[src/trunk]: src/usr.bin/make make(1): make variable names in SysV modifier m...

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

details:   https://anonhg.NetBSD.org/src/rev/f83e29dbb868
branches:  trunk
changeset: 936667:f83e29dbb868
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Aug 01 13:16:29 2020 +0000

description:
make(1): make variable names in SysV modifier more expressive

When matching a word against a substitution having a lhs and a rhs,
including a possible wildcard, there are just too many string variables
around to know what a simple "len" means and where it belongs.

diffstat:

 usr.bin/make/var.c |  91 ++++++++++++++++++++++++++---------------------------
 1 files changed, 44 insertions(+), 47 deletions(-)

diffs (170 lines):

diff -r fc3054135acd -r f83e29dbb868 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sat Aug 01 12:47:56 2020 +0000
+++ b/usr.bin/make/var.c        Sat Aug 01 13:16:29 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.376 2020/08/01 12:04:46 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.377 2020/08/01 13:16:29 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -69,14 +69,14 @@
  */
 
 #ifndef MAKE_NATIVE
-static char rcsid[] = "$NetBSD: var.c,v 1.376 2020/08/01 12:04:46 rillig Exp $";
+static char rcsid[] = "$NetBSD: var.c,v 1.377 2020/08/01 13:16:29 rillig Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)var.c      8.3 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: var.c,v 1.376 2020/08/01 12:04:46 rillig Exp $");
+__RCSID("$NetBSD: var.c,v 1.377 2020/08/01 13:16:29 rillig Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -1165,55 +1165,55 @@
  * Input:
  *     word            Word to examine
  *     pattern         Pattern to examine against
- *     len             Number of characters to substitute
  *
  * Results:
- *     Returns the beginning position of a match or null. The number
- *     of characters matched is returned in len.
+ *     Returns the start of the match, or NULL.
+ *     *match_len returns the length of the match, if any.
+ *     *hasPercent returns whether the pattern contains a percent.
  *-----------------------------------------------------------------------
  */
 static const char *
-Str_SYSVMatch(const char *word, const char *pattern, size_t *len,
+Str_SYSVMatch(const char *word, const char *pattern, size_t *match_len,
     Boolean *hasPercent)
 {
     const char *p = pattern;
     const char *w = word;
-    const char *m;
 
     *hasPercent = FALSE;
-    if (*p == '\0') {
-       /* Null pattern is the whole string */
-       *len = strlen(w);
+    if (*p == '\0') {          /* ${VAR:=suffix} */
+       *match_len = strlen(w); /* Null pattern is the whole string */
        return w;
     }
 
-    if ((m = strchr(p, '%')) != NULL) {
+    const char *percent = strchr(p, '%');
+    if (percent != NULL) {     /* ${VAR:...%...=...} */
        *hasPercent = TRUE;
-       if (*w == '\0') {
-               /* empty word does not match pattern */
-               return NULL;
-       }
+       if (*w == '\0')
+           return NULL;        /* empty word does not match pattern */
+
        /* check that the prefix matches */
-       for (; p != m && *w && *w == *p; w++, p++)
+       for (; p != percent && *w != '\0' && *w == *p; w++, p++)
             continue;
-
-       if (p != m)
+       if (p != percent)
            return NULL;        /* No match */
 
-       if (*++p == '\0') {
+       p++;                    /* Skip the percent */
+       if (*p == '\0') {
            /* No more pattern, return the rest of the string */
-           *len = strlen(w);
+           *match_len = strlen(w);
            return w;
        }
     }
 
-    m = w;
+    const char *suffix = w;
 
     /* Find a matching tail */
+    /* XXX: This loop should not be necessary since there is only one
+     * possible position where strcmp could ever return 0. */
     do {
        if (strcmp(p, w) == 0) {
-           *len = w - m;
-           return m;
+           *match_len = w - suffix;
+           return suffix;
        }
     } while (*w++ != '\0');
 
@@ -1224,32 +1224,29 @@
 /*-
  *-----------------------------------------------------------------------
  * Str_SYSVSubst --
- *     Substitute '%' on the pattern with len characters from src.
- *     If the pattern does not contain a '%' prepend len characters
- *     from src.
- *
- * Side Effects:
- *     Places result on buf
+ *     Append rhs to the buffer, substituting the first '%' with the
+ *     match, but only if the lhs had a '%' as well.
+ *     If the rhs does not contain a '%', prepend the match.
  *-----------------------------------------------------------------------
  */
 static void
-Str_SYSVSubst(SepBuf *buf, const char *pat, const char *src, size_t src_len,
-             Boolean lhsHasPercent)
+Str_SYSVSubst(SepBuf *buf, const char *rhs,
+             const char *match, size_t match_len, Boolean lhsHasPercent)
 {
-    const char *percent = strchr(pat, '%');
+    const char *percent = strchr(rhs, '%');
 
     if (percent != NULL && lhsHasPercent) {
-       /* Copy the prefix */
-       SepBuf_AddBytesBetween(buf, pat, percent);
-       pat = percent + 1;
+       /* Copy the prefix of the replacement pattern */
+       SepBuf_AddBytesBetween(buf, rhs, percent);
+       rhs = percent + 1;
     }
     if (percent != NULL || !lhsHasPercent) {
-       /* Copy the pattern */
-       SepBuf_AddBytes(buf, src, src_len);
+       /* Copy the matched part of the original word */
+       SepBuf_AddBytes(buf, match, match_len);
     }
 
-    /* append the rest */
-    SepBuf_AddStr(buf, pat);
+    /* Append the suffix of the replacement pattern */
+    SepBuf_AddStr(buf, rhs);
 }
 
 
@@ -1265,13 +1262,13 @@
 {
     const ModifyWord_SYSVSubstArgs *args = data;
 
-    size_t len;
-    Boolean hasPercent;
-    const char *ptr = Str_SYSVMatch(word, args->lhs, &len, &hasPercent);
-    if (ptr != NULL) {
-       char *varexp = Var_Subst(args->rhs, args->ctx, VARE_WANTRES);
-       Str_SYSVSubst(buf, varexp, ptr, len, hasPercent);
-       free(varexp);
+    size_t match_len;
+    Boolean lhsPercent;
+    const char *match = Str_SYSVMatch(word, args->lhs, &match_len, &lhsPercent);
+    if (match != NULL) {
+       char *rhs_expanded = Var_Subst(args->rhs, args->ctx, VARE_WANTRES);
+       Str_SYSVSubst(buf, rhs_expanded, match, match_len, lhsPercent);
+       free(rhs_expanded);
     } else {
        SepBuf_AddStr(buf, word);
     }