[libc] Add malloc_usable_size, write general-purpose realloc

libc/include/malloc.h

@@ -4,27 +4,32 @@
 #include <sys/types.h>
 
 /* default malloc (dev86) */
-void *malloc(size_t);
-void *realloc(void *, size_t);
-void  free(void *);
+void  *malloc(size_t);
+void   free(void *);
+size_t malloc_usable_size(void *);
 
 /* debug malloc (v7 malloc) */
-void *__dmalloc(size_t);
-void *__drealloc(void *, size_t);
-void  __dfree(void *);
+void  *__dmalloc(size_t);
+void  *__drealloc(void *, size_t);
+void   __dfree(void *);
+size_t __dmalloc_usable_size(void *);
 
 /* arena malloc (64k near/unlimited far heap) */
-void *__amalloc(size_t);
-int   __amalloc_add_heap(char __far *start, size_t size);
-void *__arealloc(void *, size_t);       /* NYI */
-void  __afree(void *);
+void  *__amalloc(size_t);
+int    __amalloc_add_heap(char __far *start, size_t size);
+void  *__arealloc(void *, size_t);       /* NYI */
+void   __afree(void *);
+size_t __dmalloc_usable_size(void *);
 
-void *calloc(size_t elm, size_t sz);
+/* usable with all mallocs */
+void  *realloc(void *, size_t);
+void  *calloc(size_t elm, size_t sz);
 
 /* alloc/free from main memory */
 void __far *fmemalloc(unsigned long size);
-int fmemfree(void __far *ptr);
-int _fmemalloc(int paras, unsigned short *pseg);
-int _fmemfree(unsigned short seg);
+int         fmemfree(void __far *ptr);
+
+int        _fmemalloc(int paras, unsigned short *pseg); /* syscall */
+int        _fmemfree(unsigned short seg);               /* syscall */
 
 #endif

libc/malloc/Makefile

@@ -18,7 +18,6 @@ CFLAGS	+= -DMCHUNK=16
 DEFAULT_MALLOC_OBJS = \
 	malloc.o \
 	free.o \
-	realloc.o \
 	__mini_malloc.o \
 	__alloca_alloc.o \
 	__freed_list.o \
@@ -33,6 +32,7 @@ ARENA_MALLOC_OBJS = amalloc.o
 
 # these objects work with any malloc
 OBJS = \
+	realloc.o \
 	calloc.o \
 	brk.o \
 	sbrk.o \

libc/malloc/amalloc.c

@@ -249,6 +249,19 @@ __afree(void *ptr)
     malloc_show_heap();
 }
 
+size_t __amalloc_usable_size(void *ptr)
+{
+    NPTR p = (NPTR)ptr;
+
+    if (p == NULL)
+        return 0;
+    ASSERT(FP_SEG(ptr)==allocseg);
+    ASSERT(p>clearbusy(allocs[allocsize-1].ptr)&&p<=alloct);
+    --p;
+    ASSERT(testbusy(next(p)));
+    return (clearbusy(next(p)) - clearbusy(p)) * sizeof(union store);
+}
+
 #if LATER
 /*  realloc(p, nbytes) reallocates a block obtained from malloc()
  *  and freed since last call of malloc()

libc/malloc/malloc.c

@@ -188,6 +188,13 @@ __search_chunk(unsigned int mem_size)
    return p1;
 }
 
+size_t malloc_usable_size(void *ptr)
+{
+    if (ptr == 0)
+        return 0;
+    return (m_size(((mem *) ptr) - 1) - 1) * sizeof(mem);
+}
+
 void *
 malloc(size_t size)
 {

libc/malloc/realloc.c

@@ -1,26 +1,22 @@
 #include <malloc.h>
 #include <string.h>
 
-#include "_malloc.h"
-
-#undef malloc
-
-void *
-realloc(void *ptr, size_t size)
+/* this realloc usable with all malloc allocators */
+void *realloc(void *ptr, size_t size)
 {
 	void *nptr;
-	unsigned int osize;
+    size_t osize;
 
 	if (ptr == 0)
 		return malloc(size);
 
-	osize = (m_size(((mem *) ptr) - 1) - 1) * sizeof(mem);
-
+	osize = malloc_usable_size(ptr);
+#if LATER
 	if (size <= osize)
 		return ptr;
+#endif
 
 	nptr = malloc(size);
-
 	if (nptr == 0)
 		return 0;
 

libc/malloc/v7malloc.c

@@ -109,8 +109,8 @@ __dmalloc(size_t nbytes)
     if (nbytes < MINALLOC)
         nbytes = MINALLOC;
 
-    /* check INT overflow beyond 32762 (nbytes/WORD+WORD+WORD+(WORD-1) > 0xFFFF/WORD/WORD)*/
-    if (nbytes > ((unsigned)-1)/WORD-WORD-WORD-(WORD-1)) {
+    /* check INT overflow beyond 32762 (nbytes/WORD+2*WORD+(WORD-1) > 0xFFFF/WORD/WORD) */
+    if (nbytes > ((unsigned)-1)/WORD-2*WORD-(WORD-1)) {
         debug(" (req too big) = NULL\n");
         errno = ENOMEM;
         return(NULL);
@@ -133,8 +133,8 @@ __dmalloc(size_t nbytes)
                         (next(q) - q) * sizeof(union store));
                     next(p) = next(q);
                 }
-                debug2("q %04x p %04x nw %d p+nw %04x ", (unsigned)q, (unsigned)p,
-                    nw, (unsigned)(p+nw));
+                /*debug2("q %04x p %04x nw %d p+nw %04x ", (unsigned)q, (unsigned)p,
+                    nw, (unsigned)(p+nw));*/
                 if(q>=p+nw && p+nw>=p)
                     goto found;
             }
@@ -227,6 +227,18 @@ __dfree(void *ptr)
     malloc_show_heap();
 }
 
+size_t __dmalloc_usable_size(void *ptr)
+{
+    NPTR p = (NPTR)ptr;
+
+    if (p == NULL)
+        return 0;
+    ASSERT(p>clearbusy(allocs[SIZE-1].ptr)&&p<=alloct);
+    --p;
+    ASSERT(testbusy(next(p)));
+    return (clearbusy(next(p)) - clearbusy(p)) * sizeof(union store);
+}
+
 /*  realloc(p, nbytes) reallocates a block obtained from malloc()
  *  and freed since last call of malloc()
  *  to have new size nbytes, and old content