From ef9164520c81ea61efe88777a8ad61bf17a54201 Mon Sep 17 00:00:00 2001

From: Mark Wielaard <mark@klomp.org>

Date: Sat, 22 Apr 2023 01:26:17 +0200

Subject: [PATCH] elfcompress: Don't compress if section already compressed

 unless forced

Before commit a5b07cdf9 "support ZSTD compression algorithm"

elfcompress would not try to compress a section if it already

had the requested compression type (or was already uncompressed)

unless the --force flag was given. An else if construct was changed

to an if in the commit causing elfcompress to warn (in verbose mode)

but then still try to (re)compress the section.

Add an explicit check so if nothing needs (un)compressing, the file

isn't changed.

The diff looks large, but git diff -b -w is just:

+     if (force || type != schtype)

+       {

          if (shdr->sh_type != SHT_NOBITS

              && (shdr->sh_flags & SHF_ALLOC) == 0)

            {

@@ -554,6 +556,7 @@ process_file (const char *fname)

              printf ("[%zd] %s ignoring %s section\n", ndx, sname,

                      (shdr->sh_type == SHT_NOBITS ? "no bits" : "allocated"));

        }

+   }

Signed-off-by: Mark Wielaard <mark@klomp.org>

---

 src/elfcompress.c | 43 +++++++++++++++++++++++--------------------

 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/src/elfcompress.c b/src/elfcompress.c

index 18ade66f..f771b92a 100644

--- a/src/elfcompress.c

+++ b/src/elfcompress.c

@@ -529,30 +529,33 @@ process_file (const char *fname)

 		  }

 	    }

-	  if (shdr->sh_type != SHT_NOBITS

-	      && (shdr->sh_flags & SHF_ALLOC) == 0)

+	  if (force || type != schtype)

 	    {

-	      set_section (sections, ndx);

-	      /* Check if we might want to change this section name.  */

-	      if (! adjust_names

-		  && ((type != ZLIB_GNU

-		       && startswith (sname, ".zdebug"))

-		      || (type == ZLIB_GNU

-			  && startswith (sname, ".debug"))))

-		adjust_names = true;

-

-	      /* We need a buffer this large if we change the names.  */

-	      if (adjust_names)

+	      if (shdr->sh_type != SHT_NOBITS

+		  && (shdr->sh_flags & SHF_ALLOC) == 0)

 		{

-		  size_t slen = strlen (sname);

-		  if (slen > maxnamelen)

-		    maxnamelen = slen;

+		  set_section (sections, ndx);

+		  /* Check if we might want to change this section name.  */

+		  if (! adjust_names

+		      && ((type != ZLIB_GNU

+			   && startswith (sname, ".zdebug"))

+			  || (type == ZLIB_GNU

+			      && startswith (sname, ".debug"))))

+		    adjust_names = true;

+

+		  /* We need a buffer this large if we change the names.  */

+		  if (adjust_names)

+		    {

+		      size_t slen = strlen (sname);

+		      if (slen > maxnamelen)

+			maxnamelen = slen;

+		    }

 		}

+	      else

+		if (verbose >= 0)

+		  printf ("[%zd] %s ignoring %s section\n", ndx, sname,

+			  (shdr->sh_type == SHT_NOBITS ? "no bits" : "allocated"));

 	    }

-	  else

-	    if (verbose >= 0)

-	      printf ("[%zd] %s ignoring %s section\n", ndx, sname,

-		      (shdr->sh_type == SHT_NOBITS ? "no bits" : "allocated"));

 	}

       if (shdr->sh_type == SHT_SYMTAB)

-- 

2.31.1