Re: Conflict between FPAT and empty RS

[arnold]

luciole75w <address@hidden> wrote:

> Hello,
>
> I'm having an odd behavior with GNU awk when using FPAT and RS together. 
> Here is the code.
>
> $ awk '{ print ; $2 = "-" ; print }' RS='' FPAT='\\w+' <<<'a b c d'
> a b c d
> a -
>
> $ ... | xxd -g1 -c8
> 00000000: 61 20 62 20 63 20 64 0a  a b c d.
> 00000008: 61 20 2d 20 20 20 20 0a  a -    .
>
> I'd expect the 2nd print to output "a - c d" but as you can see, 
> modifying the field 2 replaces fields 3 and 4 with spaces in $0. When RS 
> is set to something other than the empty string (or just not set), the 
> output is correct.

This was an interesting one to track down. Thanks for the clear
reproducer. The fix is below. I will push it to git shortly.

Arnold
------------------------------------------------
diff --git a/field.c b/field.c
index 80495862..45ab9f5f 100644
--- a/field.c
+++ b/field.c
@@ -74,6 +74,9 @@ static bool resave_fs;
 static NODE *save_FS;          /* save current value of FS when line is read,
                                 * to be used in deferred parsing
                                 */
+static NODE *save_FPAT;                /* save current value of FPAT when line 
is read,
+                                * to be used in deferred parsing
+                                */
 static awk_fieldwidth_info_t *FIELDWIDTHS = NULL;
 
 NODE **fields_arr;             /* array of pointers to the field nodes */
@@ -842,6 +845,8 @@ get_field(long requested, Func_ptr *assign)
        bool in_middle = false;
        static bool warned = false;
        extern int currule;
+       NODE *saved_fs;
+       Regexp *fs_regexp;
 
        if (do_lint && currule == END && ! warned) {
                warned = true;
@@ -857,10 +862,17 @@ get_field(long requested, Func_ptr *assign)
                        /* first, parse remainder of input record */
                        if (NF == -1) {
                                in_middle = (parse_high_water != 0);
+                               if (current_field_sep() == Using_FPAT) {
+                                       saved_fs = save_FPAT;
+                                       fs_regexp = FPAT_regexp;
+                               } else {
+                                       saved_fs = save_FS;
+                                       fs_regexp = FS_regexp;
+                               }
                                NF = (*parse_field)(UNLIMITED - 1, 
&parse_extent,
                                        fields_arr[0]->stlen -
                                        (parse_extent - fields_arr[0]->stptr),
-                                       save_FS, FS_regexp, set_field,
+                                       saved_fs, fs_regexp, set_field,
                                        (NODE *) NULL,
                                        (NODE *) NULL,
                                        in_middle);
@@ -1424,7 +1436,6 @@ void
 set_FPAT()
 {
        static bool warned = false;
-       static NODE *save_fpat = NULL;
        bool remake_re = true;
        NODE *fpat;
 
@@ -1447,9 +1458,9 @@ set_FPAT()
         * This comparison can't use cmp_nodes(), which pays attention
         * to IGNORECASE, and that's not what we want.
         */
-       if (save_fpat
-               && FPAT_node->var_value->stlen == save_fpat->stlen
-               && memcmp(FPAT_node->var_value->stptr, save_fpat->stptr, 
save_fpat->stlen) == 0) {
+       if (save_FPAT
+               && FPAT_node->var_value->stlen == save_FPAT->stlen
+               && memcmp(FPAT_node->var_value->stptr, save_FPAT->stptr, 
save_FPAT->stlen) == 0) {
                if (FPAT_regexp != NULL)
                        FPAT_regexp = (IGNORECASE ? FPAT_re_no_case : 
FPAT_re_yes_case);
 
@@ -1462,8 +1473,8 @@ set_FPAT()
                }
        }
 
-       unref(save_fpat);
-       save_fpat = dupnode(FPAT_node->var_value);
+       unref(save_FPAT);
+       save_FPAT = dupnode(FPAT_node->var_value);
        refree(FPAT_re_yes_case);
        refree(FPAT_re_no_case);
        FPAT_re_yes_case = FPAT_re_no_case = FPAT_regexp = NULL;