Changeset 8cffa4f for libcfa

Timestamp:

Oct 5, 2023, 2:30:54 PM (7 months ago)

Author:

Michael Brooks <mlbrooks@…>

Branches:

master

Children:

b67b632

Parents:

bf1cbde

Message:

Support match-failure reporting for string input.

On failed match, assign the empty-string value to the target.
Prior handling did not modify the target,
which in context like char s[10]; sin | exclude("\n", s);,
left s uninitialized, and invalid for strlen, when the input's next character is a newline.
In this case, scanf offers the return value, the count of output arguments written,
to say, "I did not write to your buffer," a feature lost in the pipe abstraction.

Add tests to exercise such cases.

(Prior "leave uninitialized" treatment was discovered by surprise, while debugging a test program for an upcoming commit.)

File:

• libcfa/src/iostream.cfa (modified) (1 diff)

libcfa/src/iostream.cfa

@@ -1011 +1011 @@
 
                 int check = f.wd - 2;
-                if ( ! f.flags.rwd ) f.s[check] = '\0';                 // insert sentinel
+                if (! f.flags.ignore ) {
+                        f.s[0] = '\0';
+                        if ( ! f.flags.rwd ) f.s[check] = '\0';         // insert sentinel
+                }
                 len = fmt( is, fmtstr, f.s );
                 //fprintf( stderr, "KK %s %zd %d %c %s\n", fmtstr, len, check, f.s[check], f.s );
 
-                if ( ! f.flags.rwd && f.s[check] != '\0' )              // sentinel overwritten ?
+                if (! f.flags.ignore && ! f.flags.rwd && f.s[check] != '\0' ) // sentinel overwritten ?
                         throw (cstring_length){ &cstring_length_vt };