commit 47499e57d9321f4e45f33a3c1ab12264510ee7a4
Author: Mark Wielaard <mark@klomp.org>
Date:   Sat Jul 21 16:10:25 2018 +0200

    elfcompress: Swap fchmod and fchown calls on new file.
    
    Calling fchmod with a suid bit on a file might silently fail or the suid
    bit might be slilently cleared by a call to fchown if already set. Swap
    the calls so that the owner is set first and then set the suid bit.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1607044
    
    Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/src/elfcompress.c b/src/elfcompress.c
index bdb0e3b..1a0f984 100644
--- a/src/elfcompress.c
+++ b/src/elfcompress.c
@@ -1235,13 +1235,16 @@ process_file (const char *fname)
   elf_end (elfnew);
   elfnew = NULL;
 
-  /* Try to match mode and owner.group of the original file.  */
-  if (fchmod (fdnew, st.st_mode & ALLPERMS) != 0)
-    if (verbose >= 0)
-      error (0, errno, "Couldn't fchmod %s", fnew);
+  /* Try to match mode and owner.group of the original file.
+     Note to set suid bits we have to make sure the owner is setup
+     correctly first. Otherwise fchmod will drop them silently
+     or fchown may clear them.  */
   if (fchown (fdnew, st.st_uid, st.st_gid) != 0)
     if (verbose >= 0)
       error (0, errno, "Couldn't fchown %s", fnew);
+  if (fchmod (fdnew, st.st_mode & ALLPERMS) != 0)
+    if (verbose >= 0)
+      error (0, errno, "Couldn't fchmod %s", fnew);
 
   /* Finally replace the old file with the new file.  */
   if (foutput == NULL)

commit d676c839e783996409d7845ea236e0883a827cbb
Author: Mark Wielaard <mark@klomp.org>
Date:   Sat Jul 21 17:07:12 2018 +0200

    elfcompress: Don't rewrite file if no section data needs to be updated.
    
    If the input and output file are the same and no section needs to
    be updated we really don't need to rewrite the file. Check whether
    any matching section is already compressed or (GNU) decompressed.
    Skip the section if it doesn't need to be changed. If no section data
    needs updating end with success without rewriting/updating file.
    With --force the file will still always be updated/rewritten even if
    no section data needs to be (de)compressed.
    
    Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/src/elfcompress.c b/src/elfcompress.c
index 1a0f984..ae4708c 100644
--- a/src/elfcompress.c
+++ b/src/elfcompress.c
@@ -1,5 +1,5 @@
 /* Compress or decompress an ELF file.
-   Copyright (C) 2015, 2016 Red Hat, Inc.
+   Copyright (C) 2015, 2016, 2018 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -286,6 +286,15 @@ process_file (const char *fname)
     return (sections[ndx / WORD_BITS] & (1U << (ndx % WORD_BITS))) != 0;
   }
 
+  /* How many sections are we going to change?  */
+  size_t get_sections (void)
+  {
+    size_t s = 0;
+    for (size_t i = 0; i < shnum / WORD_BITS + 1; i++)
+      s += __builtin_popcount (sections[i]);
+    return s;
+  }
+
   int cleanup (int res)
   {
     elf_end (elf);
@@ -422,6 +431,9 @@ process_file (const char *fname)
      names change and whether there is a symbol table that might need
      to be adjusted be if the section header name table is changed.
 
+     If nothing needs changing, and the input and output file are the
+     same, we are done.
+
      Second a collection pass that creates the Elf sections and copies
      the data.  This pass will compress/decompress section data when
      needed.  And it will collect all data needed if we'll need to
@@ -464,7 +476,26 @@ process_file (const char *fname)
 
       if (section_name_matches (sname))
 	{
-	  if (shdr->sh_type != SHT_NOBITS
+	  if (!force && type == T_DECOMPRESS
+	      && (shdr->sh_flags & SHF_COMPRESSED) == 0
+	      && strncmp (sname, ".zdebug", strlen (".zdebug")) != 0)
+	    {
+	      if (verbose > 0)
+		printf ("[%zd] %s already decompressed\n", ndx, sname);
+	    }
+	  else if (!force && type == T_COMPRESS_ZLIB
+		   && (shdr->sh_flags & SHF_COMPRESSED) != 0)
+	    {
+	      if (verbose > 0)
+		printf ("[%zd] %s already compressed\n", ndx, sname);
+	    }
+	  else if (!force && type == T_COMPRESS_GNU
+		   && strncmp (sname, ".zdebug", strlen (".zdebug")) == 0)
+	    {
+	      if (verbose > 0)
+		printf ("[%zd] %s already GNU compressed\n", ndx, sname);
+	    }
+	  else if (shdr->sh_type != SHT_NOBITS
 	      && (shdr->sh_flags & SHF_ALLOC) == 0)
 	    {
 	      set_section (ndx);
@@ -518,6 +549,14 @@ process_file (const char *fname)
 	  }
     }
 
+  if (foutput == NULL && get_sections () == 0)
+    {
+      if (verbose > 0)
+	printf ("Nothing to do.\n");
+      fnew = NULL;
+      return cleanup (0);
+    }
+
   if (adjust_names)
     {
       names = dwelf_strtab_init (true);