Attachment 1486675 Details for Bug 1538073 – Short C program which emits a Valgrind warning

Short C program which emits a Valgrind warning

mbsbug.c (text/plain), 1.14 KB, created by Victor Stinner on 2018-09-25 09:59:36 UTC

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Creator: Victor Stinner

Created: 2018-09-25 09:59:36 UTC

Size: 1.14 KB

patch

obsolete

>/*
> * wcstombs() after mbstowcs() causes a Valgrind warning on Fedora 27:
> *
> * gcc mbsbug.c -g -o mbsbug -O2
> * valgrind ./mbsbug
> */
>
>#include <stdio.h>
>#include <stdlib.h>
>#include <string.h>
>#include <wchar.h>
>#include <assert.h>
>
>int
>main(int argc, char **argv)
>{
>    char *arg0 = argv[0];
>
>    size_t argsize = mbstowcs(NULL, arg0, 0);
>    wchar_t *res = malloc((argsize + 1) * sizeof(wchar_t));
>    if (res == NULL) { return 1; }
>    memset(res, 0, (argsize + 1) * sizeof(wchar_t));
>    size_t count = mbstowcs(res, arg0, argsize + 1);
>
>    size_t argsize2 = wcstombs(NULL, res, 0);
>    char *res2 = malloc(argsize2 + 1);
>    if (res2 == NULL) { return 1; }
>    memset(res2, 0, argsize2 + 1);
>    /* valgrind warning:
>
>       Conditional jump or move depends on uninitialised value(s)
>          at 0x4F99097: __wcsnlen_avx2 (in /usr/lib64/libc-2.27.so)
>          by 0x4EDF871: wcsrtombs (in /usr/lib64/libc-2.27.so)
>          by 0x4E75000: wcstombs (in /usr/lib64/libc-2.27.so)
>          by 0x400632: main (mbsbug.c:36) */
>    size_t count2 = wcstombs(res2, res, argsize2 + 1);
>
>    assert(count2 == argsize);
>
>    free(res);
>    free(res2);
>    return 0;
>}

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Attachments on bug 1538073: 1486675