Actually free Process fd_map entries when a file is closed...

amazingly we never did that before.  Caused us to run out of
file descriptors in twolf.

sim/process.cc:
    Add free_fd() method to free closed target fd in simulator fd map.
    Rename open_fd() to alloc_fd() for symmetry with free_fd().
sim/process.hh:
    Add free_fd() method to free closed target fd in simulator fd map.
    Rename open_fd() to alloc_fd() for symmetry with free_fd().
    Crank up MAX_FD while we're at it.
sim/syscall_emul.cc:
    Call free_fd() on process when target closes a file.
sim/syscall_emul.hh:
    Process open_fd() renamed to alloc_fd().

--HG--
extra : convert_revision : d780f4ccfd5a0989230b0afbdbd276212b87550c

1 files changed, 5 insertions, 2 deletions

diff --git a/sim/syscall_emul.cc b/sim/syscall_emul.cc
index 4ae2d2631..50650018e 100644
--- a/sim/syscall_emul.cc
+++ b/sim/syscall_emul.cc
@@ -110,8 +110,11 @@ obreakFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
 SyscallReturn
 closeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
 {
-    int fd = p->sim_fd(xc->getSyscallArg(0));
-    return close(fd);
+    int target_fd = xc->getSyscallArg(0);
+    int status = close(p->sim_fd(target_fd));
+    if (status >= 0)
+        p->free_fd(target_fd);
+    return status;
 }