changes to compile with musl (avoid sbrk)

1 files changed, 44 insertions, 0 deletions

diff --git a/brk_shim.c b/brk_shim.c
new file mode 100644
index 0000000..1680a18
--- /dev/null
+++ b/brk_shim.c
@@ -0,0 +1,44 @@
+#include "brk_shim.h"
+
+#include <errno.h>
+
+/*
+ * The idea is to just allocate a large buffer and rely on lazy page
+ * loading to not use more physical memory than necessary.
+ */
+
+#ifdef LARGEF
+#define SHIMSIZE 0x4000000
+/* 64MB */
+#else
+#define SHIMSIZE 0x200000
+/* 2MB */
+#endif
+
+static char shim_space[SHIMSIZE];
+static intptr_t shim_size = 0;
+
+void *shim_sbrk(intptr_t increment) {
+  void* current = (void*)(shim_space + shim_size);
+  shim_size += increment;
+  if (shim_size < 0) {
+    shim_size = 0;
+    return (void*)-1;
+  } else if (shim_size > SHIMSIZE) {
+    shim_size = SHIMSIZE;
+    return (void*)-1;
+  }
+  return current;
+}
+
+int shim_brk(void* addr) {
+  if (addr < (void*)shim_space ||
+      addr > (void*)(shim_space + SHIMSIZE)) {
+    errno = EINVAL;
+    return -1;    
+  }
+  shim_size = ((void*)shim_space) - addr;
+  return 0;
+}
+
+