On 04/05/26 13:50, Dan Carpenter wrote:
On Mon, May 04, 2026 at 01:25:43PM +0530, Harshit Mogalapalli wrote:
Hi Dan,
Build error:
pre-process.c: In function ‘parse_expansion’:
pre-process.c:1648:16: error: variable-sized object may not be initialized
1648 | struct arg_state args[slots] = {};
| ^~~~~~~~~
What compiler are you using? This is a bug in Sparse. We should
probably fix it there.
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-host-pie
--enable-host-bind-now --enable-languages=c,c++,fortran,lto
--prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --with-linker-hash-style=gnu
--enable-plugin --enable-initfini-array --without-isl
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-gnu-indirect-function --enable-cet --with-tune=generic
--with-arch_64=x86-64-v2 --with-arch_32=x86-64
--build=x86_64-redhat-linux --with-build-config=bootstrap-lto
--enable-link-serialization=1
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.3.1 20220421 (Red Hat 11.3.1-2.1.0.2) (GCC)
Apparently you can't use variable length arrays with an initializer.
Why do C compilers have to suck? They should have made an exception for
memset to zero.
pre-process.c: In function ‘find_include’:
pre-process.c:1015:56: warning: ‘%s’ directive output may be truncated
writing up to 255 bytes into a region of size between 1 and 4096
[-Wformat-truncation=]
1015 | snprintf(buf, sizeof(buf), "%s/%s", cwd,
entry->d_name);
| ^~
pre-process.c:1015:25: note: ‘snprintf’ output between 2 and 4352 bytes into
a destination of size 4097
1015 | snprintf(buf, sizeof(buf), "%s/%s", cwd,
entry->d_name);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I think the problem is introduced by:
Fixes: 1a9a98e3c7b8 ("__VA_OPT__: parsing")
I think we need a memset() in parse_expansion()
The snprintf() warnings are my fault but I hate that warning. I don't
care if the snprintf() truncates... Truncating is the whole reason that
I use it... Anyway, sure let me silence that.
regards,
dan carpenter
From bcc58b9ccf06d28ab6be4f0992bc74f462aa12f8 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <[email protected]>
Date: Mon, 4 May 2026 11:16:24 +0300
Subject: [PATCH] pre-process: silence a -Wformat-truncation warning
Add a check for snprintf() overflows to make GCC happy.
Signed-off-by: Dan Carpenter <[email protected]>
---
pre-process.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/pre-process.c b/pre-process.c
index d9a0a9e73a73..fdcc29338c94 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -1012,7 +1012,11 @@ const char *find_include(const char *skip, const char
*look_for)
lstat(entry->d_name, &statbuf);
if (strcmp(entry->d_name, look_for) == 0) {
- snprintf(buf, sizeof(buf), "%s/%s", cwd, entry->d_name);
+ int cnt;
+
+ cnt = snprintf(buf, sizeof(buf), "%s/%s", cwd,
entry->d_name);
+ if (cnt >= sizeof(buf))
+ return NULL;
closedir(dp);
return buf;
}
This works for silencing snprintf warning.
Thanks for the fix.
Regards,
Harshit
