PerlIO friendly version of speed up of $/ = undef case.

p4raw-id: //depot/perlio@18612

diff --git a/sv.c b/sv.c
index 5a99375..4c148d8 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -6173,10 +6173,18 @@ Perl_sv_gets(pTHX_ register SV *sv, register PerlIO *fp, I32 append)
        rslen = 1;
     }
     else if (RsSNARF(PL_rs)) {
+       /* If it is a regular disk file use size from stat() as estimate 
+          of amount we are going to read - may result in malloc-ing 
+          more memory than we realy need if layers bellow reduce 
+          size we read (e.g. CRLF or a gzip layer)
+        */
        Stat_t st;
-       if (!PerlLIO_fstat(PerlIO_fileno(fp), &st) && st.st_size
-               && (recsize = st.st_size - PerlIO_tell(fp)))
-           goto read_record;
+       if (!PerlLIO_fstat(PerlIO_fileno(fp), &st) && S_ISREG(st.st_mode))  {
+           Off_t offset = PerlIO_tell(fp);
+           if (offset != (Off_t) -1) {
+               (void) SvGROW(sv, (STRLEN)((st.st_size - offset) + append + 1));
+           }
+       }
        rsptr = NULL;
        rslen = 0;
     }
@@ -6186,14 +6194,14 @@ Perl_sv_gets(pTHX_ register SV *sv, register PerlIO *fp, I32 append)
 
       /* Grab the size of the record we're getting */
       recsize = SvIV(SvRV(PL_rs));
-
-    read_record:
       buffer = SvGROW(sv, (STRLEN)(recsize + append + 1)) + append;
       /* Go yank in */
 #ifdef VMS
       /* VMS wants read instead of fread, because fread doesn't respect */
       /* RMS record boundaries. This is not necessarily a good thing to be */
-      /* doing, but we've got no other real choice */
+      /* doing, but we've got no other real choice - except avoid stdio
+         as implementation - perhaps write a :vms layer ?
+       */
       bytesread = PerlLIO_read(PerlIO_fileno(fp), buffer, recsize);
 #else
       bytesread = PerlIO_read(fp, buffer, recsize);
@@ -6269,8 +6277,13 @@ Perl_sv_gets(pTHX_ register SV *sv, register PerlIO *fp, I32 append)
     /* Here is some breathtakingly efficient cheating */
 
     cnt = PerlIO_get_cnt(fp);                  /* get count into register */
-    if ((I32)(SvLEN(sv) - append) <= cnt + 1) { /* make sure we have the room */
-       if (cnt > 80 && (I32)SvLEN(sv) > append) {
+    /* make sure we have the room */
+    if ((I32)(SvLEN(sv) - append) <= cnt + 1) { 
+       /* Not room for all of it
+          if we are looking for a separator and room for some 
+        */
+       if (rslen && cnt > 80 && (I32)SvLEN(sv) > append) {
+           /* just process what we have room for */ 
            shortbuffered = cnt - SvLEN(sv) + append + 1;
            cnt -= shortbuffered;
        }
@@ -6280,7 +6293,7 @@ Perl_sv_gets(pTHX_ register SV *sv, register PerlIO *fp, I32 append)
            SvGROW(sv, (STRLEN)(append + (cnt <= 0 ? 2 : (cnt + 1))));
        }
     }
-    else
+    else 
        shortbuffered = 0;
     bp = (STDCHAR*)SvPVX(sv) + append;  /* move these two too to registers */
     ptr = (STDCHAR*)PerlIO_get_ptr(fp);