[src/trunk]: src/usr.bin/make make(1): add CandidateSearcher to resolve trans...

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

details:   https://anonhg.NetBSD.org/src/rev/0e31b21d3aa6
branches:  trunk
changeset: 957273:0e31b21d3aa6
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Nov 22 22:27:19 2020 +0000

description:
make(1): add CandidateSearcher to resolve transformation rules

Having a simple list of candidates is not enough.  It is currently
possible to construct endless loops with huge memory usage, as
demonstrated in suff-transform-endless.mk.

To fix this, a straight-forward idea is to remember which candidates
have already been searched and to not search them again.

This also fixes a small inconsistency in the code.  Most parameters had
been named slst (the s came from a time when Candidate was named Src),
except for Suff_FindDeps, where the variable was named srcs.  The
confusing thing about this was that the name srcs is used throughout the
file for a different purpose.  Only in FindThem there were two
parameters of the same type, which made this even more confusing.

diffstat:

 usr.bin/make/suff.c |  64 ++++++++++++++++++++++++++++++----------------------
 1 files changed, 37 insertions(+), 27 deletions(-)

diffs (198 lines):

diff -r 2e245b5ce9df -r 0e31b21d3aa6 usr.bin/make/suff.c
--- a/usr.bin/make/suff.c       Sun Nov 22 21:37:09 2020 +0000
+++ b/usr.bin/make/suff.c       Sun Nov 22 22:27:19 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: suff.c,v 1.301 2020/11/22 21:34:34 rillig Exp $        */
+/*     $NetBSD: suff.c,v 1.302 2020/11/22 22:27:19 rillig Exp $        */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -114,7 +114,7 @@
 #include "dir.h"
 
 /*     "@(#)suff.c     8.4 (Berkeley) 3/21/94" */
-MAKE_RCSID("$NetBSD: suff.c,v 1.301 2020/11/22 21:34:34 rillig Exp $");
+MAKE_RCSID("$NetBSD: suff.c,v 1.302 2020/11/22 22:27:19 rillig Exp $");
 
 #define SUFF_DEBUG0(text) DEBUG0(SUFF, text)
 #define SUFF_DEBUG1(fmt, arg1) DEBUG1(SUFF, fmt, arg1)
@@ -209,6 +209,17 @@
 #endif
 } Candidate;
 
+typedef struct CandidateSearcher {
+
+    CandidateList *list;
+
+    /*
+     * TODO: Add HashSet for seen entries, to avoid endless loops such as
+     * in suff-transform-endless.mk.
+     */
+
+} CandidateSearcher;
+
 
 /* TODO: Document the difference between nullSuff and emptySuff. */
 /* The NULL suffix for this run */
@@ -1011,9 +1022,8 @@
 }
 
 /* Find the first existing file/target in srcs. */
-/* XXX: The parameter names are too similar. */
 static Candidate *
-FindThem(CandidateList *srcs, CandidateList *slst)
+FindThem(CandidateList *srcs, CandidateSearcher *cs)
 {
     Candidate *retsrc = NULL;
 
@@ -1051,7 +1061,7 @@
        SUFF_DEBUG0("not there\n");
 
        CandidateList_AddCandidatesFor(srcs, src);
-       Lst_Append(slst, src);
+       Lst_Append(cs->list, src);
     }
 
     if (retsrc) {
@@ -1066,7 +1076,7 @@
  * for it and returned.
  */
 static Candidate *
-FindCmds(Candidate *targ, CandidateList *slst)
+FindCmds(Candidate *targ, CandidateSearcher *cs)
 {
     GNodeListNode *gln;
     GNode *tgn;                        /* Target GNode */
@@ -1127,7 +1137,7 @@
                 targ, targ->file, ret, ret->file);
     Lst_Append(targ->childrenList, ret);
 #endif
-    Lst_Append(slst, ret);
+    Lst_Append(cs->list, ret);
     SUFF_DEBUG1("\tusing existing source %s\n", sgn->name);
     return ret;
 }
@@ -1471,7 +1481,7 @@
     }
 }
 
-static void FindDeps(GNode *, CandidateList *);
+static void FindDeps(GNode *, CandidateSearcher *);
 
 /* Locate dependencies for an OP_ARCHV node.
  *
@@ -1482,7 +1492,7 @@
  *     Same as Suff_FindDeps
  */
 static void
-FindDepsArchive(GNode *gn, CandidateList *slst)
+FindDepsArchive(GNode *gn, CandidateSearcher *cs)
 {
     char *eoarch;              /* End of archive portion */
     char *eoname;              /* End of member portion */
@@ -1517,7 +1527,7 @@
      * suffix list, backtracking for each one...
      */
     mem = Targ_GetNode(name);
-    FindDeps(mem, slst);
+    FindDeps(mem, cs);
 
     /*
      * Create the link between the two nodes right off
@@ -1733,7 +1743,7 @@
  *     Same as Suff_FindDeps
  */
 static void
-FindDepsRegular(GNode *gn, CandidateList *slst)
+FindDepsRegular(GNode *gn, CandidateSearcher *cs)
 {
     CandidateList *srcs;       /* List of sources at which to look */
     CandidateList *targs;      /* List of targets to which things can be
@@ -1788,7 +1798,7 @@
         * Using the list of possible sources built up from the target
         * suffix(es), try and find an existing file/target that matches.
         */
-       bottom = FindThem(srcs, slst);
+       bottom = FindThem(srcs, cs);
 
        if (bottom == NULL) {
            /*
@@ -1843,7 +1853,7 @@
      * Check for overriding transformation rule implied by sources
      */
     if (!Lst_IsEmpty(gn->children)) {
-       src = FindCmds(targ, slst);
+       src = FindCmds(targ, cs);
 
        if (src != NULL) {
            /*
@@ -1851,8 +1861,8 @@
             * up to but not including the parent node.
             */
            while (bottom != NULL && bottom->parent != NULL) {
-               if (Lst_FindDatum(slst, bottom) == NULL)
-                   Lst_Append(slst, bottom);
+               if (Lst_FindDatum(cs->list, bottom) == NULL)
+                   Lst_Append(cs->list, bottom);
                bottom = bottom->parent;
            }
            bottom = src;
@@ -1914,14 +1924,14 @@
      * two lists.
      */
 sfnd_return:
-    if (bottom != NULL && Lst_FindDatum(slst, bottom) == NULL)
-       Lst_Append(slst, bottom);
+    if (bottom != NULL && Lst_FindDatum(cs->list, bottom) == NULL)
+       Lst_Append(cs->list, bottom);
 
     while (RemoveCandidate(srcs) || RemoveCandidate(targs))
        continue;
 
-    Lst_MoveAll(slst, srcs);
-    Lst_MoveAll(slst, targs);
+    Lst_MoveAll(cs->list, srcs);
+    Lst_MoveAll(cs->list, targs);
 }
 
 
@@ -1942,19 +1952,19 @@
 void
 Suff_FindDeps(GNode *gn)
 {
-    CandidateList *srcs = Lst_New();
+    CandidateSearcher cs = { Lst_New() };
 
-    FindDeps(gn, srcs);
+    FindDeps(gn, &cs);
 
-    while (RemoveCandidate(srcs))
+    while (RemoveCandidate(cs.list))
        continue;
 
-    assert(Lst_IsEmpty(srcs));
-    Lst_Free(srcs);
+    assert(Lst_IsEmpty(cs.list));
+    Lst_Free(cs.list);
 }
 
 static void
-FindDeps(GNode *gn, CandidateList *slst)
+FindDeps(GNode *gn, CandidateSearcher *cs)
 {
     if (gn->type & OP_DEPS_FOUND)
        return;
@@ -1969,11 +1979,11 @@
     SUFF_DEBUG1("SuffFindDeps \"%s\"\n", gn->name);
 
     if (gn->type & OP_ARCHV)
-       FindDepsArchive(gn, slst);
+       FindDepsArchive(gn, cs);
     else if (gn->type & OP_LIB)
        FindDepsLib(gn);
     else
-       FindDepsRegular(gn, slst);
+       FindDepsRegular(gn, cs);
 }
 
 /* Define which suffix is the null suffix.