[PATCH 2/2] kexec: Enable zstd in kexec decompression paths

[Jeremy Linton]

The kexec decompression routines support detecting zlib or lzma
compressed images. Lets add the ability to automatically decompress
zstd ones as well. The zstd attempt is made after gzip because its
fairly inexpensive relative lzma and gzip at this point remains a
popular option.

Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
---
 kexec/kexec-pe-zboot.c |  3 ++-
 kexec/kexec.c          | 10 +++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/kexec/kexec-pe-zboot.c b/kexec/kexec-pe-zboot.c
index 3abd17d..0a82097 100644
--- a/kexec/kexec-pe-zboot.c
+++ b/kexec/kexec-pe-zboot.c
@@ -59,8 +59,9 @@ int pez_prepare(const char *crude_buf, off_t buf_sz, int *kernel_fd,
 	 * algorithms than are supported here, error out if we detect that.
 	 */
 	if (memcmp(&z->compress_type, "gzip", 4) &&
+	    memcmp(&z->compress_type, "zstd", 4) &&
 	    memcmp(&z->compress_type, "lzma", 4)) {
-		dbgprintf("%s: kexec can only decompress gziped and lzma images.\n", __func__);
+		dbgprintf("%s: kexec can only decompress gziped, lzma and zstd images\n", __func__);
 		return -1;
 	}
 
diff --git a/kexec/kexec.c b/kexec/kexec.c
index 4f51987..70097ae 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -55,6 +55,7 @@
 #include "kexec-sha256.h"
 #include "kexec-zlib.h"
 #include "kexec-lzma.h"
+#include "kexec-zstd.h"
 #include <arch/options.h>
 
 #define KEXEC_LOADED_PATH "/sys/kernel/kexec_loaded"
@@ -639,9 +640,12 @@ char *slurp_decompress_file(const char *filename, off_t *r_size)
 
 	kernel_buf = zlib_decompress_file(filename, r_size);
 	if (!kernel_buf) {
-		kernel_buf = lzma_decompress_file(filename, r_size);
-		if (!kernel_buf)
-			return slurp_file(filename, r_size);
+	        kernel_buf = zstd_decompress_file(filename, r_size);	        
+		if (!kernel_buf) {
+                        kernel_buf = lzma_decompress_file(filename, r_size);
+			if (!kernel_buf)
+				return slurp_file(filename, r_size);
+		}
 	}
 	return kernel_buf;
 }
-- 
2.47.0