Merge pull request #169 from jterrace/mmap_malloc_dlmalloc_fixes

malloc and mmap fixes

2 files changed, 18 insertions, 7 deletions

diff --git a/src/dlmalloc.c b/src/dlmalloc.c
index aa37dc0d..6185b1c7 100644
--- a/src/dlmalloc.c
+++ b/src/dlmalloc.c
@@ -588,7 +588,10 @@ MAX_RELEASE_CHECK_RATE   default: 4095 unless not HAVE_MMAP
 #define INSECURE 0
 #endif  /* INSECURE */
 #ifndef HAVE_MMAP
-#define HAVE_MMAP 1
+/* XXX Emscripten
+ * mmap uses malloc, so malloc can't use mmap
+ */
+#define HAVE_MMAP 0
 #endif  /* HAVE_MMAP */
 #ifndef MMAP_CLEARS
 #define MMAP_CLEARS 1
diff --git a/src/library.js b/src/library.js
index 5a77315c..a0160279 100644
--- a/src/library.js
+++ b/src/library.js
@@ -3177,10 +3177,13 @@ LibraryManager.library = {
 
   mmap__deps: ['$FS'],
   mmap: function(start, num, prot, flags, stream, offset) {
-    // FIXME: Leaky and non-share
-    //if (stream == -1) { // XXX We should handle -1 here, but this code leads to an infinite loop
-    //  return allocate(num, 'i8', ALLOC_NORMAL);
-    //}
+    /* FIXME: Since mmap is normally implemented at the kernel level,
+     * this implementation simply uses malloc underneath the call to
+     * mmap.
+     */
+    if (stream == -1) {
+      return allocate(num, 'i8', ALLOC_NORMAL);
+    }
     var info = FS.streams[stream];
     if (!info) return -1;
     return allocate(info.object.contents.slice(offset, offset+num),
@@ -3189,7 +3192,6 @@ LibraryManager.library = {
   __01mmap64_: 'mmap',
 
   munmap: function(start, num) {
-    // FIXME: Not really correct at all.
     _free(start);
   },
 
@@ -3200,7 +3202,13 @@ LibraryManager.library = {
   // ==========================================================================
 
   malloc: function(bytes) {
-    return Runtime.staticAlloc(bytes || 1); // accept 0 as an input because libc implementations tend to
+    /* Over-allocate to make sure it is byte-aligned by 8.
+     * This will leak memory, but this is only the dummy
+     * implementation (replaced by dlmalloc normally) so
+     * not an issue.
+     */
+    ptr = Runtime.staticAlloc(bytes + 8);
+    return (ptr+8) & 0xFFFFFFF8;
   },
   _Znwj: 'malloc',
   _Znaj: 'malloc',