Red Hat Bugzilla – Bug 88095
RFE: initialize 'dummy' locals to be valgrind-friendly
Last modified: 2016-11-24 09:53:51 EST
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Description of problem:
Please initialize don't-care local variables [typically named 'dummy'] that are
passed by reference to wide-string (multi-byte character) routines which use
their storage as counters. Leaving them uninitialized causes valgrind to report
bad usage, which must be investigated and ignored. The runtime cost is 7 bytes
of .text, and at most 1.5 CPU cycles, per variable.
Here are 13 cases. Just initialize to 0.
./libio/iofwide.c:230: size_t dummy;
./libio/iofwide.c:297: size_t dummy;
./libio/iofwide.c:359: size_t dummy;
./libio/iofwide.c:457: size_t dummy;
./wcsmbs/btowc.c:57: size_t dummy;
./wcsmbs/mbrtowc.c:42: size_t dummy;
./wcsmbs/mbsnrtowcs.c:53: size_t dummy;
./wcsmbs/wcrtomb.c:44: size_t dummy;
./wcsmbs/wcsnrtombs.c:76: size_t dummy;
./wcsmbs/wcsnrtombs.c:105: size_t dummy;
./wcsmbs/wcsrtombs.c:70: size_t dummy;
./wcsmbs/wcsrtombs.c:106: size_t dummy;
./wcsmbs/wctob.c:36: size_t dummy;
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.Run any testcase which calls the indicated routines.
Actual Results: valgrind complains of uninitialized memory.
Expected Results: No complaints from valgrind.
Two more cases are:
wcsmbs/mbsrtowcs.c:60: size_t non_reversible;
Created attachment 91160 [details]
proposed patch for glibc-2.3.2-27.9
Here are the changes in patch format, including several other files with
'struct's with "don't care" pieces that a memory checker thinks will be read.
glibc is a runtime library. No work which isn't necessary is done.