[binutils-gdb] zlib-gabi to zstd woes

[binutils-gdb] zlib-gabi to zstd woes

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=206e9791cb09459bf92603428370c16bfde282ac

commit 206e9791cb09459bf92603428370c16bfde282ac
Author: Alan Modra <amodra@gmail.com>
Date:   Fri Oct 14 21:59:23 2022 +1030

    zlib-gabi to zstd woes
    
    So we had a zlib-gabi .debug_info section that increased in size with
    zstd, so much so that it was better to leave the section
    uncompressed.  Things went horribly wrong when the section was read
    again later.  The section was read again off disk using the
    uncompressed size.  So you get the zlib section again with some
    garbage at the end.  Fix that particular problem by setting the
    section flag SEC_IN_MEMORY.  Any future read will get sec->contents.
    
    Also, if the section is to be left uncompressed, the input
    SHF_COMPRESSED flag needs to be reset otherwise objcopy will copy it
    to output.
    
    Finally, bfd_convert_section_contents needed a small update to handle
    zstd compressed sections, and I've deleted bfd_cache_section_contents.
    
            * bfd.c (bfd_convert_section_contents): Handle zstd.
            * compress.c (bfd_compress_section_contents): When section
            contents are uncompressed set SEC_IN_MEMORY flag,
            compress_status to COMRESS_SECTION_NONE, and clear
            SHF_COMPRESSED.  Set SEC_IN_MEMORY for compressed contents.
            (bfd_get_full_section_contents): Don't check section size
            against file size when SEC_IN_MEMORY.
            (bfd_cache_section_contents): Delete function.
            * elf32-arm.c (elf32_arm_get_synthetic_symtab): Expand
            bfd_cache_section_contents here.
            * bfd-in2.h: Regenerate.

Diff:
---
 bfd/bfd-in2.h   |  3 ---
 bfd/bfd.c       |  4 ++--
 bfd/compress.c  | 29 +++++------------------------
 bfd/elf32-arm.c |  6 ++++--
 4 files changed, 11 insertions(+), 31 deletions(-)

diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 25e1806e689..534a46439fc 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -7964,9 +7964,6 @@ bfd_byte *bfd_simple_get_relocated_section_contents
 bool bfd_get_full_section_contents
    (bfd *abfd, asection *section, bfd_byte **ptr);
 
-void bfd_cache_section_contents
-   (asection *sec, void *contents);
-
 bool bfd_is_section_compressed_info
    (bfd *abfd, asection *section,
     int *compression_header_size_p,
diff --git a/bfd/bfd.c b/bfd/bfd.c
index 5f2033bee7a..4fca8250082 100644
--- a/bfd/bfd.c
+++ b/bfd/bfd.c
@@ -2801,14 +2801,14 @@ bfd_convert_section_contents (bfd *ibfd, sec_ptr isec, bfd *obfd,
   if (ohdr_size == sizeof (Elf32_External_Chdr))
     {
       Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
-      bfd_put_32 (obfd, ELFCOMPRESS_ZLIB, &echdr->ch_type);
+      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);
       bfd_put_32 (obfd, chdr.ch_size, &echdr->ch_size);
       bfd_put_32 (obfd, chdr.ch_addralign, &echdr->ch_addralign);
     }
   else
     {
       Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
-      bfd_put_32 (obfd, ELFCOMPRESS_ZLIB, &echdr->ch_type);
+      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);
       bfd_put_32 (obfd, 0, &echdr->ch_reserved);
       bfd_put_64 (obfd, chdr.ch_size, &echdr->ch_size);
       bfd_put_64 (obfd, chdr.ch_addralign, &echdr->ch_addralign);
diff --git a/bfd/compress.c b/bfd/compress.c
index 364df14142b..9608a0a6341 100644
--- a/bfd/compress.c
+++ b/bfd/compress.c
@@ -151,7 +151,8 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec)
 	  free (input_buffer);
 	  bfd_set_section_alignment (sec, uncompressed_alignment_pow);
 	  sec->contents = buffer;
-	  sec->compress_status = COMPRESS_SECTION_DONE;
+	  sec->flags |= SEC_IN_MEMORY;
+	  sec->compress_status = COMPRESS_SECTION_NONE;
 	  sec->size = uncompressed_size;
 	  input_buffer = buffer;
 	}
@@ -206,6 +207,7 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec)
   if (compressed_size >= uncompressed_size)
     {
       memcpy (buffer, input_buffer, uncompressed_size);
+      elf_section_flags (sec) &= ~SHF_COMPRESSED;
       sec->compress_status = COMPRESS_SECTION_NONE;
     }
   else
@@ -216,6 +218,7 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec)
       sec->compress_status = COMPRESS_SECTION_DONE;
     }
   sec->contents = buffer;
+  sec->flags |= SEC_IN_MEMORY;
   free (input_buffer);
   return uncompressed_size;
 }
@@ -268,6 +271,7 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 	  ufile_ptr filesize = bfd_get_file_size (abfd);
 	  if (filesize > 0
 	      && filesize < sz
+	      && (bfd_section_flags (sec) & SEC_IN_MEMORY) == 0
 	      /* PR 24753: Linker created sections can be larger than
 		 the file size, eg if they are being used to hold stubs.  */
 	      && (bfd_section_flags (sec) & SEC_LINKER_CREATED) == 0
@@ -380,29 +384,6 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
     }
 }
 
-/*
-FUNCTION
-	bfd_cache_section_contents
-
-SYNOPSIS
-	void bfd_cache_section_contents
-	  (asection *sec, void *contents);
-
-DESCRIPTION
-	Stash @var(contents) so any following reads of @var(sec) do
-	not need to decompress again.
-*/
-
-void
-bfd_cache_section_contents (asection *sec, void *contents)
-{
-  if (sec->compress_status == DECOMPRESS_SECTION_ZLIB
-      || sec->compress_status == DECOMPRESS_SECTION_ZSTD)
-    sec->compress_status = COMPRESS_SECTION_DONE;
-  sec->contents = contents;
-  sec->flags |= SEC_IN_MEMORY;
-}
-
 /*
 FUNCTION
 	bfd_is_section_compressed_info
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 0852b38ae4c..ec18a8ab362 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -20020,9 +20020,11 @@ elf32_arm_get_synthetic_symtab (bfd *abfd,
   data = plt->contents;
   if (data == NULL)
     {
-      if (!bfd_get_full_section_contents (abfd, (asection *) plt, &data) || data == NULL)
+      if (!bfd_get_full_section_contents (abfd, plt, &data)
+	  || data == NULL)
 	return -1;
-      bfd_cache_section_contents ((asection *) plt, data);
+      plt->contents = data;
+      plt->flags |= SEC_IN_MEMORY;
     }
 
   count = relplt->size / hdr->sh_entsize;