Bug#397262: grep: Patch to dlopen PCRE so we can have -P

[Reuben Thomas]

To clarify: my patch applies cleanly to current CVS.

Ah, but the one in the BTS appears to be out of date.

I attach the patch I have.
Binary files grep/src/egrep and grep-dlopen-pcre/src/egrep differ
Binary files grep/src/egrep.o and grep-dlopen-pcre/src/egrep.o differ
Binary files grep/src/fgrep and grep-dlopen-pcre/src/fgrep differ
Binary files grep/src/fgrep.o and grep-dlopen-pcre/src/fgrep.o differ
Binary files grep/src/grep and grep-dlopen-pcre/src/grep differ
Binary files grep/src/grep.o and grep-dlopen-pcre/src/grep.o differ
diff -Nur --exclude=CVS --exclude='*.pot' --exclude='*.Po' grep/src/search.c grep-dlopen-pcre/src/search.c
--- grep/src/search.c	2007-07-18 23:59:36.000000000 +0100
+++ grep-dlopen-pcre/src/search.c	2008-04-30 20:25:38.000000000 +0100
@@ -41,6 +41,7 @@
 #include "error.h"
 #include "xalloc.h"
 #ifdef HAVE_LIBPCRE
+# include <dlfcn.h>
 # include <pcre.h>
 #endif
 
@@ -84,6 +85,35 @@
 struct patterns *patterns;
 size_t pcount;
 
+
+static pcre *(*dl_pcre_compile)(const char *pattern, int options, const char **errptr, int *erroffset, const unsigned char *tableptr);
+static pcre_extra *(*dl_pcre_study)(const pcre *code, int options, const char **errptr);
+static int (*dl_pcre_exec)(const pcre *code, const pcre_extra *extra, const char *subject, int length, int startoffset, int options, int *ovector, int ovecsize);
+static const unsigned char *(*dl_pcre_maketables)(void);
+
+static int map_pcre(void)
+{
+  static int library_mapped = 0;
+  void *library;
+
+  if (library_mapped) return 0;
+
+  library = dlopen("libpcre.so",RTLD_NOW);
+
+  if (!(dl_pcre_compile = dlsym(library,"pcre_compile")))
+    return -1;
+  if (!(dl_pcre_study = dlsym(library,"pcre_study")))
+    return -1;
+  if (!(dl_pcre_exec = dlsym(library,"pcre_exec")))
+    return -1;
+  if (!(dl_pcre_maketables = dlsym(library,"pcre_maketables")))
+    return -1;
+
+  library_mapped++;
+  return 0;
+}
+
+
 void
 dfaerror (char const *mesg)
 {
@@ -627,6 +657,9 @@
   char const *p;
   char const *pnul;
 
+  if (map_pcre ())
+    error (2, 0, _("The -P option is not supported"));
+
   /* FIXME: Remove these restrictions.  */
   if (eolbyte != '\n')
     error (2, 0, _("The -P and -z options cannot be combined"));
@@ -667,11 +700,11 @@
   if (match_lines)
     strcpy (n, ")$");
 
-  cre = pcre_compile (re, flags, &ep, &e, pcre_maketables ());
+  cre = dl_pcre_compile (re, flags, &ep, &e, dl_pcre_maketables ());
   if (!cre)
     error (2, 0, ep);
 
-  extra = pcre_study (cre, 0, &ep);
+  extra = dl_pcre_study (cre, 0, &ep);
   if (ep)
     error (2, 0, ep);
 
@@ -689,9 +722,17 @@
      is just for performance improvement in pcre_exec.  */
   int sub[300];
 
-  int e = pcre_exec (cre, extra, buf, size,
-		     start_ptr ? (start_ptr - buf) : 0, 0,
-		     sub, sizeof sub / sizeof *sub);
+  int e;
+
+  if (map_pcre ())
+    {
+      abort ();
+      return -1;
+    }
+
+  e = pcre_exec (cre, extra, buf, size,
+                 start_ptr ? (start_ptr - buf) : 0, 0,
+                 sub, sizeof sub / sizeof *sub);
 
   if (e <= 0)
     {
Binary files grep/src/search.o and grep-dlopen-pcre/src/search.o differ