Initial import

third_party/dlmalloc/mallinfo.c

@@ -0,0 +1,60 @@
+#include "third_party/dlmalloc/dlmalloc.h"
+#include "libc/mem/mem.h"
+
+/**
+ * Returns (by copy) a struct containing various summary statistics:
+ *
+ * arena:     current total non-mmapped bytes allocated from system
+ * ordblks:   the number of free chunks
+ * smblks:    always zero.
+ * hblks:     current number of mmapped regions
+ * hblkhd:    total bytes held in mmapped regions
+ * usmblks:   the maximum total allocated space. This will be greater
+ *            than current total if trimming has occurred.
+ * fsmblks:   always zero
+ * uordblks:  current total allocated space (normal or mmapped)
+ * fordblks:  total free space
+ * keepcost:  the maximum number of bytes that could ideally be released
+ *            back to system via malloc_trim. ("ideally" means that
+ *            it ignores page restrictions etc.)
+ *
+ * Because these fields are ints, but internal bookkeeping may
+ * be kept as longs, the reported values may wrap around zero and
+ * thus be inaccurate.
+ */
+struct mallinfo mallinfo(void) {
+  struct mallinfo nm = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+  ensure_initialization();
+  if (!PREACTION(gm)) {
+    check_malloc_state(gm);
+    if (is_initialized(gm)) {
+      size_t nfree = SIZE_T_ONE; /* top always free */
+      size_t mfree = gm->topsize + TOP_FOOT_SIZE;
+      size_t sum = mfree;
+      msegmentptr s = &gm->seg;
+      while (s != 0) {
+        mchunkptr q = align_as_chunk(s->base);
+        while (segment_holds(s, q) && q != gm->top &&
+               q->head != FENCEPOST_HEAD) {
+          size_t sz = chunksize(q);
+          sum += sz;
+          if (!is_inuse(q)) {
+            mfree += sz;
+            ++nfree;
+          }
+          q = next_chunk(q);
+        }
+        s = s->next;
+      }
+      nm.arena = sum;
+      nm.ordblks = nfree;
+      nm.hblkhd = gm->footprint - sum;
+      nm.usmblks = gm->max_footprint;
+      nm.uordblks = gm->footprint - mfree;
+      nm.fordblks = mfree;
+      nm.keepcost = gm->topsize;
+    }
+    POSTACTION(gm);
+  }
+  return nm;
+}