Fix simple malloc to work on systems with an MMU

diff --git a/libc/stdlib/malloc-simple/alloc.c b/libc/stdlib/malloc-simple/alloc.c
index 79ea17794bd0b0039c5e5a75b938c4676c4596a4..b6a3cfcb6629eceeb482860be72a574c1e22fd7e 100644 (file)
--- a/libc/stdlib/malloc-simple/alloc.c
+++ b/libc/stdlib/malloc-simple/alloc.c
@@ -1,3 +1,9 @@
+
+/*
+ *     For MMU hosts we need to track the size of the allocations otherwise
+ *     munmap will fail to free the memory (EINVAL).
+ */
+
 #include <features.h>
 #include <unistd.h>
 #include <stdio.h>
@@ -68,23 +74,28 @@ void *calloc(size_t num, size_t size)
 void *malloc(size_t size)
 {
        void *result;
-#if 1
+
     /* Some programs will call malloc (0).  Lets be strict and return NULL */
     if (size == 0)
-       return NULL;
-#endif
-       result = mmap((void *) 0, size, PROT_READ | PROT_WRITE,
+               return NULL;
+
 #ifdef __UCLIBC_HAS_MMU__
-                                               MAP_PRIVATE | MAP_ANONYMOUS, 0, 0
+       result = mmap((void *) 0, size + sizeof(size_t), PROT_READ | PROT_WRITE,
+                                               MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
 #else
-                                               MAP_SHARED | MAP_ANONYMOUS, 0, 0
+       result = mmap((void *) 0, size, PROT_READ | PROT_WRITE,
+                                               MAP_SHARED | MAP_ANONYMOUS, 0, 0);
 #endif
-                                                   );
 
        if (result == MAP_FAILED)
                return 0;
-
-       return result;
+       
+#ifdef __UCLIBC_HAS_MMU__
+       * (size_t *) result = size;
+       return(result + sizeof(size_t));
+#else
+       return(result);
+#endif
 }
 
 #endif
@@ -93,7 +104,14 @@ void *malloc(size_t size)
 
 void free(void *ptr)
 {
+#ifdef __UCLIBC_HAS_MMU__
+       if (ptr) {
+               ptr -= sizeof(size_t);
+               munmap(ptr, * (size_t *) ptr);
+       }
+#else
        munmap(ptr, 0);
+#endif
 }
 
 #endif
@@ -107,7 +125,11 @@ void *realloc(void *ptr, size_t size)
        if (size > 0) {
                newptr = malloc(size);
                if (newptr && ptr) {
+#ifdef __UCLIBC_HAS_MMU__
+                       memcpy(newptr, ptr, * ((size_t *) (ptr - sizeof(size_t))));
+#else
                        memcpy(newptr, ptr, size);
+#endif
                        free(ptr);
                }
        }