cmd: ximg: handle Z_BUF_ERROR explicitly in GZIP decompression

When decompressing GZIP-compressed image parts via the `imxtract` command,
explicitly handle the `Z_BUF_ERROR` return value from `gunzip()` to provide
a clearer diagnostic. This error typically indicates that the destination
buffer is too small to hold the uncompressed data.

Signed-off-by: Aristo Chen <aristo.chen@canonical.com>
[trini: Rework to indent the whole case with { } due to not using the
C23 extension]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/ximg.c b/cmd/ximg.c
index 29d7c32..e97167a 100644
--- a/cmd/ximg.c
+++ b/cmd/ximg.c
@@ -27,6 +27,7 @@
 #include <asm/byteorder.h>
 #include <asm/cache.h>
 #include <asm/io.h>
+#include <u-boot/zlib.h>
 
 static int
 do_imgextract(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
@@ -206,11 +207,18 @@
 			break;
 #ifdef CONFIG_GZIP
 		case IH_COMP_GZIP:
-			printf("   Uncompressing part %d ... ", part);
-			if (gunzip((void *) dest, unc_len,
-				   (uchar *) data, &len) != 0) {
-				puts("GUNZIP ERROR - image not loaded\n");
-				return 1;
+			{
+				int ret = 0;
+				printf("   Uncompressing part %d ... ", part);
+				ret = gunzip((void *)dest, unc_len,
+					     (uchar *)data, &len);
+				if (ret == Z_BUF_ERROR) {
+					puts("Image too large: increase CONFIG_SYS_XIMG_LEN\n");
+					return 1;
+				} else if (ret != 0) {
+					puts("GUNZIP ERROR - image not loaded\n");
+					return 1;
+				}
 			}
 			break;
 #endif