Fix apr_snprintf() to respect precision for small floating point

numbers.
PR:           29621
Submitted by: Artur Zaprzala <zybi talex.pl>
Reviewed by:  Jeff Trawick


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@65222 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 24 insertions, 1 deletions

diff --git a/CHANGES b/CHANGES
index 0c504ed3c..2e82371e1 100644
--- a/CHANGES
+++ b/CHANGES
@@ -142,6 +142,9 @@ Changes with APR 1.0
 
 Changes with APR 0.9.5
 
+  *) Fix apr_snprintf() to respect precision for small floating point
+     numbers.  PR 29621.  [Artur Zaprzala <zybi talex.pl>]
+
   *) Add command type APR_SHELLCMD_ENV for creating a process
      which is started by the shell and which inherits the parent's
      environment variables.  [Jeff Trawick]
diff --git a/strings/apr_snprintf.c b/strings/apr_snprintf.c
index 73856a257..fa4cee3a0 100644
--- a/strings/apr_snprintf.c
+++ b/strings/apr_snprintf.c
@@ -132,11 +132,12 @@ static char *apr_cvt(double arg, int ndigits, int *decpt, int *sign,
     p1 = &buf[ndigits];
     if (eflag == 0)
         p1 += r2;
-    *decpt = r2;
     if (p1 < &buf[0]) {
+        *decpt = -ndigits;
         buf[0] = '\0';
         return (buf);
     }
+    *decpt = r2;
     while (p <= p1 && p < &buf[NDIG]) {
         arg *= 10;
         arg = modf(arg, &fj);
diff --git a/test/teststr.c b/test/teststr.c
index a046660cb..300a1b576 100644
--- a/test/teststr.c
+++ b/test/teststr.c
@@ -125,6 +125,24 @@ static void snprintf_0nonNULL(abts_case *tc, void *data)
     ABTS_ASSERT(tc, "buff unmangled", strcmp(buff, "FOOBAR") != 0);
 }
 
+static void snprintf_underflow(abts_case *tc, void *data)
+{
+    char buf[20];
+    int rv;
+
+    rv = apr_snprintf(buf, sizeof buf, "%.2f", (double)0.0001);
+    ABTS_INT_EQUAL(tc, 4, rv);
+    ABTS_STR_EQUAL(tc, "0.00", buf);
+    
+    rv = apr_snprintf(buf, sizeof buf, "%.2f", (double)0.001);
+    ABTS_INT_EQUAL(tc, 4, rv);
+    ABTS_STR_EQUAL(tc, "0.00", buf);
+    
+    rv = apr_snprintf(buf, sizeof buf, "%.2f", (double)0.01);
+    ABTS_INT_EQUAL(tc, 4, rv);
+    ABTS_STR_EQUAL(tc, "0.01", buf);
+}
+
 static void string_error(abts_case *tc, void *data)
 {
      char buf[128], *rv;
@@ -267,6 +285,7 @@ abts_suite *teststr(abts_suite *suite)
     abts_run_test(suite, snprintf_0NULL, NULL);
     abts_run_test(suite, snprintf_0nonNULL, NULL);
     abts_run_test(suite, snprintf_noNULL, NULL);
+    abts_run_test(suite, snprintf_underflow, NULL);
     abts_run_test(suite, test_strtok, NULL);
     abts_run_test(suite, string_error, NULL);
     abts_run_test(suite, string_long, NULL);