linux-toradex.git/lib/xz/xz_dec_stream.c, branch v6.16

xz: remove XZ_EXTERN and extern from functions

2024-09-02T03:43:27+00:00

XZ_EXTERN was used to make internal functions static in the preboot code. 
However, in other decompressors this hasn't been done.  On x86-64, this
makes no difference to the kernel image size.

Omit XZ_EXTERN and let some of the internal functions be extern in the
preboot code.  Omitting XZ_EXTERN from include/linux/xz.h fixes warnings
in "make htmldocs" and makes the intradocument links to xz_dec functions
work in Documentation/staging/xz.rst.  The alternative would have been to
add "XZ_EXTERN" to c_id_attributes in Documentation/conf.py but omitting
XZ_EXTERN seemed cleaner.

Link: https://lore.kernel.org/lkml/20240723205437.3c0664b0@kaneli/
Link: https://lkml.kernel.org/r/20240724110544.16430-1-lasse.collin@tukaani.org
Signed-off-by: Lasse Collin 
Tested-by: Michael Ellerman  (powerpc)
Cc: Jonathan Corbet 
Cc: Sam James 
Cc: Albert Ou 
Cc: Catalin Marinas 
Cc: Emil Renner Berthing 
Cc: Greg Kroah-Hartman 
Cc: Herbert Xu 
Cc: Joel Stanley 
Cc: Jubin Zhong 
Cc: Jules Maselbas 
Cc: Krzysztof Kozlowski 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Randy Dunlap 
Cc: Rui Li 
Cc: Simon Glass 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

xz: switch from public domain to BSD Zero Clause License (0BSD)

2024-09-02T03:43:24+00:00

Remove the public domain notices and add SPDX license identifiers.

Change MODULE_LICENSE from "GPL" to "Dual BSD/GPL" because 0BSD should
count as a BSD license variant here.

The switch to 0BSD was done in the upstream XZ Embedded project because
public domain has (real or perceived) legal issues in some jurisdictions.

Link: https://lkml.kernel.org/r/20240721133633.47721-4-lasse.collin@tukaani.org
Signed-off-by: Lasse Collin 
Reviewed-by: Sam James 
Cc: Thomas Gleixner 
Cc: Greg Kroah-Hartman 
Cc: Albert Ou 
Cc: Catalin Marinas 
Cc: Emil Renner Berthing 
Cc: Herbert Xu 
Cc: Joel Stanley 
Cc: Jonathan Corbet 
Cc: Jubin Zhong 
Cc: Jules Maselbas 
Cc: Krzysztof Kozlowski 
Cc: Michael Ellerman 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Randy Dunlap 
Cc: Rui Li 
Cc: Simon Glass 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

lib/xz: Validate the value before assigning it to an enum variable

2021-10-19T15:44:30+00:00

This might matter, for example, if the underlying type of enum xz_check
was a signed char. In such a case the validation wouldn't have caught an
unsupported header. I don't know if this problem can occur in the kernel
on any arch but it's still good to fix it because some people might copy
the XZ code to their own projects from Linux instead of the upstream
XZ Embedded repository.

This change may increase the code size by a few bytes. An alternative
would have been to use an unsigned int instead of enum xz_check but
using an enumeration looks cleaner.

Link: https://lore.kernel.org/r/20211010213145.17462-3-xiang@kernel.org
Signed-off-by: Lasse Collin 
Signed-off-by: Gao Xiang

Revert "lib: Revert use of fallthrough pseudo-keyword in lib/"

2020-11-18T20:15:17+00:00

This reverts commit 6a9dc5fd6170 ("lib: Revert use of fallthrough
pseudo-keyword in lib/")

Now that we can build arch/powerpc/boot/ free of -Wimplicit-fallthrough,
re-enable these fixes for lib/.

Signed-off-by: Nick Desaulniers 
Tested-by: Nathan Chancellor 
Reviewed-by: Nathan Chancellor 
Reviewed-by: Gustavo A. R. Silva 
Reviewed-by: Miguel Ojeda 
Link: https://github.com/ClangBuiltLinux/linux/issues/236
Signed-off-by: Gustavo A. R. Silva

lib: Revert use of fallthrough pseudo-keyword in lib/

2020-08-24T21:17:44+00:00

The following build error for powerpc64 was reported by Nathan Chancellor:

  "$ scripts/config --file arch/powerpc/configs/powernv_defconfig -e KERNEL_XZ

   $ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc64le-linux- distclean powernv_defconfig zImage
   ...
   In file included from arch/powerpc/boot/../../../lib/decompress_unxz.c:234,
                    from arch/powerpc/boot/decompress.c:38:
   arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c: In function 'dec_main':
   arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c:586:4: error: 'fallthrough' undeclared (first use in this function)
     586 |    fallthrough;
         |    ^~~~~~~~~~~

   This will end up affecting distribution configurations such as Debian
   and OpenSUSE according to my testing. I am not sure what the solution
   is, the PowerPC wrapper does not set -D__KERNEL__ so I am not sure
   that compiler_attributes.h can be safely included."

In order to avoid these sort of problems, it seems that the best
solution is to use /* fall through */ comments instead of the
fallthrough pseudo-keyword macro in lib/, for now.

Reported-by: Nathan Chancellor 
Fixes: df561f6688fe ("treewide: Use fallthrough pseudo-keyword")
Signed-off-by: Gustavo A. R. Silva 
Reviewed-and-tested-by: Nathan Chancellor 
Signed-off-by: Linus Torvalds

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

lib/xz: Add fall-through comments to a switch statement

2017-10-12T13:10:12+00:00

It's good style. I was also told that GCC 7 is more strict and might
give a warning when such comments are missing.

Signed-off-by: Lasse Collin 
Suggested-by: Andrei Borzenkov 
Signed-off-by: Jiri Kosina

decompressors: add XZ decompressor module

2011-01-13T16:03:24+00:00

In userspace, the .lzma format has become mostly a legacy file format that
got superseded by the .xz format.  Similarly, LZMA Utils was superseded by
XZ Utils.

These patches add support for XZ decompression into the kernel.  Most of
the code is as is from XZ Embedded .
It was written for the Linux kernel but is usable in other projects too.

Advantages of XZ over the current LZMA code in the kernel:
  - Nice API that can be used by other kernel modules; it's
    not limited to kernel, initramfs, and initrd decompression.
  - Integrity check support (CRC32)
  - BCJ filters improve compression of executable code on
    certain architectures. These together with LZMA2 can
    produce a few percent smaller kernel or Squashfs images
    than plain LZMA without making the decompression slower.

This patch: Add the main decompression code (xz_dec), testing module
(xz_dec_test), wrapper script (xz_wrap.sh) for the xz command line tool,
and documentation.  The xz_dec module is enough to have a usable XZ
decompressor e.g.  for Squashfs.

Signed-off-by: Lasse Collin 
Cc: "H. Peter Anvin" 
Cc: Alain Knaff 
Cc: Albin Tonnerre 
Cc: Phillip Lougher 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds