$foo .= $bar doesn't warn if $foo is undefined, so simplify code.

[p5sagit/p5-mst-13.2.git] / pp_ctl.c

diff --git a/pp_ctl.c b/pp_ctl.c
index 2c36b59..7ea62e5 100644 (file)
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -4516,7 +4516,6 @@ S_run_user_filter(pTHX_ int idx, SV *buf_sv, int maxlen)
     dVAR;
     SV * const datasv = FILTER_DATA(idx);
     const int filter_has_file = IoLINES(datasv);
-    GV * const filter_child_proc = (GV *)IoFMT_GV(datasv);
     SV * const filter_state = (SV *)IoTOP_GV(datasv);
     SV * const filter_sub = (SV *)IoBOTTOM_GV(datasv);
     int len = 0;
@@ -4535,6 +4534,26 @@ S_run_user_filter(pTHX_ int idx, SV *buf_sv, int maxlen)
        for PL_error_count == 0.)  Solaris doesn't segfault --
        not sure where the trouble is yet.  XXX */
 
+    if (maxlen && IoFMT_GV(datasv)) {
+       SV *const cache = (SV *)IoFMT_GV(datasv);
+       if (SvOK(cache)) {
+           STRLEN cache_len;
+           const char *cache_p = SvPV(cache, cache_len);
+           /* Running in block mode and we have some cached data already.  */
+           if (cache_len >= maxlen) {
+               /* In fact, so much data we don't even need to call
+                  filter_read.  */
+               sv_catpvn(buf_sv, cache_p, maxlen);
+               sv_chop(cache, cache_p + maxlen);
+               /* Definately not EOF  */
+               return 1;
+           }
+           sv_catsv(buf_sv, cache);
+           maxlen -= cache_len;
+           SvOK_off(cache);
+       }
+    }
+       
     if (filter_has_file) {
        len = FILTER_READ(idx+1, upstream, maxlen);
     }
@@ -4570,12 +4589,41 @@ S_run_user_filter(pTHX_ int idx, SV *buf_sv, int maxlen)
        LEAVE;
     }
 
+    if (maxlen) {
+       /* Running in block mode.  */
+       STRLEN got_len;
+       const char *got_p = SvPV(upstream, got_len);
+
+       if (got_len > maxlen) {
+           /* Oh. Too long. Stuff some in our cache.  */
+           SV *cache = (SV *)IoFMT_GV(datasv);
+
+           if (!cache) {
+               IoFMT_GV(datasv) = (GV*) (cache = newSV(got_len - maxlen));
+           } else if (SvOK(cache)) {
+               /* Cache should be empty.  */
+               assert(!SvCUR(cache));
+           }
+
+           sv_setpvn(cache, got_p + maxlen, got_len - maxlen);
+           /* If you ask for block mode, you may well split UTF-8 characters.
+              "If it breaks, you get to keep both parts"
+              (Your code is broken if you  don't put them back together again
+              before something notices.) */
+           if (SvUTF8(upstream)) {
+               SvUTF8_on(cache);
+           }
+           SvCUR_set(upstream, maxlen);
+       }
+    }
+
+    if (upstream != buf_sv) {
+       sv_catsv(buf_sv, upstream);
+    }
+
     if (len <= 0) {
        IoLINES(datasv) = 0;
-       if (filter_child_proc) {
-           SvREFCNT_dec(filter_child_proc);
-           IoFMT_GV(datasv) = NULL;
-       }
+       SvREFCNT_dec(IoFMT_GV(datasv));
        if (filter_state) {
            SvREFCNT_dec(filter_state);
            IoTOP_GV(datasv) = NULL;
@@ -4586,10 +4634,6 @@ S_run_user_filter(pTHX_ int idx, SV *buf_sv, int maxlen)
        }
        filter_del(S_run_user_filter);
     }
-
-    if (upstream != buf_sv) {
-       sv_catsv(buf_sv, upstream);
-    }
     return len;
 }