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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