source/lib/talloc.c

   1 /*
   2    Samba Unix SMB/CIFS implementation.
   3    Samba temporary memory allocation functions
   4    Copyright (C) Andrew Tridgell 2000
   5    Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /**
  23    @defgroup talloc Simple memory allocator
  24    @{
  25
  26    This is a very simple temporary memory allocator. To use it do the following:
  27
  28    1) when you first want to allocate a pool of meomry use
  29    talloc_init() and save the resulting context pointer somewhere
  30
  31    2) to allocate memory use talloc()
  32
  33    3) when _all_ of the memory allocated using this context is no longer needed
  34    use talloc_destroy()
  35
  36    talloc does not zero the memory. It guarantees memory of a
  37    TALLOC_ALIGN alignment
  38
  39    @sa talloc.h
  40 */
  41
  42 /**
  43  * @todo We could allocate both the talloc_chunk structure, and the
  44  * memory it contains all in one allocation, which might be a bit
  45  * faster and perhaps use less memory overhead.
  46  *
  47  * That smells like a premature optimization, though.  -- mbp
  48  **/
  49
  50 /**
  51  * If you want testing for memory corruption, link with dmalloc or use
  52  * Insure++.  It doesn't seem useful to duplicate them here.
  53  **/
  54
  55 #include "includes.h"
  56
  57 struct talloc_chunk {
  58         struct talloc_chunk *next;
  59         size_t size;
  60         void *ptr;
  61 };
  62
  63
  64 struct talloc_ctx {
  65         struct talloc_chunk *list;
  66         size_t total_alloc_size;
  67
  68         /** The name recorded for this pool, if any.  Should describe
  69          * the purpose for which it was allocated.  The string is
  70          * allocated within the pool. **/
  71         char *name;
  72
  73         /** Pointer to the next allocate talloc pool, so that we can
  74          * summarize all talloc memory usage. **/
  75         struct talloc_ctx *next_ctx;
  76 };
  77
  78
  79 /**
  80  * Start of linked list of all talloc pools.
  81  *
  82  * @todo We should turn the global list off when using Insure++,
  83  * otherwise all the memory will be seen as still reachable.
  84  **/
  85 TALLOC_CTX *list_head = NULL;
  86
  87
  88 /**
  89  * Add to the global list
  90  **/
  91 static void talloc_enroll(TALLOC_CTX *t)
  92 {
  93         t->next_ctx = list_head;
  94         list_head = t;
  95 }
  96
  97
  98 static void talloc_disenroll(TALLOC_CTX *t)
  99 {
 100         TALLOC_CTX **ttmp;
 101
 102         /* Use a double-* so that no special case is required for the
 103          * list head. */
 104         for (ttmp = &list_head; *ttmp; ttmp = &((*ttmp)->next_ctx))
 105                 if (*ttmp == t) {
 106                         /* ttmp is the link that points to t, either
 107                          * list_head or the next_ctx link in its
 108                          * predecessor */
 109                         *ttmp = t->next_ctx;
 110                         t->next_ctx = NULL;     /* clobber */
 111                         return;
 112                 }
 113         abort();                /* oops, this talloc was already
 114                                  * clobbered or something else went
 115                                  * wrong. */
 116 }
 117
 118
 119 /** Create a new talloc context. **/
 120 TALLOC_CTX *talloc_init(void)
 121 {
 122         TALLOC_CTX *t;
 123
 124         t = (TALLOC_CTX *)malloc(sizeof(TALLOC_CTX));
 125         if (t) {
 126                 t->list = NULL;
 127                 t->total_alloc_size = 0;
 128                 t->name = NULL;
 129                 talloc_enroll(t);
 130         }
 131
 132         return t;
 133 }
 134
 135
 136
 137 /**
 138  * Create a new talloc context, with a name specifying its purpose.
 139  * Please call this in preference to talloc_init().
 140  **/
 141  TALLOC_CTX *talloc_init_named(char const *fmt, ...)
 142 {
 143         TALLOC_CTX *t;
 144         va_list ap;
 145
 146         t = talloc_init();
 147         if (t && fmt) {
 148                 va_start(ap, fmt);
 149                 t->name = talloc_vasprintf(t, fmt, ap);
 150                 va_end(ap);
 151         }
 152
 153         return t;
 154 }
 155
 156
 157 /** Allocate a bit of memory from the specified pool **/
 158 void *talloc(TALLOC_CTX *t, size_t size)
 159 {
 160         void *p;
 161         struct talloc_chunk *tc;
 162
 163         if (!t || size == 0) return NULL;
 164
 165         p = malloc(size);
 166         if (p) {
 167                 tc = malloc(sizeof(*tc));
 168                 if (tc) {
 169                         tc->ptr = p;
 170                         tc->size = size;
 171                         tc->next = t->list;
 172                         t->list = tc;
 173                         t->total_alloc_size += size;
 174                 }
 175                 else {
 176                         SAFE_FREE(p);
 177                 }
 178         }
 179         return p;
 180 }
 181
 182 /** A talloc version of realloc */
 183 void *talloc_realloc(TALLOC_CTX *t, void *ptr, size_t size)
 184 {
 185         struct talloc_chunk *tc;
 186         void *new_ptr;
 187
 188         /* size zero is equivalent to free() */
 189         if (!t || size == 0)
 190                 return NULL;
 191
 192         /* realloc(NULL) is equavalent to malloc() */
 193         if (ptr == NULL)
 194                 return talloc(t, size);
 195
 196         for (tc=t->list; tc; tc=tc->next) {
 197                 if (tc->ptr == ptr) {
 198                         new_ptr = Realloc(ptr, size);
 199                         if (new_ptr) {
 200                                 t->total_alloc_size += (size - tc->size);
 201                                 tc->size = size;
 202                                 tc->ptr = new_ptr;
 203                         }
 204                         return new_ptr;
 205                 }
 206         }
 207         return NULL;
 208 }
 209
 210 /** Destroy all the memory allocated inside @p t, but not @p t
 211  * itself. */
 212 void talloc_destroy_pool(TALLOC_CTX *t)
 213 {
 214         struct talloc_chunk *c;
 215
 216         if (!t)
 217                 return;
 218
 219         while (t->list) {
 220                 c = t->list->next;
 221                 SAFE_FREE(t->list->ptr);
 222                 SAFE_FREE(t->list);
 223                 t->list = c;
 224         }
 225
 226         t->total_alloc_size = 0;
 227 }
 228
 229 /** Destroy a whole pool including the context */
 230 void talloc_destroy(TALLOC_CTX *t)
 231 {
 232         if (!t)
 233                 return;
 234
 235         talloc_destroy_pool(t);
 236         talloc_disenroll(t);
 237         memset(t, 0, sizeof(TALLOC_CTX));
 238         SAFE_FREE(t);
 239 }
 240
 241 /** Return the current total size of the pool. */
 242 size_t talloc_pool_size(TALLOC_CTX *t)
 243 {
 244         if (t)
 245                 return t->total_alloc_size;
 246         else
 247                 return 0;
 248 }
 249
 250 const char * talloc_pool_name(TALLOC_CTX const *t)
 251 {
 252         if (t)
 253                 return t->name;
 254         else
 255                 return NULL;
 256 }
 257
 258
 259 /** talloc and zero memory. */
 260 void *talloc_zero(TALLOC_CTX *t, size_t size)
 261 {
 262         void *p = talloc(t, size);
 263
 264         if (p)
 265                 memset(p, '\0', size);
 266
 267         return p;
 268 }
 269
 270 /** memdup with a talloc. */
 271 void *talloc_memdup(TALLOC_CTX *t, const void *p, size_t size)
 272 {
 273         void *newp = talloc(t,size);
 274
 275         if (newp)
 276                 memcpy(newp, p, size);
 277
 278         return newp;
 279 }
 280
 281 /** strdup with a talloc */
 282 char *talloc_strdup(TALLOC_CTX *t, const char *p)
 283 {
 284         if (p)
 285                 return talloc_memdup(t, p, strlen(p) + 1);
 286         else
 287                 return NULL;
 288 }
 289
 290 /**
 291  * Perform string formatting, and return a pointer to newly allocated
 292  * memory holding the result, inside a memory pool.
 293  **/
 294  char *talloc_asprintf(TALLOC_CTX *t, const char *fmt, ...)
 295 {
 296         va_list ap;
 297         char *ret;
 298
 299         va_start(ap, fmt);
 300         ret = talloc_vasprintf(t, fmt, ap);
 301         va_end(ap);
 302         return ret;
 303 }
 304
 305
 306  char *talloc_vasprintf(TALLOC_CTX *t, const char *fmt, va_list ap)
 307 {
 308         int len;
 309         char *ret;
 310         va_list ap2;
 311
 312         VA_COPY(ap2, ap);  /* for systems were va_list is a struct */
 313         len = vsnprintf(NULL, 0, fmt, ap2);
 314
 315         ret = talloc(t, len+1);
 316         if (ret) {
 317                 VA_COPY(ap2, ap);
 318                 vsnprintf(ret, len+1, fmt, ap2);
 319         }
 320
 321         return ret;
 322 }
 323
 324
 325 /**
 326  * Realloc @p s to append the formatted result of @p fmt and return @p
 327  * s, which may have moved.  Good for gradually accumulating output
 328  * into a string buffer.
 329  **/
 330  char *talloc_asprintf_append(TALLOC_CTX *t, char *s,
 331                               const char *fmt, ...)
 332 {
 333         va_list ap;
 334
 335         va_start(ap, fmt);
 336         s = talloc_vasprintf_append(t, s, fmt, ap);
 337         va_end(ap);
 338         return s;
 339 }
 340
 341
 342
 343 /**
 344  * Realloc @p s to append the formatted result of @p fmt and @p ap,
 345  * and return @p s, which may have moved.  Good for gradually
 346  * accumulating output into a string buffer.
 347  **/
 348  char *talloc_vasprintf_append(TALLOC_CTX *t, char *s,
 349                                const char *fmt, va_list ap)
 350 {
 351         int len, s_len;
 352         va_list ap2;
 353
 354         VA_COPY(ap2, ap);
 355         s_len = strlen(s);
 356         len = vsnprintf(NULL, 0, fmt, ap2);
 357
 358         s = talloc_realloc(t, s, s_len + len+1);
 359         if (!s) return NULL;
 360
 361         VA_COPY(ap2, ap);
 362         vsnprintf(s+s_len, len+1, fmt, ap2);
 363
 364         return s;
 365 }
 366
 367
 368 /**
 369  * Return a human-readable description of all talloc memory usage.
 370  * The result is allocated from @p t.
 371  **/
 372 char *talloc_describe_all(TALLOC_CTX *rt)
 373 {
 374         int n_pools = 0, total_chunks = 0;
 375         size_t total_bytes = 0;
 376         TALLOC_CTX *it;
 377         char *s;
 378
 379         if (!rt) return NULL;
 380
 381         s = talloc_asprintf(rt, "global talloc allocations in pid: %u\n",
 382                             (unsigned) sys_getpid());
 383         s = talloc_asprintf_append(rt, s, "%-40s %8s %8s\n",
 384                                    "name", "chunks", "bytes");
 385         s = talloc_asprintf_append(rt, s, "%-40s %8s %8s\n",
 386                                    "----------------------------------------",
 387                                    "--------",
 388                                    "--------");
 389
 390         for (it = list_head; it; it = it->next_ctx) {
 391                 size_t bytes;
 392                 int n_chunks;
 393                 fstring what;
 394
 395                 n_pools++;
 396
 397                 talloc_get_allocation(it, &bytes, &n_chunks);
 398
 399                 if (it->name)
 400                         fstrcpy(what, it->name);
 401                 else
 402                         slprintf(what, sizeof what, "@%p", it);
 403
 404                 s = talloc_asprintf_append(rt, s, "%-40s %8u %8u\n",
 405                                            what,
 406                                            (unsigned) n_chunks,
 407                                            (unsigned) bytes);
 408                 total_bytes += bytes;
 409                 total_chunks += n_chunks;
 410         }
 411
 412         s = talloc_asprintf_append(rt, s, "%-40s %8s %8s\n",
 413                                    "----------------------------------------",
 414                                    "--------",
 415                                    "--------");
 416
 417         s = talloc_asprintf_append(rt, s, "%-40s %8u %8u\n",
 418                                    "TOTAL",
 419                                    (unsigned) total_chunks, (unsigned) total_bytes);
 420
 421         return s;
 422 }
 423
 424
 425
 426 /**
 427  * Return an estimated memory usage for the specified pool.  This does
 428  * not include memory used by the underlying malloc implementation.
 429  **/
 430 void talloc_get_allocation(TALLOC_CTX *t,
 431                            size_t *total_bytes,
 432                            int *n_chunks)
 433 {
 434         struct talloc_chunk *chunk;
 435
 436         if (t) {
 437                 *total_bytes = 0;
 438                 *n_chunks = 0;
 439
 440                 for (chunk = t->list; chunk; chunk = chunk->next) {
 441                         n_chunks[0]++;
 442                         *total_bytes += chunk->size;
 443                 }
 444         }
 445 }
 446
 447
 448 /** @} */