[src/trunk]: src/usr.bin/indent indent: replace inp_enlarge with inp_add

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a7f0815b4ff2
branches:  trunk
changeset: 1026489:a7f0815b4ff2
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Nov 26 15:08:48 2021 +0000

description:
indent: replace inp_enlarge with inp_add

Previously, inbuf.inp.s was only updated at the very end of reading a
line from the input file, which meant that during debugging, it pointed
to invalid memory. Updating all fields in inbuf.inp after every
reallocation makes the code less tricky to understand.

No functional change.

diffstat:

 usr.bin/indent/io.c |  43 +++++++++++++++++++++----------------------
 1 files changed, 21 insertions(+), 22 deletions(-)

diffs (81 lines):

diff -r b6c7801988d3 -r a7f0815b4ff2 usr.bin/indent/io.c
--- a/usr.bin/indent/io.c       Fri Nov 26 14:48:03 2021 +0000
+++ b/usr.bin/indent/io.c       Fri Nov 26 15:08:48 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: io.c,v 1.137 2021/11/26 14:48:03 rillig Exp $  */
+/*     $NetBSD: io.c,v 1.138 2021/11/26 15:08:48 rillig Exp $  */
 
 /*-
  * SPDX-License-Identifier: BSD-4-Clause
@@ -43,7 +43,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__NetBSD__)
-__RCSID("$NetBSD: io.c,v 1.137 2021/11/26 14:48:03 rillig Exp $");
+__RCSID("$NetBSD: io.c,v 1.138 2021/11/26 15:08:48 rillig Exp $");
 #elif defined(__FreeBSD__)
 __FBSDID("$FreeBSD: head/usr.bin/indent/io.c 334927 2018-06-10 16:44:18Z pstef $");
 #endif
@@ -306,43 +306,42 @@
     inbuf.save_com_s[0] = '{';
 }
 
-static char *
-inp_enlarge(char *p)
+static void
+inp_add(char ch)
 {
-    size_t new_size = (size_t)(inbuf.inp.l - inbuf.inp.buf) * 2 + 10;
-    size_t offset = (size_t)(p - inbuf.inp.buf);
-    inbuf.inp.buf = xrealloc(inbuf.inp.buf, new_size);
-    inbuf.inp.l = inbuf.inp.buf + new_size - 2;
-    return inbuf.inp.buf + offset;
+    if (inbuf.inp.e >= inbuf.inp.l) {
+       size_t new_size = (size_t)(inbuf.inp.l - inbuf.inp.buf) * 2 + 10;
+       size_t offset = (size_t)(inbuf.inp.e - inbuf.inp.buf);
+       inbuf.inp.buf = xrealloc(inbuf.inp.buf, new_size);
+       inbuf.inp.s = inbuf.inp.buf;
+       inbuf.inp.e = inbuf.inp.buf + offset;
+       inbuf.inp.l = inbuf.inp.buf + new_size - 2;
+    }
+    *inbuf.inp.e++ = ch;
 }
 
 static void
 inp_read_next_line(FILE *f)
 {
-    char *p;
-    int ch;
+    inbuf.inp.s = inbuf.inp.buf;
+    inbuf.inp.e = inbuf.inp.buf;
 
-    for (p = inbuf.inp.buf;;) {
-       if (p >= inbuf.inp.l)
-           p = inp_enlarge(p);
-
-       if ((ch = getc(f)) == EOF) {
+    for (;;) {
+       int ch = getc(f);
+       if (ch == EOF) {
            if (!inhibit_formatting) {
-               *p++ = ' ';
-               *p++ = '\n';
+               inp_add(' ');
+               inp_add('\n');
            }
            had_eof = true;
            break;
        }
 
        if (ch != '\0')
-           *p++ = (char)ch;
+           inp_add((char)ch);
        if (ch == '\n')
            break;
     }
-
-    inbuf.inp.s = inbuf.inp.buf;
-    inbuf.inp.e = p;
 }
 
 static void