Added utime.h (#188)

* Added utime.h

* Changes after code review

* Auto-generated expected files instead of manually editing
* Fix libpreopoen stat and utime not following symlinks correctly

Makefile

@@ -316,8 +316,7 @@ MUSL_OMIT_HEADERS += \
     "netinet/ether.h" \
     "sys/timerfd.h" \
     "libintl.h" \
-    "sys/sysmacros.h" \
+    "sys/sysmacros.h"
-    "utime.h"
 
 ifeq ($(THREAD_MODEL), single)
 # Remove headers not supported in single-threaded mode.

expected/wasm32-wasi/defined-symbols.txt

@@ -1028,6 +1028,7 @@ unlinkat
 unsetenv
 uselocale
 usleep
+utime
 utimensat
 vasprintf
 vdprintf

expected/wasm32-wasi/include-all.c

@@ -164,6 +164,7 @@
 #include <time.h>
 #include <uchar.h>
 #include <unistd.h>
+#include <utime.h>
 #include <values.h>
 #include <wasi/api.h>
 #include <wasi/libc-environ.h>

expected/wasm32-wasi/predefined-macros.txt

@@ -2407,6 +2407,7 @@
 #define _TIME_H 
 #define _UCHAR_H 
 #define _UNISTD_H 
+#define _UTIME_H 
 #define _VALUES_H 
 #define _VA_LIST 
 #define _WCHAR_H 

libc-bottom-half/libpreopen/libpreopen.c

@@ -44,6 +44,7 @@
 
 #define _ALL_SOURCE
 #include <sys/stat.h>
+#include <utime.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <stdlib.h>
@@ -152,7 +153,24 @@ stat(const char *path, struct stat *st)
         return -1;
     }
 
-    return fstatat(dirfd, relative_path, st, AT_SYMLINK_NOFOLLOW);
+    return fstatat(dirfd, relative_path, st, 0);
+}
+
+int
+utime(const char *path, const struct utimbuf *times)
+{
+    const char *relative_path;
+    int fd = __wasilibc_find_relpath(path, &relative_path);
+
+    // If we can't find a preopened directory handle to open this file with,
+    // indicate that the program lacks the capabilities.
+    if (fd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+    return utimensat(fd, relative_path, times ? ((struct timespec [2]){
+		{ .tv_sec = times->actime }, { .tv_sec = times->modtime }})
+        : 0, 0);
 }
 
 int