Fixes mpaland#113 : Now properly zero-padding left-aligned values wit…

…h precision set. Also, added a relevant test suite check.
eyalroz · Jul 30, 2021 · 8f9f51c · 8f9f51c
1 parent 0fe7787
commit 8f9f51c
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Showing 2 changed files with 21 additions and 14 deletions.
diff --git a/printf.c b/printf.c
@@ -230,17 +230,22 @@ static size_t _out_rev(out_fct_type out, char* buffer, size_t idx, size_t maxlen
 static size_t _ntoa_format(out_fct_type out, char* buffer, size_t idx, size_t maxlen, char* buf, size_t len, bool negative, unsigned int base, unsigned int precision, unsigned int width, unsigned int flags)
 {
   size_t unpadded_len = len;
-  // pad leading zeros
-  if (!(flags & FLAGS_LEFT)) {
-    if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
-      width--;
+
+  // pad with leading zeros
+  {
+    if (!(flags & FLAGS_LEFT)) {
+      if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
+        width--;
+      }
+      while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
+        buf[len++] = '0';
+      }
     }
+
     while ((len < precision) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
       buf[len++] = '0';
     }
-    while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
-      buf[len++] = '0';
-    }
+
     if (base == 8U && (len > unpadded_len)) {
       // Since we've written some zeros, we've satisfied the alternative format leading space requirement
       flags &= ~FLAGS_HASH;

diff --git a/test/test_suite.cpp b/test/test_suite.cpp
@@ -1010,13 +1010,15 @@ DISABLE_WARNING_POP
 
 TEST_CASE("misc", "[]" ) {
   char buffer[100];
-  PRINTING_CHECK("53000atest-20 bit", ==, test::sprintf_, buffer, "%u%u%ctest%d %s", 5, 3000, 'a', -20, "bit");
-  PRINTING_CHECK("0.33",              ==, test::sprintf_, buffer, "%.*f", 2, 0.33333333);
-  PRINTING_CHECK("1",                 ==, test::sprintf_, buffer, "%.*d", -1, 1);
-  PRINTING_CHECK("foo",               ==, test::sprintf_, buffer, "%.3s", "foobar");
-  PRINTING_CHECK(" ",                 ==, test::sprintf_, buffer, "% .0d", 0);
-  PRINTING_CHECK("     00004",        ==, test::sprintf_, buffer, "%10.5d", 4);
-  PRINTING_CHECK("hi x",              ==, test::sprintf_, buffer, "%*sx", -3, "hi");
+  PRINTING_CHECK("53000atest-20 bit",    ==, test::sprintf_, buffer, "%u%u%ctest%d %s", 5, 3000, 'a', -20, "bit");
+  PRINTING_CHECK("0.33",                 ==, test::sprintf_, buffer, "%.*f", 2, 0.33333333);
+  PRINTING_CHECK("1",                    ==, test::sprintf_, buffer, "%.*d", -1, 1);
+  PRINTING_CHECK("foo",                  ==, test::sprintf_, buffer, "%.3s", "foobar");
+  PRINTING_CHECK(" ",                    ==, test::sprintf_, buffer, "% .0d", 0);
+  PRINTING_CHECK("     00004",           ==, test::sprintf_, buffer, "%10.5d", 4);
+  PRINTING_CHECK("hi x",                 ==, test::sprintf_, buffer, "%*sx", -3, "hi");
+  PRINTING_CHECK("00123               ", ==, test::sprintf_, buffer, "%-20.5i", 123);
+
 
 #if PRINTF_SUPPORT_EXPONENTIAL_SPECIFIERS
   PRINTING_CHECK("0.33",              ==, test::sprintf_, buffer, "%.*g", 2, 0.33333333);