[PATCH v2 1/1] bootm: improve error message when gzip decompression buffer is too small

[Aristo Chen]

Currently, when decompressing a gzip-compressed image during bootm, a
generic error such as "inflate() returned -5" is shown when the buffer is
too small. However, it is not immediately clear that this is caused by
CONFIG_SYS_BOOTM_LEN being too small.

This patch improves error handling by:
- Detecting Z_BUF_ERROR (-5) returned from the inflate() call
- Suggesting the user to increase CONFIG_SYS_BOOTM_LEN when applicable
- Preserving the original return code from zunzip() instead of overwriting
  it with -1

By providing clearer hints when decompression fails due to insufficient
buffer size, this change helps users diagnose and fix boot failures more
easily.

Signed-off-by: Aristo Chen <aristo.c...@canonical.com>
---
 boot/bootm.c | 4 +++-
 lib/gunzip.c | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/boot/bootm.c b/boot/bootm.c
index f5cbb10f0d1..f6aa32746b7 100644
--- a/boot/bootm.c
+++ b/boot/bootm.c
@@ -34,6 +34,7 @@
 
 #include <bootm.h>
 #include <image.h>
+#include <u-boot/zlib.h>
 
 #define MAX_CMDLINE_SIZE       SZ_4K
 
@@ -578,7 +579,8 @@ static int handle_decomp_error(int comp_type, size_t 
uncomp_size,
        if (ret == -ENOSYS)
                return BOOTM_ERR_UNIMPLEMENTED;
 
-       if (uncomp_size >= buf_size)
+       if ((comp_type == IH_COMP_GZIP && ret == Z_BUF_ERROR) ||
+           uncomp_size >= buf_size)
                printf("Image too large: increase CONFIG_SYS_BOOTM_LEN\n");
        else
                printf("%s: uncompress error %d\n", name, ret);
diff --git a/lib/gunzip.c b/lib/gunzip.c
index 52007715bda..a05dcde9a75 100644
--- a/lib/gunzip.c
+++ b/lib/gunzip.c
@@ -299,7 +299,7 @@ __rcode int zunzip(void *dst, int dstlen, unsigned char 
*src,
                if (stoponerr == 1 && r != Z_STREAM_END &&
                    (s.avail_in == 0 || s.avail_out == 0 || r != Z_BUF_ERROR)) {
                        printf("Error: inflate() returned %d\n", r);
-                       err = -1;
+                       err = r;
                        break;
                }
        } while (r == Z_BUF_ERROR);
-- 
2.34.1