Support objcopy changing compression to or from zstd

Commit 2cac01e3ffff lacked support for objcopy changing compression
style.  Add that support, which meant a rewrite of
bfd_compress_section_contents.  In the process I've fixed some memory
leaks.

	* compress.c (bfd_is_section_compressed_info): Rename from
	bfd_is_section_compressed_with_header and add ch_type param
	to return compression header ch_type field.
	Update all callers.
	(decompress_section_contents): Remove buffer and size params.
	Rewrite.  Update callers.
	(bfd_init_section_compress_status): Free contents on failure.
	(bfd_compress_section): Likewise.
	* elf.c (_bfd_elf_make_section_from_shdr): Support objcopy
	changing between any of the three compression schemes.  Report
	"unable to compress/decompress" rather than "unable to
	initialize compress/decompress status" on compress/decompress
	failures.
	* bfd-in2.h: Regenerate.

1 files changed, 48 insertions, 45 deletions

diff --git a/bfd/elf.c b/bfd/elf.c
index 420b524..fe00e0f9 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1209,32 +1209,35 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       int compression_header_size;
       bfd_size_type uncompressed_size;
       unsigned int uncompressed_align_power;
+      unsigned int ch_type = 0;
       bool compressed
-	= bfd_is_section_compressed_with_header (abfd, newsect,
-						 &compression_header_size,
-						 &uncompressed_size,
-						 &uncompressed_align_power);
-      if (compressed)
-	{
-	  /* Compressed section.  Check if we should decompress.  */
-	  if ((abfd->flags & BFD_DECOMPRESS))
-	    action = decompress;
-	}
-
-      /* Compress the uncompressed section or convert from/to .zdebug*
-	 section.  Check if we should compress.  */
-      if (action == nothing)
-	{
-	  if (newsect->size != 0
-	      && (abfd->flags & BFD_COMPRESS)
-	      && compression_header_size >= 0
-	      && uncompressed_size > 0
-	      && (!compressed
-		  || ((compression_header_size > 0)
-		      != ((abfd->flags & BFD_COMPRESS_GABI) != 0))))
+	= bfd_is_section_compressed_info (abfd, newsect,
+					  &compression_header_size,
+					  &uncompressed_size,
+					  &uncompressed_align_power,
+					  &ch_type);
+
+      /* Should we decompress?  */
+      if ((abfd->flags & BFD_DECOMPRESS) != 0 && compressed)
+	action = decompress;
+
+      /* Should we compress?  Or convert to a different compression?  */
+      else if ((abfd->flags & BFD_COMPRESS) != 0
+	       && newsect->size != 0
+	       && compression_header_size >= 0
+	       && uncompressed_size > 0)
+	{
+	  if (!compressed)
 	    action = compress;
 	  else
-	    return true;
+	    {
+	      unsigned int new_ch_type = 0;
+	      if ((abfd->flags & BFD_COMPRESS_GABI) != 0)
+		new_ch_type = ((abfd->flags & BFD_COMPRESS_ZSTD) != 0
+			       ? ELFCOMPRESS_ZSTD : ELFCOMPRESS_ZLIB);
+	      if (new_ch_type != ch_type)
+		action = compress;
+	    }
 	}
 
       if (action == compress)
@@ -1243,20 +1246,17 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
 	    {
 	      _bfd_error_handler
 		/* xgettext:c-format */
-		(_("%pB: unable to initialize compress status for section %s"),
-		 abfd, name);
+		(_("%pB: unable to compress section %s"), abfd, name);
 	      return false;
 	    }
 	}
-      else
+      else if (action == decompress)
 	{
 	  if (!bfd_init_section_decompress_status (abfd, newsect))
 	    {
 	      _bfd_error_handler
 		/* xgettext:c-format */
-		(_("%pB: unable to initialize decompress status"
-		   " for section %s"),
-		 abfd, name);
+		(_("%pB: unable to decompress section %s"), abfd, name);
 	      return false;
 	    }
 #ifndef HAVE_ZSTD
@@ -1273,26 +1273,29 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
 #endif
 	}
 
-      if (abfd->is_linker_input)
+      if (action != nothing)
 	{
-	  if (name[1] == 'z'
-	      && (action == decompress
-		  || (action == compress
-		      && (abfd->flags & BFD_COMPRESS_GABI) != 0)))
+	  if (abfd->is_linker_input)
 	    {
-	      /* Convert section name from .zdebug_* to .debug_* so
-		 that linker will consider this section as a debug
-		 section.  */
-	      char *new_name = convert_zdebug_to_debug (abfd, name);
-	      if (new_name == NULL)
-		return false;
-	      bfd_rename_section (newsect, new_name);
+	      if (name[1] == 'z'
+		  && (action == decompress
+		      || (action == compress
+			  && (abfd->flags & BFD_COMPRESS_GABI) != 0)))
+		{
+		  /* Convert section name from .zdebug_* to .debug_* so
+		     that linker will consider this section as a debug
+		     section.  */
+		  char *new_name = convert_zdebug_to_debug (abfd, name);
+		  if (new_name == NULL)
+		    return false;
+		  bfd_rename_section (newsect, new_name);
+		}
 	    }
+	  else
+	    /* For objdump, don't rename the section.  For objcopy, delay
+	       section rename to elf_fake_sections.  */
+	    newsect->flags |= SEC_ELF_RENAME;
 	}
-      else
-	/* For objdump, don't rename the section.  For objcopy, delay
-	   section rename to elf_fake_sections.  */
-	newsect->flags |= SEC_ELF_RENAME;
     }
 
   /* GCC uses .gnu.lto_.lto.<some_hash> as a LTO bytecode information