perf kvm: Use strtol for walking guestmount directory

Only want to process directories under the guestmnount directory that
have a pid as a name (ie, all digits). Other entries in the guestmount
directory should be ignored.  There is already a check that requires the
first character of each entry to be a digit, but atoi is used to convert
the directory name to a pid. For example if guestmount contains a
directory with the name 1foo, atoi converts it to a pid of 1 and a
machine is created with a pid of 1. This is wrong; this directory really
should be ignored. Use strtol to do that.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1343616875-6455-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -2875,6 +2875,7 @@ int machines__create_guest_kernel_maps(struct rb_root *machines)
 	int i, items = 0;
 	char path[PATH_MAX];
 	pid_t pid;
+	char *endp;
 
 	if (symbol_conf.default_guest_vmlinux_name ||
 	    symbol_conf.default_guest_modules ||
@@ -2891,7 +2892,14 @@ int machines__create_guest_kernel_maps(struct rb_root *machines)
 				/* Filter out . and .. */
 				continue;
 			}
-			pid = atoi(namelist[i]->d_name);
+			pid = (pid_t)strtol(namelist[i]->d_name, &endp, 10);
+			if ((*endp != '\0') ||
+			    (endp == namelist[i]->d_name) ||
+			    (errno == ERANGE)) {
+				pr_debug("invalid directory (%s). Skipping.\n",
+					 namelist[i]->d_name);
+				continue;
+			}
 			sprintf(path, "%s/%s/proc/kallsyms",
 				symbol_conf.guestmount,
 				namelist[i]->d_name);