1/*
2 * jdatadst-tj.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * Modified 2009-2012 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2011, 2014, 2016, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
11 *
12 * This file contains compression data destination routines for the case of
13 * emitting JPEG data to memory or to a file (or any stdio stream).
14 * While these routines are sufficient for most applications,
15 * some will want to use a different destination manager.
16 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
17 * JOCTETs into 8-bit-wide elements on external storage.  If char is wider
18 * than 8 bits on your machine, you may need to do some tweaking.
19 */
20
21/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
22#include "jinclude.h"
23#include "jpeglib.h"
24#include "jerror.h"
25
26#ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare malloc(),free() */
27extern void *malloc (size_t size);
28extern void free (void *ptr);
29#endif
30
31
32#define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */
33
34
35/* Expanded data destination object for memory output */
36
37typedef struct {
38  struct jpeg_destination_mgr pub; /* public fields */
39
40  unsigned char **outbuffer;    /* target buffer */
41  unsigned long *outsize;
42  unsigned char *newbuffer;     /* newly allocated buffer */
43  JOCTET *buffer;               /* start of buffer */
44  size_t bufsize;
45  boolean alloc;
46} my_mem_destination_mgr;
47
48typedef my_mem_destination_mgr *my_mem_dest_ptr;
49
50
51/*
52 * Initialize destination --- called by jpeg_start_compress
53 * before any data is actually written.
54 */
55
56METHODDEF(void)
57init_mem_destination (j_compress_ptr cinfo)
58{
59  /* no work necessary here */
60}
61
62
63/*
64 * Empty the output buffer --- called whenever buffer fills up.
65 *
66 * In typical applications, this should write the entire output buffer
67 * (ignoring the current state of next_output_byte & free_in_buffer),
68 * reset the pointer & count to the start of the buffer, and return TRUE
69 * indicating that the buffer has been dumped.
70 *
71 * In applications that need to be able to suspend compression due to output
72 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
73 * In this situation, the compressor will return to its caller (possibly with
74 * an indication that it has not accepted all the supplied scanlines).  The
75 * application should resume compression after it has made more room in the
76 * output buffer.  Note that there are substantial restrictions on the use of
77 * suspension --- see the documentation.
78 *
79 * When suspending, the compressor will back up to a convenient restart point
80 * (typically the start of the current MCU). next_output_byte & free_in_buffer
81 * indicate where the restart point will be if the current call returns FALSE.
82 * Data beyond this point will be regenerated after resumption, so do not
83 * write it out when emptying the buffer externally.
84 */
85
86METHODDEF(boolean)
87empty_mem_output_buffer (j_compress_ptr cinfo)
88{
89  size_t nextsize;
90  JOCTET *nextbuffer;
91  my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
92
93  if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);
94
95  /* Try to allocate new buffer with double size */
96  nextsize = dest->bufsize * 2;
97  nextbuffer = (JOCTET *) malloc(nextsize);
98
99  if (nextbuffer == NULL)
100    ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
101
102  MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
103
104  if (dest->newbuffer != NULL)
105    free(dest->newbuffer);
106
107  dest->newbuffer = nextbuffer;
108
109  dest->pub.next_output_byte = nextbuffer + dest->bufsize;
110  dest->pub.free_in_buffer = dest->bufsize;
111
112  dest->buffer = nextbuffer;
113  dest->bufsize = nextsize;
114
115  return TRUE;
116}
117
118
119/*
120 * Terminate destination --- called by jpeg_finish_compress
121 * after all data has been written.  Usually needs to flush buffer.
122 *
123 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
124 * application must deal with any cleanup that should happen even
125 * for error exit.
126 */
127
128METHODDEF(void)
129term_mem_destination (j_compress_ptr cinfo)
130{
131  my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
132
133  if(dest->alloc) *dest->outbuffer = dest->buffer;
134  *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer);
135}
136
137
138/*
139 * Prepare for output to a memory buffer.
140 * The caller may supply an own initial buffer with appropriate size.
141 * Otherwise, or when the actual data output exceeds the given size,
142 * the library adapts the buffer size as necessary.
143 * The standard library functions malloc/free are used for allocating
144 * larger memory, so the buffer is available to the application after
145 * finishing compression, and then the application is responsible for
146 * freeing the requested memory.
147 */
148
149GLOBAL(void)
150jpeg_mem_dest_tj (j_compress_ptr cinfo,
151               unsigned char **outbuffer, unsigned long *outsize,
152               boolean alloc)
153{
154  boolean reused = FALSE;
155  my_mem_dest_ptr dest;
156
157  if (outbuffer == NULL || outsize == NULL)     /* sanity check */
158    ERREXIT(cinfo, JERR_BUFFER_SIZE);
159
160  /* The destination object is made permanent so that multiple JPEG images
161   * can be written to the same buffer without re-executing jpeg_mem_dest.
162   */
163  if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
164    cinfo->dest = (struct jpeg_destination_mgr *)
165      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
166                                  sizeof(my_mem_destination_mgr));
167    dest = (my_mem_dest_ptr) cinfo->dest;
168    dest->newbuffer = NULL;
169    dest->buffer = NULL;
170  } else if (cinfo->dest->init_destination != init_mem_destination) {
171    /* It is unsafe to reuse the existing destination manager unless it was
172     * created by this function.
173     */
174    ERREXIT(cinfo, JERR_BUFFER_SIZE);
175  }
176
177  dest = (my_mem_dest_ptr) cinfo->dest;
178  dest->pub.init_destination = init_mem_destination;
179  dest->pub.empty_output_buffer = empty_mem_output_buffer;
180  dest->pub.term_destination = term_mem_destination;
181  if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)
182    reused = TRUE;
183  dest->outbuffer = outbuffer;
184  dest->outsize = outsize;
185  dest->alloc = alloc;
186
187  if (*outbuffer == NULL || *outsize == 0) {
188    if (alloc) {
189      /* Allocate initial buffer */
190      dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
191      if (dest->newbuffer == NULL)
192        ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
193      *outsize = OUTPUT_BUF_SIZE;
194    }
195    else ERREXIT(cinfo, JERR_BUFFER_SIZE);
196  }
197
198  dest->pub.next_output_byte = dest->buffer = *outbuffer;
199  if (!reused)
200    dest->bufsize = *outsize;
201  dest->pub.free_in_buffer = dest->bufsize;
202}
203