Implemented utime.h.

src/library.js

@@ -86,7 +86,7 @@ var Library = {
         current = current.contents[target];
         if (current.link) {
           current = FS.findObject(current.link);
-          if (++linksVisited > 64) {
+          if (++linksVisited > 40) { // Usual Linux SYMLOOP_MAX.
             ___setErrNo(ERRNO_CODES.ELOOP);
             return null;
           }
@@ -320,6 +320,39 @@ var Library = {
   },
   // TODO: Check if we need to link any aliases.
 
+  // ==========================================================================
+  // utime.h
+  // ==========================================================================
+
+  // TODO: Switch to dynamically calculated layout.
+  //__utimbuf_struct_layout: Runtime.generateStructInfo('utimbuf'),
+  __utimbuf_struct_layout: {
+    __size__: 8,
+    actime: 0,
+    modtime: 4
+  },
+  utime__deps: ['$FS', '__setErrNo', '__utimbuf_struct_layout'],
+  utime: function(path, times) {
+    // int utime(const char *path, const struct utimbuf *times);
+    // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/utime.h.html
+    var time;
+    if (times) {
+      // NOTE: We don't keep track of access timestamps.
+      time = {{{ makeGetValue('times', '___utimbuf_struct_layout.modtime', 'i32') }}}
+      time = new Date(time * 1000);
+    } else {
+      time = new Date();
+    }
+    var file = FS.findObject(Pointer_stringify(path));
+    if (file === null) return -1;
+    if (!file.write) {
+      ___setErrNo(ERRNO_CODES.EPERM);
+      return -1;
+    }
+    file.timestamp = time;
+    return 0;
+  },
+
   // ==========================================================================
   // libgen.h
   // ==========================================================================

tests/runner.py

@@ -2211,6 +2211,50 @@ if 'benchmark' not in sys.argv:
       '''
       self.do_test(src, re.sub('(^|\n)\s+', '\\1', expected))
 
+    def test_utime(self):
+      def addPreRunAndChecks(filename):
+        src = open(filename, 'r').read().replace(
+          '// {{PRE_RUN_ADDITIONS}}',
+          '''
+            var TEST_F1 = FS.createFolder('/', 'writeable', true, true);
+            var TEST_F2 = FS.createFolder('/', 'unwriteable', true, false);
+          '''
+        ).replace(
+          '// {{POST_RUN_ADDITIONS}}',
+          '''
+            print('first changed: ' + (TEST_F1.timestamp.getTime() == 1200000000000));
+            print('second changed: ' + (TEST_F2.timestamp.getTime() == 1200000000000));
+          '''
+        )
+        open(filename, 'w').write(src)
+
+      src = r'''
+        #include <stdio.h>
+        #include <errno.h>
+        #include <utime.h>
+
+        int main() {
+          struct utimbuf t = {1000000000, 1200000000};
+          char* writeable = "/writeable";
+          char* unwriteable = "/unwriteable";
+
+          utime(writeable, &t);
+          printf("writeable errno: %d\n", errno);
+
+          utime(unwriteable, &t);
+          printf("unwriteable errno: %d\n", errno);
+
+          return 0;
+        }
+        '''
+      expected = '''
+        writeable errno: 0
+        unwriteable errno: 1
+        first changed: true
+        second changed: false
+      '''
+      self.do_test(src, re.sub('(^|\n)\s+', '\\1', expected), post_build=addPreRunAndChecks)
+
     ### 'Big' tests
 
     def test_fannkuch(self):