Fix EOL algorithm:

- instead of the costly algorithm: try to match with \n and retry a match with \r if failed
- try matching without \n\r, and lookback one char and test for \n\r, move on to next match if failed
- also assume objects are sequential, and look for indirect objects ahead, instead of looking from the beginning each time,
 if optimization fails, search for the indirect object from the beginning till current pos

This reduces scan time of sample from bb #1217 to 4 seconds from 8 minutes!

git-svn: trunk@4226

libclamav/pdf.c

@@ -278,20 +278,43 @@ cli_pdf(const char *dir, int desc, cli_ctx *ctx, off_t offset)
 					 *	supported
 					 */
 					if((bytesleft > 11) && strncmp(q, " 0 R", 4) == 0) {
-						const char *r;
+						const char *r, *nq;
+						int opt_failed = 0;
+						size_t len = size;
 						char b[14];
 
 						q += 4;
 						cli_dbgmsg("cli_pdf: Length is in indirect obj %lu\n",
 							length);
 						snprintf(b, sizeof(b),
-							"\n%lu 0 obj", length);
+							"%lu 0 obj", length);
 						length = (unsigned long)strlen(b);
-						r = cli_pmemstr(buf, size, b, length);
-						if(r == NULL) {
-							b[0] = '\r';
-							r = cli_pmemstr(buf, size, b, length);
-						}
+						/* optimization: assume objects
+						 * are sequential */
+						nq = q;
+						do {
+							r = cli_pmemstr(nq, len, b, length);
+							if (r > nq) {
+								const char x = *(r-1);
+								if (x == '\n' || x=='\r') {
+									--r;
+									break;
+								}
+							}
+							if (r) {
+								len -= r+1-nq;
+								nq = r + 1;
+							} else if (!opt_failed) {
+								/* we failed optimized match,
+								 * try matching from the beginning
+								 */
+								len = q - buf;
+								r = nq = buf;
+								/* prevent
+								 * infloop */
+								opt_failed = 1;
+							}
+						} while (r);
 						if(r) {
 							r += length - 1;
 							r = pdf_nextobject(r, bytesleft - (r - q));