Added _formatString() special-case for null values (similar to glibc).

4 files changed, 20 insertions, 6 deletions

diff --git a/src/library.js b/src/library.js
index 51fb6ce5..3e346280 100644
--- a/src/library.js
+++ b/src/library.js
@@ -2156,8 +2156,12 @@ LibraryManager.library = {
               argText = argText.toUpperCase();
             }
           } else if (next == 'p'.charCodeAt(0)) {
-            prefix = '0x';
-            argText = currAbsArg.toString(16);
+            if (currAbsArg === 0) {
+              argText = '(nil)';
+            } else {
+              prefix = '0x';
+              argText = currAbsArg.toString(16);
+            }
           }
           if (precisionSet) {
             while (argText.length < precision) {
@@ -2277,9 +2281,15 @@ LibraryManager.library = {
           });
         } else if (next == 's'.charCodeAt(0)) {
           // String.
-          var copiedString = String_copy(getNextArg());
-          if (precisionSet && copiedString.length > precision) {
-            copiedString = copiedString.slice(0, precision);
+          var arg = getNextArg();
+          var copiedString;
+          if (arg) {
+            copiedString = String_copy(arg);
+            if (precisionSet && copiedString.length > precision) {
+              copiedString = copiedString.slice(0, precision);
+            }
+          } else {
+            copiedString = intArrayFromString('(null)', true);
           }
           if (!flagLeftAlign) {
             while (copiedString.length < width--) {
diff --git a/tests/printf/output.txt b/tests/printf/output.txt
index 412c6b0f..01822327 100644
--- a/tests/printf/output.txt
+++ b/tests/printf/output.txt
@@ -9,6 +9,8 @@ Some different radixes: 100 64 144 0x64 0144
 floats: 3.14 +3e+00 3.141600E+00
 Width trick:    10
 A string %
+Null string:  (null)
+Null pointer: (nil)
 inf
 INF
 -inf
diff --git a/tests/printf/test.c b/tests/printf/test.c
index d12e0d2e..efd9d087 100644
--- a/tests/printf/test.c
+++ b/tests/printf/test.c
@@ -14,6 +14,8 @@ int main() {
   printf("floats: %4.2f %+.0e %E\n", 3.1416, 3.1416, 3.1416);
   printf("Width trick: %*d\n", 5, 10);
   printf("%s %%\n", "A string");
+  printf("Null string: %7s\n", NULL);
+  printf("Null pointer: %p\n", NULL);
   printf("%lf\n", INFINITY);
   printf("%lF\n", INFINITY);
   printf("%lf\n", -INFINITY);
diff --git a/tests/runner.py b/tests/runner.py
index d75d7e35..6edf9c20 100644
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -716,7 +716,7 @@ if 'benchmark' not in sys.argv:
             return 0;
           }
         '''
-        self.do_test(src, '*0x0*')
+        self.do_test(src, '*(nil)*')
 
     def test_funcs(self):
         src = '''