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() */
27 extern void *malloc(size_t size);
28 extern 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
37 typedef 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
48 typedef 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
56 METHODDEF(void)
init_mem_destination(j_compress_ptr cinfo)57 init_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
86 METHODDEF(boolean)
empty_mem_output_buffer(j_compress_ptr cinfo)87 empty_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
128 METHODDEF(void)
term_mem_destination(j_compress_ptr cinfo)129 term_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
149 GLOBAL(void)
jpeg_mem_dest_tj(j_compress_ptr cinfo,unsigned char ** outbuffer,unsigned long * outsize,boolean alloc)150 jpeg_mem_dest_tj(j_compress_ptr cinfo, unsigned char **outbuffer,
151 unsigned long *outsize, boolean alloc)
152 {
153 boolean reused = FALSE;
154 my_mem_dest_ptr dest;
155
156 if (outbuffer == NULL || outsize == NULL) /* sanity check */
157 ERREXIT(cinfo, JERR_BUFFER_SIZE);
158
159 /* The destination object is made permanent so that multiple JPEG images
160 * can be written to the same buffer without re-executing jpeg_mem_dest.
161 */
162 if (cinfo->dest == NULL) { /* first time for this JPEG object? */
163 cinfo->dest = (struct jpeg_destination_mgr *)
164 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
165 sizeof(my_mem_destination_mgr));
166 dest = (my_mem_dest_ptr)cinfo->dest;
167 dest->newbuffer = NULL;
168 dest->buffer = NULL;
169 } else if (cinfo->dest->init_destination != init_mem_destination) {
170 /* It is unsafe to reuse the existing destination manager unless it was
171 * created by this function.
172 */
173 ERREXIT(cinfo, JERR_BUFFER_SIZE);
174 }
175
176 dest = (my_mem_dest_ptr)cinfo->dest;
177 dest->pub.init_destination = init_mem_destination;
178 dest->pub.empty_output_buffer = empty_mem_output_buffer;
179 dest->pub.term_destination = term_mem_destination;
180 if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)
181 reused = TRUE;
182 dest->outbuffer = outbuffer;
183 dest->outsize = outsize;
184 dest->alloc = alloc;
185
186 if (*outbuffer == NULL || *outsize == 0) {
187 if (alloc) {
188 /* Allocate initial buffer */
189 dest->newbuffer = *outbuffer = (unsigned char *)malloc(OUTPUT_BUF_SIZE);
190 if (dest->newbuffer == NULL)
191 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
192 *outsize = OUTPUT_BUF_SIZE;
193 } else
194 ERREXIT(cinfo, JERR_BUFFER_SIZE);
195 }
196
197 dest->pub.next_output_byte = dest->buffer = *outbuffer;
198 if (!reused)
199 dest->bufsize = *outsize;
200 dest->pub.free_in_buffer = dest->bufsize;
201 }
202