If the length argument to apr_snprintf is 0, then we should return the

length that the string would be if we actually were going to fill it out.
However, if the length argument is 0, we can also accept a NULL string.
Also, added a test case for this.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@63829 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 15 insertions, 15 deletions

diff --git a/strings/apr_snprintf.c b/strings/apr_snprintf.c
index a066241df..cb97e18b5 100644
--- a/strings/apr_snprintf.c
+++ b/strings/apr_snprintf.c
@@ -294,14 +294,16 @@ static char *apr_gcvt(double number, int ndigit, char *buf, boolean_e altform)
  */
 #define INS_CHAR(c, sp, bep, cc)                    \
 {                                                   \
-    if (sp >= bep) {                                \
-        vbuff->curpos = sp;                         \
-        if (flush_func(vbuff))                      \
-            return -1;                              \
-        sp = vbuff->curpos;                         \
-        bep = vbuff->endpos;                        \
+    if (sp) {                                       \
+        if (sp >= bep) {                            \
+            vbuff->curpos = sp;                     \
+            if (flush_func(vbuff))                  \
+                return -1;                          \
+            sp = vbuff->curpos;                     \
+            bep = vbuff->endpos;                    \
+        }                                           \
+        *sp++ = (c);                                \
     }                                               \
-    *sp++ = (c);                                    \
     cc++;                                           \
 }
 
@@ -1247,16 +1249,15 @@ APR_DECLARE_NONSTD(int) apr_snprintf(char *buf, apr_size_t len,
     va_list ap;
     apr_vformatter_buff_t vbuff;
 
-    if (len == 0)
-        return 0;
-
     /* save one byte for nul terminator */
     vbuff.curpos = buf;
     vbuff.endpos = buf + len - 1;
     va_start(ap, format);
     cc = apr_vformatter(snprintf_flush, &vbuff, format, ap);
     va_end(ap);
-    *vbuff.curpos = '\0';
+    if (len != 0) {
+        *vbuff.curpos = '\0';
+    }
     return (cc == -1) ? (int)len : cc;
 }
 
@@ -1267,13 +1268,12 @@ APR_DECLARE(int) apr_vsnprintf(char *buf, apr_size_t len, const char *format,
     int cc;
     apr_vformatter_buff_t vbuff;
 
-    if (len == 0)
-        return 0;
-
     /* save one byte for nul terminator */
     vbuff.curpos = buf;
     vbuff.endpos = buf + len - 1;
     cc = apr_vformatter(snprintf_flush, &vbuff, format, ap);
-    *vbuff.curpos = '\0';
+    if (len != 0) {
+        *vbuff.curpos = '\0';
+    }
     return (cc == -1) ? (int)len : cc;
 }