import winsup-2000-02-17 snapshot

1 files changed, 140 insertions, 0 deletions

diff --git a/winsup/cygwin/heap.cc b/winsup/cygwin/heap.cc
new file mode 100644
index 000000000..7bbe882d8
--- /dev/null
+++ b/winsup/cygwin/heap.cc
@@ -0,0 +1,140 @@
+/* heap.cc: Cygwin heap manager.
+
+   Copyright 1996, 1997, 1998, 1999 Cygnus Solutions.
+
+This file is part of Cygwin.
+
+This software is a copyrighted work licensed under the terms of the
+Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+details. */
+
+#include <errno.h>
+#include "winsup.h"
+
+#define brksize ((char *) user_data->heaptop - (char *) user_data->heapbase)
+#define brk (user_data->heapptr)
+#define brkbase (user_data->heapbase)
+#define brktop (user_data->heaptop)
+#define brkchunk (cygwin_shared->heap_chunk_size ())
+#define assert(x)
+
+static unsigned page_const = 0;
+
+static int __inline
+getpagesize(void)
+{
+    SYSTEM_INFO si;
+    GetSystemInfo(&si);
+    return (int)si.dwPageSize;
+}
+
+/* Initialize the heap at process start up.  */
+
+void
+heap_init ()
+{
+  /* If we're the forkee, we must allocate the heap at exactly the same place
+     as our parent.  If not, we don't care where it ends up.  */
+
+  page_const = getpagesize();
+  if (brkbase)
+    {
+      DWORD chunk = brkchunk;	/* allocation chunk */
+      /* total size commited in parent */
+      DWORD allocsize = (char *) brktop - (char *) brkbase;
+      /* round up by chunk size */
+      DWORD reserve_size = chunk * ((allocsize + (chunk - 1)) / chunk);
+
+      /* Loop until we've managed to reserve an adequate amount of memory. */
+      char *p;
+      for (;;)
+	{
+	  p = (char *) VirtualAlloc (brkbase, reserve_size,
+				     MEM_RESERVE, PAGE_READWRITE);
+	  if (p)
+	    break;
+	  if ((reserve_size -= page_const) <= allocsize)
+	    break;
+	}
+      if (p == NULL)
+	api_fatal ("1. unable to allocate heap, heap_chunk_size %d, pid %d, %E",
+		   brkchunk, myself->pid);
+      if (p != brkbase)
+	api_fatal ("heap allocated but not at %p", brkbase);
+      if (! VirtualAlloc (brkbase, allocsize, MEM_COMMIT, PAGE_READWRITE))
+	api_fatal ("MEM_COMMIT failed, %E");
+    }
+  else
+    {
+      /* Initialize page mask and default heap size.  Preallocate a heap
+       * to assure contiguous memory.  */
+      brk = brktop = brkbase = VirtualAlloc(NULL, brkchunk, MEM_RESERVE, PAGE_NOACCESS);
+      if (brkbase == NULL)
+	api_fatal ("2. unable to allocate heap, heap_chunk_size %d, %E",
+		   brkchunk);
+    }
+
+  page_const--;
+  malloc_init ();
+}
+
+#define pround(n) (((size_t)(n) + page_const) & ~page_const)
+
+/* FIXME: This function no longer handles "split heaps". */
+
+extern "C" void *
+_sbrk(int n)
+{
+  char *newtop, *newbrk;
+  unsigned commitbytes, newbrksize;
+
+  if (n == 0)
+    return brk;			/* Just wanted to find current brk address */
+
+  newbrk = (char *) brk + n;	/* Where new brk will be */
+  newtop = (char *) pround (newbrk); /* Actual top of allocated memory -
+				   on page boundary */
+
+  if (newtop == brktop)
+    goto good;
+
+  if (n < 0)
+    {				/* Freeing memory */
+      assert(newtop < brktop);
+      n = (char *) brktop - newtop;
+      if (VirtualFree(newtop, n, MEM_DECOMMIT)) /* Give it back to OS */
+	goto good;		/*  Didn't take */
+      else
+	goto err;
+    }
+
+  assert(newtop > brktop);
+
+  /* Need to grab more pages from the OS.  If this fails it may be because
+   * we have used up previously reserved memory.  Or, we're just plumb out
+   * of memory.  */
+  commitbytes = pround (newtop - (char *) brktop);
+  if (VirtualAlloc(brktop, commitbytes, MEM_COMMIT, PAGE_READWRITE) != NULL)
+    goto good;
+
+  /* Couldn't allocate memory.  Maybe we can reserve some more.
+     Reserve either the maximum of the standard brkchunk or the requested
+     amount.  Then attempt to actually allocate it.  */
+
+  if ((newbrksize = brkchunk) < commitbytes)
+    newbrksize = commitbytes;
+
+  if ((VirtualAlloc(brktop, newbrksize, MEM_RESERVE, PAGE_NOACCESS) != NULL) &&
+      (VirtualAlloc(brktop, commitbytes, MEM_COMMIT, PAGE_READWRITE) != NULL))
+    goto good;
+
+err:
+  set_errno (ENOMEM);
+  return (void *) -1;
+
+good:
+  void *oldbrk = brk;
+  brk = newbrk;
+  brktop = newtop;
+  return oldbrk;
+}