• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * jmemmgr.c
3  *
4  * This file was part of the Independent JPEG Group's software:
5  * Copyright (C) 1991-1997, Thomas G. Lane.
6  * libjpeg-turbo Modifications:
7  * Copyright (C) 2016, D. R. Commander.
8  * For conditions of distribution and use, see the accompanying README.ijg
9  * file.
10  *
11  * This file contains the JPEG system-independent memory management
12  * routines.  This code is usable across a wide variety of machines; most
13  * of the system dependencies have been isolated in a separate file.
14  * The major functions provided here are:
15  *   * pool-based allocation and freeing of memory;
16  *   * policy decisions about how to divide available memory among the
17  *     virtual arrays;
18  *   * control logic for swapping virtual arrays between main memory and
19  *     backing storage.
20  * The separate system-dependent file provides the actual backing-storage
21  * access code, and it contains the policy decision about how much total
22  * main memory to use.
23  * This file is system-dependent in the sense that some of its functions
24  * are unnecessary in some systems.  For example, if there is enough virtual
25  * memory so that backing storage will never be used, much of the virtual
26  * array control logic could be removed.  (Of course, if you have that much
27  * memory then you shouldn't care about a little bit of unused code...)
28  */
29 
30 #define JPEG_INTERNALS
31 #define AM_MEMORY_MANAGER       /* we define jvirt_Xarray_control structs */
32 #include "jinclude.h"
33 #include "jpeglib.h"
34 #include "jmemsys.h"            /* import the system-dependent declarations */
35 #if !defined(_MSC_VER) || _MSC_VER > 1600
36 #include <stdint.h>
37 #endif
38 #include <limits.h>
39 
40 #ifndef NO_GETENV
41 #ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare getenv() */
42 extern char *getenv(const char *name);
43 #endif
44 #endif
45 
46 
47 LOCAL(size_t)
round_up_pow2(size_t a,size_t b)48 round_up_pow2(size_t a, size_t b)
49 /* a rounded up to the next multiple of b, i.e. ceil(a/b)*b */
50 /* Assumes a >= 0, b > 0, and b is a power of 2 */
51 {
52   return ((a + b - 1) & (~(b - 1)));
53 }
54 
55 
56 /*
57  * Some important notes:
58  *   The allocation routines provided here must never return NULL.
59  *   They should exit to error_exit if unsuccessful.
60  *
61  *   It's not a good idea to try to merge the sarray and barray routines,
62  *   even though they are textually almost the same, because samples are
63  *   usually stored as bytes while coefficients are shorts or ints.  Thus,
64  *   in machines where byte pointers have a different representation from
65  *   word pointers, the resulting machine code could not be the same.
66  */
67 
68 
69 /*
70  * Many machines require storage alignment: longs must start on 4-byte
71  * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()
72  * always returns pointers that are multiples of the worst-case alignment
73  * requirement, and we had better do so too.
74  * There isn't any really portable way to determine the worst-case alignment
75  * requirement.  This module assumes that the alignment requirement is
76  * multiples of ALIGN_SIZE.
77  * By default, we define ALIGN_SIZE as sizeof(double).  This is necessary on
78  * some workstations (where doubles really do need 8-byte alignment) and will
79  * work fine on nearly everything.  If your machine has lesser alignment needs,
80  * you can save a few bytes by making ALIGN_SIZE smaller.
81  * The only place I know of where this will NOT work is certain Macintosh
82  * 680x0 compilers that define double as a 10-byte IEEE extended float.
83  * Doing 10-byte alignment is counterproductive because longwords won't be
84  * aligned well.  Put "#define ALIGN_SIZE 4" in jconfig.h if you have
85  * such a compiler.
86  */
87 
88 #ifndef ALIGN_SIZE              /* so can override from jconfig.h */
89 #ifndef WITH_SIMD
90 #define ALIGN_SIZE  sizeof(double)
91 #else
92 #define ALIGN_SIZE  32 /* Most of the SIMD instructions we support require
93                           16-byte (128-bit) alignment, but AVX2 requires
94                           32-byte alignment. */
95 #endif
96 #endif
97 
98 /*
99  * We allocate objects from "pools", where each pool is gotten with a single
100  * request to jpeg_get_small() or jpeg_get_large().  There is no per-object
101  * overhead within a pool, except for alignment padding.  Each pool has a
102  * header with a link to the next pool of the same class.
103  * Small and large pool headers are identical.
104  */
105 
106 typedef struct small_pool_struct *small_pool_ptr;
107 
108 typedef struct small_pool_struct {
109   small_pool_ptr next;          /* next in list of pools */
110   size_t bytes_used;            /* how many bytes already used within pool */
111   size_t bytes_left;            /* bytes still available in this pool */
112 } small_pool_hdr;
113 
114 typedef struct large_pool_struct *large_pool_ptr;
115 
116 typedef struct large_pool_struct {
117   large_pool_ptr next;          /* next in list of pools */
118   size_t bytes_used;            /* how many bytes already used within pool */
119   size_t bytes_left;            /* bytes still available in this pool */
120 } large_pool_hdr;
121 
122 /*
123  * Here is the full definition of a memory manager object.
124  */
125 
126 typedef struct {
127   struct jpeg_memory_mgr pub;   /* public fields */
128 
129   /* Each pool identifier (lifetime class) names a linked list of pools. */
130   small_pool_ptr small_list[JPOOL_NUMPOOLS];
131   large_pool_ptr large_list[JPOOL_NUMPOOLS];
132 
133   /* Since we only have one lifetime class of virtual arrays, only one
134    * linked list is necessary (for each datatype).  Note that the virtual
135    * array control blocks being linked together are actually stored somewhere
136    * in the small-pool list.
137    */
138   jvirt_sarray_ptr virt_sarray_list;
139   jvirt_barray_ptr virt_barray_list;
140 
141   /* This counts total space obtained from jpeg_get_small/large */
142   size_t total_space_allocated;
143 
144   /* alloc_sarray and alloc_barray set this value for use by virtual
145    * array routines.
146    */
147   JDIMENSION last_rowsperchunk; /* from most recent alloc_sarray/barray */
148 } my_memory_mgr;
149 
150 typedef my_memory_mgr *my_mem_ptr;
151 
152 
153 /*
154  * The control blocks for virtual arrays.
155  * Note that these blocks are allocated in the "small" pool area.
156  * System-dependent info for the associated backing store (if any) is hidden
157  * inside the backing_store_info struct.
158  */
159 
160 struct jvirt_sarray_control {
161   JSAMPARRAY mem_buffer;        /* => the in-memory buffer */
162   JDIMENSION rows_in_array;     /* total virtual array height */
163   JDIMENSION samplesperrow;     /* width of array (and of memory buffer) */
164   JDIMENSION maxaccess;         /* max rows accessed by access_virt_sarray */
165   JDIMENSION rows_in_mem;       /* height of memory buffer */
166   JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
167   JDIMENSION cur_start_row;     /* first logical row # in the buffer */
168   JDIMENSION first_undef_row;   /* row # of first uninitialized row */
169   boolean pre_zero;             /* pre-zero mode requested? */
170   boolean dirty;                /* do current buffer contents need written? */
171   boolean b_s_open;             /* is backing-store data valid? */
172   jvirt_sarray_ptr next;        /* link to next virtual sarray control block */
173   backing_store_info b_s_info;  /* System-dependent control info */
174 };
175 
176 struct jvirt_barray_control {
177   JBLOCKARRAY mem_buffer;       /* => the in-memory buffer */
178   JDIMENSION rows_in_array;     /* total virtual array height */
179   JDIMENSION blocksperrow;      /* width of array (and of memory buffer) */
180   JDIMENSION maxaccess;         /* max rows accessed by access_virt_barray */
181   JDIMENSION rows_in_mem;       /* height of memory buffer */
182   JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
183   JDIMENSION cur_start_row;     /* first logical row # in the buffer */
184   JDIMENSION first_undef_row;   /* row # of first uninitialized row */
185   boolean pre_zero;             /* pre-zero mode requested? */
186   boolean dirty;                /* do current buffer contents need written? */
187   boolean b_s_open;             /* is backing-store data valid? */
188   jvirt_barray_ptr next;        /* link to next virtual barray control block */
189   backing_store_info b_s_info;  /* System-dependent control info */
190 };
191 
192 
193 #ifdef MEM_STATS                /* optional extra stuff for statistics */
194 
195 LOCAL(void)
print_mem_stats(j_common_ptr cinfo,int pool_id)196 print_mem_stats(j_common_ptr cinfo, int pool_id)
197 {
198   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
199   small_pool_ptr shdr_ptr;
200   large_pool_ptr lhdr_ptr;
201 
202   /* Since this is only a debugging stub, we can cheat a little by using
203    * fprintf directly rather than going through the trace message code.
204    * This is helpful because message parm array can't handle longs.
205    */
206   fprintf(stderr, "Freeing pool %d, total space = %ld\n",
207           pool_id, mem->total_space_allocated);
208 
209   for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;
210        lhdr_ptr = lhdr_ptr->next) {
211     fprintf(stderr, "  Large chunk used %ld\n", (long)lhdr_ptr->bytes_used);
212   }
213 
214   for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
215        shdr_ptr = shdr_ptr->next) {
216     fprintf(stderr, "  Small chunk used %ld free %ld\n",
217             (long)shdr_ptr->bytes_used, (long)shdr_ptr->bytes_left);
218   }
219 }
220 
221 #endif /* MEM_STATS */
222 
223 
224 LOCAL(void)
out_of_memory(j_common_ptr cinfo,int which)225 out_of_memory(j_common_ptr cinfo, int which)
226 /* Report an out-of-memory error and stop execution */
227 /* If we compiled MEM_STATS support, report alloc requests before dying */
228 {
229 #ifdef MEM_STATS
230   cinfo->err->trace_level = 2;  /* force self_destruct to report stats */
231 #endif
232   ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);
233 }
234 
235 
236 /*
237  * Allocation of "small" objects.
238  *
239  * For these, we use pooled storage.  When a new pool must be created,
240  * we try to get enough space for the current request plus a "slop" factor,
241  * where the slop will be the amount of leftover space in the new pool.
242  * The speed vs. space tradeoff is largely determined by the slop values.
243  * A different slop value is provided for each pool class (lifetime),
244  * and we also distinguish the first pool of a class from later ones.
245  * NOTE: the values given work fairly well on both 16- and 32-bit-int
246  * machines, but may be too small if longs are 64 bits or more.
247  *
248  * Since we do not know what alignment malloc() gives us, we have to
249  * allocate ALIGN_SIZE-1 extra space per pool to have room for alignment
250  * adjustment.
251  */
252 
253 static const size_t first_pool_slop[JPOOL_NUMPOOLS] = {
254   1600,                         /* first PERMANENT pool */
255   16000                         /* first IMAGE pool */
256 };
257 
258 static const size_t extra_pool_slop[JPOOL_NUMPOOLS] = {
259   0,                            /* additional PERMANENT pools */
260   5000                          /* additional IMAGE pools */
261 };
262 
263 #define MIN_SLOP  50            /* greater than 0 to avoid futile looping */
264 
265 
266 METHODDEF(void *)
alloc_small(j_common_ptr cinfo,int pool_id,size_t sizeofobject)267 alloc_small(j_common_ptr cinfo, int pool_id, size_t sizeofobject)
268 /* Allocate a "small" object */
269 {
270   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
271   small_pool_ptr hdr_ptr, prev_hdr_ptr;
272   char *data_ptr;
273   size_t min_request, slop;
274 
275   /*
276    * Round up the requested size to a multiple of ALIGN_SIZE in order
277    * to assure alignment for the next object allocated in the same pool
278    * and so that algorithms can straddle outside the proper area up
279    * to the next alignment.
280    */
281   if (sizeofobject > MAX_ALLOC_CHUNK) {
282     /* This prevents overflow/wrap-around in round_up_pow2() if sizeofobject
283        is close to SIZE_MAX. */
284     out_of_memory(cinfo, 7);
285   }
286   sizeofobject = round_up_pow2(sizeofobject, ALIGN_SIZE);
287 
288   /* Check for unsatisfiable request (do now to ensure no overflow below) */
289   if ((sizeof(small_pool_hdr) + sizeofobject + ALIGN_SIZE - 1) >
290       MAX_ALLOC_CHUNK)
291     out_of_memory(cinfo, 1);    /* request exceeds malloc's ability */
292 
293   /* See if space is available in any existing pool */
294   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
295     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
296   prev_hdr_ptr = NULL;
297   hdr_ptr = mem->small_list[pool_id];
298   while (hdr_ptr != NULL) {
299     if (hdr_ptr->bytes_left >= sizeofobject)
300       break;                    /* found pool with enough space */
301     prev_hdr_ptr = hdr_ptr;
302     hdr_ptr = hdr_ptr->next;
303   }
304 
305   /* Time to make a new pool? */
306   if (hdr_ptr == NULL) {
307     /* min_request is what we need now, slop is what will be leftover */
308     min_request = sizeof(small_pool_hdr) + sizeofobject + ALIGN_SIZE - 1;
309     if (prev_hdr_ptr == NULL)   /* first pool in class? */
310       slop = first_pool_slop[pool_id];
311     else
312       slop = extra_pool_slop[pool_id];
313     /* Don't ask for more than MAX_ALLOC_CHUNK */
314     if (slop > (size_t)(MAX_ALLOC_CHUNK - min_request))
315       slop = (size_t)(MAX_ALLOC_CHUNK - min_request);
316     /* Try to get space, if fail reduce slop and try again */
317     for (;;) {
318       hdr_ptr = (small_pool_ptr)jpeg_get_small(cinfo, min_request + slop);
319       if (hdr_ptr != NULL)
320         break;
321       slop /= 2;
322       if (slop < MIN_SLOP)      /* give up when it gets real small */
323         out_of_memory(cinfo, 2); /* jpeg_get_small failed */
324     }
325     mem->total_space_allocated += min_request + slop;
326     /* Success, initialize the new pool header and add to end of list */
327     hdr_ptr->next = NULL;
328     hdr_ptr->bytes_used = 0;
329     hdr_ptr->bytes_left = sizeofobject + slop;
330     if (prev_hdr_ptr == NULL)   /* first pool in class? */
331       mem->small_list[pool_id] = hdr_ptr;
332     else
333       prev_hdr_ptr->next = hdr_ptr;
334   }
335 
336   /* OK, allocate the object from the current pool */
337   data_ptr = (char *)hdr_ptr; /* point to first data byte in pool... */
338   data_ptr += sizeof(small_pool_hdr); /* ...by skipping the header... */
339   if ((size_t)data_ptr % ALIGN_SIZE) /* ...and adjust for alignment */
340     data_ptr += ALIGN_SIZE - (size_t)data_ptr % ALIGN_SIZE;
341   data_ptr += hdr_ptr->bytes_used; /* point to place for object */
342   hdr_ptr->bytes_used += sizeofobject;
343   hdr_ptr->bytes_left -= sizeofobject;
344 
345   return (void *)data_ptr;
346 }
347 
348 
349 /*
350  * Allocation of "large" objects.
351  *
352  * The external semantics of these are the same as "small" objects.  However,
353  * the pool management heuristics are quite different.  We assume that each
354  * request is large enough that it may as well be passed directly to
355  * jpeg_get_large; the pool management just links everything together
356  * so that we can free it all on demand.
357  * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY
358  * structures.  The routines that create these structures (see below)
359  * deliberately bunch rows together to ensure a large request size.
360  */
361 
362 METHODDEF(void *)
alloc_large(j_common_ptr cinfo,int pool_id,size_t sizeofobject)363 alloc_large(j_common_ptr cinfo, int pool_id, size_t sizeofobject)
364 /* Allocate a "large" object */
365 {
366   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
367   large_pool_ptr hdr_ptr;
368   char *data_ptr;
369 
370   /*
371    * Round up the requested size to a multiple of ALIGN_SIZE so that
372    * algorithms can straddle outside the proper area up to the next
373    * alignment.
374    */
375   if (sizeofobject > MAX_ALLOC_CHUNK) {
376     /* This prevents overflow/wrap-around in round_up_pow2() if sizeofobject
377        is close to SIZE_MAX. */
378     out_of_memory(cinfo, 8);
379   }
380   sizeofobject = round_up_pow2(sizeofobject, ALIGN_SIZE);
381 
382   /* Check for unsatisfiable request (do now to ensure no overflow below) */
383   if ((sizeof(large_pool_hdr) + sizeofobject + ALIGN_SIZE - 1) >
384       MAX_ALLOC_CHUNK)
385     out_of_memory(cinfo, 3);    /* request exceeds malloc's ability */
386 
387   /* Always make a new pool */
388   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
389     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
390 
391   hdr_ptr = (large_pool_ptr)jpeg_get_large(cinfo, sizeofobject +
392                                            sizeof(large_pool_hdr) +
393                                            ALIGN_SIZE - 1);
394   if (hdr_ptr == NULL)
395     out_of_memory(cinfo, 4);    /* jpeg_get_large failed */
396   mem->total_space_allocated += sizeofobject + sizeof(large_pool_hdr) +
397                                 ALIGN_SIZE - 1;
398 
399   /* Success, initialize the new pool header and add to list */
400   hdr_ptr->next = mem->large_list[pool_id];
401   /* We maintain space counts in each pool header for statistical purposes,
402    * even though they are not needed for allocation.
403    */
404   hdr_ptr->bytes_used = sizeofobject;
405   hdr_ptr->bytes_left = 0;
406   mem->large_list[pool_id] = hdr_ptr;
407 
408   data_ptr = (char *)hdr_ptr; /* point to first data byte in pool... */
409   data_ptr += sizeof(small_pool_hdr); /* ...by skipping the header... */
410   if ((size_t)data_ptr % ALIGN_SIZE) /* ...and adjust for alignment */
411     data_ptr += ALIGN_SIZE - (size_t)data_ptr % ALIGN_SIZE;
412 
413   return (void *)data_ptr;
414 }
415 
416 
417 /*
418  * Creation of 2-D sample arrays.
419  *
420  * To minimize allocation overhead and to allow I/O of large contiguous
421  * blocks, we allocate the sample rows in groups of as many rows as possible
422  * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.
423  * NB: the virtual array control routines, later in this file, know about
424  * this chunking of rows.  The rowsperchunk value is left in the mem manager
425  * object so that it can be saved away if this sarray is the workspace for
426  * a virtual array.
427  *
428  * Since we are often upsampling with a factor 2, we align the size (not
429  * the start) to 2 * ALIGN_SIZE so that the upsampling routines don't have
430  * to be as careful about size.
431  */
432 
433 METHODDEF(JSAMPARRAY)
alloc_sarray(j_common_ptr cinfo,int pool_id,JDIMENSION samplesperrow,JDIMENSION numrows)434 alloc_sarray(j_common_ptr cinfo, int pool_id, JDIMENSION samplesperrow,
435              JDIMENSION numrows)
436 /* Allocate a 2-D sample array */
437 {
438   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
439   JSAMPARRAY result;
440   JSAMPROW workspace;
441   JDIMENSION rowsperchunk, currow, i;
442   long ltemp;
443 
444   /* Make sure each row is properly aligned */
445   if ((ALIGN_SIZE % sizeof(JSAMPLE)) != 0)
446     out_of_memory(cinfo, 5);    /* safety check */
447 
448   if (samplesperrow > MAX_ALLOC_CHUNK) {
449     /* This prevents overflow/wrap-around in round_up_pow2() if sizeofobject
450        is close to SIZE_MAX. */
451     out_of_memory(cinfo, 9);
452   }
453   samplesperrow = (JDIMENSION)round_up_pow2(samplesperrow, (2 * ALIGN_SIZE) /
454                                                            sizeof(JSAMPLE));
455 
456   /* Calculate max # of rows allowed in one allocation chunk */
457   ltemp = (MAX_ALLOC_CHUNK - sizeof(large_pool_hdr)) /
458           ((long)samplesperrow * sizeof(JSAMPLE));
459   if (ltemp <= 0)
460     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
461   if (ltemp < (long)numrows)
462     rowsperchunk = (JDIMENSION)ltemp;
463   else
464     rowsperchunk = numrows;
465   mem->last_rowsperchunk = rowsperchunk;
466 
467   /* Get space for row pointers (small object) */
468   result = (JSAMPARRAY)alloc_small(cinfo, pool_id,
469                                    (size_t)(numrows * sizeof(JSAMPROW)));
470 
471   /* Get the rows themselves (large objects) */
472   currow = 0;
473   while (currow < numrows) {
474     rowsperchunk = MIN(rowsperchunk, numrows - currow);
475     workspace = (JSAMPROW)alloc_large(cinfo, pool_id,
476       (size_t)((size_t)rowsperchunk * (size_t)samplesperrow *
477                sizeof(JSAMPLE)));
478     for (i = rowsperchunk; i > 0; i--) {
479       result[currow++] = workspace;
480       workspace += samplesperrow;
481     }
482   }
483 
484   return result;
485 }
486 
487 
488 /*
489  * Creation of 2-D coefficient-block arrays.
490  * This is essentially the same as the code for sample arrays, above.
491  */
492 
493 METHODDEF(JBLOCKARRAY)
alloc_barray(j_common_ptr cinfo,int pool_id,JDIMENSION blocksperrow,JDIMENSION numrows)494 alloc_barray(j_common_ptr cinfo, int pool_id, JDIMENSION blocksperrow,
495              JDIMENSION numrows)
496 /* Allocate a 2-D coefficient-block array */
497 {
498   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
499   JBLOCKARRAY result;
500   JBLOCKROW workspace;
501   JDIMENSION rowsperchunk, currow, i;
502   long ltemp;
503 
504   /* Make sure each row is properly aligned */
505   if ((sizeof(JBLOCK) % ALIGN_SIZE) != 0)
506     out_of_memory(cinfo, 6);    /* safety check */
507 
508   /* Calculate max # of rows allowed in one allocation chunk */
509   ltemp = (MAX_ALLOC_CHUNK - sizeof(large_pool_hdr)) /
510           ((long)blocksperrow * sizeof(JBLOCK));
511   if (ltemp <= 0)
512     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
513   if (ltemp < (long)numrows)
514     rowsperchunk = (JDIMENSION)ltemp;
515   else
516     rowsperchunk = numrows;
517   mem->last_rowsperchunk = rowsperchunk;
518 
519   /* Get space for row pointers (small object) */
520   result = (JBLOCKARRAY)alloc_small(cinfo, pool_id,
521                                     (size_t)(numrows * sizeof(JBLOCKROW)));
522 
523   /* Get the rows themselves (large objects) */
524   currow = 0;
525   while (currow < numrows) {
526     rowsperchunk = MIN(rowsperchunk, numrows - currow);
527     workspace = (JBLOCKROW)alloc_large(cinfo, pool_id,
528         (size_t)((size_t)rowsperchunk * (size_t)blocksperrow *
529                   sizeof(JBLOCK)));
530     for (i = rowsperchunk; i > 0; i--) {
531       result[currow++] = workspace;
532       workspace += blocksperrow;
533     }
534   }
535 
536   return result;
537 }
538 
539 
540 /*
541  * About virtual array management:
542  *
543  * The above "normal" array routines are only used to allocate strip buffers
544  * (as wide as the image, but just a few rows high).  Full-image-sized buffers
545  * are handled as "virtual" arrays.  The array is still accessed a strip at a
546  * time, but the memory manager must save the whole array for repeated
547  * accesses.  The intended implementation is that there is a strip buffer in
548  * memory (as high as is possible given the desired memory limit), plus a
549  * backing file that holds the rest of the array.
550  *
551  * The request_virt_array routines are told the total size of the image and
552  * the maximum number of rows that will be accessed at once.  The in-memory
553  * buffer must be at least as large as the maxaccess value.
554  *
555  * The request routines create control blocks but not the in-memory buffers.
556  * That is postponed until realize_virt_arrays is called.  At that time the
557  * total amount of space needed is known (approximately, anyway), so free
558  * memory can be divided up fairly.
559  *
560  * The access_virt_array routines are responsible for making a specific strip
561  * area accessible (after reading or writing the backing file, if necessary).
562  * Note that the access routines are told whether the caller intends to modify
563  * the accessed strip; during a read-only pass this saves having to rewrite
564  * data to disk.  The access routines are also responsible for pre-zeroing
565  * any newly accessed rows, if pre-zeroing was requested.
566  *
567  * In current usage, the access requests are usually for nonoverlapping
568  * strips; that is, successive access start_row numbers differ by exactly
569  * num_rows = maxaccess.  This means we can get good performance with simple
570  * buffer dump/reload logic, by making the in-memory buffer be a multiple
571  * of the access height; then there will never be accesses across bufferload
572  * boundaries.  The code will still work with overlapping access requests,
573  * but it doesn't handle bufferload overlaps very efficiently.
574  */
575 
576 
577 METHODDEF(jvirt_sarray_ptr)
request_virt_sarray(j_common_ptr cinfo,int pool_id,boolean pre_zero,JDIMENSION samplesperrow,JDIMENSION numrows,JDIMENSION maxaccess)578 request_virt_sarray(j_common_ptr cinfo, int pool_id, boolean pre_zero,
579                     JDIMENSION samplesperrow, JDIMENSION numrows,
580                     JDIMENSION maxaccess)
581 /* Request a virtual 2-D sample array */
582 {
583   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
584   jvirt_sarray_ptr result;
585 
586   /* Only IMAGE-lifetime virtual arrays are currently supported */
587   if (pool_id != JPOOL_IMAGE)
588     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
589 
590   /* get control block */
591   result = (jvirt_sarray_ptr)alloc_small(cinfo, pool_id,
592                                          sizeof(struct jvirt_sarray_control));
593 
594   result->mem_buffer = NULL;    /* marks array not yet realized */
595   result->rows_in_array = numrows;
596   result->samplesperrow = samplesperrow;
597   result->maxaccess = maxaccess;
598   result->pre_zero = pre_zero;
599   result->b_s_open = FALSE;     /* no associated backing-store object */
600   result->next = mem->virt_sarray_list; /* add to list of virtual arrays */
601   mem->virt_sarray_list = result;
602 
603   return result;
604 }
605 
606 
607 METHODDEF(jvirt_barray_ptr)
request_virt_barray(j_common_ptr cinfo,int pool_id,boolean pre_zero,JDIMENSION blocksperrow,JDIMENSION numrows,JDIMENSION maxaccess)608 request_virt_barray(j_common_ptr cinfo, int pool_id, boolean pre_zero,
609                     JDIMENSION blocksperrow, JDIMENSION numrows,
610                     JDIMENSION maxaccess)
611 /* Request a virtual 2-D coefficient-block array */
612 {
613   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
614   jvirt_barray_ptr result;
615 
616   /* Only IMAGE-lifetime virtual arrays are currently supported */
617   if (pool_id != JPOOL_IMAGE)
618     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
619 
620   /* get control block */
621   result = (jvirt_barray_ptr)alloc_small(cinfo, pool_id,
622                                          sizeof(struct jvirt_barray_control));
623 
624   result->mem_buffer = NULL;    /* marks array not yet realized */
625   result->rows_in_array = numrows;
626   result->blocksperrow = blocksperrow;
627   result->maxaccess = maxaccess;
628   result->pre_zero = pre_zero;
629   result->b_s_open = FALSE;     /* no associated backing-store object */
630   result->next = mem->virt_barray_list; /* add to list of virtual arrays */
631   mem->virt_barray_list = result;
632 
633   return result;
634 }
635 
636 
637 METHODDEF(void)
realize_virt_arrays(j_common_ptr cinfo)638 realize_virt_arrays(j_common_ptr cinfo)
639 /* Allocate the in-memory buffers for any unrealized virtual arrays */
640 {
641   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
642   size_t space_per_minheight, maximum_space, avail_mem;
643   size_t minheights, max_minheights;
644   jvirt_sarray_ptr sptr;
645   jvirt_barray_ptr bptr;
646 
647   /* Compute the minimum space needed (maxaccess rows in each buffer)
648    * and the maximum space needed (full image height in each buffer).
649    * These may be of use to the system-dependent jpeg_mem_available routine.
650    */
651   space_per_minheight = 0;
652   maximum_space = 0;
653   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
654     if (sptr->mem_buffer == NULL) { /* if not realized yet */
655       size_t new_space = (long)sptr->rows_in_array *
656                          (long)sptr->samplesperrow * sizeof(JSAMPLE);
657 
658       space_per_minheight += (long)sptr->maxaccess *
659                              (long)sptr->samplesperrow * sizeof(JSAMPLE);
660       if (SIZE_MAX - maximum_space < new_space)
661         out_of_memory(cinfo, 10);
662       maximum_space += new_space;
663     }
664   }
665   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
666     if (bptr->mem_buffer == NULL) { /* if not realized yet */
667       size_t new_space = (long)bptr->rows_in_array *
668                          (long)bptr->blocksperrow * sizeof(JBLOCK);
669 
670       space_per_minheight += (long)bptr->maxaccess *
671                              (long)bptr->blocksperrow * sizeof(JBLOCK);
672       if (SIZE_MAX - maximum_space < new_space)
673         out_of_memory(cinfo, 11);
674       maximum_space += new_space;
675     }
676   }
677 
678   if (space_per_minheight <= 0)
679     return;                     /* no unrealized arrays, no work */
680 
681   /* Determine amount of memory to actually use; this is system-dependent. */
682   avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,
683                                  mem->total_space_allocated);
684 
685   /* If the maximum space needed is available, make all the buffers full
686    * height; otherwise parcel it out with the same number of minheights
687    * in each buffer.
688    */
689   if (avail_mem >= maximum_space)
690     max_minheights = 1000000000L;
691   else {
692     max_minheights = avail_mem / space_per_minheight;
693     /* If there doesn't seem to be enough space, try to get the minimum
694      * anyway.  This allows a "stub" implementation of jpeg_mem_available().
695      */
696     if (max_minheights <= 0)
697       max_minheights = 1;
698   }
699 
700   /* Allocate the in-memory buffers and initialize backing store as needed. */
701 
702   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
703     if (sptr->mem_buffer == NULL) { /* if not realized yet */
704       minheights = ((long)sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;
705       if (minheights <= max_minheights) {
706         /* This buffer fits in memory */
707         sptr->rows_in_mem = sptr->rows_in_array;
708       } else {
709         /* It doesn't fit in memory, create backing store. */
710         sptr->rows_in_mem = (JDIMENSION)(max_minheights * sptr->maxaccess);
711         jpeg_open_backing_store(cinfo, &sptr->b_s_info,
712                                 (long)sptr->rows_in_array *
713                                 (long)sptr->samplesperrow *
714                                 (long)sizeof(JSAMPLE));
715         sptr->b_s_open = TRUE;
716       }
717       sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,
718                                       sptr->samplesperrow, sptr->rows_in_mem);
719       sptr->rowsperchunk = mem->last_rowsperchunk;
720       sptr->cur_start_row = 0;
721       sptr->first_undef_row = 0;
722       sptr->dirty = FALSE;
723     }
724   }
725 
726   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
727     if (bptr->mem_buffer == NULL) { /* if not realized yet */
728       minheights = ((long)bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;
729       if (minheights <= max_minheights) {
730         /* This buffer fits in memory */
731         bptr->rows_in_mem = bptr->rows_in_array;
732       } else {
733         /* It doesn't fit in memory, create backing store. */
734         bptr->rows_in_mem = (JDIMENSION)(max_minheights * bptr->maxaccess);
735         jpeg_open_backing_store(cinfo, &bptr->b_s_info,
736                                 (long)bptr->rows_in_array *
737                                 (long)bptr->blocksperrow *
738                                 (long)sizeof(JBLOCK));
739         bptr->b_s_open = TRUE;
740       }
741       bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,
742                                       bptr->blocksperrow, bptr->rows_in_mem);
743       bptr->rowsperchunk = mem->last_rowsperchunk;
744       bptr->cur_start_row = 0;
745       bptr->first_undef_row = 0;
746       bptr->dirty = FALSE;
747     }
748   }
749 }
750 
751 
752 LOCAL(void)
do_sarray_io(j_common_ptr cinfo,jvirt_sarray_ptr ptr,boolean writing)753 do_sarray_io(j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)
754 /* Do backing store read or write of a virtual sample array */
755 {
756   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
757 
758   bytesperrow = (long)ptr->samplesperrow * sizeof(JSAMPLE);
759   file_offset = ptr->cur_start_row * bytesperrow;
760   /* Loop to read or write each allocation chunk in mem_buffer */
761   for (i = 0; i < (long)ptr->rows_in_mem; i += ptr->rowsperchunk) {
762     /* One chunk, but check for short chunk at end of buffer */
763     rows = MIN((long)ptr->rowsperchunk, (long)ptr->rows_in_mem - i);
764     /* Transfer no more than is currently defined */
765     thisrow = (long)ptr->cur_start_row + i;
766     rows = MIN(rows, (long)ptr->first_undef_row - thisrow);
767     /* Transfer no more than fits in file */
768     rows = MIN(rows, (long)ptr->rows_in_array - thisrow);
769     if (rows <= 0)              /* this chunk might be past end of file! */
770       break;
771     byte_count = rows * bytesperrow;
772     if (writing)
773       (*ptr->b_s_info.write_backing_store) (cinfo, &ptr->b_s_info,
774                                             (void *)ptr->mem_buffer[i],
775                                             file_offset, byte_count);
776     else
777       (*ptr->b_s_info.read_backing_store) (cinfo, &ptr->b_s_info,
778                                            (void *)ptr->mem_buffer[i],
779                                            file_offset, byte_count);
780     file_offset += byte_count;
781   }
782 }
783 
784 
785 LOCAL(void)
do_barray_io(j_common_ptr cinfo,jvirt_barray_ptr ptr,boolean writing)786 do_barray_io(j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)
787 /* Do backing store read or write of a virtual coefficient-block array */
788 {
789   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
790 
791   bytesperrow = (long)ptr->blocksperrow * sizeof(JBLOCK);
792   file_offset = ptr->cur_start_row * bytesperrow;
793   /* Loop to read or write each allocation chunk in mem_buffer */
794   for (i = 0; i < (long)ptr->rows_in_mem; i += ptr->rowsperchunk) {
795     /* One chunk, but check for short chunk at end of buffer */
796     rows = MIN((long)ptr->rowsperchunk, (long)ptr->rows_in_mem - i);
797     /* Transfer no more than is currently defined */
798     thisrow = (long)ptr->cur_start_row + i;
799     rows = MIN(rows, (long)ptr->first_undef_row - thisrow);
800     /* Transfer no more than fits in file */
801     rows = MIN(rows, (long)ptr->rows_in_array - thisrow);
802     if (rows <= 0)              /* this chunk might be past end of file! */
803       break;
804     byte_count = rows * bytesperrow;
805     if (writing)
806       (*ptr->b_s_info.write_backing_store) (cinfo, &ptr->b_s_info,
807                                             (void *)ptr->mem_buffer[i],
808                                             file_offset, byte_count);
809     else
810       (*ptr->b_s_info.read_backing_store) (cinfo, &ptr->b_s_info,
811                                            (void *)ptr->mem_buffer[i],
812                                            file_offset, byte_count);
813     file_offset += byte_count;
814   }
815 }
816 
817 
818 METHODDEF(JSAMPARRAY)
access_virt_sarray(j_common_ptr cinfo,jvirt_sarray_ptr ptr,JDIMENSION start_row,JDIMENSION num_rows,boolean writable)819 access_virt_sarray(j_common_ptr cinfo, jvirt_sarray_ptr ptr,
820                    JDIMENSION start_row, JDIMENSION num_rows, boolean writable)
821 /* Access the part of a virtual sample array starting at start_row */
822 /* and extending for num_rows rows.  writable is true if  */
823 /* caller intends to modify the accessed area. */
824 {
825   JDIMENSION end_row = start_row + num_rows;
826   JDIMENSION undef_row;
827 
828   /* debugging check */
829   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
830       ptr->mem_buffer == NULL)
831     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
832 
833   /* Make the desired part of the virtual array accessible */
834   if (start_row < ptr->cur_start_row ||
835       end_row > ptr->cur_start_row + ptr->rows_in_mem) {
836     if (!ptr->b_s_open)
837       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
838     /* Flush old buffer contents if necessary */
839     if (ptr->dirty) {
840       do_sarray_io(cinfo, ptr, TRUE);
841       ptr->dirty = FALSE;
842     }
843     /* Decide what part of virtual array to access.
844      * Algorithm: if target address > current window, assume forward scan,
845      * load starting at target address.  If target address < current window,
846      * assume backward scan, load so that target area is top of window.
847      * Note that when switching from forward write to forward read, will have
848      * start_row = 0, so the limiting case applies and we load from 0 anyway.
849      */
850     if (start_row > ptr->cur_start_row) {
851       ptr->cur_start_row = start_row;
852     } else {
853       /* use long arithmetic here to avoid overflow & unsigned problems */
854       long ltemp;
855 
856       ltemp = (long)end_row - (long)ptr->rows_in_mem;
857       if (ltemp < 0)
858         ltemp = 0;              /* don't fall off front end of file */
859       ptr->cur_start_row = (JDIMENSION)ltemp;
860     }
861     /* Read in the selected part of the array.
862      * During the initial write pass, we will do no actual read
863      * because the selected part is all undefined.
864      */
865     do_sarray_io(cinfo, ptr, FALSE);
866   }
867   /* Ensure the accessed part of the array is defined; prezero if needed.
868    * To improve locality of access, we only prezero the part of the array
869    * that the caller is about to access, not the entire in-memory array.
870    */
871   if (ptr->first_undef_row < end_row) {
872     if (ptr->first_undef_row < start_row) {
873       if (writable)             /* writer skipped over a section of array */
874         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
875       undef_row = start_row;    /* but reader is allowed to read ahead */
876     } else {
877       undef_row = ptr->first_undef_row;
878     }
879     if (writable)
880       ptr->first_undef_row = end_row;
881     if (ptr->pre_zero) {
882       size_t bytesperrow = (size_t)ptr->samplesperrow * sizeof(JSAMPLE);
883       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
884       end_row -= ptr->cur_start_row;
885       while (undef_row < end_row) {
886         jzero_far((void *)ptr->mem_buffer[undef_row], bytesperrow);
887         undef_row++;
888       }
889     } else {
890       if (!writable)            /* reader looking at undefined data */
891         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
892     }
893   }
894   /* Flag the buffer dirty if caller will write in it */
895   if (writable)
896     ptr->dirty = TRUE;
897   /* Return address of proper part of the buffer */
898   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
899 }
900 
901 
902 METHODDEF(JBLOCKARRAY)
access_virt_barray(j_common_ptr cinfo,jvirt_barray_ptr ptr,JDIMENSION start_row,JDIMENSION num_rows,boolean writable)903 access_virt_barray(j_common_ptr cinfo, jvirt_barray_ptr ptr,
904                    JDIMENSION start_row, JDIMENSION num_rows, boolean writable)
905 /* Access the part of a virtual block array starting at start_row */
906 /* and extending for num_rows rows.  writable is true if  */
907 /* caller intends to modify the accessed area. */
908 {
909   JDIMENSION end_row = start_row + num_rows;
910   JDIMENSION undef_row;
911 
912   /* debugging check */
913   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
914       ptr->mem_buffer == NULL)
915     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
916 
917   /* Make the desired part of the virtual array accessible */
918   if (start_row < ptr->cur_start_row ||
919       end_row > ptr->cur_start_row + ptr->rows_in_mem) {
920     if (!ptr->b_s_open)
921       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
922     /* Flush old buffer contents if necessary */
923     if (ptr->dirty) {
924       do_barray_io(cinfo, ptr, TRUE);
925       ptr->dirty = FALSE;
926     }
927     /* Decide what part of virtual array to access.
928      * Algorithm: if target address > current window, assume forward scan,
929      * load starting at target address.  If target address < current window,
930      * assume backward scan, load so that target area is top of window.
931      * Note that when switching from forward write to forward read, will have
932      * start_row = 0, so the limiting case applies and we load from 0 anyway.
933      */
934     if (start_row > ptr->cur_start_row) {
935       ptr->cur_start_row = start_row;
936     } else {
937       /* use long arithmetic here to avoid overflow & unsigned problems */
938       long ltemp;
939 
940       ltemp = (long)end_row - (long)ptr->rows_in_mem;
941       if (ltemp < 0)
942         ltemp = 0;              /* don't fall off front end of file */
943       ptr->cur_start_row = (JDIMENSION)ltemp;
944     }
945     /* Read in the selected part of the array.
946      * During the initial write pass, we will do no actual read
947      * because the selected part is all undefined.
948      */
949     do_barray_io(cinfo, ptr, FALSE);
950   }
951   /* Ensure the accessed part of the array is defined; prezero if needed.
952    * To improve locality of access, we only prezero the part of the array
953    * that the caller is about to access, not the entire in-memory array.
954    */
955   if (ptr->first_undef_row < end_row) {
956     if (ptr->first_undef_row < start_row) {
957       if (writable)             /* writer skipped over a section of array */
958         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
959       undef_row = start_row;    /* but reader is allowed to read ahead */
960     } else {
961       undef_row = ptr->first_undef_row;
962     }
963     if (writable)
964       ptr->first_undef_row = end_row;
965     if (ptr->pre_zero) {
966       size_t bytesperrow = (size_t)ptr->blocksperrow * sizeof(JBLOCK);
967       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
968       end_row -= ptr->cur_start_row;
969       while (undef_row < end_row) {
970         jzero_far((void *)ptr->mem_buffer[undef_row], bytesperrow);
971         undef_row++;
972       }
973     } else {
974       if (!writable)            /* reader looking at undefined data */
975         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
976     }
977   }
978   /* Flag the buffer dirty if caller will write in it */
979   if (writable)
980     ptr->dirty = TRUE;
981   /* Return address of proper part of the buffer */
982   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
983 }
984 
985 
986 /*
987  * Release all objects belonging to a specified pool.
988  */
989 
990 METHODDEF(void)
free_pool(j_common_ptr cinfo,int pool_id)991 free_pool(j_common_ptr cinfo, int pool_id)
992 {
993   my_mem_ptr mem = (my_mem_ptr)cinfo->mem;
994   small_pool_ptr shdr_ptr;
995   large_pool_ptr lhdr_ptr;
996   size_t space_freed;
997 
998   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
999     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
1000 
1001 #ifdef MEM_STATS
1002   if (cinfo->err->trace_level > 1)
1003     print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */
1004 #endif
1005 
1006   /* If freeing IMAGE pool, close any virtual arrays first */
1007   if (pool_id == JPOOL_IMAGE) {
1008     jvirt_sarray_ptr sptr;
1009     jvirt_barray_ptr bptr;
1010 
1011     for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
1012       if (sptr->b_s_open) {     /* there may be no backing store */
1013         sptr->b_s_open = FALSE; /* prevent recursive close if error */
1014         (*sptr->b_s_info.close_backing_store) (cinfo, &sptr->b_s_info);
1015       }
1016     }
1017     mem->virt_sarray_list = NULL;
1018     for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
1019       if (bptr->b_s_open) {     /* there may be no backing store */
1020         bptr->b_s_open = FALSE; /* prevent recursive close if error */
1021         (*bptr->b_s_info.close_backing_store) (cinfo, &bptr->b_s_info);
1022       }
1023     }
1024     mem->virt_barray_list = NULL;
1025   }
1026 
1027   /* Release large objects */
1028   lhdr_ptr = mem->large_list[pool_id];
1029   mem->large_list[pool_id] = NULL;
1030 
1031   while (lhdr_ptr != NULL) {
1032     large_pool_ptr next_lhdr_ptr = lhdr_ptr->next;
1033     space_freed = lhdr_ptr->bytes_used +
1034                   lhdr_ptr->bytes_left +
1035                   sizeof(large_pool_hdr);
1036     jpeg_free_large(cinfo, (void *)lhdr_ptr, space_freed);
1037     mem->total_space_allocated -= space_freed;
1038     lhdr_ptr = next_lhdr_ptr;
1039   }
1040 
1041   /* Release small objects */
1042   shdr_ptr = mem->small_list[pool_id];
1043   mem->small_list[pool_id] = NULL;
1044 
1045   while (shdr_ptr != NULL) {
1046     small_pool_ptr next_shdr_ptr = shdr_ptr->next;
1047     space_freed = shdr_ptr->bytes_used + shdr_ptr->bytes_left +
1048                   sizeof(small_pool_hdr);
1049     jpeg_free_small(cinfo, (void *)shdr_ptr, space_freed);
1050     mem->total_space_allocated -= space_freed;
1051     shdr_ptr = next_shdr_ptr;
1052   }
1053 }
1054 
1055 
1056 /*
1057  * Close up shop entirely.
1058  * Note that this cannot be called unless cinfo->mem is non-NULL.
1059  */
1060 
1061 METHODDEF(void)
self_destruct(j_common_ptr cinfo)1062 self_destruct(j_common_ptr cinfo)
1063 {
1064   int pool;
1065 
1066   /* Close all backing store, release all memory.
1067    * Releasing pools in reverse order might help avoid fragmentation
1068    * with some (brain-damaged) malloc libraries.
1069    */
1070   for (pool = JPOOL_NUMPOOLS - 1; pool >= JPOOL_PERMANENT; pool--) {
1071     free_pool(cinfo, pool);
1072   }
1073 
1074   /* Release the memory manager control block too. */
1075   jpeg_free_small(cinfo, (void *)cinfo->mem, sizeof(my_memory_mgr));
1076   cinfo->mem = NULL;            /* ensures I will be called only once */
1077 
1078   jpeg_mem_term(cinfo);         /* system-dependent cleanup */
1079 }
1080 
1081 
1082 /*
1083  * Memory manager initialization.
1084  * When this is called, only the error manager pointer is valid in cinfo!
1085  */
1086 
1087 GLOBAL(void)
jinit_memory_mgr(j_common_ptr cinfo)1088 jinit_memory_mgr(j_common_ptr cinfo)
1089 {
1090   my_mem_ptr mem;
1091   long max_to_use;
1092   int pool;
1093   size_t test_mac;
1094 
1095   cinfo->mem = NULL;            /* for safety if init fails */
1096 
1097   /* Check for configuration errors.
1098    * sizeof(ALIGN_TYPE) should be a power of 2; otherwise, it probably
1099    * doesn't reflect any real hardware alignment requirement.
1100    * The test is a little tricky: for X>0, X and X-1 have no one-bits
1101    * in common if and only if X is a power of 2, ie has only one one-bit.
1102    * Some compilers may give an "unreachable code" warning here; ignore it.
1103    */
1104   if ((ALIGN_SIZE & (ALIGN_SIZE - 1)) != 0)
1105     ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);
1106   /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be
1107    * a multiple of ALIGN_SIZE.
1108    * Again, an "unreachable code" warning may be ignored here.
1109    * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.
1110    */
1111   test_mac = (size_t)MAX_ALLOC_CHUNK;
1112   if ((long)test_mac != MAX_ALLOC_CHUNK ||
1113       (MAX_ALLOC_CHUNK % ALIGN_SIZE) != 0)
1114     ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);
1115 
1116   max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */
1117 
1118   /* Attempt to allocate memory manager's control block */
1119   mem = (my_mem_ptr)jpeg_get_small(cinfo, sizeof(my_memory_mgr));
1120 
1121   if (mem == NULL) {
1122     jpeg_mem_term(cinfo);       /* system-dependent cleanup */
1123     ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);
1124   }
1125 
1126   /* OK, fill in the method pointers */
1127   mem->pub.alloc_small = alloc_small;
1128   mem->pub.alloc_large = alloc_large;
1129   mem->pub.alloc_sarray = alloc_sarray;
1130   mem->pub.alloc_barray = alloc_barray;
1131   mem->pub.request_virt_sarray = request_virt_sarray;
1132   mem->pub.request_virt_barray = request_virt_barray;
1133   mem->pub.realize_virt_arrays = realize_virt_arrays;
1134   mem->pub.access_virt_sarray = access_virt_sarray;
1135   mem->pub.access_virt_barray = access_virt_barray;
1136   mem->pub.free_pool = free_pool;
1137   mem->pub.self_destruct = self_destruct;
1138 
1139   /* Make MAX_ALLOC_CHUNK accessible to other modules */
1140   mem->pub.max_alloc_chunk = MAX_ALLOC_CHUNK;
1141 
1142   /* Initialize working state */
1143   mem->pub.max_memory_to_use = max_to_use;
1144 
1145   for (pool = JPOOL_NUMPOOLS - 1; pool >= JPOOL_PERMANENT; pool--) {
1146     mem->small_list[pool] = NULL;
1147     mem->large_list[pool] = NULL;
1148   }
1149   mem->virt_sarray_list = NULL;
1150   mem->virt_barray_list = NULL;
1151 
1152   mem->total_space_allocated = sizeof(my_memory_mgr);
1153 
1154   /* Declare ourselves open for business */
1155   cinfo->mem = &mem->pub;
1156 
1157   /* Check for an environment variable JPEGMEM; if found, override the
1158    * default max_memory setting from jpeg_mem_init.  Note that the
1159    * surrounding application may again override this value.
1160    * If your system doesn't support getenv(), define NO_GETENV to disable
1161    * this feature.
1162    */
1163 #ifndef NO_GETENV
1164   {
1165     char *memenv;
1166 
1167     if ((memenv = getenv("JPEGMEM")) != NULL) {
1168       char ch = 'x';
1169 
1170       if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {
1171         if (ch == 'm' || ch == 'M')
1172           max_to_use *= 1000L;
1173         mem->pub.max_memory_to_use = max_to_use * 1000L;
1174       }
1175     }
1176   }
1177 #endif
1178 
1179 }
1180