xref: /PHP-7.3/ext/gd/libgd/gd_io_dp.c (revision 5cd348c1)
1 /*
2    * io_dp.c
3    *
4    * Implements the dynamic pointer interface.
5    *
6    * Based on GD.pm code by Lincoln Stein for interfacing to libgd.
7    * Added support for reading as well as support for 'tell' and 'seek'.
8    *
9    * As will all I/O modules, most functions are for local use only (called
10    * via function pointers in the I/O context).
11    *
12    * gdDPExtractData is the exception to this: it will return the pointer to
13    * the internal data, and reset the internal storage.
14    *
15    * Written/Modified 1999, Philip Warner.
16    *
17  */
18 
19 #include <math.h>
20 #include <string.h>
21 #include <stdlib.h>
22 #include "gd.h"
23 #include "gdhelpers.h"
24 
25 #define TRUE 1
26 #define FALSE 0
27 
28 /* this is used for creating images in main memory */
29 typedef struct dpStruct
30 {
31 	void *data;
32 	int logicalSize;
33 	int realSize;
34 	int dataGood;
35 	int pos;
36 	int freeOK;
37 } dynamicPtr;
38 
39 typedef struct dpIOCtx
40 {
41 	gdIOCtx ctx;
42 	dynamicPtr *dp;
43 } dpIOCtx;
44 
45 typedef struct dpIOCtx *dpIOCtxPtr;
46 
47 /* these functions operate on in-memory dynamic pointers */
48 static int allocDynamic (dynamicPtr * dp, int initialSize, void *data);
49 static int appendDynamic (dynamicPtr * dp, const void *src, int size);
50 static int gdReallocDynamic (dynamicPtr * dp, int required);
51 static int trimDynamic (dynamicPtr * dp);
52 static void gdFreeDynamicCtx (struct gdIOCtx *ctx);
53 static dynamicPtr *newDynamic (int initialSize, void *data, int freeOKFlag);
54 
55 static int dynamicPutbuf (struct gdIOCtx *, const void *, int);
56 static void dynamicPutchar (struct gdIOCtx *, int a);
57 
58 static int dynamicGetbuf (gdIOCtxPtr ctx, void *buf, int len);
59 static int dynamicGetchar (gdIOCtxPtr ctx);
60 
61 static int dynamicSeek (struct gdIOCtx *, const int);
62 static long dynamicTell (struct gdIOCtx *);
63 
64 /* return data as a dynamic pointer */
gdNewDynamicCtx(int initialSize,void * data)65 gdIOCtx * gdNewDynamicCtx (int initialSize, void *data)
66 {
67 	return gdNewDynamicCtxEx(initialSize, data, 1);
68 }
69 
gdNewDynamicCtxEx(int initialSize,void * data,int freeOKFlag)70 gdIOCtx * gdNewDynamicCtxEx (int initialSize, void *data, int freeOKFlag)
71 {
72 	dpIOCtx *ctx;
73 	dynamicPtr *dp;
74 
75 	ctx = (dpIOCtx *) gdMalloc (sizeof (dpIOCtx));
76 
77 	dp = newDynamic(initialSize, data, freeOKFlag);
78 
79 	ctx->dp = dp;
80 
81 	ctx->ctx.getC = dynamicGetchar;
82 	ctx->ctx.putC = dynamicPutchar;
83 
84 	ctx->ctx.getBuf = dynamicGetbuf;
85 	ctx->ctx.putBuf = dynamicPutbuf;
86 
87 	ctx->ctx.seek = dynamicSeek;
88 	ctx->ctx.tell = dynamicTell;
89 
90 	ctx->ctx.gd_free = gdFreeDynamicCtx;
91 
92 	return (gdIOCtx *) ctx;
93 }
94 
gdDPExtractData(struct gdIOCtx * ctx,int * size)95 void * gdDPExtractData (struct gdIOCtx *ctx, int *size)
96 {
97 	dynamicPtr *dp;
98 	dpIOCtx *dctx;
99 	void *data;
100 
101 	dctx = (dpIOCtx *) ctx;
102 	dp = dctx->dp;
103 
104 	/* clean up the data block and return it */
105 	if (dp->dataGood) {
106 		trimDynamic (dp);
107 		*size = dp->logicalSize;
108 		data = dp->data;
109 	} else {
110 		*size = 0;
111 		data = NULL;
112 		if (dp->data != NULL && dp->freeOK) {
113 			gdFree(dp->data);
114 		}
115 	}
116 
117 	dp->data = NULL;
118 	dp->realSize = 0;
119 	dp->logicalSize = 0;
120 
121 	return data;
122 }
123 
gdFreeDynamicCtx(struct gdIOCtx * ctx)124 static void gdFreeDynamicCtx (struct gdIOCtx *ctx)
125 {
126 	dynamicPtr *dp;
127 	dpIOCtx *dctx;
128 
129 	dctx = (dpIOCtx *) ctx;
130 	dp = dctx->dp;
131 
132 	gdFree(ctx);
133 
134 	dp->realSize = 0;
135 	dp->logicalSize = 0;
136 
137 	gdFree(dp);
138 }
139 
dynamicTell(struct gdIOCtx * ctx)140 static long dynamicTell (struct gdIOCtx *ctx)
141 {
142 	dpIOCtx *dctx;
143 
144 	dctx = (dpIOCtx *) ctx;
145 
146 	return (dctx->dp->pos);
147 }
148 
dynamicSeek(struct gdIOCtx * ctx,const int pos)149 static int dynamicSeek (struct gdIOCtx *ctx, const int pos)
150 {
151 	int bytesNeeded;
152 	dynamicPtr *dp;
153 	dpIOCtx *dctx;
154 
155 	if (pos < 0) {
156 		return FALSE;
157 	}
158 	dctx = (dpIOCtx *) ctx;
159 	dp = dctx->dp;
160 
161 	if (!dp->dataGood) {
162 		return FALSE;
163 	}
164 
165 	bytesNeeded = pos;
166 	if (bytesNeeded > dp->realSize) {
167 		/* 2.0.21 */
168 		if (!dp->freeOK) {
169 			return FALSE;
170 		}
171 		gdReallocDynamic (dp, dp->realSize * 2);
172 	}
173 
174 	/* if we get here, we can be sure that we have enough bytes to copy safely */
175 
176 	/* Extend the logical size if we seek beyond EOF. */
177 	if (pos > dp->logicalSize) {
178 		dp->logicalSize = pos;
179 	}
180 
181 	dp->pos = pos;
182 
183 	return TRUE;
184 }
185 
186 /* return data as a dynamic pointer */
newDynamic(int initialSize,void * data,int freeOKFlag)187 static dynamicPtr * newDynamic (int initialSize, void *data, int freeOKFlag)
188 {
189 	dynamicPtr *dp;
190 	dp = (dynamicPtr *) gdMalloc (sizeof (dynamicPtr));
191 
192 	allocDynamic (dp, initialSize, data);
193 
194 	dp->pos = 0;
195 	dp->freeOK = freeOKFlag;
196 
197 	return dp;
198 }
199 
200 static int
dynamicPutbuf(struct gdIOCtx * ctx,const void * buf,int size)201 dynamicPutbuf (struct gdIOCtx *ctx, const void *buf, int size)
202 {
203   dpIOCtx *dctx;
204   dctx = (dpIOCtx *) ctx;
205 
206   appendDynamic (dctx->dp, buf, size);
207 
208   if (dctx->dp->dataGood)
209     {
210       return size;
211     }
212   else
213     {
214       return -1;
215     };
216 
217 }
218 
dynamicPutchar(struct gdIOCtx * ctx,int a)219 static void dynamicPutchar (struct gdIOCtx *ctx, int a)
220 {
221 	unsigned char b;
222 	dpIOCtxPtr dctx;
223 
224 	b = a;
225 	dctx = (dpIOCtxPtr) ctx;
226 
227 	appendDynamic(dctx->dp, &b, 1);
228 }
229 
dynamicGetbuf(gdIOCtxPtr ctx,void * buf,int len)230 static int dynamicGetbuf (gdIOCtxPtr ctx, void *buf, int len)
231 {
232 	int rlen, remain;
233 	dpIOCtxPtr dctx;
234 	dynamicPtr *dp;
235 
236 	dctx = (dpIOCtxPtr) ctx;
237 	dp = dctx->dp;
238 
239 	remain = dp->logicalSize - dp->pos;
240 	if (remain >= len) {
241 		rlen = len;
242 	} else {
243 		if (remain <= 0) {
244 			return EOF;
245 		}
246 		rlen = remain;
247 	}
248 
249 	memcpy(buf, (void *) ((char *) dp->data + dp->pos), rlen);
250 	dp->pos += rlen;
251 
252 	return rlen;
253 }
254 
dynamicGetchar(gdIOCtxPtr ctx)255 static int dynamicGetchar (gdIOCtxPtr ctx)
256 {
257 	unsigned char b;
258 	int rv;
259 
260 	rv = dynamicGetbuf (ctx, &b, 1);
261 	if (rv != 1) {
262 		return EOF;
263 	} else {
264 		return b; 		/* (b & 0xff); */
265 	}
266 }
267 
268 /* *********************************************************************
269 
270  * InitDynamic - Return a dynamically resizable void*
271  *
272  * *********************************************************************
273  */
274 static int
allocDynamic(dynamicPtr * dp,int initialSize,void * data)275 allocDynamic (dynamicPtr * dp, int initialSize, void *data)
276 {
277 
278 	if (data == NULL) {
279 		dp->logicalSize = 0;
280 		dp->dataGood = FALSE;
281 		dp->data = gdMalloc(initialSize);
282 	} else {
283 		dp->logicalSize = initialSize;
284 		dp->dataGood = TRUE;
285 		dp->data = data;
286 	}
287 
288 	dp->realSize = initialSize;
289 	dp->dataGood = TRUE;
290 	dp->pos = 0;
291 
292 	return TRUE;
293 }
294 
295 /* append bytes to the end of a dynamic pointer */
appendDynamic(dynamicPtr * dp,const void * src,int size)296 static int appendDynamic (dynamicPtr * dp, const void *src, int size)
297 {
298 	int bytesNeeded;
299 	char *tmp;
300 
301 	if (!dp->dataGood) {
302 		return FALSE;
303 	}
304 
305 	/*  bytesNeeded = dp->logicalSize + size; */
306 	bytesNeeded = dp->pos + size;
307 
308 	if (bytesNeeded > dp->realSize) {
309 		/* 2.0.21 */
310 		if (!dp->freeOK) {
311 			return FALSE;
312 		}
313 		gdReallocDynamic(dp, bytesNeeded * 2);
314 	}
315 
316 	/* if we get here, we can be sure that we have enough bytes to copy safely */
317 	/*printf("Mem OK Size: %d, Pos: %d\n", dp->realSize, dp->pos); */
318 
319 	tmp = (char *) dp->data;
320 	memcpy((void *) (tmp + (dp->pos)), src, size);
321 	dp->pos += size;
322 
323 	if (dp->pos > dp->logicalSize) {
324 		dp->logicalSize = dp->pos;
325 	}
326 
327 	return TRUE;
328 }
329 
330 /* grow (or shrink) dynamic pointer */
gdReallocDynamic(dynamicPtr * dp,int required)331 static int gdReallocDynamic (dynamicPtr * dp, int required)
332 {
333 	void *newPtr;
334 
335 	/* First try gdRealloc(). If that doesn't work, make a new memory block and copy. */
336 	if ((newPtr = gdRealloc(dp->data, required))) {
337 		dp->realSize = required;
338 		dp->data = newPtr;
339 		return TRUE;
340 	}
341 
342 	/* create a new pointer */
343 	newPtr = gdMalloc(required);
344 
345 	/* copy the old data into it */
346 	memcpy(newPtr, dp->data, dp->logicalSize);
347 	gdFree(dp->data);
348 	dp->data = newPtr;
349 
350 	dp->realSize = required;
351 
352 	return TRUE;
353 }
354 
355 /* trim pointer so that its real and logical sizes match */
trimDynamic(dynamicPtr * dp)356 static int trimDynamic (dynamicPtr * dp)
357 {
358 	/* 2.0.21: we don't reallocate memory we don't own */
359 	if (!dp->freeOK) {
360 		return FALSE;
361 	}
362 	return gdReallocDynamic(dp, dp->logicalSize);
363 }
364