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make(1): add CandidateSearcher to resolve transformation rules

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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.
This commit is contained in:
rillig 2020-11-22 22:27:19 +00:00
parent 0a0d44f067
commit 1f8c1f89fc
1 changed files with 37 additions and 27 deletions
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64
usr.bin/make/suff.c
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@ -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 * Copyright (c) 1988, 1989, 1990, 1993
@ -114,7 +114,7 @@
#include "dir.h" #include "dir.h"
/* "@(#)suff.c 8.4 (Berkeley) 3/21/94" */ /* "@(#)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_DEBUG0(text) DEBUG0(SUFF, text)
#define SUFF_DEBUG1(fmt, arg1) DEBUG1(SUFF, fmt, arg1) #define SUFF_DEBUG1(fmt, arg1) DEBUG1(SUFF, fmt, arg1)
@ -209,6 +209,17 @@ typedef struct Candidate {
#endif #endif
} Candidate; } 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. */ /* TODO: Document the difference between nullSuff and emptySuff. */
/* The NULL suffix for this run */ /* The NULL suffix for this run */
@ -1011,9 +1022,8 @@ RemoveCandidate(CandidateList *srcs)
} }
/* Find the first existing file/target in srcs. */ /* Find the first existing file/target in srcs. */
/* XXX: The parameter names are too similar. */
static Candidate * static Candidate *
FindThem(CandidateList *srcs, CandidateList *slst) FindThem(CandidateList *srcs, CandidateSearcher *cs)
{ {
Candidate *retsrc = NULL; Candidate *retsrc = NULL;
@ -1051,7 +1061,7 @@ FindThem(CandidateList *srcs, CandidateList *slst)
SUFF_DEBUG0("not there\n"); SUFF_DEBUG0("not there\n");
CandidateList_AddCandidatesFor(srcs, src); CandidateList_AddCandidatesFor(srcs, src);
Lst_Append(slst, src); Lst_Append(cs->list, src);
} }
if (retsrc) { if (retsrc) {
@ -1066,7 +1076,7 @@ FindThem(CandidateList *srcs, CandidateList *slst)
* for it and returned. * for it and returned.
*/ */
static Candidate * static Candidate *
FindCmds(Candidate *targ, CandidateList *slst) FindCmds(Candidate *targ, CandidateSearcher *cs)
{ {
GNodeListNode *gln; GNodeListNode *gln;
GNode *tgn; /* Target GNode */ GNode *tgn; /* Target GNode */
@ -1127,7 +1137,7 @@ FindCmds(Candidate *targ, CandidateList *slst)
targ, targ->file, ret, ret->file); targ, targ->file, ret, ret->file);
Lst_Append(targ->childrenList, ret); Lst_Append(targ->childrenList, ret);
#endif #endif
Lst_Append(slst, ret); Lst_Append(cs->list, ret);
SUFF_DEBUG1("\tusing existing source %s\n", sgn->name); SUFF_DEBUG1("\tusing existing source %s\n", sgn->name);
return ret; return ret;
} }
@ -1471,7 +1481,7 @@ ExpandMember(GNode *gn, const char *eoarch, GNode *mem, Suffix *memSuff)
} }
} }
static void FindDeps(GNode *, CandidateList *); static void FindDeps(GNode *, CandidateSearcher *);
/* Locate dependencies for an OP_ARCHV node. /* Locate dependencies for an OP_ARCHV node.
* *
@ -1482,7 +1492,7 @@ static void FindDeps(GNode *, CandidateList *);
* Same as Suff_FindDeps * Same as Suff_FindDeps
*/ */
static void static void
FindDepsArchive(GNode *gn, CandidateList *slst) FindDepsArchive(GNode *gn, CandidateSearcher *cs)
{ {
char *eoarch; /* End of archive portion */ char *eoarch; /* End of archive portion */
char *eoname; /* End of member portion */ char *eoname; /* End of member portion */
@ -1517,7 +1527,7 @@ FindDepsArchive(GNode *gn, CandidateList *slst)
* suffix list, backtracking for each one... * suffix list, backtracking for each one...
*/ */
mem = Targ_GetNode(name); mem = Targ_GetNode(name);
FindDeps(mem, slst); FindDeps(mem, cs);
/* /*
* Create the link between the two nodes right off * Create the link between the two nodes right off
@ -1733,7 +1743,7 @@ FindDepsRegularPath(GNode *gn, Candidate *targ)
* Same as Suff_FindDeps * Same as Suff_FindDeps
*/ */
static void static void
FindDepsRegular(GNode *gn, CandidateList *slst) FindDepsRegular(GNode *gn, CandidateSearcher *cs)
{ {
CandidateList *srcs; /* List of sources at which to look */ CandidateList *srcs; /* List of sources at which to look */
CandidateList *targs; /* List of targets to which things can be CandidateList *targs; /* List of targets to which things can be
@ -1788,7 +1798,7 @@ FindDepsRegular(GNode *gn, CandidateList *slst)
* Using the list of possible sources built up from the target * Using the list of possible sources built up from the target
* suffix(es), try and find an existing file/target that matches. * suffix(es), try and find an existing file/target that matches.
*/ */
bottom = FindThem(srcs, slst); bottom = FindThem(srcs, cs);
if (bottom == NULL) { if (bottom == NULL) {
/* /*
@ -1843,7 +1853,7 @@ sfnd_abort:
* Check for overriding transformation rule implied by sources * Check for overriding transformation rule implied by sources
*/ */
if (!Lst_IsEmpty(gn->children)) { if (!Lst_IsEmpty(gn->children)) {
src = FindCmds(targ, slst); src = FindCmds(targ, cs);
if (src != NULL) { if (src != NULL) {
/* /*
@ -1851,8 +1861,8 @@ sfnd_abort:
* up to but not including the parent node. * up to but not including the parent node.
*/ */
while (bottom != NULL && bottom->parent != NULL) { while (bottom != NULL && bottom->parent != NULL) {
if (Lst_FindDatum(slst, bottom) == NULL) if (Lst_FindDatum(cs->list, bottom) == NULL)
Lst_Append(slst, bottom); Lst_Append(cs->list, bottom);
bottom = bottom->parent; bottom = bottom->parent;
} }
bottom = src; bottom = src;
@ -1914,14 +1924,14 @@ sfnd_abort:
* two lists. * two lists.
*/ */
sfnd_return: sfnd_return:
if (bottom != NULL && Lst_FindDatum(slst, bottom) == NULL) if (bottom != NULL && Lst_FindDatum(cs->list, bottom) == NULL)
Lst_Append(slst, bottom); Lst_Append(cs->list, bottom);
while (RemoveCandidate(srcs) || RemoveCandidate(targs)) while (RemoveCandidate(srcs) || RemoveCandidate(targs))
continue; continue;
Lst_MoveAll(slst, srcs); Lst_MoveAll(cs->list, srcs);
Lst_MoveAll(slst, targs); Lst_MoveAll(cs->list, targs);
} }
@ -1942,19 +1952,19 @@ sfnd_return:
void void
Suff_FindDeps(GNode *gn) 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; continue;
assert(Lst_IsEmpty(srcs)); assert(Lst_IsEmpty(cs.list));
Lst_Free(srcs); Lst_Free(cs.list);
} }
static void static void
FindDeps(GNode *gn, CandidateList *slst) FindDeps(GNode *gn, CandidateSearcher *cs)
{ {
if (gn->type & OP_DEPS_FOUND) if (gn->type & OP_DEPS_FOUND)
return; return;
@ -1969,11 +1979,11 @@ FindDeps(GNode *gn, CandidateList *slst)
SUFF_DEBUG1("SuffFindDeps \"%s\"\n", gn->name); SUFF_DEBUG1("SuffFindDeps \"%s\"\n", gn->name);
if (gn->type & OP_ARCHV) if (gn->type & OP_ARCHV)
FindDepsArchive(gn, slst); FindDepsArchive(gn, cs);
else if (gn->type & OP_LIB) else if (gn->type & OP_LIB)
FindDepsLib(gn); FindDepsLib(gn);
else else
FindDepsRegular(gn, slst); FindDepsRegular(gn, cs);
} }
/* Define which suffix is the null suffix. /* Define which suffix is the null suffix.