From 8df03ef746dec2d4612ef7ea1933e8066783ad27 Mon Sep 17 00:00:00 2001 From: Jane Malalane Date: Wed, 25 Aug 2021 15:10:32 +0200 Subject: [PATCH] xen/lib: Fix strcmp() and strncmp() 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 Signed-off-by: Jane Malalane Reviewed-by: Ian Jackson master commit: 3747a2bb67daa5a8baeff6cda57dc98a5ef79c3e master date: 2021-07-30 10:52:46 +0100 --- xen/common/string.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/xen/common/string.c b/xen/common/string.c index af3d96ad0f..43624b1b45 100644 --- a/xen/common/string.c +++ b/xen/common/string.c @@ -119,14 +119,16 @@ EXPORT_SYMBOL(strlcat); */ 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; } #endif @@ -139,15 +141,17 @@ int (strcmp)(const char *cs, const char *ct) */ 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; } #endif -- 2.30.2