[PATCH] kexec-tools: Determine if the image is lzma commpressed

[Martin Faltesek]

Sorry I don't have overall observations about this patch. But saw
missing fclose after size != 13.

On Fri, Mar 25, 2022 at 2:09 AM Lichen Liu <lichliu at redhat.com> wrote:
>
> Currently there are 2 functions for decompressing compressed image. The
> zlib_decompress_file() will determine if the image is compressed by gzip
> before read, but lzma_decompress_file() will not. This can cause misleading
> information to be printed when the image is not compressed by lzma and
> debug option is used:
>
> ]# kexec -d -s -l /boot/vmlinuz-5.14.10-300.fc35.x86_64 \
> --initrd /boot/initramfs-5.14.10-300.fc35.x86_64.img \
> --reuse-cmdline
> Try gzip decompression.
> Try LZMA decompression.
> lzma_decompress_file: read on /boot/vmlinuz-5.14.10-300.fc35.x86_64 of
> 65536 bytes failed
>
> Add a helper function is_lzma_file() to help behave consistently.
>
> Signed-off-by: Lichen Liu <lichliu at redhat.com>
> ---
>  kexec/lzma.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/kexec/lzma.c b/kexec/lzma.c
> index 5bfccb7..f27cfe2 100644
> --- a/kexec/lzma.c
> +++ b/kexec/lzma.c
> @@ -155,6 +155,39 @@ ssize_t lzread(LZFILE *lzfile, void *buf, size_t len)
>         }
>  }
>
> +int is_lzma_file(const char *filename)
> +{
> +       FILE *fp;
> +       int ret = 0;
> +       uint8_t buf[13];
> +
> +       if (!filename)
> +               return 0;
> +
> +       fp = fopen(filename, "r");
> +       if (fp == NULL)
> +               return 0;
> +
> +       const size_t size = fread(buf, 1, sizeof(buf), fp);
> +
> +       if (size != 13)
> +               return 0;
> +
> +       lzma_filter filter = { .id = LZMA_FILTER_LZMA1 };
> +
> +       switch (lzma_properties_decode(&filter, NULL, buf, 5)) {
> +       case LZMA_OK:
> +               ret = 1;
> +               break;
> +       default:
> +               /* It's not a lzma file */
> +               ret = 0;
> +       }
> +
> +       fclose(fp);
> +       return ret;
> +}
> +
>  char *lzma_decompress_file(const char *filename, off_t *r_size)
>  {
>         LZFILE *fp;
> @@ -168,6 +201,9 @@ char *lzma_decompress_file(const char *filename, off_t *r_size)
>         if (!filename)
>                 return NULL;
>
> +       if (!is_lzma_file(filename))
> +               return NULL;
> +
>         fp = lzopen(filename, "rb");
>         if (fp == 0) {
>                 dbgprintf("Cannot open `%s'\n", filename);
> --
> 2.27.0
>
>
> _______________________________________________
> kexec mailing list
> kexec at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec