[newlib-cygwin] Cygwin: Don't dump non-writable image regions

[Jon TURNEY]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=35227fec9781dd85ef30257f12b857d58dec1840

commit 35227fec9781dd85ef30257f12b857d58dec1840
Author: Jon Turney <jon.turney@dronecode.org.uk>
Date:   Sun Jul 5 14:42:59 2020 +0100

    Cygwin: Don't dump non-writable image regions
    
    After this, we will end up dumping memory regions where:
    
    - state is MEM_COMMIT (i.e. is not MEM_RESERVE or MEM_FREE), and
    -- type is MEM_PRIVATE and protection allows reads (i.e. not a guardpage), or
    -- type is MEM_IMAGE and protection allows writes
    
    Making this decision based on the current protection isn't 100% correct,
    because it may have been changed using VirtualProtect().  But we don't
    know how to determine if a region is shareable.
    
    (As a practical matter, anything which gets us the stack (MEM_PRIVATE)
    and .data/.bss (RW MEM_IMAGE) is going to be enough for 99% of cases)

Diff:
---
 winsup/utils/dumper.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/winsup/utils/dumper.cc b/winsup/utils/dumper.cc
index 2a0c66002..b96ee54cc 100644
--- a/winsup/utils/dumper.cc
+++ b/winsup/utils/dumper.cc
@@ -292,6 +292,12 @@ dumper::collect_memory_sections ()
       int skip_region_p = 0;
       const char *disposition = "dumped";
 
+      if ((mbi.Type & MEM_IMAGE) && !(mbi.Protect & (PAGE_EXECUTE_READWRITE | PAGE_READWRITE)))
+	{
+	  skip_region_p = 1;
+	  disposition = "skipped due to non-writeable MEM_IMAGE";
+	}
+
       if (mbi.Protect & PAGE_NOACCESS)
 	{
 	  skip_region_p = 1;