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

[Lichen Liu]

Thank you, Martin!
I'll post a new version to fix it.


On Wed, Mar 30, 2022 at 10:10 AM Martin Faltesek <mfaltesek at google.com> wrote:
>
> 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
>