WIP

Makefile

@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-Wall -Wextra -O3 $(XCFLAGS)
+CFLAGS=-Wall -Wextra -O3 -fPIC $(XCFLAGS) -DPOSIXLY_CORRUPT
 #CFLAGS=-Wall -Wextra -ggdb3 -O $(XCFLAGS)
 ANALYZE=-fanalyzer
 LIB=libscary.so
@@ -16,7 +16,7 @@ testlib.o scary.o: scary.h
 	$(CC) $(CFLAGS) -S -c $<
 
 %.so:
-	$(CC) $(CFLAGS) -shared -fPIC $^ -o $@
+	$(CC) $(CFLAGS) -shared $^ -o $@
 
 test: testlib
 	env LD_LIBRARY_PATH=. ./$<

scary.c

@@ -4,6 +4,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
+#ifdef POSIXLY_CORRUPT
+#include <unistd.h>
+#include <sys/types.h>
+#endif
 
 #include "scary.h"
 
@@ -23,16 +28,24 @@ static inline void *xmalloc(size_t size)
     return p;
 }
 
+#ifndef POSIXLY_CORRUPT
 static inline void *xrealloc(void *p0, size_t size)
 {
     void *p;
     NONNULL(p = realloc(p0, size));
     return p;
 }
+#endif
 
 typedef struct {
+#ifdef POSIXLY_CORRUPT
+    FILE *stream;
+    size_t capacity, elem_size;
+    void *space;
+#else
     size_t capacity, length, elem_size;
     uint8_t space[];
+#endif
 } Scary;
 
 enum {
@@ -43,7 +56,8 @@ enum {
 
 static inline void *opaque(Scary *a)
 {
-    return a->space;
+    uint8_t *bp = (void *) a;
+    return bp + SCARY_OFFSET;
 }
 
 static inline Scary *get(const void *p)
@@ -54,12 +68,19 @@ static inline Scary *get(const void *p)
 
 void *scary_new(size_t elem_size)
 {
+#ifdef POSIXLY_CORRUPT
+    Scary *ary = xmalloc(sizeof(Scary) + sizeof(void *));
+    ary->elem_size = elem_size;
+    ary->stream = open_memstream((char **) &ary->space, &ary->capacity);
+    return opaque(ary);
+#else
     size_t cap = elem_size * SCARY_INIT;
     Scary *ary = xmalloc(sizeof(Scary) + cap);
     ary->capacity = cap;
     ary->length = 0;
     ary->elem_size = elem_size;
     return opaque(ary);
+#endif
 }
 
 void scary_free(void *p)
@@ -71,26 +92,43 @@ static Scary *maybe_resize(void *p)
 {
     const void **pp = p;
     Scary *ary = get(*pp);
+#ifndef POSIXLY_CORRUPT
     if (ary->capacity <= ary->length * ary->elem_size) {
         ary->capacity *= SCARY_INC_RATIO;
         ary = xrealloc(ary, sizeof(Scary) + ary->capacity);
         *pp = opaque(ary);
     }
+#endif
     return ary;
 }
 
 size_t scary_length(const void *p)
 {
+#ifdef POSIXLY_CORRUPT
+    const Scary *ary = get(p);
+    return ary->capacity / ary->elem_size;
+#else
     return get(p)->length;
+#endif
 }
 
+#ifdef POSIXLY_CORRUPT
+#define DEF_PUSH_VARIANT2(type, suffix) \
+    void scary_push_##suffix(type **p, type elem) \
+    { \
+        Scary *ary = maybe_resize(p); \
+        fwrite(&elem, ary->elem_size, 1, ary->stream); \
+        fflush(ary->stream); \
+    }
+#else
 #define DEF_PUSH_VARIANT2(type, suffix) \
     void scary_push_##suffix(type **p, type elem) \
     { \
         Scary *ary = maybe_resize(p); \
         type *sp = (type *) ary->space; \
         sp[ary->length++] = elem; \
     }
+#endif
 #define DEF_PUSH_VARIANT_T(type) DEF_PUSH_VARIANT2(type##_t, type)
 #define DEF_PUSH_VARIANT1(type) DEF_PUSH_VARIANT2(type, type)
 DEF_PUSH_VARIANT_T(int8)
@@ -106,8 +144,14 @@ DEF_PUSH_VARIANT1(char)
 static void scary_push_ptr(void *p, const void *elem)
 {
     Scary *ary = maybe_resize(p);
+#ifdef POSIXLY_CORRUPT
+    size_t n = fwrite(elem, ary->elem_size, 1, ary->stream);
+    fprintf(stderr, "wrote: %zu\n", n);
+    fflush(ary->stream);
+#else
     const void **sp = (const void **) ary->space;
     sp[ary->length++] = elem;
+#endif
 }
 
 #define DEF_PUSH_VARIANT_PTR(type, suffix) \
@@ -134,7 +178,14 @@ void scary_push_ccharp(const char ***p, const char *elem)
 
 void scary_pop(void *p)
 {
+#ifdef POSIXLY_CORRUPT
+    Scary *ary = get(p);
+    fseek(ary->stream, -ary->elem_size, SEEK_CUR);
+    ftruncate(fileno(ary->stream), ary->capacity - ary->elem_size);
+    fflush(ary->stream);
+#else
     get(p)->length--; // do not shrink for speed
+#endif
 }
 
 void *scary_dup(void *p)