[PATCH 1/3] [binutils/readelf] Fix printing of dwarf4 .debug_str_offsets.dwo

[Alan Modra]

On Tue, May 14, 2024 at 12:55:20PM +0200, Tom de Vries wrote:
> When compiling a hello world with dwarf4 split dwarf:
> ...
> $ gcc -gdwarf-4 -gsplit-dwarf hello.c -save-temps -dA
> ...
> we have in a-hello.s these three initial entries in .debug_str_offsets:
> ...
> 	.section        .debug_str_offsets.dwo,"e",@progbits
> 	.4byte  0       // indexed string 0x0: short int
> 	.4byte  0xa     // indexed string 0x1: /home/vries/binutils
> 	.4byte  0x1f    // indexed string 0x2: main
> ...
> but "readelf -ws a.out" starts at the third entry:
> ...
> Contents of the .debug_str_offsets.dwo section (loaded from a-hello.dwo):
> 
>     Length: 0x30
>        Index   Offset [String]
>            0 00000000  main
> ...
> 
> This is a regression since commit 407115429b3 ("Modified changes for
> split-dwarf and dwarf-5."), which introduced a variable
> debug_str_offsets_hdr_len in display_debug_str_offsets.
> 
> Fix this by setting display_debug_str_offsets to 0 for the dwarf4 case.
> 
> PR 31734
> ---
>  binutils/dwarf.c                                   |  1 +
>  .../binutils-all/readelf-debug-str-offsets-dw4.d   | 14 ++++++++++++++
>  .../binutils-all/readelf-debug-str-offsets-dw4.s   |  6 ++++++
>  binutils/testsuite/binutils-all/readelf.exp        |  1 +
>  4 files changed, 22 insertions(+)
>  create mode 100644 binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.d
>  create mode 100644 binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.s
> 
> diff --git a/binutils/dwarf.c b/binutils/dwarf.c
> index c5ccc50dae7..8125c64e1b6 100644
> --- a/binutils/dwarf.c
> +++ b/binutils/dwarf.c
> @@ -7969,6 +7969,7 @@ display_debug_str_offsets (struct dwarf_section *section,
>  	  length = section->size;
>  	  curr   = section->start;
>  	  entries_end = end;
> +	  debug_str_offsets_hdr_len = 0;
>  
>  	  printf (_("    Length: %#" PRIx64 "\n"), length);
>  	  printf (_("       Index   Offset [String]\n"));
> diff --git a/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.d b/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.d
> new file mode 100644
> index 00000000000..23581e70f3e
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.d
> @@ -0,0 +1,14 @@
> +#name: readelf -ws readelf-debug-str-offsets-dw4
> +#source: readelf-debug-str-offsets-dw4.s
> +#readelf: -ws
> +
> +Contents of the .debug_str.dwo section:
> +
> +  0x00000000 46495253 54005345 434f4e44 00       FIRST.SECOND.
> +
> +Contents of the .debug_str_offsets.dwo section:
> +
> +    Length: 0x8
> +       Index   Offset \[String\]
> +           0 00000000  FIRST
> +           1 00000006  SECOND
> diff --git a/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.s b/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.s
> new file mode 100644
> index 00000000000..68f64dde234
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/readelf-debug-str-offsets-dw4.s
> @@ -0,0 +1,6 @@
> +	.section	.debug_str.dwo,"MS",@progbits,1

Use %progbits here and elsewhere, otherwise this will break on arm.

> +	.string	"FIRST"

Use .asciz rather than .string, for hppa.  .string on hppa doesn't
have a terminating zero.  OK with those changes.

> +	.string	"SECOND"
> +	.section	.debug_str_offsets.dwo,"MS",@progbits,1
> +	.4byte 0
> +	.4byte 6
> diff --git a/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
> index 09ed75f8761..9f20cb42812 100644
> --- a/binutils/testsuite/binutils-all/readelf.exp
> +++ b/binutils/testsuite/binutils-all/readelf.exp
> @@ -402,6 +402,7 @@ if {[which $AS] != 0} then {
>      run_dump_test "retain1b"
>      run_dump_test "readelf-maskos-1a"
>      run_dump_test "readelf-maskos-1b"
> +    run_dump_test "readelf-debug-str-offsets-dw4"
>      if {![istarget *-*-hpux*]} then {
>  	run_dump_test pr26548
>  	if {![binutils_assemble_flags $srcdir/$subdir/pr26548.s tmpdir/pr26548e.o {--defsym ERROR=1}]} then {
> 
> base-commit: 414aa6987f21a814851e5f3113388a3616993fa3
> -- 
> 2.35.3

-- 
Alan Modra