[#134008] More carefully ignore negative precision in sprintf

Check has_precis more consistently; ensure precis is left as 0 if provided
as a negative number.

(cherry picked from commit b0f5b1daacb21ab7e46a772a6ff0f70ca627cb58)

2 files changed, 8 insertions, 2 deletions

diff --git a/sv.c b/sv.c
index ee1bb1390e..d650eafd51 100644
--- a/sv.c
+++ b/sv.c
@@ -11763,11 +11763,11 @@ S_format_hexfp(pTHX_ char * const buf, const STRLEN bufsize, const char c,
     else {
         *p++ = '0';
         exponent = 0;
-        zerotail = precis;
+        zerotail = has_precis ? precis : 0;
     }
 
     /* The radix is always output if precis, or if alt. */
-    if (precis > 0 || alt) {
+    if ((has_precis && precis > 0) || alt) {
       hexradix = TRUE;
     }
 
@@ -12221,6 +12221,9 @@ Perl_sv_vcatpvfn_flags(pTHX_ SV *const sv, const char *const pat, const STRLEN p
                     }
                     precis = S_sprintf_arg_num_val(aTHX_ args, i, sv, &neg);
                     has_precis = !neg;
+                    /* ignore negative precision */
+                    if (!has_precis)
+                        precis = 0;
                 }
 	    }
 	    else {
diff --git a/t/op/sprintf2.t b/t/op/sprintf2.t
index dc87821152..569bd8053d 100644
--- a/t/op/sprintf2.t
+++ b/t/op/sprintf2.t
@@ -838,6 +838,9 @@ SKIP: {
     # [rt.perl.org #128889]
     is(sprintf("%.*a", -1, 1.03125), "0x1.08p+0", "[rt.perl.org #128889]");
 
+    # [rt.perl.org #134008]
+    is(sprintf("%.*a", -99999, 1.03125), "0x1.08p+0", "[rt.perl.org #134008]");
+
     # [rt.perl.org #128890]
     is(sprintf("%a", 0x1.18p+0), "0x1.18p+0");
     is(sprintf("%.1a", 0x1.08p+0), "0x1.0p+0");