contrib/xml2/xslt_proc.c

   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 */
  38 extern PgXmlErrorContext *pgxml_parser_init(PgXmlStrictness strictness);
  39
  40 /* local defs */
  41 static const char **parse_params(text *paramstr);
  42 #endif                                                  /* USE_LIBXSLT */
  43
  44
  45 PG_FUNCTION_INFO_V1(xslt_process);
  46
  47 Datum
  48 xslt_process(PG_FUNCTION_ARGS)
  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 */
  80         xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);
  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 */