PostgreSQL Source Code  git master
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 = xmlReadMemory((char *) VARDATA_ANY(doct),
89  VARSIZE_ANY_EXHDR(doct), NULL, NULL,
90  XML_PARSE_NOENT);
91 
92  if (doctree == NULL)
93  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
94  "error parsing XML document");
95 
96  /* Same for stylesheet */
97  ssdoc = xmlReadMemory((char *) VARDATA_ANY(ssheet),
98  VARSIZE_ANY_EXHDR(ssheet), NULL, NULL,
99  XML_PARSE_NOENT);
100 
101  if (ssdoc == NULL)
102  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
103  "error parsing stylesheet as XML document");
104 
105  /* After this call we need not free ssdoc separately */
106  stylesheet = xsltParseStylesheetDoc(ssdoc);
107 
108  if (stylesheet == NULL)
109  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
110  "failed to parse stylesheet");
111 
112  xslt_ctxt = xsltNewTransformContext(stylesheet, doctree);
113 
114  xslt_sec_prefs_error = false;
115  if ((xslt_sec_prefs = xsltNewSecurityPrefs()) == NULL)
116  xslt_sec_prefs_error = true;
117 
118  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_READ_FILE,
119  xsltSecurityForbid) != 0)
120  xslt_sec_prefs_error = true;
121  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_WRITE_FILE,
122  xsltSecurityForbid) != 0)
123  xslt_sec_prefs_error = true;
124  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_CREATE_DIRECTORY,
125  xsltSecurityForbid) != 0)
126  xslt_sec_prefs_error = true;
127  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_READ_NETWORK,
128  xsltSecurityForbid) != 0)
129  xslt_sec_prefs_error = true;
130  if (xsltSetSecurityPrefs(xslt_sec_prefs, XSLT_SECPREF_WRITE_NETWORK,
131  xsltSecurityForbid) != 0)
132  xslt_sec_prefs_error = true;
133  if (xsltSetCtxtSecurityPrefs(xslt_sec_prefs, xslt_ctxt) != 0)
134  xslt_sec_prefs_error = true;
135 
136  if (xslt_sec_prefs_error)
137  ereport(ERROR,
138  (errmsg("could not set libxslt security preferences")));
139 
140  restree = xsltApplyStylesheetUser(stylesheet, doctree, params,
141  NULL, NULL, xslt_ctxt);
142 
143  if (restree == NULL)
144  xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
145  "failed to apply stylesheet");
146 
147  resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
148  }
149  PG_CATCH();
150  {
151  if (restree != NULL)
152  xmlFreeDoc(restree);
153  if (xslt_ctxt != NULL)
154  xsltFreeTransformContext(xslt_ctxt);
155  if (xslt_sec_prefs != NULL)
156  xsltFreeSecurityPrefs(xslt_sec_prefs);
157  if (stylesheet != NULL)
158  xsltFreeStylesheet(stylesheet);
159  if (doctree != NULL)
160  xmlFreeDoc(doctree);
161  xsltCleanupGlobals();
162 
163  pg_xml_done(xmlerrcxt, true);
164 
165  PG_RE_THROW();
166  }
167  PG_END_TRY();
168 
169  xmlFreeDoc(restree);
170  xsltFreeTransformContext(xslt_ctxt);
171  xsltFreeSecurityPrefs(xslt_sec_prefs);
172  xsltFreeStylesheet(stylesheet);
173  xmlFreeDoc(doctree);
174  xsltCleanupGlobals();
175 
176  pg_xml_done(xmlerrcxt, false);
177 
178  /* XXX this is pretty dubious, really ought to throw error instead */
179  if (resstat < 0)
180  PG_RETURN_NULL();
181 
182  result = cstring_to_text_with_len((char *) resstr, reslen);
183 
184  if (resstr)
185  xmlFree(resstr);
186 
187  PG_RETURN_TEXT_P(result);
188 #else /* !USE_LIBXSLT */
189 
190  ereport(ERROR,
191  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
192  errmsg("xslt_process() is not available without libxslt")));
193  PG_RETURN_NULL();
194 #endif /* USE_LIBXSLT */
195 }
196 
197 #ifdef USE_LIBXSLT
198 
199 static const char **
200 parse_params(text *paramstr)
201 {
202  char *pos;
203  char *pstr;
204  char *nvsep = "=";
205  char *itsep = ",";
206  const char **params;
207  int max_params;
208  int nparams;
209 
210  pstr = text_to_cstring(paramstr);
211 
212  max_params = 20; /* must be even! */
213  params = (const char **) palloc((max_params + 1) * sizeof(char *));
214  nparams = 0;
215 
216  pos = pstr;
217 
218  while (*pos != '\0')
219  {
220  if (nparams >= max_params)
221  {
222  max_params *= 2;
223  params = (const char **) repalloc(params,
224  (max_params + 1) * sizeof(char *));
225  }
226  params[nparams++] = pos;
227  pos = strstr(pos, nvsep);
228  if (pos != NULL)
229  {
230  *pos = '\0';
231  pos++;
232  }
233  else
234  {
235  /* No equal sign, so ignore this "parameter" */
236  nparams--;
237  break;
238  }
239 
240  /* since max_params is even, we still have nparams < max_params */
241  params[nparams++] = pos;
242  pos = strstr(pos, itsep);
243  if (pos != NULL)
244  {
245  *pos = '\0';
246  pos++;
247  }
248  else
249  break;
250  }
251 
252  /* Add the terminator marker; we left room for it in the palloc's */
253  params[nparams] = NULL;
254 
255  return params;
256 }
257 
258 #endif /* USE_LIBXSLT */
int errcode(int sqlerrcode)
Definition: elog.c:857
int errmsg(const char *fmt,...)
Definition: elog.c:1070
#define PG_RE_THROW()
Definition: elog.h:411
#define PG_TRY(...)
Definition: elog.h:370
#define PG_END_TRY(...)
Definition: elog.h:395
#define ERROR
Definition: elog.h:39
#define PG_CATCH(...)
Definition: elog.h:380
#define ereport(elevel,...)
Definition: elog.h:149
#define PG_GETARG_TEXT_PP(n)
Definition: fmgr.h:309
#define PG_RETURN_NULL()
Definition: fmgr.h:345
#define PG_RETURN_TEXT_P(x)
Definition: fmgr.h:372
#define PG_FUNCTION_ARGS
Definition: fmgr.h:193
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1540
void * palloc(Size size)
Definition: mcxt.c:1316
uintptr_t Datum
Definition: postgres.h:64
Definition: c.h:687
#define VARDATA_ANY(PTR)
Definition: varatt.h:324
#define VARSIZE_ANY_EXHDR(PTR)
Definition: varatt.h:317
char * text_to_cstring(const text *t)
Definition: varlena.c:217
text * cstring_to_text_with_len(const char *s, int len)
Definition: varlena.c:196
struct PgXmlErrorContext PgXmlErrorContext
Definition: xml.h:48
void xml_ereport(PgXmlErrorContext *errcxt, int level, int sqlcode, const char *msg)
void pg_xml_done(PgXmlErrorContext *errcxt, bool isError)
PgXmlStrictness
Definition: xml.h:40
@ PG_XML_STRICTNESS_LEGACY
Definition: xml.h:41
PgXmlErrorContext * pgxml_parser_init(PgXmlStrictness strictness)
Definition: xpath.c:65
PG_FUNCTION_INFO_V1(xslt_process)
Datum xslt_process(PG_FUNCTION_ARGS)
Definition: xslt_proc.c:48