -79,12 +79,16 @@ ssize_t
 sys_pread(int fd, void *ubuf, size_t count, off_t offset)
 {
  struct file *f;
+  uptr i = (uptr)ubuf;
  int r;
  if(fd < 0 || fd >= NOFILE || (f=myproc()->ofile[fd]) == 0)
    return -1;
+  for(uptr va = PGROUNDDOWN(i); va < i+count; va = va + PGSIZE)
+    if(pagefault(myproc()->vmap, va, 0) < 0)
+      return -1;
-  // XXX(sbw) assuming ubuf is ok
  if(f->type == file::FD_INODE){
    ilock(f->ip, 0);
    if(f->ip->type == 0)

--- a/usertests.cc
+++ b/usertests.cc
@@ -1544,6 +1544,50 @@ unopentest(void)
  printf(stdout, "concurrent unlink/open ok\n");
 }
+void
+preads(void)
+{
+  static const int fsize = (64 << 10);
+  static const int bsize = 4096;
+  static const int nprocs = 4;
+  static const int iters = 100;
+  static char buf[bsize];
+  int fd;
+  int pid;
+  printf(1, "concurrent preads\n");
+  fd = open("preads.x", O_CREATE|O_RDWR);
+  if (fd < 0)
+    die("preads: open failed");
+  for (int i = 0; i < fsize/bsize; i++)
+    if (write(fd, buf, bsize) != bsize)
+      die("preads: write failed");
+  close(fd);
+  for (int i = 0; i < nprocs; i++) {
+    pid = fork(0);
+    if (pid < 0)
+      die("preads: fork failed");
+    if (pid == 0)
+      break;
+  }
+  for (int k = 0; k < iters; k++) {
+    fd = open("preads.x", O_RDONLY);
+    for (int i = 0; i < fsize; i+=bsize)
+      if (pread(fd, buf, bsize, i) != bsize)
+        die("preads: pread failed");
+    close(fd);
+  }
+  if (pid == 0)
+    exit();
+  printf(1, "concurrent preads OK\n");
+}
 int
 main(int argc, char *argv[])
 {
@@ -1567,6 +1611,7 @@ main(int argc, char *argv[])
  writetest();
  writetest1();
  createtest();
+  preads();
  // mem();
  pipe1();