path: root/usr.bin/make/arch.c

/*	$OpenBSD: arch.c,v 1.85 2015/01/16 15:36:29 deraadt Exp $ */
/*	$NetBSD: arch.c,v 1.17 1996/11/06 17:58:59 christos Exp $	*/

/*
 * Copyright (c) 1999,2000 Marc Espie.
 *
 * Extensive code changes for the OpenBSD project.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OPENBSD
 * PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 *	Once again, cacheing/hashing comes into play in the manipulation
 * of archives. The first time an archive is referenced, all of its members'
 * headers are read and hashed and the archive closed again. All hashed
 * archives are kept in a hash (archives) which is searched each time
 * an archive member is referenced.
 *
 */

#include <ar.h>
#include <assert.h>
#include <ctype.h>
#include <fcntl.h>
#include <limits.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ohash.h>
#include "config.h"
#include "defines.h"
#include "buf.h"
#include "dir.h"
#include "direxpand.h"
#include "arch.h"
#include "var.h"
#include "targ.h"
#include "memory.h"
#include "gnode.h"
#include "timestamp.h"
#include "lst.h"

#ifdef TARGET_MACHINE
#undef MACHINE
#define MACHINE TARGET_MACHINE
#endif
#ifdef TARGET_MACHINE_ARCH
#undef MACHINE_ARCH
#define MACHINE_ARCH TARGET_MACHINE_ARCH
#endif
#ifdef TARGET_MACHINE_CPU
#undef MACHINE_CPU
#define MACHINE_CPU TARGET_MACHINE_CPU
#endif

static struct ohash archives;	/* Archives we've already examined.  */

typedef struct Arch_ {
	struct ohash members;	/* All the members of this archive, as
				 * struct arch_member entries.  */
	char name[1];		/* Archive name. */
} Arch;

/* Used to get to ar's field sizes.  */
static struct ar_hdr *dummy;
#define AR_NAME_SIZE		(sizeof(dummy->ar_name))
#define AR_DATE_SIZE		(sizeof(dummy->ar_date))

/* Each archive member is tied to an arch_member structure,
 * suitable for hashing.  */
struct arch_member {
	struct timespec mtime;		/* Member modification date.  */
	char date[AR_DATE_SIZE+1];	/* Same, before conversion to numeric
					 * value.  */
	char name[1];			/* Member name.  */
};

static struct ohash_info members_info = {
	offsetof(struct arch_member, name), NULL,
	hash_calloc, hash_free, element_alloc
};

static struct ohash_info arch_info = {
	offsetof(Arch, name), NULL, hash_calloc, hash_free, element_alloc
};



static struct arch_member *new_arch_member(struct ar_hdr *, const char *);
static struct timespec mtime_of_member(struct arch_member *);
static long field2long(const char *, size_t);
static Arch *read_archive(const char *, const char *);

static struct timespec ArchMTimeMember(const char *, const char *, bool);
static FILE *ArchFindMember(const char *, const char *, struct ar_hdr *, const char *);
static void ArchTouch(const char *, const char *);
#if defined(__svr4__) || defined(__SVR4) || \
    (defined(__OpenBSD__) && defined(__ELF__))
#define SVR4ARCHIVES
#endif
static bool parse_archive(Buffer, const char **, Lst, SymTable *);
static void add_archive_node(Lst, const char *);

struct SVR4namelist {
	char *fnametab;		/* Extended name table strings */
	size_t fnamesize;	/* Size of the string table */
};

#ifdef SVR4ARCHIVES
static const char *svr4list = "Archive list";

static char *ArchSVR4Entry(struct SVR4namelist *, const char *, size_t, FILE *);
#endif

static struct arch_member *
new_arch_member(struct ar_hdr *hdr, const char *name)
{
	const char *end = NULL;
	struct arch_member *n;

	n = ohash_create_entry(&members_info, name, &end);
	/* XXX ar entries are NOT null terminated.	*/
	memcpy(n->date, &(hdr->ar_date), AR_DATE_SIZE);
	n->date[AR_DATE_SIZE] = '\0';
	/* Don't compute mtime before it is needed. */
	ts_set_out_of_date(n->mtime);
	return n;
}

static struct timespec
mtime_of_member(struct arch_member *m)
{
	if (is_out_of_date(m->mtime))
		ts_set_from_time_t((time_t) strtoll(m->date, NULL, 10),
		    m->mtime);
	return m->mtime;
}

bool
Arch_ParseArchive(const char **line, Lst nodes, SymTable *ctxt)
{
	bool result;
	BUFFER expand;

	Buf_Init(&expand, MAKE_BSIZE);
	result = parse_archive(&expand, line, nodes, ctxt);
	Buf_Destroy(&expand);
	return result;
}

static void
add_archive_node(Lst nodes, const char *name)
{
	GNode *gn;

	gn = Targ_FindNode(name, TARG_CREATE);
	gn->type |= OP_ARCHV;
	Lst_AtEnd(nodes, gn);
}

static bool
parse_archive(Buffer expand, const char **linePtr, Lst nodeLst, SymTable *ctxt)
{
	const char *cp;    	/* Pointer into line */
	const char *lib;	/* Library-part of specification */
	const char *elib;
	const char *member;    	/* Member-part of specification */
	const char *emember;
	bool subst_lib;

	/* figure out the library name part */
	lib = *linePtr;
	subst_lib = false;

	for (cp = lib; *cp != '(' && *cp != '\0';) {
		if (*cp == '$') {
			if (!Var_ParseSkip(&cp, ctxt))
				return false;
			subst_lib = true;
		} else
			cp++;
	}

	elib = cp;
	if (subst_lib) {
		lib = Var_Substi(lib, elib, ctxt, true);
		elib = lib + strlen(lib);
	}

	cp++;
	/* iterate on members, that may be separated by spaces */
	for (;;) {
		/* First skip to the start of the member's name, mark that
		 * place and skip to the end of it (either white-space or
		 * a close paren).  */
		bool subst_member = false;

		while (ISSPACE(*cp))
			cp++;
		member = cp;
		while (*cp != '\0' && *cp != ')' && !ISSPACE(*cp)) {
			if (*cp == '$') {
				if (!Var_ParseSkip(&cp, ctxt))
					return false;
				subst_member = true;
			} else
				cp++;
		}

		/* If the specification ends without a closing parenthesis,
		 * chances are there's something wrong (like a missing
		 * backslash), so it's better to return failure than allow such
		 * things to happen.  */
		if (*cp == '\0') {
			printf("No closing parenthesis in archive specification\n");
			return false;
		}

		/* If we didn't move anywhere, we must be done.  */
		if (cp == member)
			break;

		emember = cp;

		/* XXX: This should be taken care of intelligently by
		 * SuffExpandChildren, both for the archive and the member
		 * portions.  */

		/* If member contains variables, try and substitute for them.
		 * This will slow down archive specs with dynamic sources, of
		 * course, since we'll be (non-)substituting them three times,
		 * but them's the breaks -- we need to do this since
		 * SuffExpandChildren calls us, otherwise we could assume the
		 * thing would be taken care of later.  */
		if (subst_member) {
			const char *oldMemberName = member;
			const char *result;

			member = Var_Substi(member, emember, ctxt, true);

			/* Now form an archive spec and recurse to deal with
			 * nested variables and multi-word variable values....
			 * The results are just placed at the end of the
			 * nodeLst we're returning.  */
			Buf_Addi(expand, lib, elib);
			Buf_AddChar(expand, '(');
			Buf_AddString(expand, member);
			Buf_AddChar(expand, ')');
			result = Buf_Retrieve(expand);

			if (strchr(member, '$') &&
			    memcmp(member, oldMemberName,
				emember - oldMemberName) == 0) {
				/* Must contain dynamic sources, so we can't
				 * deal with it now.  let SuffExpandChildren
				 * handle it later  */
				add_archive_node(nodeLst, result);
			} else if (!Arch_ParseArchive(&result, nodeLst, ctxt))
				return false;
			Buf_Reset(expand);
		} else if (Dir_HasWildcardsi(member, emember)) {
			LIST  members;
			char  *m;

			Lst_Init(&members);

			Dir_Expandi(member, emember, defaultPath, &members);
			while ((m = (char *)Lst_DeQueue(&members)) != NULL) {
				Buf_Addi(expand, lib, elib);
				Buf_AddChar(expand, '(');
				Buf_AddString(expand, m);
				Buf_AddChar(expand, ')');
				free(m);
				add_archive_node(nodeLst, Buf_Retrieve(expand));
				Buf_Reset(expand);
			}
		} else {
			Buf_Addi(expand, lib, elib);
			Buf_AddChar(expand, '(');
			Buf_Addi(expand, member, emember);
			Buf_AddChar(expand, ')');
			add_archive_node(nodeLst, Buf_Retrieve(expand));
			Buf_Reset(expand);
		}
		if (subst_member)
			free((char *)member);

	}

	if (subst_lib)
		free((char *)lib);

	/* We promised the pointer would be set up at the next non-space, so
	 * we must advance cp there before setting *linePtr... (note that on
	 * entrance to the loop, cp is guaranteed to point at a ')') */
	do {
		cp++;
	} while (ISSPACE(*cp));

	*linePtr = cp;
	return true;
}

/* Helper function: ar fields are not null terminated.	*/
static long
field2long(const char *field, size_t length)
{
	static char enough[32];

	assert(length < sizeof(enough));
	memcpy(enough, field, length);
	enough[length] = '\0';
	return strtol(enough, NULL, 10);
}

static Arch *
read_archive(const char *archive, const char *earchive)
{
	FILE *arch;       /* Stream to archive */
	char magic[SARMAG];
	Arch *ar;
	struct SVR4namelist list;

	list.fnametab = NULL;

	/* When we encounter an archive for the first time, we read its
	 * whole contents, to place it in the cache.  */
	arch = fopen(archive, "r");
	if (arch == NULL)
		return NULL;

	/* Make sure this is an archive we can handle.  */
	if ((fread(magic, SARMAG, 1, arch) != 1) ||
	    (strncmp(magic, ARMAG, SARMAG) != 0)) {
		fclose(arch);
		return NULL;
	}

	ar = ohash_create_entry(&arch_info, archive, &earchive);
	ohash_init(&ar->members, 8, &members_info);

	for (;;) {
		size_t n;
		struct ar_hdr arHeader;	/* Archive-member header */
		off_t size;		/* Size of archive member */
		char buffer[PATH_MAX];
		char *memberName; 	/* Current member name while hashing. */
		char *cp;

		memberName = buffer;
		n = fread(&arHeader, 1, sizeof(struct ar_hdr), arch);

		/*  Whole archive read ok.  */
		if (n == 0 && feof(arch)) {
			efree(list.fnametab);
			fclose(arch);
			return ar;
		}
		if (n < sizeof(struct ar_hdr))
			break;

		if (memcmp(arHeader.ar_fmag, ARFMAG, sizeof(arHeader.ar_fmag))
		    != 0) {
			/* header is bogus.  */
			break;
		} else {
			/* We need to advance the stream's pointer to the start
			 * of the next header.  Records are padded with
			 * newlines to an even-byte boundary, so we need to
			 * extract the size of the record and round it up
			 * during the seek.  */
			size = (off_t) field2long(arHeader.ar_size,
			    sizeof(arHeader.ar_size));

			(void)memcpy(memberName, arHeader.ar_name,
			    AR_NAME_SIZE);
			/* Find real end of name (strip extranous ' ')  */
			for (cp = memberName + AR_NAME_SIZE - 1; *cp == ' ';)
				cp--;
			cp[1] = '\0';

#ifdef SVR4ARCHIVES
			/* SVR4 names are slash terminated.  Also svr4 extended
			 * AR format.
			 */
			if (memberName[0] == '/') {
				/* SVR4 magic mode.  */
				memberName = ArchSVR4Entry(&list, memberName,
				    size, arch);
				if (memberName == NULL)
					/* Invalid data */
					break;
				else if (memberName == svr4list)
					/* List of files entry */
					continue;
				/* Got the entry.  */
				/* XXX this assumes further processing, such as
				 * AR_EFMT1, also applies to SVR4ARCHIVES.  */
			}
			else {
				if (cp[0] == '/')
					cp[0] = '\0';
			}
#endif

#ifdef AR_EFMT1
			/* BSD 4.4 extended AR format: #1/<namelen>, with name
			 * as the first <namelen> bytes of the file.  */
			if (memcmp(memberName, AR_EFMT1, sizeof(AR_EFMT1) - 1)
			    == 0 && ISDIGIT(memberName[sizeof(AR_EFMT1) - 1])) {

				int elen = atoi(memberName +
				    sizeof(AR_EFMT1)-1);

				if (elen <= 0 || elen >= PATH_MAX)
					break;
				memberName = buffer;
				if (fread(memberName, elen, 1, arch) != 1)
					break;
				memberName[elen] = '\0';
				if (fseek(arch, -elen, SEEK_CUR) != 0)
					break;
				if (DEBUG(ARCH) || DEBUG(MAKE))
					printf("ArchStat: Extended format entry for %s\n",
					    memberName);
			}
#endif

			ohash_insert(&ar->members,
			    ohash_qlookup(&ar->members, memberName),
				new_arch_member(&arHeader, memberName));
		}
		if (fseek(arch, (size + 1) & ~1, SEEK_CUR) != 0)
			break;
	}

	fclose(arch);
	ohash_delete(&ar->members);
	efree(list.fnametab);
	free(ar);
	return NULL;
}

/*-
 *-----------------------------------------------------------------------
 * ArchMTimeMember --
 *	Find the modification time of an archive's member, given the
 *	path to the archive and the path to the desired member.
 *
 * Results:
 *	The archive member's modification time, or OUT_OF_DATE if member
 *	was not found (convenient, so that missing members are always
 *	out of date).
 *
 * Side Effects:
 *	Cache the whole archive contents if hash is true.
 *-----------------------------------------------------------------------
 */
static struct timespec
ArchMTimeMember(
    const char *archive,	/* Path to the archive */
    const char *member, 	/* Name of member. If it is a path, only the
				 * last component is used. */
    bool hash)       		/* true if archive should be hashed if not
				 * already so. */
{
	FILE *arch;     	/* Stream to archive */
	Arch *ar;		/* Archive descriptor */
	unsigned int slot;	/* Place of archive in the archives hash */
	const char *end = NULL;
	const char *cp;
	struct timespec result;

	ts_set_out_of_date(result);
	/* Because of space constraints and similar things, files are archived
	 * using their final path components, not the entire thing, so we need
	 * to point 'member' to the final component, if there is one, to make
	 * the comparisons easier...  */
	cp = strrchr(member, '/');
	if (cp != NULL)
		member = cp + 1;

	/* Try to find archive in cache.  */
	slot = ohash_qlookupi(&archives, archive, &end);
	ar = ohash_find(&archives, slot);

	/* If not found, get it now.  */
	if (ar == NULL) {
		if (!hash) {
			/* Quick path:  no need to hash the whole archive, just
			 * use ArchFindMember to get the member's header and
			 * close the stream again.  */
			struct ar_hdr arHeader;

			arch = ArchFindMember(archive, member, &arHeader, "r");

			if (arch != NULL) {
				fclose(arch);
				ts_set_from_time_t(
				    (time_t)strtol(arHeader.ar_date, NULL, 10),
				    result);
			}
			return result;
		}
		ar = read_archive(archive, end);
		if (ar != NULL)
			ohash_insert(&archives, slot, ar);
	}

	/* If archive was found, get entry we seek.  */
	if (ar != NULL) {
		struct arch_member *he;
		end = NULL;

		he = ohash_find(&ar->members, ohash_qlookupi(&ar->members,
		    member, &end));
		if (he != NULL)
			return mtime_of_member(he);
		else {
			if ((size_t)(end - member) > AR_NAME_SIZE) {
				/* Try truncated name.	*/
				end = member + AR_NAME_SIZE;
				he = ohash_find(&ar->members,
				    ohash_qlookupi(&ar->members, member, &end));
				if (he != NULL)
					return mtime_of_member(he);
			}
		}
	}
	return result;
}

#ifdef SVR4ARCHIVES
/*-
 *-----------------------------------------------------------------------
 * ArchSVR4Entry --
 *	Parse an SVR4 style entry that begins with a slash.
 *	If it is "//", then load the table of filenames
 *	If it is "/<offset>", then try to substitute the long file name
 *	from offset of a table previously read.
 *
 * Results:
 *	svr4list: just read a list of names
 *	NULL:	  error occurred
 *	extended name
 *
 * Side-effect:
 *	For a list of names, store the list in l.
 *-----------------------------------------------------------------------
 */

static char *
ArchSVR4Entry(struct SVR4namelist *l, const char *name, size_t size, FILE *arch)
{
#define ARLONGNAMES1 "/"
#define ARLONGNAMES2 "ARFILENAMES"
	size_t entry;
	char *ptr, *eptr;

	assert(name[0] == '/');
	name++;
	/* First comes a table of archive names, to be used by subsequent
	 * calls.  */
	if (memcmp(name, ARLONGNAMES1, sizeof(ARLONGNAMES1) - 1) == 0 ||
	    memcmp(name, ARLONGNAMES2, sizeof(ARLONGNAMES2) - 1) == 0) {

		if (l->fnametab != NULL) {
			if (DEBUG(ARCH))
				printf("Attempted to redefine an SVR4 name table\n");
			return NULL;
		}

		l->fnametab = emalloc(size);
		l->fnamesize = size;

		if (fread(l->fnametab, size, 1, arch) != 1) {
			if (DEBUG(ARCH))
				printf("Reading an SVR4 name table failed\n");
			return NULL;
		}

		eptr = l->fnametab + size;
		for (entry = 0, ptr = l->fnametab; ptr < eptr; ptr++)
			switch (*ptr) {
			case '/':
				entry++;
				*ptr = '\0';
				break;

			case '\n':
				break;

			default:
				break;
			}
		if (DEBUG(ARCH))
			printf("Found svr4 archive name table with %lu entries\n",
			    (u_long)entry);
		return (char *)svr4list;
	}
	/* Then the names themselves are given as offsets in this table.  */
	if (*name == ' ' || *name == '\0')
		return NULL;

	entry = (size_t) strtol(name, &eptr, 0);
	if ((*eptr != ' ' && *eptr != '\0') || eptr == name) {
		if (DEBUG(ARCH))
			printf("Could not parse SVR4 name /%s\n", name);
		return NULL;
	}
	if (entry >= l->fnamesize) {
		if (DEBUG(ARCH))
			printf("SVR4 entry offset /%s is greater than %lu\n",
			    name, (u_long)l->fnamesize);
		return NULL;
	}

	if (DEBUG(ARCH))
		printf("Replaced /%s with %s\n", name, l->fnametab + entry);

	return l->fnametab + entry;
}
#endif


/*-
 *-----------------------------------------------------------------------
 * ArchFindMember --
 *	Locate a member of an archive, given the path of the archive and
 *	the path of the desired member. If the archive is to be modified,
 *	the mode should be "r+", if not, it should be "r".
 *
 * Results:
 *	A FILE *, opened for reading and writing, positioned right after
 *	the member's header, or NULL if the member was nonexistent.
 *
 * Side Effects:
 *	Fill the struct ar_hdr pointed by arHeaderPtr.
 *-----------------------------------------------------------------------
 */
static FILE *
ArchFindMember(
    const char	  *archive,   /* Path to the archive */
    const char	  *member,    /* Name of member. If it is a path, only the
			       * last component is used. */
    struct ar_hdr *arHeaderPtr,/* Pointer to header structure to be filled in */
    const char	  *mode)      /* mode for opening the stream */
{
	FILE *	  arch;       /* Stream to archive */
	char	  *cp;
	char	  magic[SARMAG];
	size_t	  length;
	struct SVR4namelist list;

	list.fnametab = NULL;

	arch = fopen(archive, mode);
	if (arch == NULL)
		return NULL;

	/* Make sure this is an archive we can handle.  */
	if (fread(magic, SARMAG, 1, arch) != 1 ||
	    strncmp(magic, ARMAG, SARMAG) != 0) {
		fclose(arch);
		return NULL;
	}

	/* Because of space constraints and similar things, files are archived
	 * using their final path components, not the entire thing, so we need
	 * to point 'member' to the final component, if there is one, to make
	 * the comparisons easier...  */
	cp = strrchr(member, '/');
	if (cp != NULL)
		member = cp + 1;

	length = strlen(member);
	if (length >= AR_NAME_SIZE)
		length = AR_NAME_SIZE;

	/* Error handling is simpler than for read_archive, since we just
	 * look for a given member.  */
	while (fread(arHeaderPtr, sizeof(struct ar_hdr), 1, arch) == 1) {
		off_t size;       /* Size of archive member */
		char *memberName;

		if (memcmp(arHeaderPtr->ar_fmag, ARFMAG,
		    sizeof(arHeaderPtr->ar_fmag) ) != 0)
			 /* The header is bogus, so the archive is bad.  */
			 break;

		memberName = arHeaderPtr->ar_name;
		if (memcmp(member, memberName, length) == 0) {
			/* If the member's name doesn't take up the entire
			 * 'name' field, we have to be careful of matching
			 * prefixes. Names are space- padded to the right, so
			 * if the character in 'name' at the end of the matched
			 * string is anything but a space, this isn't the
			 * member we sought.  */
#ifdef SVR4ARCHIVES
			if (length < sizeof(arHeaderPtr->ar_name) &&
			    memberName[length] == '/')
				length++;
#endif
			if (length == sizeof(arHeaderPtr->ar_name) ||
			    memberName[length] == ' ') {
				efree(list.fnametab);
				return arch;
			}
		}

		size = (off_t) field2long(arHeaderPtr->ar_size,
		    sizeof(arHeaderPtr->ar_size));

#ifdef SVR4ARCHIVES
		/* svr4 names are slash terminated. Also svr4 extended AR
		 * format.
		 */
		if (memberName[0] == '/') {
			/* svr4 magic mode.  */
			memberName = ArchSVR4Entry(&list, arHeaderPtr->ar_name,
			    size, arch);
			if (memberName == NULL)
				/* Invalid data */
				break;
			else if (memberName == svr4list)
				/* List of files entry */
				continue;
			/* Got the entry.  */
			if (strcmp(memberName, member) == 0) {
				efree(list.fnametab);
				return arch;
			}
		}
#endif

#ifdef AR_EFMT1
		/* BSD 4.4 extended AR format: #1/<namelen>, with name as the
		 * first <namelen> bytes of the file.  */
		if (memcmp(memberName, AR_EFMT1, sizeof(AR_EFMT1) - 1) == 0 &&
		    ISDIGIT(memberName[sizeof(AR_EFMT1) - 1])) {
			char ename[PATH_MAX];

			int elength = atoi(memberName + sizeof(AR_EFMT1)-1);

			if (elength <= 0 || elength >= PATH_MAX)
				break;
			if (fread(ename, elength, 1, arch) != 1)
				break;
			if (fseek(arch, -elength, SEEK_CUR) != 0)
				break;
			ename[elength] = '\0';
			if (DEBUG(ARCH) || DEBUG(MAKE))
				printf("ArchFind: Extended format entry for %s\n", ename);
			/* Found as extended name.	*/
			if (strcmp(ename, member) == 0) {
				efree(list.fnametab);
				return arch;
			}
		}
#endif
		/* This isn't the member we're after, so we need to advance the
		 * stream's pointer to the start of the next header.  */
		if (fseek(arch, (size + 1) & ~1, SEEK_CUR) != 0)
			break;
	}

	/* We did not find the member, or we ran into an error while reading
	 * the archive.  */
#ifdef SVRARCHIVES
	efree(list.fnametab);
#endif
	fclose(arch);
	return NULL;
}

static void
ArchTouch(const char *archive, const char *member)
{
	FILE *arch;
	struct ar_hdr arHeader;

	arch = ArchFindMember(archive, member, &arHeader, "r+");
	if (arch != NULL) {
		snprintf(arHeader.ar_date, sizeof(arHeader.ar_date),
		    "%-12ld", (long) time(NULL));
		if (fseek(arch, -sizeof(struct ar_hdr), SEEK_CUR) == 0)
			(void)fwrite(&arHeader, sizeof(struct ar_hdr), 1, arch);
		fclose(arch);
	}
}

/*
 * Side Effects:
 *	The modification time of the entire archive is also changed.
 *	For a library, this could necessitate the re-ranlib'ing of the
 *	whole thing.
 */
void
Arch_Touch(GNode *gn)
{
	ArchTouch(Var(ARCHIVE_INDEX, gn), Var(MEMBER_INDEX, gn));
}

struct timespec
Arch_MTime(GNode *gn)
{
	gn->mtime = ArchMTimeMember(Var(ARCHIVE_INDEX, gn),
	     Var(MEMBER_INDEX, gn), true);

	return gn->mtime;
}

struct timespec
Arch_MemMTime(GNode *gn)
{
	LstNode ln;

	for (ln = Lst_First(&gn->parents); ln != NULL; ln = Lst_Adv(ln)) {
		GNode *pgn;
		char *nameStart;
		char *nameEnd;

		pgn = (GNode *)Lst_Datum(ln);

		if (pgn->type & OP_ARCHV) {
			/* If the parent is an archive specification and is
			 * being made and its member's name matches the name of
			 * the node we were given, record the modification time
			 * of the parent in the child. We keep searching its
			 * parents in case some other parent requires this
			 * child to exist...  */
			if ((nameStart = strchr(pgn->name, '(') ) != NULL) {
				nameStart++;
				nameEnd = strchr(nameStart, ')');
			} else
				nameEnd = NULL;

			if (pgn->must_make && nameEnd != NULL &&
			    strncmp(nameStart, gn->name, nameEnd - nameStart)
			    == 0 && gn->name[nameEnd-nameStart] == '\0')
				gn->mtime = Arch_MTime(pgn);
		} else if (pgn->must_make) {
			/* Something which isn't a library depends on the
			 * existence of this target, so it needs to exist.  */
			ts_set_out_of_date(gn->mtime);
			break;
		}
	}
	return gn->mtime;
}

void
Arch_Init(void)
{
	ohash_init(&archives, 4, &arch_info);
}