Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * read.c
4 : * routines to convert a string (legal ascii representation of node) back
5 : * to nodes
6 : *
7 : * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : *
11 : * IDENTIFICATION
12 : * src/backend/nodes/read.c
13 : *
14 : * HISTORY
15 : * AUTHOR DATE MAJOR EVENT
16 : * Andrew Yu Nov 2, 1994 file creation
17 : *
18 : *-------------------------------------------------------------------------
19 : */
20 : #include "postgres.h"
21 :
22 : #include <ctype.h>
23 :
24 : #include "nodes/pg_list.h"
25 : #include "nodes/readfuncs.h"
26 : #include "nodes/value.h"
27 :
28 :
29 : /* Static state for pg_strtok */
30 : static char *pg_strtok_ptr = NULL;
31 :
32 :
33 : /*
34 : * stringToNode -
35 : * returns a Node with a given legal ASCII representation
36 : */
37 : void *
38 5155 : stringToNode(char *str)
39 : {
40 : char *save_strtok;
41 : void *retval;
42 :
43 : /*
44 : * We save and restore the pre-existing state of pg_strtok. This makes the
45 : * world safe for re-entrant invocation of stringToNode, without incurring
46 : * a lot of notational overhead by having to pass the next-character
47 : * pointer around through all the readfuncs.c code.
48 : */
49 5155 : save_strtok = pg_strtok_ptr;
50 :
51 5155 : pg_strtok_ptr = str; /* point pg_strtok at the string to read */
52 :
53 5155 : retval = nodeRead(NULL, 0); /* do the reading */
54 :
55 5155 : pg_strtok_ptr = save_strtok;
56 :
57 5155 : return retval;
58 : }
59 :
60 : /*****************************************************************************
61 : *
62 : * the lisp token parser
63 : *
64 : *****************************************************************************/
65 :
66 : /*
67 : * pg_strtok --- retrieve next "token" from a string.
68 : *
69 : * Works kinda like strtok, except it never modifies the source string.
70 : * (Instead of storing nulls into the string, the length of the token
71 : * is returned to the caller.)
72 : * Also, the rules about what is a token are hard-wired rather than being
73 : * configured by passing a set of terminating characters.
74 : *
75 : * The string is assumed to have been initialized already by stringToNode.
76 : *
77 : * The rules for tokens are:
78 : * * Whitespace (space, tab, newline) always separates tokens.
79 : * * The characters '(', ')', '{', '}' form individual tokens even
80 : * without any whitespace around them.
81 : * * Otherwise, a token is all the characters up to the next whitespace
82 : * or occurrence of one of the four special characters.
83 : * * A backslash '\' can be used to quote whitespace or one of the four
84 : * special characters, so that it is treated as a plain token character.
85 : * Backslashes themselves must also be backslashed for consistency.
86 : * Any other character can be, but need not be, backslashed as well.
87 : * * If the resulting token is '<>' (with no backslash), it is returned
88 : * as a non-NULL pointer to the token but with length == 0. Note that
89 : * there is no other way to get a zero-length token.
90 : *
91 : * Returns a pointer to the start of the next token, and the length of the
92 : * token (including any embedded backslashes!) in *length. If there are
93 : * no more tokens, NULL and 0 are returned.
94 : *
95 : * NOTE: this routine doesn't remove backslashes; the caller must do so
96 : * if necessary (see "debackslash").
97 : *
98 : * NOTE: prior to release 7.0, this routine also had a special case to treat
99 : * a token starting with '"' as extending to the next '"'. This code was
100 : * broken, however, since it would fail to cope with a string containing an
101 : * embedded '"'. I have therefore removed this special case, and instead
102 : * introduced rules for using backslashes to quote characters. Higher-level
103 : * code should add backslashes to a string constant to ensure it is treated
104 : * as a single token.
105 : */
106 : char *
107 1530114 : pg_strtok(int *length)
108 : {
109 : char *local_str; /* working pointer to string */
110 : char *ret_str; /* start of token to return */
111 :
112 1530114 : local_str = pg_strtok_ptr;
113 :
114 4360621 : while (*local_str == ' ' || *local_str == '\n' || *local_str == '\t')
115 1300393 : local_str++;
116 :
117 1530114 : if (*local_str == '\0')
118 : {
119 0 : *length = 0;
120 0 : pg_strtok_ptr = local_str;
121 0 : return NULL; /* no more tokens */
122 : }
123 :
124 : /*
125 : * Now pointing at start of next token.
126 : */
127 1530114 : ret_str = local_str;
128 :
129 2980234 : if (*local_str == '(' || *local_str == ')' ||
130 2827954 : *local_str == '{' || *local_str == '}')
131 : {
132 : /* special 1-character token */
133 224566 : local_str++;
134 : }
135 : else
136 : {
137 : /* Normal token, possibly containing backslashes */
138 19536763 : while (*local_str != '\0' &&
139 24915420 : *local_str != ' ' && *local_str != '\n' &&
140 15800282 : *local_str != '\t' &&
141 23676602 : *local_str != '(' && *local_str != ')' &&
142 15752640 : *local_str != '{' && *local_str != '}')
143 : {
144 7810529 : if (*local_str == '\\' && local_str[1] != '\0')
145 274 : local_str += 2;
146 : else
147 7810255 : local_str++;
148 : }
149 : }
150 :
151 1530114 : *length = local_str - ret_str;
152 :
153 : /* Recognize special case for "empty" token */
154 1530114 : if (*length == 2 && ret_str[0] == '<' && ret_str[1] == '>')
155 50594 : *length = 0;
156 :
157 1530114 : pg_strtok_ptr = local_str;
158 :
159 1530114 : return ret_str;
160 : }
161 :
162 : /*
163 : * debackslash -
164 : * create a palloc'd string holding the given token.
165 : * any protective backslashes in the token are removed.
166 : */
167 : char *
168 56917 : debackslash(char *token, int length)
169 : {
170 56917 : char *result = palloc(length + 1);
171 56917 : char *ptr = result;
172 :
173 545138 : while (length > 0)
174 : {
175 431304 : if (*token == '\\' && length > 1)
176 274 : token++, length--;
177 431304 : *ptr++ = *token++;
178 431304 : length--;
179 : }
180 56917 : *ptr = '\0';
181 56917 : return result;
182 : }
183 :
184 : #define RIGHT_PAREN (1000000 + 1)
185 : #define LEFT_PAREN (1000000 + 2)
186 : #define LEFT_BRACE (1000000 + 3)
187 : #define OTHER_TOKEN (1000000 + 4)
188 :
189 : /*
190 : * nodeTokenType -
191 : * returns the type of the node token contained in token.
192 : * It returns one of the following valid NodeTags:
193 : * T_Integer, T_Float, T_String, T_BitString
194 : * and some of its own:
195 : * RIGHT_PAREN, LEFT_PAREN, LEFT_BRACE, OTHER_TOKEN
196 : *
197 : * Assumption: the ascii representation is legal
198 : */
199 : static NodeTag
200 186137 : nodeTokenType(char *token, int length)
201 : {
202 : NodeTag retval;
203 : char *numptr;
204 : int numlen;
205 :
206 : /*
207 : * Check if the token is a number
208 : */
209 186137 : numptr = token;
210 186137 : numlen = length;
211 186137 : if (*numptr == '+' || *numptr == '-')
212 0 : numptr++, numlen--;
213 186137 : if ((numlen > 0 && isdigit((unsigned char) *numptr)) ||
214 41567 : (numlen > 1 && *numptr == '.' && isdigit((unsigned char) numptr[1])))
215 : {
216 : /*
217 : * Yes. Figure out whether it is integral or float; this requires
218 : * both a syntax check and a range check. strtol() can do both for us.
219 : * We know the token will end at a character that strtol will stop at,
220 : * so we do not need to modify the string.
221 : */
222 : long val;
223 : char *endptr;
224 :
225 0 : errno = 0;
226 0 : val = strtol(token, &endptr, 10);
227 : (void) val; /* avoid compiler warning if unused */
228 0 : if (endptr != token + length || errno == ERANGE
229 : #ifdef HAVE_LONG_INT_64
230 : /* if long > 32 bits, check for overflow of int4 */
231 : || val != (long) ((int32) val)
232 : #endif
233 : )
234 0 : return T_Float;
235 0 : return T_Integer;
236 : }
237 :
238 : /*
239 : * these three cases do not need length checks, since pg_strtok() will
240 : * always treat them as single-byte tokens
241 : */
242 186137 : else if (*token == '(')
243 22723 : retval = LEFT_PAREN;
244 163414 : else if (*token == ')')
245 0 : retval = RIGHT_PAREN;
246 163414 : else if (*token == '{')
247 72286 : retval = LEFT_BRACE;
248 91128 : else if (*token == '"' && length > 1 && token[length - 1] == '"')
249 41567 : retval = T_String;
250 49561 : else if (*token == 'b')
251 0 : retval = T_BitString;
252 : else
253 49561 : retval = OTHER_TOKEN;
254 186137 : return retval;
255 : }
256 :
257 : /*
258 : * nodeRead -
259 : * Slightly higher-level reader.
260 : *
261 : * This routine applies some semantic knowledge on top of the purely
262 : * lexical tokenizer pg_strtok(). It can read
263 : * * Value token nodes (integers, floats, or strings);
264 : * * General nodes (via parseNodeString() from readfuncs.c);
265 : * * Lists of the above;
266 : * * Lists of integers or OIDs.
267 : * The return value is declared void *, not Node *, to avoid having to
268 : * cast it explicitly in callers that assign to fields of different types.
269 : *
270 : * External callers should always pass NULL/0 for the arguments. Internally
271 : * a non-NULL token may be passed when the upper recursion level has already
272 : * scanned the first token of a node's representation.
273 : *
274 : * We assume pg_strtok is already initialized with a string to read (hence
275 : * this should only be invoked from within a stringToNode operation).
276 : */
277 : void *
278 186137 : nodeRead(char *token, int tok_len)
279 : {
280 : Node *result;
281 : NodeTag type;
282 :
283 186137 : if (token == NULL) /* need to read a token? */
284 : {
285 98987 : token = pg_strtok(&tok_len);
286 :
287 98987 : if (token == NULL) /* end of input */
288 0 : return NULL;
289 : }
290 :
291 186137 : type = nodeTokenType(token, tok_len);
292 :
293 186137 : switch ((int) type)
294 : {
295 : case LEFT_BRACE:
296 72286 : result = parseNodeString();
297 72286 : token = pg_strtok(&tok_len);
298 72286 : if (token == NULL || token[0] != '}')
299 0 : elog(ERROR, "did not find '}' at end of input node");
300 72286 : break;
301 : case LEFT_PAREN:
302 : {
303 22723 : List *l = NIL;
304 :
305 : /*----------
306 : * Could be an integer list: (i int int ...)
307 : * or an OID list: (o int int ...)
308 : * or a list of nodes/values: (node node ...)
309 : *----------
310 : */
311 22723 : token = pg_strtok(&tok_len);
312 22723 : if (token == NULL)
313 0 : elog(ERROR, "unterminated List structure");
314 22964 : if (tok_len == 1 && token[0] == 'i')
315 : {
316 : /* List of integers */
317 : for (;;)
318 : {
319 : int val;
320 : char *endptr;
321 :
322 1029 : token = pg_strtok(&tok_len);
323 1029 : if (token == NULL)
324 0 : elog(ERROR, "unterminated List structure");
325 1029 : if (token[0] == ')')
326 241 : break;
327 788 : val = (int) strtol(token, &endptr, 10);
328 788 : if (endptr != token + tok_len)
329 0 : elog(ERROR, "unrecognized integer: \"%.*s\"",
330 : tok_len, token);
331 788 : l = lappend_int(l, val);
332 788 : }
333 : }
334 23051 : else if (tok_len == 1 && token[0] == 'o')
335 : {
336 : /* List of OIDs */
337 : for (;;)
338 : {
339 : Oid val;
340 : char *endptr;
341 :
342 2275 : token = pg_strtok(&tok_len);
343 2275 : if (token == NULL)
344 0 : elog(ERROR, "unterminated List structure");
345 2275 : if (token[0] == ')')
346 569 : break;
347 1706 : val = (Oid) strtoul(token, &endptr, 10);
348 1706 : if (endptr != token + tok_len)
349 0 : elog(ERROR, "unrecognized OID: \"%.*s\"",
350 : tok_len, token);
351 1706 : l = lappend_oid(l, val);
352 1706 : }
353 : }
354 : else
355 : {
356 : /* List of other node types */
357 : for (;;)
358 : {
359 : /* We have already scanned next token... */
360 109063 : if (token[0] == ')')
361 21913 : break;
362 87150 : l = lappend(l, nodeRead(token, tok_len));
363 87150 : token = pg_strtok(&tok_len);
364 87150 : if (token == NULL)
365 0 : elog(ERROR, "unterminated List structure");
366 87150 : }
367 : }
368 22723 : result = (Node *) l;
369 22723 : break;
370 : }
371 : case RIGHT_PAREN:
372 0 : elog(ERROR, "unexpected right parenthesis");
373 : result = NULL; /* keep compiler happy */
374 : break;
375 : case OTHER_TOKEN:
376 49561 : if (tok_len == 0)
377 : {
378 : /* must be "<>" --- represents a null pointer */
379 49561 : result = NULL;
380 : }
381 : else
382 : {
383 0 : elog(ERROR, "unrecognized token: \"%.*s\"", tok_len, token);
384 : result = NULL; /* keep compiler happy */
385 : }
386 49561 : break;
387 : case T_Integer:
388 :
389 : /*
390 : * we know that the token terminates on a char atol will stop at
391 : */
392 0 : result = (Node *) makeInteger(atol(token));
393 0 : break;
394 : case T_Float:
395 : {
396 0 : char *fval = (char *) palloc(tok_len + 1);
397 :
398 0 : memcpy(fval, token, tok_len);
399 0 : fval[tok_len] = '\0';
400 0 : result = (Node *) makeFloat(fval);
401 : }
402 0 : break;
403 : case T_String:
404 : /* need to remove leading and trailing quotes, and backslashes */
405 41567 : result = (Node *) makeString(debackslash(token + 1, tok_len - 2));
406 41567 : break;
407 : case T_BitString:
408 : {
409 0 : char *val = palloc(tok_len);
410 :
411 : /* skip leading 'b' */
412 0 : memcpy(val, token + 1, tok_len - 1);
413 0 : val[tok_len - 1] = '\0';
414 0 : result = (Node *) makeBitString(val);
415 0 : break;
416 : }
417 : default:
418 0 : elog(ERROR, "unrecognized node type: %d", (int) type);
419 : result = NULL; /* keep compiler happy */
420 : break;
421 : }
422 :
423 186137 : return (void *) result;
424 : }
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