7 * My own versions of malloc, realloc and free. Because I want
8 * malloc and realloc to bomb out and exit the program if they run
9 * out of memory, realloc to reliably call malloc if passed a NULL
10 * pointer, and free to reliably do nothing if passed a NULL
11 * pointer. We can also put trace printouts in, if we need to; and
12 * we can also replace the allocator with an ElectricFence-like
18 * Minefield - a Windows equivalent for Electric Fence
26 * We start by reserving as much virtual address space as Windows
27 * will sensibly (or not sensibly) let us have. We flag it all as
30 * Any allocation attempt is satisfied by committing one or more
31 * pages, with an uncommitted page on either side. The returned
32 * memory region is jammed up against the _end_ of the pages.
34 * Freeing anything causes instantaneous decommitment of the pages
35 * involved, so stale pointers are caught as soon as possible.
38 static int minefield_initialised
= 0;
39 static void *minefield_region
= NULL
;
40 static long minefield_size
= 0;
41 static long minefield_npages
= 0;
42 static long minefield_curpos
= 0;
43 static unsigned short *minefield_admin
= NULL
;
44 static void *minefield_pages
= NULL
;
46 static void minefield_admin_hide(int hide
) {
47 int access
= hide ? PAGE_NOACCESS
: PAGE_READWRITE
;
48 VirtualProtect(minefield_admin
, minefield_npages
*2, access
, NULL
);
51 static void minefield_init(void) {
56 for (size
= 0x40000000; size
> 0; size
= ((size
>> 3) * 7) &~ 0xFFF) {
57 minefield_region
= VirtualAlloc(NULL
, size
,
58 MEM_RESERVE
, PAGE_NOACCESS
);
62 minefield_size
= size
;
65 * Firstly, allocate a section of that to be the admin block.
66 * We'll need a two-byte field for each page.
68 minefield_admin
= minefield_region
;
69 minefield_npages
= minefield_size
/ PAGESIZE
;
70 admin_size
= (minefield_npages
* 2 + PAGESIZE
-1) &~ (PAGESIZE
-1);
71 minefield_npages
= (minefield_size
- admin_size
) / PAGESIZE
;
72 minefield_pages
= (char *)minefield_region
+ admin_size
;
75 * Commit the admin region.
77 VirtualAlloc(minefield_admin
, minefield_npages
* 2,
78 MEM_COMMIT
, PAGE_READWRITE
);
81 * Mark all pages as unused (0xFFFF).
83 for (i
= 0; i
< minefield_npages
; i
++)
84 minefield_admin
[i
] = 0xFFFF;
87 * Hide the admin region.
89 minefield_admin_hide(1);
91 minefield_initialised
= 1;
94 static void minefield_bomb(void) {
95 div(1, *(int*)minefield_pages
);
98 static void *minefield_alloc(int size
) {
100 int pos
, lim
, region_end
, region_start
;
104 npages
= (size
+ PAGESIZE
-1) / PAGESIZE
;
106 minefield_admin_hide(0);
109 * Search from current position until we find a contiguous
110 * bunch of npages+2 unused pages.
112 pos
= minefield_curpos
;
113 lim
= minefield_npages
;
115 /* Skip over used pages. */
116 while (pos
< lim
&& minefield_admin
[pos
] != 0xFFFF)
118 /* Count unused pages. */
120 while (pos
< lim
&& pos
- start
< npages
+2 &&
121 minefield_admin
[pos
] == 0xFFFF)
123 if (pos
- start
== npages
+2)
125 /* If we've reached the limit, reset the limit or stop. */
127 if (lim
== minefield_npages
) {
128 /* go round and start again at zero */
129 lim
= minefield_curpos
;
132 minefield_admin_hide(1);
138 minefield_curpos
= pos
-1;
141 * We have npages+2 unused pages starting at start. We leave
142 * the first and last of these alone and use the rest.
144 region_end
= (start
+ npages
+1) * PAGESIZE
;
145 region_start
= region_end
- size
;
146 /* FIXME: could align here if we wanted */
149 * Update the admin region.
151 for (i
= start
+ 2; i
< start
+ npages
-1; i
++)
152 minefield_admin
[i
] = 0xFFFE; /* used but no region starts here */
153 minefield_admin
[start
+1] = region_start
% PAGESIZE
;
155 minefield_admin_hide(1);
157 VirtualAlloc((char *)minefield_pages
+ region_start
, size
,
158 MEM_COMMIT
, PAGE_READWRITE
);
159 return (char *)minefield_pages
+ region_start
;
162 static void minefield_free(void *ptr
) {
163 int region_start
, i
, j
;
165 minefield_admin_hide(0);
167 region_start
= (char *)ptr
- (char *)minefield_pages
;
168 i
= region_start
/ PAGESIZE
;
169 if (i
< 0 || i
>= minefield_npages
||
170 minefield_admin
[i
] != region_start
% PAGESIZE
)
172 for (j
= i
; j
< minefield_npages
&& minefield_admin
[j
] != 0xFFFF; j
++) {
173 minefield_admin
[j
] = 0xFFFF;
176 VirtualFree(ptr
, j
*PAGESIZE
- region_start
, MEM_DECOMMIT
);
178 minefield_admin_hide(1);
181 static int minefield_get_size(void *ptr
) {
182 int region_start
, i
, j
;
184 minefield_admin_hide(0);
186 region_start
= (char *)ptr
- (char *)minefield_pages
;
187 i
= region_start
/ PAGESIZE
;
188 if (i
< 0 || i
>= minefield_npages
||
189 minefield_admin
[i
] != region_start
% PAGESIZE
)
191 for (j
= i
; j
< minefield_npages
&& minefield_admin
[j
] != 0xFFFF; j
++);
193 minefield_admin_hide(1);
195 return j
*PAGESIZE
- region_start
;
198 static void *minefield_c_malloc(size_t size
) {
199 if (!minefield_initialised
) minefield_init();
200 return minefield_alloc(size
);
203 static void minefield_c_free(void *p
) {
204 if (!minefield_initialised
) minefield_init();
209 * realloc _always_ moves the chunk, for rapid detection of code
210 * that assumes it won't.
212 static void *minefield_c_realloc(void *p
, size_t size
) {
215 if (!minefield_initialised
) minefield_init();
216 q
= minefield_alloc(size
);
217 oldsize
= minefield_get_size(p
);
218 memcpy(q
, p
, (oldsize
< size ? oldsize
: size
));
223 #endif /* MINEFIELD */
226 static FILE *fp
= NULL
;
228 void mlog(char *file
, int line
) {
230 fp
= fopen("putty_mem.log", "w");
231 setvbuf(fp
, NULL
, _IONBF
, BUFSIZ
);
234 fprintf (fp
, "%s:%d: ", file
, line
);
238 void *safemalloc(size_t size
) {
241 p
= minefield_c_malloc (size
);
246 MessageBox(NULL
, "Out of memory!", "PuTTY Fatal Error",
247 MB_SYSTEMMODAL
| MB_ICONERROR
| MB_OK
);
252 fprintf(fp
, "malloc(%d) returns %p\n", size
, p
);
257 void *saferealloc(void *ptr
, size_t size
) {
261 p
= minefield_c_malloc (size
);
267 p
= minefield_c_realloc (ptr
, size
);
269 p
= realloc (ptr
, size
);
273 MessageBox(NULL
, "Out of memory!", "PuTTY Fatal Error",
274 MB_SYSTEMMODAL
| MB_ICONERROR
| MB_OK
);
279 fprintf(fp
, "realloc(%p,%d) returns %p\n", ptr
, size
, p
);
284 void safefree(void *ptr
) {
288 fprintf(fp
, "free(%p)\n", ptr
);
291 minefield_c_free (ptr
);
298 fprintf(fp
, "freeing null pointer - no action taken\n");
303 static FILE *debug_fp
= NULL
;
304 static int debug_got_console
= 0;
306 static void dputs (char *buf
) {
309 if (!debug_got_console
) {
311 debug_got_console
= 1;
314 debug_fp
= fopen("debug.log", "w");
317 WriteFile(GetStdHandle(STD_OUTPUT_HANDLE
), buf
, strlen(buf
), &dw
, NULL
);
318 fputs(buf
, debug_fp
);
323 void dprintf(char *fmt
, ...) {
328 vsprintf(buf
, fmt
, ap
);
334 void debug_memdump (void *buf
, int len
, int L
) {
336 unsigned char *p
= buf
;
339 dprintf ("\t%d (0x%x) bytes:\n", len
, len
);
340 delta
= 15 & (int) p
;
344 for (; 0 < len
; p
+= 16, len
-= 16) {
346 if (L
) dprintf ("%p: ", p
);
347 for (i
= 0; i
< 16 && i
< len
; ++i
) {
348 if (&p
[i
] < (unsigned char *) buf
) {
349 dputs (" "); /* 3 spaces */
353 &p
[i
] != (unsigned char *) buf
&& i
% 4 ?
'.' : ' ',
362 #endif /* def DEBUG */