15.03.2025 19:32, Wietse Venema via Postfix-devel пишет:
Michael Tokarev via Postfix-devel:
There's an interesting twist in vstring_vstream.c, when
two typos, each of which makes the code wrong, compensate
for each other, making the result right, but the code is
confusing at least:
#define VSTRING_GET_RESULT(vp, baselen) \
(VSTRING_LEN(vp) > (base_len) ? vstring_end(vp)[-1] : VSTREAM_EOF)
int vstring_get_flags(VSTRING *vp, VSTREAM *fp, int flags)
{
ssize_t base_len = VSTRING_LEN(vp);
..
return (VSTRING_GET_RESULT(vp, baselen));
}
in the macro VSTRING_GET_RESULT(), parameter baselen is not
used, instead, some out-of-context base_len symbol is. While
in all places where VSTRING_GET_RESULT() is used, a non-existing
symbol baselen is passed as an (unused) parameter. At the same
time, local variable base_len exists which meant to be used as
the parameter.
That is low-level code that a lot of things depend on. I'll consider
this patch if you can demonstrate thet the new source code results
in the bit-wise identical object code as the origiinal code.
The plan is to have unit tets that cover all Postfxx code, but in
until those tests exist, changes to low-level code will require
extreme scrutiny.
To demonstrate
$ cd $original
$ make makefiles DEBUG= OPT=
$ make
$ cd $new
$ make makefiles DEBUG= OPT=
$ make
cmp $original/src/util/vstring_vstream.o $new/src/util/vstring_vstream.o
Actually this is exactly what I did, to be sure. Well, amost:
$ cd src/util
$ make vstring_vstream.o
gcc -I. -I../../include -DHAS_DEV_URANDOM -DHAS_PCRE=2 -UUSE_DYNAMIC_LIBS
-DDEF_SHLIB_DIR=\"no\" \
-UUSE_DYNAMIC_MAPS -Wmissing-prototypes -Wformat -Wno-comment -fno-common -O
-I. -DLINUX6 -c vstring_vstream.c
$ mv vstring_vstream.o vstring_vstream-orig.o
$ patch -p3 < ../../0001-vstring_stream-fix-baselen-vs-base_len-confusion.patch
<== this is the patch I sent
$ make vstring_vstream.o
gcc -I. -I../../include -DHAS_DEV_URANDOM -DHAS_PCRE=2 -UUSE_DYNAMIC_LIBS
-DDEF_SHLIB_DIR=\"no\" \
-UUSE_DYNAMIC_MAPS -Wmissing-prototypes -Wformat -Wno-comment -fno-common -O
-I. -DLINUX6 -c vstring_vstream.c
$ mv vstring_vstream.o vstring_vstream-fixed.o
$ ls -l vstring_vstream-*.o
-rw-r--r-- 1 mjt mjt 3976 Mar 15 18:32 vstring_vstream-fixed.o
-rw-r--r-- 1 mjt mjt 3976 Mar 15 18:32 vstring_vstream-orig.o
$ cmp vstring_vstream-*.o
$ _
If you really care about such things, it's best to do this
locally, without relying on someone else's input.
Thanks,'
/mjt
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