sprintf_s: strip leading zeros and dot on %g (not %#g)

fixes parts of GH #68
rurban · Dec 26, 2024 · 7119fe0 · 7119fe0
1 parent cfcb56d
commit 7119fe0
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Showing 2 changed files with 21 additions and 8 deletions.
diff --git a/src/str/vsnprintf_s.c b/src/str/vsnprintf_s.c
@@ -392,7 +392,7 @@ static size_t safec_ftoa(out_fct_type out, const char *funcname, char *buffer,
                          unsigned int prec, unsigned int width,
                          unsigned int flags) {
     char buf[PRINTF_FTOA_BUFFER_SIZE];
-    size_t len = 0U;
+    size_t len = 0U, off = 0U;
     double tmp;
     double diff = 0.0;
     unsigned long frac;
@@ -525,6 +525,19 @@ static size_t safec_ftoa(out_fct_type out, const char *funcname, char *buffer,
         }
     }
 
+    // strip leading zeros and dots
+    if ((flags & FLAGS_ADAPT_EXP) && !(flags & FLAGS_HASH)) {
+        size_t olen = len;
+        while (buf[off] == '0') {
+            off++; len--;
+            if (off >= olen)
+                break;
+        }
+        if (buf[off] == '.' && off < olen) {
+            off++; len--;
+        }
+    }
+
     if (len < PRINTF_FTOA_BUFFER_SIZE) {
         if (negative) {
             buf[len++] = '-';
@@ -535,7 +548,7 @@ static size_t safec_ftoa(out_fct_type out, const char *funcname, char *buffer,
         }
     }
 
-    return safec_out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
+    return safec_out_rev(out, buffer, idx, maxlen, &buf[off], len, width, flags);
 }
 
 #ifdef PRINTF_SUPPORT_LONG_DOUBLE
@@ -743,7 +756,7 @@ static size_t safec_etoa(out_fct_type out, const char *funcname, char *buffer,
         const size_t start_idx = idx;
         idx = safec_ftoa(out, funcname, buffer, idx, maxlen,
                          negative ? -value : value, prec, fwidth,
-                         flags & ~FLAGS_ADAPT_EXP);
+                         flags);
 
         // output the exponent part
         if (minwidth) {

diff --git a/tests/test_sprintf_s.c b/tests/test_sprintf_s.c
@@ -393,22 +393,22 @@ int test_sprintf_s(void) {
     EXPSTR(str2, "0.100000")
     rc = sprintf_s(str2, LEN, "%g", 0.1);
     NOERRNULL()
-    EXPSTR(str2, "0.1") // FIXME 0.100000 trailing-zeros not stripped
+    EXPSTR(str2, "0.1")
     rc = sprintf_s(str2, LEN, "%#g", 0.1); // alternate form
     NOERRNULL()
     EXPSTR(str2, "0.100000")
     rc = sprintf_s(str2, LEN, "%G", 0.1);
     NOERRNULL()
-    EXPSTR(str2, "0.1") // FIXME 0.100000 trailing-zeros not stripped
+    EXPSTR(str2, "0.1")
     rc = sprintf_s(str2, LEN, "%g", 0.1f);
     NOERRNULL()
-    EXPSTR(str2, "0.1") // FIXME 0.100000 trailing-zeros not stripped
+    EXPSTR(str2, "0.1")
     rc = sprintf_s(str2, LEN, "%g", 1.0);
     NOERRNULL()
-    EXPSTR(str2, "1") // FIXME 0.100000 trailing-zeros and dot not stripped
+    EXPSTR(str2, "1")
     rc = sprintf_s(str2, LEN, "%lg", 0.1);
     NOERRNULL()
-    EXPSTR(str2, "0.1") // FIXME 0.100000 trailing-zeros not stripped
+    EXPSTR(str2, "0.1")
     rc = sprintf_s(str2, LEN, "%a", 0.1f);
     NOERRNULL()
     EXPSTR(str2, "0x1.99999ap-4")