xref: /src/usr.bin/make/arch.c

/*	$NetBSD: arch.c,v 1.162 2020/11/07 13:03:58 rillig Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  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.
 */

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */

/* Manipulate libraries, archives and their members.
 *
 * The first time an archive is referenced, all of its members' headers are
 * read and cashed and the archive closed again.  All cashed archives are kept
 * on a list which is searched each time an archive member is referenced.
 *
 * The interface to this module is:
 *
 *	Arch_Init	Initialize this module.
 *
 *	Arch_End	Clean up this module.
 *
 *	Arch_ParseArchive
 *			Parse an archive specification such as
 *			"archive.a(member1 member2)".
 *
 *	Arch_Touch	Alter the modification time of the archive
 *			member described by the given node to be
 *			the time when make was started.
 *
 *	Arch_TouchLib	Update the modification time of the library
 *			described by the given node. This is special
 *			because it also updates the modification time
 *			of the library's table of contents.
 *
 *	Arch_MTime	Find the modification time of a member of
 *			an archive *in the archive*. The time is also
 *			placed in the member's GNode. Returns the
 *			modification time.
 *
 *	Arch_MemberMTime
 *			Find the modification time of a member of
 *			an archive. Called when the member doesn't
 *			already exist. Looks in the archive for the
 *			modification time. Returns the modification
 *			time.
 *
 *	Arch_FindLib	Search for a library along a path. The
 *			library name in the GNode should be in
 *			-l<name> format.
 *
 *	Arch_LibOODate	Decide if a library node is out-of-date.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/param.h>

#include <ar.h>
#include <utime.h>

#include "make.h"
#include "dir.h"
#include "config.h"

/*	"@(#)arch.c	8.2 (Berkeley) 1/2/94"	*/
MAKE_RCSID("$NetBSD: arch.c,v 1.162 2020/11/07 13:03:58 rillig Exp $");

typedef struct List ArchList;
typedef struct ListNode ArchListNode;

static ArchList *archives;	/* The archives we've already examined */

typedef struct Arch {
    char *name;			/* Name of archive */
    HashTable members;		/* All the members of the archive described
				 * by <name, struct ar_hdr *> key/value pairs */
    char *fnametab;		/* Extended name table strings */
    size_t fnamesize;		/* Size of the string table */
} Arch;

static FILE *ArchFindMember(const char *, const char *,
			    struct ar_hdr *, const char *);
#if defined(__svr4__) || defined(__SVR4) || defined(__ELF__)
#define SVR4ARCHIVES
static int ArchSVR4Entry(Arch *, char *, size_t, FILE *);
#endif

#ifdef CLEANUP
static void
ArchFree(void *ap)
{
    Arch *a = ap;
    HashIter hi;

    /* Free memory from hash entries */
    HashIter_Init(&hi, &a->members);
    while (HashIter_Next(&hi) != NULL)
	free(hi.entry->value);

    free(a->name);
    free(a->fnametab);
    HashTable_Done(&a->members);
    free(a);
}
#endif


/*
 * Parse an archive specification such as "archive.a(member1 member2.${EXT})",
 * adding nodes for the expanded members to nodeLst.  Nodes are created as
 * necessary.
 *
 * Input:
 *	pp		The start of the specification.
 *	nodeLst		The list on which to place the nodes.
 *	ctxt		The context in which to expand variables.
 *
 * Output:
 *	return		TRUE if it was a valid specification.
 *	*pp		Points to the first non-space after the archive spec.
 *	*nodeLst	Nodes for the members have been added.
 */
Boolean
Arch_ParseArchive(char **pp, GNodeList *nodeLst, GNode *ctxt)
{
    char *cp;			/* Pointer into line */
    GNode *gn;			/* New node */
    char *libName;		/* Library-part of specification */
    char *libName_freeIt = NULL;
    char *memName;		/* Member-part of specification */
    char saveChar;		/* Ending delimiter of member-name */
    Boolean expandLibName;	/* Whether the parsed libName contains
				 * variable expressions that need to be
				 * expanded */

    libName = *pp;
    expandLibName = FALSE;

    for (cp = libName; *cp != '(' && *cp != '\0';) {
	if (*cp == '$') {
	    /*
	     * Variable spec, so call the Var module to parse the puppy
	     * so we can safely advance beyond it...
	     */
	    const char *nested_p = cp;
	    void *result_freeIt;
	    const char *result;
	    Boolean isError;

	    /* XXX: is expanded twice: once here and once below */
	    (void)Var_Parse(&nested_p, ctxt, VARE_UNDEFERR|VARE_WANTRES,
			    &result, &result_freeIt);
	    /* TODO: handle errors */
	    isError = result == var_Error;
	    free(result_freeIt);
	    if (isError)
		return FALSE;

	    expandLibName = TRUE;
	    cp += nested_p - cp;
	} else
	    cp++;
    }

    *cp++ = '\0';
    if (expandLibName) {
	(void)Var_Subst(libName, ctxt, VARE_UNDEFERR|VARE_WANTRES, &libName);
	/* TODO: handle errors */
	libName_freeIt = libName;
    }


    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).
	 */
	Boolean doSubst = FALSE; /* TRUE if need to substitute in memName */

	pp_skip_whitespace(&cp);

	memName = cp;
	while (*cp != '\0' && *cp != ')' && !ch_isspace(*cp)) {
	    if (*cp == '$') {
		/*
		 * Variable spec, so call the Var module to parse the puppy
		 * so we can safely advance beyond it...
		 */
		void *freeIt;
		const char *result;
		Boolean isError;
		const char *nested_p = cp;

		(void)Var_Parse(&nested_p, ctxt, VARE_UNDEFERR|VARE_WANTRES,
				&result, &freeIt);
		/* TODO: handle errors */
		isError = result == var_Error;
		free(freeIt);

		if (isError)
		    return FALSE;

		doSubst = TRUE;
		cp += nested_p - cp;
	    } 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 == memName) {
	    break;
	}

	saveChar = *cp;
	*cp = '\0';

	/*
	 * 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 (doSubst) {
	    char *buf;
	    char *sacrifice;
	    char *oldMemName = memName;

	    (void)Var_Subst(memName, ctxt, VARE_UNDEFERR|VARE_WANTRES,
			    &memName);
	    /* TODO: handle errors */

	    /*
	     * 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 = sacrifice = str_concat4(libName, "(", memName, ")");

	    if (strchr(memName, '$') != NULL &&
		strcmp(memName, oldMemName) == 0) {
		/*
		 * Must contain dynamic sources, so we can't deal with it now.
		 * Just create an ARCHV node for the thing and let
		 * SuffExpandChildren handle it...
		 */
		gn = Targ_GetNode(buf);
		gn->type |= OP_ARCHV;
		Lst_Append(nodeLst, gn);

	    } else if (!Arch_ParseArchive(&sacrifice, nodeLst, ctxt)) {
		/* Error in nested call. */
		free(buf);
		return FALSE;
	    }
	    free(buf);

	} else if (Dir_HasWildcards(memName)) {
	    StringList *members = Lst_New();
	    Dir_Expand(memName, dirSearchPath, members);

	    while (!Lst_IsEmpty(members)) {
		char *member = Lst_Dequeue(members);
		char *fullname = str_concat4(libName, "(", member, ")");
		free(member);

		gn = Targ_GetNode(fullname);
		free(fullname);

		gn->type |= OP_ARCHV;
		Lst_Append(nodeLst, gn);
	    }
	    Lst_Free(members);

	} else {
	    char *fullname = str_concat4(libName, "(", memName, ")");
	    gn = Targ_GetNode(fullname);
	    free(fullname);

	    /*
	     * We've found the node, but have to make sure the rest of the
	     * world knows it's an archive member, without having to
	     * constantly check for parentheses, so we type the thing with
	     * the OP_ARCHV bit before we place it on the end of the
	     * provided list.
	     */
	    gn->type |= OP_ARCHV;
	    Lst_Append(nodeLst, gn);
	}
	if (doSubst) {
	    free(memName);
	}

	*cp = saveChar;
    }

    free(libName_freeIt);

    cp++;			/* skip the ')' */
    /* We promised that pp would be set up at the next non-space. */
    pp_skip_whitespace(&cp);
    *pp = cp;
    return TRUE;
}

/* Locate a member of an archive, given the path of the archive and the path
 * of the desired member.
 *
 * Input:
 *	archive		Path to the archive
 *	member		Name of member; only its basename is used.
 *	hash		TRUE if archive should be hashed if not already so.
 *
 * Results:
 *	The ar_hdr for the member.
 */
static struct ar_hdr *
ArchStatMember(const char *archive, const char *member, Boolean hash)
{
#define AR_MAX_NAME_LEN (sizeof arh.ar_name - 1)
    FILE *arch;			/* Stream to archive */
    size_t size;		/* Size of archive member */
    char magic[SARMAG];
    ArchListNode *ln;
    Arch *ar;			/* Archive descriptor */
    struct ar_hdr arh;		/* archive-member header for reading archive */
    char memName[MAXPATHLEN + 1];
				/* Current member name while hashing. */

    /*
     * Because of space constraints and similar things, files are archived
     * using their basename, not the entire path.
     */
    const char *lastSlash = strrchr(member, '/');
    if (lastSlash != NULL)
	member = lastSlash + 1;

    for (ln = archives->first; ln != NULL; ln = ln->next) {
	const Arch *a = ln->datum;
	if (strcmp(a->name, archive) == 0)
	    break;
    }

    if (ln != NULL) {
	struct ar_hdr *hdr;

	ar = ln->datum;
	hdr = HashTable_FindValue(&ar->members, member);
	if (hdr != NULL)
	    return hdr;

	{
	    /* Try truncated name */
	    char copy[AR_MAX_NAME_LEN + 1];
	    size_t len = strlen(member);

	    if (len > AR_MAX_NAME_LEN) {
		len = AR_MAX_NAME_LEN;
		snprintf(copy, sizeof copy, "%s", member);
	    }
	    hdr = HashTable_FindValue(&ar->members, copy);
	    return hdr;
	}
    }

    if (!hash) {
	/*
	 * Caller doesn't want the thing hashed, just use ArchFindMember
	 * to read the header for the member out and close down the stream
	 * again. Since the archive is not to be hashed, we assume there's
	 * no need to allocate extra room for the header we're returning,
	 * so just declare it static.
	 */
	static struct ar_hdr sarh;

	arch = ArchFindMember(archive, member, &sarh, "r");
	if (arch == NULL)
	    return NULL;

	fclose(arch);
	return &sarh;
    }

    /*
     * We don't have this archive on the list yet, so we want to find out
     * everything that's in it and cache it so we can get at it quickly.
     */
    arch = fopen(archive, "r");
    if (arch == NULL)
	return NULL;

    /*
     * We use the ARMAG string to 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 = bmake_malloc(sizeof *ar);
    ar->name = bmake_strdup(archive);
    ar->fnametab = NULL;
    ar->fnamesize = 0;
    HashTable_Init(&ar->members);
    memName[AR_MAX_NAME_LEN] = '\0';

    while (fread(&arh, sizeof arh, 1, arch) == 1) {
	if (strncmp(arh.ar_fmag, ARFMAG, sizeof arh.ar_fmag) != 0) {
	    /*
	     * The header is bogus, so the archive is bad
	     * and there's no way we can recover...
	     */
	    goto badarch;
	} else {
	    char *nameend;

	    /*
	     * We need to advance the stream's pointer to the start of the
	     * next header. Files are padded with newlines to an even-byte
	     * boundary, so we need to extract the size of the file from the
	     * 'size' field of the header and round it up during the seek.
	     */
	    arh.ar_size[sizeof arh.ar_size - 1] = '\0';
	    size = (size_t)strtol(arh.ar_size, NULL, 10);

	    memcpy(memName, arh.ar_name, sizeof arh.ar_name);
	    nameend = memName + AR_MAX_NAME_LEN;
	    while (*nameend == ' ') {
		nameend--;
	    }
	    nameend[1] = '\0';

#ifdef SVR4ARCHIVES
	    /*
	     * svr4 names are slash terminated. Also svr4 extended AR format.
	     */
	    if (memName[0] == '/') {
		/*
		 * svr4 magic mode; handle it
		 */
		switch (ArchSVR4Entry(ar, memName, size, arch)) {
		case -1:	/* Invalid data */
		    goto badarch;
		case 0:		/* List of files entry */
		    continue;
		default:	/* Got the entry */
		    break;
		}
	    } else {
		if (nameend[0] == '/')
		    nameend[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 (strncmp(memName, AR_EFMT1, sizeof AR_EFMT1 - 1) == 0 &&
		ch_isdigit(memName[sizeof AR_EFMT1 - 1])) {

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

		if ((unsigned int)elen > MAXPATHLEN)
		    goto badarch;
		if (fread(memName, (size_t)elen, 1, arch) != 1)
		    goto badarch;
		memName[elen] = '\0';
		if (fseek(arch, -elen, SEEK_CUR) != 0)
		    goto badarch;
		if (DEBUG(ARCH) || DEBUG(MAKE)) {
		    debug_printf("ArchStat: Extended format entry for %s\n",
				 memName);
		}
	    }
#endif

	    {
		HashEntry *he;
		he = HashTable_CreateEntry(&ar->members, memName, NULL);
		HashEntry_Set(he, bmake_malloc(sizeof arh));
		memcpy(HashEntry_Get(he), &arh, sizeof arh);
	    }
	}
	if (fseek(arch, ((long)size + 1) & ~1, SEEK_CUR) != 0)
	    goto badarch;
    }

    fclose(arch);

    Lst_Append(archives, ar);

    /*
     * Now that the archive has been read and cached, we can look into
     * the hash table to find the desired member's header.
     */
    return HashTable_FindValue(&ar->members, member);

badarch:
    fclose(arch);
    HashTable_Done(&ar->members);
    free(ar->fnametab);
    free(ar);
    return NULL;
}

#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.
 *	If a table is read, the file pointer is moved to the next archive
 *	member.
 *
 * Results:
 *	-1: Bad data in archive
 *	 0: A table was loaded from the file
 *	 1: Name was successfully substituted from table
 *	 2: Name was not successfully substituted from table
 *-----------------------------------------------------------------------
 */
static int
ArchSVR4Entry(Arch *ar, char *inout_name, size_t size, FILE *arch)
{
#define ARLONGNAMES1 "//"
#define ARLONGNAMES2 "/ARFILENAMES"
    size_t entry;
    char *ptr, *eptr;

    if (strncmp(inout_name, ARLONGNAMES1, sizeof ARLONGNAMES1 - 1) == 0 ||
	strncmp(inout_name, ARLONGNAMES2, sizeof ARLONGNAMES2 - 1) == 0) {

	if (ar->fnametab != NULL) {
	    DEBUG0(ARCH, "Attempted to redefine an SVR4 name table\n");
	    return -1;
	}

	/*
	 * This is a table of archive names, so we build one for
	 * ourselves
	 */
	ar->fnametab = bmake_malloc(size);
	ar->fnamesize = size;

	if (fread(ar->fnametab, size, 1, arch) != 1) {
	    DEBUG0(ARCH, "Reading an SVR4 name table failed\n");
	    return -1;
	}
	eptr = ar->fnametab + size;
	for (entry = 0, ptr = ar->fnametab; ptr < eptr; ptr++)
	    if (*ptr == '/') {
		entry++;
		*ptr = '\0';
	    }
	DEBUG1(ARCH, "Found svr4 archive name table with %lu entries\n",
	       (unsigned long)entry);
	return 0;
    }

    if (inout_name[1] == ' ' || inout_name[1] == '\0')
	return 2;

    entry = (size_t)strtol(&inout_name[1], &eptr, 0);
    if ((*eptr != ' ' && *eptr != '\0') || eptr == &inout_name[1]) {
	DEBUG1(ARCH, "Could not parse SVR4 name %s\n", inout_name);
	return 2;
    }
    if (entry >= ar->fnamesize) {
	DEBUG2(ARCH, "SVR4 entry offset %s is greater than %lu\n",
	       inout_name, (unsigned long)ar->fnamesize);
	return 2;
    }

    DEBUG2(ARCH, "Replaced %s with %s\n", inout_name, &ar->fnametab[entry]);

    snprintf(inout_name, MAXPATHLEN + 1, "%s", &ar->fnametab[entry]);
    return 1;
}
#endif


static Boolean
ArchiveMember_HasName(const struct ar_hdr *hdr,
		      const char *name, size_t namelen)
{
    const size_t ar_name_len = sizeof hdr->ar_name;
    const char *ar_name = hdr->ar_name;

    if (strncmp(ar_name, name, namelen) != 0)
	return FALSE;

    if (namelen >= ar_name_len)
	return namelen == ar_name_len;

    /* hdr->ar_name is space-padded to the right. */
    if (ar_name[namelen] == ' ')
	return TRUE;

    /* In archives created by GNU binutils 2.27, the member names end with
     * a slash. */
    if (ar_name[namelen] == '/' &&
	(namelen == ar_name_len || ar_name[namelen + 1] == ' '))
	return TRUE;

    return FALSE;
}

/* Locate a member of an archive, given the path of the archive and the path
 * of the desired member.
 *
 * Input:
 *	archive		Path to the archive
 *	member		Name of member. If it is a path, only the last
 *			component is used.
 *	out_arh		Archive header to be filled in
 *	mode		"r" for read-only access, "r+" for read-write access
 *
 * Output:
 *	return		The archive file, positioned at the start of the
 *			member's struct ar_hdr, or NULL if the member doesn't
 *			exist.
 *	*out_arh	The current struct ar_hdr for member.
 */
static FILE *
ArchFindMember(const char *archive, const char *member, struct ar_hdr *out_arh,
	       const char *mode)
{
    FILE *arch;			/* Stream to archive */
    int size;			/* Size of archive member */
    char magic[SARMAG];
    size_t len, tlen;
    const char *lastSlash;

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

    /*
     * We use the ARMAG string to 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 basename, not the entire path.
     */
    lastSlash = strrchr(member, '/');
    if (lastSlash != NULL)
	member = lastSlash + 1;

    len = tlen = strlen(member);
    if (len > sizeof out_arh->ar_name) {
	tlen = sizeof out_arh->ar_name;
    }

    while (fread(out_arh, sizeof *out_arh, 1, arch) == 1) {

	if (strncmp(out_arh->ar_fmag, ARFMAG, sizeof out_arh->ar_fmag) != 0) {
	    /*
	     * The header is bogus, so the archive is bad
	     * and there's no way we can recover...
	     */
	    fclose(arch);
	    return NULL;
	}

	DEBUG5(ARCH, "Reading archive %s member %.*s mtime %.*s\n",
	       archive,
	       (int)sizeof out_arh->ar_name, out_arh->ar_name,
	       (int)sizeof out_arh->ar_date, out_arh->ar_date);

	if (ArchiveMember_HasName(out_arh, member, len)) {
	    /*
	     * To make life easier for callers that want to update the
	     * archive, we reposition the file at the start
	     * of the header we just read before we return the stream.
	     * In a more general situation, it might be better to leave
	     * the file at the actual member, rather than its header, but
	     * not here.
	     */
	    if (fseek(arch, -(long)sizeof *out_arh, SEEK_CUR) != 0) {
		fclose(arch);
		return NULL;
	    }
	    return arch;
	}

#ifdef AR_EFMT1
	/*
	 * BSD 4.4 extended AR format: #1/<namelen>, with name as the
	 * first <namelen> bytes of the file
	 */
	if (strncmp(out_arh->ar_name, AR_EFMT1, sizeof AR_EFMT1 - 1) == 0 &&
	    ch_isdigit(out_arh->ar_name[sizeof AR_EFMT1 - 1]))
	{
	    int elen = atoi(&out_arh->ar_name[sizeof AR_EFMT1 - 1]);
	    char ename[MAXPATHLEN + 1];

	    if ((unsigned int)elen > MAXPATHLEN) {
		fclose(arch);
		return NULL;
	    }
	    if (fread(ename, (size_t)elen, 1, arch) != 1) {
		fclose(arch);
		return NULL;
	    }
	    ename[elen] = '\0';
	    if (DEBUG(ARCH) || DEBUG(MAKE)) {
		debug_printf("ArchFind: Extended format entry for %s\n", ename);
	    }
	    if (strncmp(ename, member, len) == 0) {
		/* Found as extended name */
		if (fseek(arch, -(long)sizeof(struct ar_hdr) - elen,
			  SEEK_CUR) != 0) {
		    fclose(arch);
		    return NULL;
		}
		return arch;
	    }
	    if (fseek(arch, -elen, SEEK_CUR) != 0) {
		fclose(arch);
		return NULL;
	    }
	}
#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. Files are
	 * padded with newlines to an even-byte boundary, so we need to
	 * extract the size of the file from the 'size' field of the
	 * header and round it up during the seek.
	 */
	out_arh->ar_size[sizeof out_arh->ar_size - 1] = '\0';
	size = (int)strtol(out_arh->ar_size, NULL, 10);
	if (fseek(arch, (size + 1) & ~1, SEEK_CUR) != 0) {
	    fclose(arch);
	    return NULL;
	}
    }

    fclose(arch);
    return NULL;
}

/* Touch a member of an archive, on disk.
 * The GNode's modification time is left as-is.
 *
 * The st_mtime of the entire archive is also changed.
 * For a library, it may be required to run ranlib after this.
 *
 * Input:
 *	gn		Node of member to touch
 *
 * Results:
 *	The 'time' field of the member's header is updated.
 */
void
Arch_Touch(GNode *gn)
{
    FILE *f;
    struct ar_hdr arh;

    f = ArchFindMember(GNode_VarArchive(gn), GNode_VarMember(gn), &arh, "r+");
    if (f == NULL)
	return;

    snprintf(arh.ar_date, sizeof arh.ar_date, "%-ld", (unsigned long)now);
    (void)fwrite(&arh, sizeof arh, 1, f);
    fclose(f);			/* TODO: handle errors */
}

/* Given a node which represents a library, touch the thing, making sure that
 * the table of contents is also touched.
 *
 * Both the modification time of the library and of the RANLIBMAG member are
 * set to 'now'. */
void
Arch_TouchLib(GNode *gn MAKE_ATTR_UNUSED)
{
#ifdef RANLIBMAG
    FILE *f;
    struct ar_hdr arh;		/* Header describing table of contents */
    struct utimbuf times;

    f = ArchFindMember(gn->path, RANLIBMAG, &arh, "r+");
    if (f == NULL)
	return;

    snprintf(arh.ar_date, sizeof arh.ar_date, "%-ld", (unsigned long)now);
    (void)fwrite(&arh, sizeof arh, 1, f);
    fclose(f);			/* TODO: handle errors */

    times.actime = times.modtime = now;
    utime(gn->path, &times);	/* TODO: handle errors */
#endif
}

/* Update the mtime of the GNode with the mtime from the archive member on
 * disk (or in the cache). */
time_t
Arch_MTime(GNode *gn)
{
    struct ar_hdr *arh;
    time_t modTime;

    arh = ArchStatMember(GNode_VarArchive(gn), GNode_VarMember(gn), TRUE);
    if (arh != NULL) {
	modTime = (time_t)strtol(arh->ar_date, NULL, 10);
    } else {
	modTime = 0;
    }

    gn->mtime = modTime;
    return modTime;
}

/* Given a non-existent archive member's node, get its modification time from
 * its archived form, if it exists. gn->mtime is filled in as well. */
time_t
Arch_MemberMTime(GNode *gn)
{
    GNodeListNode *ln;

    for (ln = gn->parents->first; ln != NULL; ln = ln->next) {
	GNode *pgn = ln->datum;

	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...
	     */
	    const char *nameStart = strchr(pgn->name, '(') + 1;
	    const char *nameEnd = strchr(nameStart, ')');
	    size_t nameLen = (size_t)(nameEnd - nameStart);

	    if ((pgn->flags & REMAKE) &&
		strncmp(nameStart, gn->name, nameLen) == 0) {
		gn->mtime = Arch_MTime(pgn);
	    }
	} else if (pgn->flags & REMAKE) {
	    /*
	     * Something which isn't a library depends on the existence of
	     * this target, so it needs to exist.
	     */
	    gn->mtime = 0;
	    break;
	}
    }

    return gn->mtime;
}

/* Search for a library along the given search path.
 *
 * The node's 'path' field is set to the found path (including the
 * actual file name, not -l...). If the system can handle the -L
 * flag when linking (or we cannot find the library), we assume that
 * the user has placed the .LIBS variable in the final linking
 * command (or the linker will know where to find it) and set the
 * TARGET variable for this node to be the node's name. Otherwise,
 * we set the TARGET variable to be the full path of the library,
 * as returned by Dir_FindFile.
 *
 * Input:
 *	gn		Node of library to find
 */
void
Arch_FindLib(GNode *gn, SearchPath *path)
{
    char *libName = str_concat3("lib", gn->name + 2, ".a");
    gn->path = Dir_FindFile(libName, path);
    free(libName);

#ifdef LIBRARIES
    Var_Set(TARGET, gn->name, gn);
#else
    Var_Set(TARGET, gn->path == NULL ? gn->name : gn->path, gn);
#endif
}

/* Decide if a node with the OP_LIB attribute is out-of-date. Called from
 * Make_OODate to make its life easier.
 * The library is cached if it hasn't been already.
 *
 * There are several ways for a library to be out-of-date that are
 * not available to ordinary files. In addition, there are ways
 * that are open to regular files that are not available to
 * libraries. A library that is only used as a source is never
 * considered out-of-date by itself. This does not preclude the
 * library's modification time from making its parent be out-of-date.
 * A library will be considered out-of-date for any of these reasons,
 * given that it is a target on a dependency line somewhere:
 *
 *	Its modification time is less than that of one of its sources
 *	(gn->mtime < gn->youngestChild->mtime).
 *
 *	Its modification time is greater than the time at which the make
 *	began (i.e. it's been modified in the course of the make, probably
 *	by archiving).
 *
 *	The modification time of one of its sources is greater than the one
 *	of its RANLIBMAG member (i.e. its table of contents is out-of-date).
 *	We don't compare of the archive time vs. TOC time because they can be
 *	too close. In my opinion we should not bother with the TOC at all
 *	since this is used by 'ar' rules that affect the data contents of the
 *	archive, not by ranlib rules, which affect the TOC.
 *
 * Input:
 *	gn		The library's graph node
 *
 * Results:
 *	TRUE if the library is out-of-date. FALSE otherwise.
 */
Boolean
Arch_LibOODate(GNode *gn)
{
    Boolean oodate;

    if (gn->type & OP_PHONY) {
	oodate = TRUE;
    } else if (!GNode_IsTarget(gn) && Lst_IsEmpty(gn->children)) {
	oodate = FALSE;
    } else if ((!Lst_IsEmpty(gn->children) && gn->youngestChild == NULL) ||
	       (gn->mtime > now) ||
	       (gn->youngestChild != NULL &&
		gn->mtime < gn->youngestChild->mtime)) {
	oodate = TRUE;
    } else {
#ifdef RANLIBMAG
	struct ar_hdr *arh;	/* Header for __.SYMDEF */
	int modTimeTOC;		/* The table-of-contents's mod time */

	arh = ArchStatMember(gn->path, RANLIBMAG, FALSE);

	if (arh != NULL) {
	    modTimeTOC = (int)strtol(arh->ar_date, NULL, 10);

	    if (DEBUG(ARCH) || DEBUG(MAKE)) {
		debug_printf("%s modified %s...", RANLIBMAG, Targ_FmtTime(modTimeTOC));
	    }
	    oodate = (gn->youngestChild == NULL || gn->youngestChild->mtime > modTimeTOC);
	} else {
	    /*
	     * A library w/o a table of contents is out-of-date
	     */
	    if (DEBUG(ARCH) || DEBUG(MAKE)) {
		debug_printf("No t.o.c....");
	    }
	    oodate = TRUE;
	}
#else
	oodate = FALSE;
#endif
    }
    return oodate;
}

/* Initialize the archives module. */
void
Arch_Init(void)
{
    archives = Lst_New();
}

/* Clean up the archives module. */
void
Arch_End(void)
{
#ifdef CLEANUP
    Lst_Destroy(archives, ArchFree);
#endif
}

Boolean
Arch_IsLib(GNode *gn)
{
    static const char armag[] = "!<arch>\n";
    char buf[sizeof armag - 1];
    int fd;

    if ((fd = open(gn->path, O_RDONLY)) == -1)
	return FALSE;

    if (read(fd, buf, sizeof buf) != sizeof buf) {
	(void)close(fd);
	return FALSE;
    }

    (void)close(fd);

    return memcmp(buf, armag, sizeof buf) == 0;
}