1 /* 2 * jdatadst.c 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * Modified 2009-2019 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains compression data destination routines for the case of 10 * emitting JPEG data to memory or to a file (or any stdio stream). 11 * While these routines are sufficient for most applications, 12 * some will want to use a different destination manager. 13 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of 14 * JOCTETs into 8-bit-wide elements on external storage. If char is wider 15 * than 8 bits on your machine, you may need to do some tweaking. 16 */ 17 18 /* this is not a core library module, so it doesn't define JPEG_INTERNALS */ 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 #include "jerror.h" 22 23 #ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */ 24 extern void * malloc JPP((size_t size)); 25 extern void free JPP((void *ptr)); 26 #endif 27 28 29 /* Expanded data destination object for stdio output */ 30 31 typedef struct { 32 struct jpeg_destination_mgr pub; /* public fields */ 33 34 FILE * outfile; /* target stream */ 35 JOCTET * buffer; /* start of buffer */ 36 } my_destination_mgr; 37 38 typedef my_destination_mgr * my_dest_ptr; 39 40 #define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */ 41 42 43 /* Expanded data destination object for memory output */ 44 45 typedef struct { 46 struct jpeg_destination_mgr pub; /* public fields */ 47 48 unsigned char ** outbuffer; /* target buffer */ 49 size_t * outsize; 50 unsigned char * newbuffer; /* newly allocated buffer */ 51 JOCTET * buffer; /* start of buffer */ 52 size_t bufsize; 53 } my_mem_destination_mgr; 54 55 typedef my_mem_destination_mgr * my_mem_dest_ptr; 56 57 58 /* 59 * Initialize destination --- called by jpeg_start_compress 60 * before any data is actually written. 61 */ 62 63 METHODDEF(void) 64 init_destination (j_compress_ptr cinfo) 65 { 66 my_dest_ptr dest = (my_dest_ptr) cinfo->dest; 67 68 /* Allocate the output buffer --- it will be released when done with image */ 69 dest->buffer = (JOCTET *) (*cinfo->mem->alloc_small) 70 ((j_common_ptr) cinfo, JPOOL_IMAGE, OUTPUT_BUF_SIZE * SIZEOF(JOCTET)); 71 72 dest->pub.next_output_byte = dest->buffer; 73 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE; 74 } 75 76 METHODDEF(void) 77 init_mem_destination (j_compress_ptr cinfo) 78 { 79 /* no work necessary here */ 80 } 81 82 83 /* 84 * Empty the output buffer --- called whenever buffer fills up. 85 * 86 * In typical applications, this should write the entire output buffer 87 * (ignoring the current state of next_output_byte & free_in_buffer), 88 * reset the pointer & count to the start of the buffer, and return TRUE 89 * indicating that the buffer has been dumped. 90 * 91 * In applications that need to be able to suspend compression due to output 92 * overrun, a FALSE return indicates that the buffer cannot be emptied now. 93 * In this situation, the compressor will return to its caller (possibly with 94 * an indication that it has not accepted all the supplied scanlines). The 95 * application should resume compression after it has made more room in the 96 * output buffer. Note that there are substantial restrictions on the use of 97 * suspension --- see the documentation. 98 * 99 * When suspending, the compressor will back up to a convenient restart point 100 * (typically the start of the current MCU). next_output_byte & free_in_buffer 101 * indicate where the restart point will be if the current call returns FALSE. 102 * Data beyond this point will be regenerated after resumption, so do not 103 * write it out when emptying the buffer externally. 104 */ 105 106 METHODDEF(boolean) 107 empty_output_buffer (j_compress_ptr cinfo) 108 { 109 my_dest_ptr dest = (my_dest_ptr) cinfo->dest; 110 111 if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) != 112 (size_t) OUTPUT_BUF_SIZE) 113 ERREXIT(cinfo, JERR_FILE_WRITE); 114 115 dest->pub.next_output_byte = dest->buffer; 116 dest->pub.free_in_buffer = OUTPUT_BUF_SIZE; 117 118 return TRUE; 119 } 120 121 METHODDEF(boolean) 122 empty_mem_output_buffer (j_compress_ptr cinfo) 123 { 124 size_t nextsize; 125 JOCTET * nextbuffer; 126 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest; 127 128 /* Try to allocate new buffer with double size */ 129 nextsize = dest->bufsize * 2; 130 nextbuffer = (JOCTET *) malloc(nextsize); 131 132 if (nextbuffer == NULL) 133 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 11); 134 135 MEMCOPY(nextbuffer, dest->buffer, dest->bufsize); 136 137 if (dest->newbuffer != NULL) 138 free(dest->newbuffer); 139 140 dest->newbuffer = nextbuffer; 141 142 dest->pub.next_output_byte = nextbuffer + dest->bufsize; 143 dest->pub.free_in_buffer = dest->bufsize; 144 145 dest->buffer = nextbuffer; 146 dest->bufsize = nextsize; 147 148 return TRUE; 149 } 150 151 152 /* 153 * Terminate destination --- called by jpeg_finish_compress 154 * after all data has been written. Usually needs to flush buffer. 155 * 156 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding 157 * application must deal with any cleanup that should happen even 158 * for error exit. 159 */ 160 161 METHODDEF(void) 162 term_destination (j_compress_ptr cinfo) 163 { 164 my_dest_ptr dest = (my_dest_ptr) cinfo->dest; 165 size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer; 166 167 /* Write any data remaining in the buffer */ 168 if (datacount > 0) { 169 if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount) 170 ERREXIT(cinfo, JERR_FILE_WRITE); 171 } 172 JFFLUSH(dest->outfile); 173 /* Make sure we wrote the output file OK */ 174 if (JFERROR(dest->outfile)) 175 ERREXIT(cinfo, JERR_FILE_WRITE); 176 } 177 178 METHODDEF(void) 179 term_mem_destination (j_compress_ptr cinfo) 180 { 181 my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest; 182 183 *dest->outbuffer = dest->buffer; 184 *dest->outsize = dest->bufsize - dest->pub.free_in_buffer; 185 } 186 187 188 /* 189 * Prepare for output to a stdio stream. 190 * The caller must have already opened the stream, and is responsible 191 * for closing it after finishing compression. 192 */ 193 194 GLOBAL(void) 195 jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile) 196 { 197 my_dest_ptr dest; 198 199 /* The destination object is made permanent so that multiple JPEG images 200 * can be written to the same file without re-executing jpeg_stdio_dest. 201 * This makes it dangerous to use this manager and a different destination 202 * manager serially with the same JPEG object, because their private object 203 * sizes may be different. Caveat programmer. 204 */ 205 if (cinfo->dest == NULL) { /* first time for this JPEG object? */ 206 cinfo->dest = (struct jpeg_destination_mgr *) (*cinfo->mem->alloc_small) 207 ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(my_destination_mgr)); 208 } 209 210 dest = (my_dest_ptr) cinfo->dest; 211 dest->pub.init_destination = init_destination; 212 dest->pub.empty_output_buffer = empty_output_buffer; 213 dest->pub.term_destination = term_destination; 214 dest->outfile = outfile; 215 } 216 217 218 /* 219 * Prepare for output to a memory buffer. 220 * The caller may supply an own initial buffer with appropriate size. 221 * Otherwise, or when the actual data output exceeds the given size, 222 * the library adapts the buffer size as necessary. 223 * The standard library functions malloc/free are used for allocating 224 * larger memory, so the buffer is available to the application after 225 * finishing compression, and then the application is responsible for 226 * freeing the requested memory. 227 * Note: An initial buffer supplied by the caller is expected to be 228 * managed by the application. The library does not free such buffer 229 * when allocating a larger buffer. 230 */ 231 232 GLOBAL(void) 233 jpeg_mem_dest (j_compress_ptr cinfo, 234 unsigned char ** outbuffer, size_t * outsize) 235 { 236 my_mem_dest_ptr dest; 237 238 if (outbuffer == NULL || outsize == NULL) /* sanity check */ 239 ERREXIT(cinfo, JERR_BUFFER_SIZE); 240 241 /* The destination object is made permanent so that multiple JPEG images 242 * can be written to the same buffer without re-executing jpeg_mem_dest. 243 */ 244 if (cinfo->dest == NULL) { /* first time for this JPEG object? */ 245 cinfo->dest = (struct jpeg_destination_mgr *) (*cinfo->mem->alloc_small) 246 ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(my_mem_destination_mgr)); 247 } 248 249 dest = (my_mem_dest_ptr) cinfo->dest; 250 dest->pub.init_destination = init_mem_destination; 251 dest->pub.empty_output_buffer = empty_mem_output_buffer; 252 dest->pub.term_destination = term_mem_destination; 253 dest->outbuffer = outbuffer; 254 dest->outsize = outsize; 255 dest->newbuffer = NULL; 256 257 if (*outbuffer == NULL || *outsize == 0) { 258 /* Allocate initial buffer */ 259 dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE); 260 if (dest->newbuffer == NULL) 261 ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10); 262 *outsize = OUTPUT_BUF_SIZE; 263 } 264 265 dest->pub.next_output_byte = dest->buffer = *outbuffer; 266 dest->pub.free_in_buffer = dest->bufsize = *outsize; 267 } 268