The C standard requires that each character be compared as unsigned char. Xen's current behaviour compares as signed char, which changes the answer when chars with a value greater than 0x7f are used.
Suggested-by: Andrew Cooper <[email protected]> Signed-off-by: Jane Malalane <[email protected]> --- CC: Andrew Cooper <[email protected]> CC: George Dunlap <[email protected]> CC: Ian Jackson <[email protected]> CC: Jan Beulich <[email protected]> CC: Julien Grall <[email protected]> CC: Stefano Stabellini <[email protected]> CC: Wei Liu <[email protected]> --- xen/lib/strcmp.c | 8 +++++--- xen/lib/strncmp.c | 8 +++++--- 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/xen/lib/strcmp.c b/xen/lib/strcmp.c index 465f1c4191..f85c1e8741 100644 --- a/xen/lib/strcmp.c +++ b/xen/lib/strcmp.c @@ -11,14 +11,16 @@ */ int (strcmp)(const char *cs, const char *ct) { - register signed char __res; + unsigned char *csu = (unsigned char *)cs; + unsigned char *ctu = (unsigned char *)ct; + int res; while (1) { - if ((__res = *cs - *ct++) != 0 || !*cs++) + if ((res = *csu - *ctu++) != 0 || !*csu++) break; } - return __res; + return res; } /* diff --git a/xen/lib/strncmp.c b/xen/lib/strncmp.c index 9af7fa1c99..1480f58c2e 100644 --- a/xen/lib/strncmp.c +++ b/xen/lib/strncmp.c @@ -12,15 +12,17 @@ */ int (strncmp)(const char *cs, const char *ct, size_t count) { - register signed char __res = 0; + unsigned char *csu = (unsigned char *)cs; + unsigned char *ctu = (unsigned char *)ct; + int res = 0; while (count) { - if ((__res = *cs - *ct++) != 0 || !*cs++) + if ((res = *csu - *ctu++) != 0 || !*csu++) break; count--; } - return __res; + return res; } /* -- 2.11.0
