ape: threadsafe errno

store errno on the private process stack so its always per process
and not just per memory space. errno itself becomes a macro
dereferencing int *_errnoloc; which is initialized from main9.s
pointing to the private stack location.

various fixes in programs that just imported errno variable with
"extern int errno;" instead of including <errno.h>.

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/src/ape/lib/ap/stdio/perror.c b/sys/src/ape/lib/ap/stdio/perror.c
index 71f5c41f0..19a078b39 100644
--- a/sys/src/ape/lib/ap/stdio/perror.c
+++ b/sys/src/ape/lib/ap/stdio/perror.c
@@ -2,8 +2,9 @@
  * pANS stdio -- perror
  */
 #include "iolib.h"
+#include <errno.h>
+
 void perror(const char *s){
-	extern int errno;
 	if(s!=NULL && *s != '\0') fputs(s, stderr), fputs(": ", stderr);
 	fputs(strerror(errno), stderr);
 	putc('\n', stderr);