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xslt_proc.c
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1 /*
2  * contrib/xml2/xslt_proc.c
3  *
4  * XSLT processing functions (requiring libxslt)
5  *
6  * John Gray, for Torchbox 2003-04-01
7  */
8 #include "postgres.h"
9 
10 #include "executor/spi.h"
11 #include "fmgr.h"
12 #include "funcapi.h"
13 #include "miscadmin.h"
14 #include "utils/builtins.h"
15 #include "utils/xml.h"
16 
17 #ifdef USE_LIBXSLT
18 
19 /* libxml includes */
20 
21 #include <libxml/xpath.h>
22 #include <libxml/tree.h>
23 #include <libxml/xmlmemory.h>
24 
25 /* libxslt includes */
26 
27 #include <libxslt/xslt.h>
28 #include <libxslt/xsltInternals.h>
29 #include <libxslt/security.h>
30 #include <libxslt/transform.h>
31 #include <libxslt/xsltutils.h>
32 #endif /* USE_LIBXSLT */
33 
34 
35 #ifdef USE_LIBXSLT
36 
37 /* declarations to come from xpath.c */
39 
40 /* local defs */
41 static const char **parse_params(text *paramstr);
42 #endif /* USE_LIBXSLT */
43 
44 
46 
47 Datum
49 {
50 #ifdef USE_LIBXSLT
51 
52  text *doct = PG_GETARG_TEXT_PP(0);
53  text *ssheet = PG_GETARG_TEXT_PP(1);
54  text *result;
55  text *paramstr;
56  const char **params;
57  PgXmlErrorContext *xmlerrcxt;
58  volatile xsltStylesheetPtr stylesheet = NULL;
59  volatile xmlDocPtr doctree = NULL;
60  volatile xmlDocPtr restree = NULL;
61  volatile xsltSecurityPrefsPtr xslt_sec_prefs = NULL;
62  volatile xsltTransformContextPtr xslt_ctxt = NULL;
63  volatile int resstat = -1;
64  xmlChar *resstr = NULL;
65  int reslen = 0;
66 
67  if (fcinfo->nargs == 3)
68  {
69  paramstr = PG_GETARG_TEXT_PP(2);
70  params = parse_params(paramstr);
71  }
72  else
73  {
74  /* No parameters */
75  params = (const char **) palloc(sizeof(char *));
76  params[0] = NULL;
77  }
78 
79  /* Setup parser */
81 
82  PG_TRY();
83  {
84  xmlDocPtr ssdoc;
85  bool xslt_sec_prefs_error;
86 
87  /* Parse document */
88  doctree = xmlParseMemory((char *) VARDATA_ANY(doct),
89  VARSIZE_ANY_EXHDR(doct));
90 
91  if (doctree == NULL)
92  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
93  "error parsing XML document");
94 
95  /* Same for stylesheet */
96  ssdoc = xmlParseMemory((char *) VARDATA_ANY(ssheet),
97  VARSIZE_ANY_EXHDR(ssheet));
98 
99  if (ssdoc == NULL)
100  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
101  "error parsing stylesheet as XML document");
102 
103  /* After this call we need not free ssdoc separately */
104  stylesheet = xsltParseStylesheetDoc(ssdoc);
105 
106  if (stylesheet == NULL)
107  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
108  "failed to parse stylesheet");
109 
110  xslt_ctxt = xsltNewTransformContext(stylesheet, doctree);
111 
112  xslt_sec_prefs_error = false;
113  if ((xslt_sec_prefs = xsltNewSecurityPrefs()) == NULL)
114  xslt_sec_prefs_error = true;
115 
116  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_READ_FILE,
117  xsltSecurityForbid) != 0)
118  xslt_sec_prefs_error = true;
119  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_WRITE_FILE,
120  xsltSecurityForbid) != 0)
121  xslt_sec_prefs_error = true;
122  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_CREATE_DIRECTORY,
123  xsltSecurityForbid) != 0)
124  xslt_sec_prefs_error = true;
125  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_READ_NETWORK,
126  xsltSecurityForbid) != 0)
127  xslt_sec_prefs_error = true;
128  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_WRITE_NETWORK,
129  xsltSecurityForbid) != 0)
130  xslt_sec_prefs_error = true;
131  if (xsltSetCtxtSecurityPrefs(xslt_sec_prefs, xslt_ctxt) != 0)
132  xslt_sec_prefs_error = true;
133 
134  if (xslt_sec_prefs_error)
135  ereport(ERROR,
136  (errmsg("could not set libxslt security preferences")));
137 
138  restree = xsltApplyStylesheetUser(stylesheet, doctree, params,
139  NULL, NULL, xslt_ctxt);
140 
141  if (restree == NULL)
142  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
143  "failed to apply stylesheet");
144 
145  resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
146  }
147  PG_CATCH();
148  {
149  if (restree != NULL)
150  xmlFreeDoc(restree);
151  if (xslt_ctxt != NULL)
152  xsltFreeTransformContext(xslt_ctxt);
153  if (xslt_sec_prefs != NULL)
154  xsltFreeSecurityPrefs(xslt_sec_prefs);
155  if (stylesheet != NULL)
156  xsltFreeStylesheet(stylesheet);
157  if (doctree != NULL)
158  xmlFreeDoc(doctree);
159  xsltCleanupGlobals();
160 
161  pg_xml_done(xmlerrcxt, true);
162 
163  PG_RE_THROW();
164  }
165  PG_END_TRY();
166 
167  xmlFreeDoc(restree);
168  xsltFreeTransformContext(xslt_ctxt);
169  xsltFreeSecurityPrefs(xslt_sec_prefs);
170  xsltFreeStylesheet(stylesheet);
171  xmlFreeDoc(doctree);
172  xsltCleanupGlobals();
173 
174  pg_xml_done(xmlerrcxt, false);
175 
176  /* XXX this is pretty dubious, really ought to throw error instead */
177  if (resstat < 0)
178  PG_RETURN_NULL();
179 
180  result = cstring_to_text_with_len((char *) resstr, reslen);
181 
182  if (resstr)
183  xmlFree(resstr);
184 
185  PG_RETURN_TEXT_P(result);
186 #else /* !USE_LIBXSLT */
187 
188  ereport(ERROR,
189  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
190  errmsg("xslt_process() is not available without libxslt")));
191  PG_RETURN_NULL();
192 #endif /* USE_LIBXSLT */
193 }
194 
195 #ifdef USE_LIBXSLT
196 
197 static const char **
198 parse_params(text *paramstr)
199 {
200  char *pos;
201  char *pstr;
202  char *nvsep = "=";
203  char *itsep = ",";
204  const char **params;
205  int max_params;
206  int nparams;
207 
208  pstr = text_to_cstring(paramstr);
209 
210  max_params = 20; /* must be even! */
211  params = (const char **) palloc((max_params + 1) * sizeof(char *));
212  nparams = 0;
213 
214  pos = pstr;
215 
216  while (*pos != '\0')
217  {
218  if (nparams >= max_params)
219  {
220  max_params *= 2;
221  params = (const char **) repalloc(params,
222  (max_params + 1) * sizeof(char *));
223  }
224  params[nparams++] = pos;
225  pos = strstr(pos, nvsep);
226  if (pos != NULL)
227  {
228  *pos = '\0';
229  pos++;
230  }
231  else
232  {
233  /* No equal sign, so ignore this "parameter" */
234  nparams--;
235  break;
236  }
237 
238  /* since max_params is even, we still have nparams < max_params */
239  params[nparams++] = pos;
240  pos = strstr(pos, itsep);
241  if (pos != NULL)
242  {
243  *pos = '\0';
244  pos++;
245  }
246  else
247  break;
248  }
249 
250  /* Add the terminator marker; we left room for it in the palloc's */
251  params[nparams] = NULL;
252 
253  return params;
254 }
255 
256 #endif /* USE_LIBXSLT */
#define VARDATA_ANY(PTR)
Definition: postgres.h:347
struct PgXmlErrorContext PgXmlErrorContext
Definition: xml.h:48
int errcode(int sqlerrcode)
Definition: elog.c:575
PgXmlErrorContext * pgxml_parser_init(PgXmlStrictness strictness)
Definition: xpath.c:65
#define PG_GETARG_TEXT_PP(n)
Definition: fmgr.h:273
#define ERROR
Definition: elog.h:43
text * cstring_to_text_with_len(const char *s, int len)
Definition: varlena.c:161
void pg_xml_done(PgXmlErrorContext *errcxt, bool isError)
#define ereport(elevel, rest)
Definition: elog.h:122
Datum xslt_process(PG_FUNCTION_ARGS)
Definition: xslt_proc.c:48
uintptr_t Datum
Definition: postgres.h:372
#define PG_RETURN_TEXT_P(x)
Definition: fmgr.h:331
#define PG_CATCH()
Definition: elog.h:293
PG_FUNCTION_INFO_V1(xslt_process)
#define PG_RE_THROW()
Definition: elog.h:314
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:962
char * text_to_cstring(const text *t)
Definition: varlena.c:182
#define VARSIZE_ANY_EXHDR(PTR)
Definition: postgres.h:340
void * palloc(Size size)
Definition: mcxt.c:848
int errmsg(const char *fmt,...)
Definition: elog.c:797
Definition: c.h:433
#define PG_FUNCTION_ARGS
Definition: fmgr.h:158
#define PG_TRY()
Definition: elog.h:284
PgXmlStrictness
Definition: xml.h:39
#define PG_RETURN_NULL()
Definition: fmgr.h:305
#define PG_END_TRY()
Definition: elog.h:300
void xml_ereport(PgXmlErrorContext *errcxt, int level, int sqlcode, const char *msg)