forward port some of apple's gdb tricks

gdb-apple.diff

Index: gdb/environ.h
===================================================================
RCS file: /cvs/src/src/gdb/environ.h,v
retrieving revision 1.12
diff -u -r1.12 environ.h
--- gdb/environ.h	4 Jan 2012 08:17:01 -0000	1.12
+++ gdb/environ.h	23 Jul 2012 02:16:58 -0000
@@ -47,4 +47,8 @@
 
 extern char **environ_vector (struct gdb_environ *);
 
+#ifdef __APPLE__
+extern void smuggle_dyld_settings (struct gdb_environ *);
+#endif
+
 #endif /* defined (ENVIRON_H) */
Index: gdb/environ.c
===================================================================
RCS file: /cvs/src/src/gdb/environ.c,v
retrieving revision 1.24
diff -u -r1.24 environ.c
--- gdb/environ.c	4 Jan 2012 08:17:01 -0000	1.24
+++ gdb/environ.c	23 Jul 2012 02:16:58 -0000
@@ -87,6 +87,64 @@
     }
 }
 
+#ifdef __APPLE__
+/* APPLE LOCAL: gdb has to run setgid on MacOS X and
+   dyld truncates the DYLD_* environment variables on set[ug]id
+   binaries so their environment isn't mucked with by an evil user.
+
+   To work around this, the /usr/bin/gdb shell script copies DYLD_*
+   into GDB_DYLD_*, and in this function we look for DYLD_* env
+   vars that have been truncated and a matching GDB_DYLD_* env var.
+   If this exists, we copy the GDB_DYLD_* value into DYLD_* so that
+   it will take effect when the inferior process is run. */
+
+struct dyld_smuggle_pairs {
+  const char *real_name;
+  const char *smuggled_name;
+};
+
+void
+smuggle_dyld_settings (struct gdb_environ *e)
+{
+  /* The list of DYLD_* names was gleaned from dyld's src/dyld.cpp.  */
+
+  struct dyld_smuggle_pairs env_names[] = { 
+       {"DYLD_FRAMEWORK_PATH", "GDB_DYLD_FRAMEWORK_PATH"},
+       {"DYLD_FALLBACK_FRAMEWORK_PATH", "GDB_DYLD_FALLBACK_FRAMEWORK_PATH"},
+       {"DYLD_LIBRARY_PATH", "GDB_DYLD_LIBRARY_PATH"},
+       {"DYLD_FALLBACK_LIBRARY_PATH", "GDB_DYLD_FALLBACK_LIBRARY_PATH"},
+       {"DYLD_ROOT_PATH", "GDB_DYLD_ROOT_PATH"},
+       {"DYLD_PATHS_ROOT", "GDB_DYLD_PATHS_ROOT"},
+       {"DYLD_IMAGE_SUFFIX", "GDB_DYLD_IMAGE_SUFFIX"},
+       {"DYLD_INSERT_LIBRARIES", "GDB_DYLD_INSERT_LIBRARIES"},
+       { NULL, NULL } };
+  int i;
+
+  for (i = 0; env_names[i].real_name != NULL; i++)
+    {
+      const char *real_val = get_in_environ (e, env_names[i].real_name);
+      const char *smuggled_val = get_in_environ (e, env_names[i].smuggled_name);
+
+      if (real_val == NULL && smuggled_val == NULL)
+        continue;
+
+      if (smuggled_val == NULL)
+        continue;
+
+      /* Is the value of the DYLD_* env var truncated to ""? */
+      if (real_val != NULL && real_val[0] != '\0')
+        continue;
+
+      /* real_val has a value and it looks legitimate - don't overwrite it
+         with the smuggled version.  */
+      if (real_val != NULL)
+        continue;
+
+      set_in_environ (e, env_names[i].real_name, smuggled_val);
+    }
+}
+#endif
+
 /* Return the vector of environment E.
    This is used to get something to pass to execve.  */
 
Index: gdb/inferior.c
===================================================================
RCS file: /cvs/src/src/gdb/inferior.c,v
retrieving revision 1.36
diff -u -r1.36 inferior.c
--- gdb/inferior.c	12 May 2012 06:35:08 -0000	1.36
+++ gdb/inferior.c	23 Jul 2012 02:16:58 -0000
@@ -136,6 +136,10 @@
   inf->environment = make_environ ();
   init_environ (inf->environment);
 
+#ifdef __APPLE__
+  smuggle_dyld_settings(inf->environment);
+#endif
+
   inferior_alloc_data (inf);
 
   observer_notify_inferior_added (inf);