Hi Bruno,
I was looking at the gzip CI to double check that FreeBSD was the known
error "pipe-output", and it was. But I also noticed some warnings that
occur on all systems that use Clang by default. Here is the steps that I
used to reproduce on GNU/Linux:
$ clang --version | sed 1q
clang version 20.1.3 (Fedora 20.1.3-1.fc42)
$ gnulib-tool --create-testdir --dir testdir1 --single-configure
c-vasnprintf
$ cd testdir1 && ./configure CC='clang' CFLAGS='-Wsometimes-uninitialized'
$ make
[...]
make[4]: Entering directory '/home/collin/.local/src/gnulib/testdir1/gllib'
depbase=`echo c-vasnprintf.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
clang -DHAVE_CONFIG_H -I. -I.. -DGNULIB_STRICT_CHECKING=1
-Wsometimes-uninitialized -MT c-vasnprintf.o -MD -MP -MF $depbase.Tpo -c -o
c-vasnprintf.o c-vasnprintf.c &&\
mv -f $depbase.Tpo $depbase.Po
In file included from c-vasnprintf.c:46:
./vasnprintf.c:6203:49: warning: variable 'thousep_len' is used
uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
6203 | if ((flags &
FLAG_GROUP) && (intpart_digits > 1))
|
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./vasnprintf.c:6232:76: note: uninitialized use occurs here
6232 | p += intpart_digits +
insert * thousep_len;
|
^~~~~~~~~~~
./vasnprintf.c:6203:45: note: remove the 'if' if its condition is always
true
6203 | if ((flags &
FLAG_GROUP) && (intpart_digits > 1))
|
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6204 | {
[...]
These warnings look correct to me since we always do
"p += intpart_digits + insert * thousep_len" unconditionally without an
early return.
Can you confirm the attached patch is correct? Since this was introduced
by your grouping fixes ~2 months ago.
Collin
>From 27045298b98c7fd07c848326af3556971c48d264 Mon Sep 17 00:00:00 2001
Message-ID: <27045298b98c7fd07c848326af3556971c48d264.1748398997.git.collin.fu...@gmail.com>
From: Collin Funk <[email protected]>
Date: Tue, 27 May 2025 19:07:10 -0700
Subject: [PATCH] vasnprintf: Fix uninitialized values.
* lib/vasnprintf.c (VASNPRINFT): Initialize all occurrences of
thousep_len to zero.
---
ChangeLog | 6 ++++++
lib/vasnprintf.c | 8 ++++----
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index d14ec6f717..5f80f3f83d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2025-05-27 Collin Funk <[email protected]>
+
+ vasnprintf: Fix uninitialized values.
+ * lib/vasnprintf.c (VASNPRINFT): Initialize all occurrences of
+ thousep_len to zero.
+
2025-05-27 Bruno Haible <[email protected]>
stddef-h: Make 'unreachable' usable in C++ mode.
diff --git a/lib/vasnprintf.c b/lib/vasnprintf.c
index a5a956603a..f46e8701bd 100644
--- a/lib/vasnprintf.c
+++ b/lib/vasnprintf.c
@@ -5249,7 +5249,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
const DCHAR_T *thousep = NULL;
DCHAR_T thousep_buf[10];
# if !WIDE_CHAR_VERSION
- size_t thousep_len;
+ size_t thousep_len = 0;
# endif
const signed char *grouping;
size_t insert = 0;
@@ -5579,7 +5579,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
const DCHAR_T *thousep = NULL;
DCHAR_T thousep_buf[10];
# if !WIDE_CHAR_VERSION
- size_t thousep_len;
+ size_t thousep_len = 0;
# endif
const signed char *grouping;
size_t insert = 0;
@@ -5857,7 +5857,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
const DCHAR_T *thousep = NULL;
DCHAR_T thousep_buf[10];
# if !WIDE_CHAR_VERSION
- size_t thousep_len;
+ size_t thousep_len = 0;
# endif
const signed char *grouping;
size_t insert = 0;
@@ -6195,7 +6195,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
const DCHAR_T *thousep = NULL;
DCHAR_T thousep_buf[10];
# if !WIDE_CHAR_VERSION
- size_t thousep_len;
+ size_t thousep_len = 0;
# endif
const signed char *grouping;
size_t insert = 0;
--
2.49.0
