References: bsc#1212684

# Commit 82f7f7be462ddb435c60aef86960252240bf03c7
# Date 2023-08-09 09:03:51 +0200
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
libxenstat/Linux: pass nul-terminated string to strpbrk()

While what "tmp" points to has been cleared at the end of the first
iteration of parseNetDevLine()'s main loop, this is too late for the
first iteration's invocation of strpbrk() (copying the interface name).
Properly nul-terminate the string at population time instead, removing
the late clearing.

While there also eliminate a confusing (because of being wrong) comment:
A regex parsing error would be handled one further scope outwards. Here
we're dealing with field 1 vs any of the later fields.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>

--- a/tools/libs/stat/xenstat_linux.c
+++ b/tools/libs/stat/xenstat_linux.c
@@ -169,6 +169,7 @@ static int parseNetDevLine(char *line, c
 							matches[i].rm_so + 1) * sizeof(char));
 				for (x = matches[i].rm_so; x < matches[i].rm_eo; x++)
 					tmp[x - matches[i].rm_so] = line[x];
+				tmp[x - matches[i].rm_so] = 0;
 
 				/* We populate all the fields from /proc/net/dev line */
 				if (i > 1) {
@@ -225,15 +226,11 @@ static int parseNetDevLine(char *line, c
 							break;
 					}
 				}
-				else
-				/* There were errors when parsing this directly in RE. strpbrk() helps */
-				if (iface != NULL) {
+				else if (iface != NULL) {
 					char *tmp2 = strpbrk(tmp, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");
 					if (tmp2 != NULL)
 						strcpy(iface, tmp2);
 				}
-
-				memset(tmp, 0, matches[i].rm_eo - matches[i].rm_so);
 			}
 		}
 	}