implement err.h

valgrind reported invalid reads/writes with glibc err[x]|warn[x] (in
glibc printf) when stdio had been redirected in between.

define _progname (pointing to argv[0])

cpu/native/include/native_internal.h

@@ -49,6 +49,8 @@ extern ucontext_t native_isr_context;
 extern ucontext_t end_context;
 extern ucontext_t *_native_cur_ctx, *_native_isr_ctx;
 
+extern const char *_progname;
+
 #ifdef MODULE_UART0
 #include <sys/select.h>
 extern fd_set _native_rfds;

cpu/native/startup.c

@@ -41,9 +41,9 @@
 #include "tap.h"
 
 int (*real_printf)(const char *format, ...);
-char *argv0;
 int _native_null_in_pipe[2];
 int _native_null_out_file;
+const char *_progname;
 
 /**
  * initialize _native_null_in_pipe to allow for reading from stdin
@@ -152,7 +152,7 @@ void daemonize()
 
 void usage_exit()
 {
-    real_printf("usage: %s", argv0);
+    real_printf("usage: %s", _progname);
 
 #ifdef MODULE_NATIVENET
     real_printf(" <tap interface>");
@@ -189,7 +189,7 @@ __attribute__((constructor)) static void startup(int argc, char **argv)
     *(void **)(&real_write) = dlsym(RTLD_NEXT, "write");
     *(void **)(&real_printf) = dlsym(RTLD_NEXT, "printf");
 
-    argv0 = argv[0];
+    _progname = argv[0];
     int argp = 1;
     char *stderrtype = "stdio";
     char *stdouttype = "stdio";

cpu/native/syscalls.c

@@ -24,6 +24,7 @@
 #endif
 
 #include <err.h>
+#include <errno.h>
 #include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
@@ -163,3 +164,80 @@ int vprintf(const char *format, va_list argp)
 
     return r;
 }
+
+
+void vwarn(const char *fmt, va_list args)
+{
+    char *m, *e;
+
+    e = strerror(errno);
+
+    if ((m = make_message(fmt, args)) == NULL) {
+        write(STDERR_FILENO, "malloc\n", 7);
+        exit(EXIT_FAILURE);
+    }
+    write(STDERR_FILENO, _progname, strlen(_progname));
+    write(STDERR_FILENO, ": ", 2);
+    write(STDERR_FILENO, m, strlen(m));
+    write(STDERR_FILENO, ": ", 2);
+    write(STDERR_FILENO, e, strlen(e));
+    write(STDERR_FILENO, "\n", 1);
+    free(m);
+}
+
+void vwarnx(const char *fmt, va_list args)
+{
+    char *m;
+
+    if ((m = make_message(fmt, args)) == NULL) {
+        write(STDERR_FILENO, "malloc\n", 7);
+        exit(EXIT_FAILURE);
+    }
+    write(STDERR_FILENO, _progname, strlen(_progname));
+    write(STDERR_FILENO, ": ", 2);
+    write(STDERR_FILENO, m, strlen(m));
+    write(STDERR_FILENO, "\n", 1);
+    free(m);
+}
+
+void verr(int eval, const char *fmt, va_list args)
+{
+    vwarn(fmt, args);
+    exit(eval);
+}
+
+void verrx(int eval, const char *fmt, va_list args)
+{
+    vwarnx(fmt, args);
+    exit(eval);
+}
+
+void warn(const char *fmt, ...)
+{
+    va_list argp;
+    va_start(argp, fmt);
+    vwarn(fmt, argp);
+    va_end(argp);
+}
+
+void warnx(const char *fmt, ...)
+{
+    va_list argp;
+    va_start(argp, fmt);
+    vwarnx(fmt, argp);
+    va_end(argp);
+}
+
+void err(int eval, const char *fmt, ...)
+{
+    va_list argp;
+    va_start(argp, fmt);
+    verr(eval, fmt, argp);
+}
+
+void errx(int eval, const char *fmt, ...)
+{
+    va_list argp;
+    va_start(argp, fmt);
+    verrx(eval, fmt, argp);
+}