dlclose()

[Jim Kingdon <kingdon at redhat dot com>]

Here's another patch for the dlclose() problem we've been talking
about (5130 in bugzilla.redhat.com and all).  I'm not sure how well I
like this patch but it should avoid the problem with flushing and
reloading shared library symbols all the time as in the HJ/Sam patch.

Chris, want to weigh in on this (e.g. try out the patches)?  Mozilla
is going to be one of the most affected if we do something dumb (or
something great) with shared library support.

2000-02-16  Jim Kingdon  <kingdon@redhat.com>

	* solib.c (find_solib): New argument recheck.
	* solib.c (solib_add): Pass it as 1, and add logic to delete
	shared libraries which aren't still in the inferior.
	(struct so_list): New field found_me, for solib_add.
	* solib.c (other find_solib callers): Pass recheck as 0.
 
Index: solib.c
===================================================================
RCS file: /cvs/src/src/gdb/solib.c,v
retrieving revision 1.1.1.10
diff -u -r1.1.1.10 solib.c
--- solib.c	1999/11/17 02:30:28	1.1.1.10
+++ solib.c	2000/02/16 19:43:12
@@ -31,6 +31,7 @@
 #include "gdb_string.h"
 #include <sys/param.h>
 #include <fcntl.h>
+#include <assert.h>
 
 #ifndef SVR4_SHARED_LIBS
  /* SunOS shared libs need the nlist structure.  */
@@ -143,6 +144,11 @@
     char so_name[MAX_PATH_SIZE];	/* shared object lib name (FIXME) */
     char symbols_loaded;	/* flag: symbols read in yet? */
     char from_tty;		/* flag: print msgs? */
+
+    /* Flag for use within solib_add: have we seen this library actually
+       still mapped in the inferior this pass?  */
+    char found_me;
+
     struct objfile *objfile;	/* objfile for loaded lib */
     struct section_table *sections;
     struct section_table *sections_end;
@@ -181,8 +187,7 @@
 
 static int symbol_add_stub PARAMS ((PTR));
 
-static struct so_list *
-  find_solib PARAMS ((struct so_list *));
+static struct so_list *find_solib (struct so_list *, int);
 
 static struct link_map *
   first_link_map_member PARAMS ((void));
@@ -975,8 +980,10 @@
  */
 
 static struct so_list *
-find_solib (so_list_ptr)
-     struct so_list *so_list_ptr;	/* Last lm or NULL for first one */
+find_solib (struct so_list *so_list_ptr,
+	    /* Nonzero if we should read all the entries from the inferior,
+	       not just the ones at the end of the list.  */
+	    int recheck)
 {
   struct so_list *so_list_next = NULL;
   struct link_map *lm = NULL;
@@ -985,7 +992,9 @@
   if (so_list_ptr == NULL)
     {
       /* We are setting up for a new scan through the loaded images. */
-      if ((so_list_next = so_list_head) == NULL)
+      so_list_next = so_list_head;
+      if (so_list_next == NULL
+	  || recheck)
 	{
 	  /* We have not already read in the dynamic linking structures
 	     from the inferior, lookup the address of the base structure. */
@@ -1002,7 +1011,8 @@
     {
       /* We have been called before, and are in the process of walking
          the shared library list.  Advance to the next shared object. */
-      if ((lm = LM_NEXT (so_list_ptr)) == NULL)
+      lm = LM_NEXT (so_list_ptr);
+      if (recheck || lm == NULL)
 	{
 	  /* We have hit the end of the list, so check to see if any were
 	     added, but be quiet if we can't read from the target any more. */
@@ -1020,7 +1030,7 @@
 	}
       so_list_next = so_list_ptr->next;
     }
-  if ((so_list_next == NULL) && (lm != NULL))
+  if ((so_list_next == NULL || recheck) && (lm != NULL))
     {
       /* Get next link map structure from inferior image and build a local
          abbreviated load_map structure */
@@ -1188,7 +1198,7 @@
       /* Count how many new section_table entries there are.  */
       so = NULL;
       count = 0;
-      while ((so = find_solib (so)) != NULL)
+      while ((so = find_solib (so, 0)) != NULL)
 	{
 	  if (so->so_name[0] && !match_main (so->so_name))
 	    {
@@ -1201,7 +1211,7 @@
 	  
 	  /* Add these section table entries to the target's table.  */
 	  old = target_resize_to_sections (target, count);
-	  while ((so = find_solib (so)) != NULL)
+	  while ((so = find_solib (so, 0)) != NULL)
 	    {
 	      if (so->so_name[0])
 		{
@@ -1215,9 +1225,13 @@
 	}
     }
 
+  for (so = so_list_head; so != NULL; so = so->next)
+    so->found_me = 0;
+
   /* Now add the symbol files.  */
-  while ((so = find_solib (so)) != NULL)
+  while ((so = find_solib (so, 1)) != NULL)
     {
+      so->found_me = 1;
       if (so->so_name[0] && re_exec (so->so_name) &&
 	  !match_main (so->so_name))
 	{
@@ -1240,6 +1254,37 @@
 	}
     }
 
+  {
+    struct so_list *prev;
+    prev = NULL;
+    for (so = so_list_head; so != NULL; so = so->next)
+      {
+	if (!so->found_me)
+	  {
+	    free_objfile (so->objfile);
+
+	    /* FIXME: also need to fix up section tables that
+	       we put in the target vector, right?  */
+	    if (so_list_head->sections)
+	      {
+		free ((PTR) so_list_head->sections);
+	      }
+
+	    assert (so->abfd != NULL);
+	    if (!bfd_close (so->abfd))
+	      warning ("cannot close \"%s\": %s",
+		       so->so_name, bfd_errmsg (bfd_get_error ()));
+	    if (prev == NULL)
+	      so_list_head = so->next;
+	    else
+	      prev->next = so->next;
+
+	    free (so);
+	  }
+	prev = so;
+      }
+  }
+
   /* Getting new symbols may change our opinion about what is
      frameless.  */
   if (so_last)
@@ -1289,7 +1334,7 @@
   addr_fmt = "016l";
 #endif
 
-  while ((so = find_solib (so)) != NULL)
+  while ((so = find_solib (so, 0)) != NULL)
     {
       if (so->so_name[0])
 	{
@@ -1347,7 +1392,7 @@
 {
   register struct so_list *so = 0;	/* link map state variable */
 
-  while ((so = find_solib (so)) != NULL)
+  while ((so = find_solib (so, 0)) != NULL)
     {
       if (so->so_name[0])
 	{