sh: Add kill builtin.

This allows specifying a %job (which is equivalent to the corresponding
process group).

Additionally, it improves reliability of kill from sh in high-load
situations and ensures "kill" finds the correct utility regardless of PATH,
as required by POSIX (unless the undocumented %builtin mechanism is used).

Side effect: fatal errors (any error other than kill(2) failure) now return
exit status 2 instead of 1. (This is consistent with other sh builtins, but
not in NetBSD.)

Code size increases about 1K on i386.

Obtained from:	NetBSD

1 files changed, 5 insertions, 0 deletions

diff --git a/bin/sh/bltin/bltin.h b/bin/sh/bltin/bltin.h
index f6e7883..e449673 100644
--- a/bin/sh/bltin/bltin.h
+++ b/bin/sh/bltin/bltin.h
@@ -43,6 +43,7 @@
 #include "../mystring.h"
 #ifdef SHELL
 #include "../output.h"
+#define FILE struct output
 #undef stdout
 #define stdout out1
 #undef stderr
@@ -58,6 +59,7 @@
 #define fflush flushout
 #define INITARGS(argv)
 #define warnx warning
+#define warn(fmt, ...) warning(fmt ": %s", __VA_ARGS__, strerror(errno))
 #define errx(exitstatus, ...) error(__VA_ARGS__)
 
 #else
@@ -67,8 +69,11 @@
 #define INITARGS(argv)	if ((commandname = argv[0]) == NULL) {fputs("Argc is zero\n", stderr); exit(2);} else
 #endif
 
+#include <unistd.h>
+
 pointer stalloc(int);
 void error(const char *, ...) __printf0like(1, 2);
+pid_t getjobpgrp(char *);
 
 int echocmd(int, char **);
 int testcmd(int, char **);