/*      $NetBSD: arch.c,v 1.223 2025/06/28 22:39:27 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 cached and the archive closed again.  All cached 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_UpdateMTime
*                      Find the modification time of a member of
*                      an archive *in the archive* and place it in the
*                      member's GNode.
*
*      Arch_UpdateMemberMTime
*                      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 1.223 2025/06/28 22:39:27 rillig Exp $");

typedef struct List ArchList;
typedef struct ListNode ArchListNode;

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

typedef struct Arch {
       char *name;
       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(Arch *a)
{
       HashIter hi;

       HashIter_Init(&hi, &a->members);
       while (HashIter_Next(&hi))
               free(hi.entry->value);

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

/* Return "archive(member)". */
MAKE_ATTR_NOINLINE static char *
FullName(const char *archive, const char *member)
{
       Buffer buf;
       Buf_Init(&buf);
       Buf_AddStr(&buf, archive);
       Buf_AddStr(&buf, "(");
       Buf_AddStr(&buf, member);
       Buf_AddStr(&buf, ")");
       return Buf_DoneData(&buf);
}

/*
* Parse an archive specification such as "archive.a(member1 member2.${EXT})",
* adding nodes for the expanded members to gns.  If successful, advance pp
* beyond the archive specification and any trailing whitespace.
*/
bool
Arch_ParseArchive(char **pp, GNodeList *gns, GNode *scope)
{
       char *spec;             /* For modifying some bytes of *pp */
       const char *cp;         /* Pointer into line */
       GNode *gn;              /* New node */
       FStr lib;               /* Library-part of specification */
       FStr mem;               /* Member-part of specification */
       char saveChar;          /* Ending delimiter of member-name */
       bool expandLib;         /* Whether the parsed lib contains
                                * expressions that need to be expanded */

       spec = *pp;
       lib = FStr_InitRefer(spec);
       expandLib = false;

       for (cp = lib.str; *cp != '(' && *cp != '\0';) {
               if (*cp == '$') {
                       /* Expand nested expressions. */
                       /* XXX: This code can probably be shortened. */
                       const char *nested_p = cp;
                       FStr result;
                       bool isError;

                       /* XXX: is expanded twice: once here and once below */
                       result = Var_Parse(&nested_p, scope,
                           VARE_EVAL_DEFINED);
                       /* TODO: handle errors */
                       isError = result.str == var_Error;
                       FStr_Done(&result);
                       if (isError)
                               return false;

                       expandLib = true;
                       cp += nested_p - cp;
               } else
                       cp++;
       }

       spec[cp++ - spec] = '\0';
       if (expandLib)
               Var_Expand(&lib, scope, VARE_EVAL_DEFINED);

       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 doSubst = false;

               cpp_skip_whitespace(&cp);

               mem = FStr_InitRefer(cp);
               while (*cp != '\0' && *cp != ')' && !ch_isspace(*cp)) {
                       if (*cp == '$') {
                               /* Expand nested expressions. */
                               /*
                                * XXX: This code can probably be shortened.
                                */
                               FStr result;
                               bool isError;
                               const char *nested_p = cp;

                               result = Var_Parse(&nested_p, scope,
                                   VARE_EVAL_DEFINED);
                               /* TODO: handle errors */
                               isError = result.str == var_Error;
                               FStr_Done(&result);

                               if (isError)
                                       return false;

                               doSubst = true;
                               cp += nested_p - cp;
                       } else {
                               cp++;
                       }
               }

               if (*cp == '\0') {
                       Parse_Error(PARSE_FATAL,
                           "Missing \")\" in archive specification");
                       return false;
               }

               if (cp == mem.str)
                       break;

               saveChar = *cp;
               spec[cp - spec] = '\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 slows down archive specs with dynamic sources, since
                * they are (non-)substituted three times, but we need to do
                * this since SuffExpandChildren calls us, otherwise we could
                * assume the substitutions would be taken care of later.
                */
               if (doSubst) {
                       char *fullName;
                       char *p;
                       const char *unexpandedMem = mem.str;

                       Var_Expand(&mem, scope, VARE_EVAL_DEFINED);

                       /*
                        * Now form an archive spec and recurse to deal with
                        * nested variables and multi-word variable values.
                        */
                       fullName = FullName(lib.str, mem.str);
                       p = fullName;

                       if (strcmp(mem.str, unexpandedMem) == 0) {
                               /*
                                * Must contain dynamic sources, so we can't
                                * deal with it now. Just create an ARCHV node
                                * and let SuffExpandChildren handle it.
                                */
                               gn = Targ_GetNode(fullName);
                               gn->type |= OP_ARCHV;
                               Lst_Append(gns, gn);

                       } else if (!Arch_ParseArchive(&p, gns, scope)) {
                               /* Error in nested call. */
                               free(fullName);
                               /* XXX: does unexpandedMemName leak? */
                               return false;
                       }
                       free(fullName);
                       /* XXX: does unexpandedMemName leak? */

               } else if (Dir_HasWildcards(mem.str)) {
                       StringList members = LST_INIT;
                       SearchPath_Expand(&dirSearchPath, mem.str, &members);

                       while (!Lst_IsEmpty(&members)) {
                               char *member = Lst_Dequeue(&members);
                               char *fullname = FullName(lib.str, member);
                               free(member);

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

                               gn->type |= OP_ARCHV;
                               Lst_Append(gns, gn);
                       }
                       Lst_Done(&members);

               } else {
                       char *fullname = FullName(lib.str, mem.str);
                       gn = Targ_GetNode(fullname);
                       free(fullname);

                       gn->type |= OP_ARCHV;
                       Lst_Append(gns, gn);
               }
               FStr_Done(&mem);

               spec[cp - spec] = saveChar;
       }

       FStr_Done(&lib);

       cp++;                   /* skip the ')' */
       cpp_skip_whitespace(&cp);
       *pp += cp - *pp;
       return true;
}

/*
* Locate a member in an archive.
*
* See ArchFindMember for an almost identical copy of this code.
*/
static struct ar_hdr *
ArchStatMember(const char *archive, const char *member, bool addToCache)
{
#define AR_MAX_NAME_LEN (sizeof arh.ar_name - 1)
       FILE *arch;
       size_t size;            /* Size of archive member */
       char magic[SARMAG];
       ArchListNode *ln;
       Arch *ar;
       struct ar_hdr arh;
       char memName[MAXPATHLEN + 1];
       /* Current member name while hashing. */

       member = str_basename(member);

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

       if (!addToCache) {
               /*
                * Since the archive is not to be cached, assume there's no
                * need to allocate the header, 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;
       }

       arch = fopen(archive, "r");
       if (arch == NULL)
               return NULL;

       if (fread(magic, SARMAG, 1, arch) != 1 ||
           strncmp(magic, ARMAG, SARMAG) != 0) {
               (void)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) {
               char *nameend;

               if (strncmp(arh.ar_fmag, ARFMAG, sizeof arh.ar_fmag) != 0)
                       goto bad_archive;

               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 > memName && *nameend == ' ')
                       nameend--;
               nameend[1] = '\0';

#ifdef SVR4ARCHIVES
               /*
                * svr4 names are slash-terminated.
                * Also svr4 extended the AR format.
                */
               if (memName[0] == '/') {
                       /* svr4 magic mode; handle it */
                       switch (ArchSVR4Entry(ar, memName, size, arch)) {
                       case -1:        /* Invalid data */
                               goto bad_archive;
                       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])) {

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

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

               {
                       struct ar_hdr *cached_hdr = bmake_malloc(
                           sizeof *cached_hdr);
                       memcpy(cached_hdr, &arh, sizeof arh);
                       HashTable_Set(&ar->members, memName, cached_hdr);
               }

               /* Files are padded with newlines to an even-byte boundary. */
               if (fseek(arch, ((long)size + 1) & ~1, SEEK_CUR) != 0)
                       goto bad_archive;
       }

       fclose(arch);

       Lst_Append(&archives, ar);

       return HashTable_FindValue(&ar->members, member);

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

#ifdef SVR4ARCHIVES
/*
* 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 bool
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] == '/' && ar_name[namelen + 1] == ' ')
               return true;

       return false;
}

/*
* Load the header of an archive member.  The mode is "r" for read-only
* access, "r+" for read-write access.
*
* Upon successful return, the archive file is positioned at the start of the
* member's struct ar_hdr.  In case of a failure or if the member doesn't
* exist, return NULL.
*
* See ArchStatMember for an almost identical copy of this code.
*/
static FILE *
ArchFindMember(const char *archive, const char *member,
              struct ar_hdr *out_arh, const char *mode)
{
       FILE *arch;
       int size;               /* Size of archive member */
       char magic[SARMAG];
       size_t len;

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

       if (fread(magic, SARMAG, 1, arch) != 1 ||
           strncmp(magic, ARMAG, SARMAG) != 0) {
               fclose(arch);
               return NULL;
       }

       /* Files are archived using their basename, not the entire path. */
       member = str_basename(member);
       len = strlen(member);

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

               if (strncmp(out_arh->ar_fmag, ARFMAG,
                           sizeof out_arh->ar_fmag) != 0) {
                       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)) {
                       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]))) {
                       size_t elen = (size_t)atoi(
                           &out_arh->ar_name[sizeof AR_EFMT1 - 1]);
                       char ename[MAXPATHLEN + 1];

                       if (elen > MAXPATHLEN) {
                               fclose(arch);
                               return NULL;
                       }
                       if (fread(ename, elen, 1, arch) != 1) {
                               fclose(arch);
                               return NULL;
                       }
                       ename[elen] = '\0';
                       if (DEBUG(ARCH) || DEBUG(MAKE))
                               debug_printf(
                                   "ArchFindMember: "
                                   "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, -(long)elen, SEEK_CUR) != 0) {
                               fclose(arch);
                               return NULL;
                       }
               }
#endif

               /* Advance to the next member. */
               out_arh->ar_size[sizeof out_arh->ar_size - 1] = '\0';
               size = (int)strtol(out_arh->ar_size, NULL, 10);
               /* Files are padded with newlines to an even-byte boundary. */
               if (fseek(arch, (size + 1) & ~1L, SEEK_CUR) != 0) {
                       fclose(arch);
                       return NULL;
               }
       }

       fclose(arch);
       return NULL;
}

/*
* Update the ar_date of the member of an archive, on disk but not in the
* GNode.  Update the st_mtime of the entire archive as well.  For a library,
* it may be required to run ranlib after this.
*/
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).
*/
void
Arch_UpdateMTime(GNode *gn)
{
       struct ar_hdr *arh;

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

/*
* Given a nonexistent archive member's node, update gn->mtime from its
* archived form, if it exists.
*/
void
Arch_UpdateMemberMTime(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) {
                               Arch_UpdateMTime(pgn);
                               gn->mtime = pgn->mtime;
                       }
               } 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;
               }
       }
}

/*
* 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.
*/
void
Arch_FindLib(GNode *gn, SearchPath *path)
{
       char *libName = str_concat3("lib", gn->name + 2, ".a");
       gn->path = Dir_FindFile(libName, path);
       free(libName);

       Var_Set(gn, TARGET, gn->name);
}

static bool
RanlibOODate(const GNode *gn MAKE_ATTR_UNUSED)
{
#ifdef RANLIBMAG
       struct ar_hdr *arh;     /* Header for __.SYMDEF */
       int tocModTime;         /* The table-of-contents' mod time */

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

       if (arh == NULL) {
               /* A library without a table of contents is out-of-date. */
               if (DEBUG(ARCH) || DEBUG(MAKE))
                       debug_printf("no toc...");
               return true;
       }

       tocModTime = (int)strtol(arh->ar_date, NULL, 10);

       if (DEBUG(ARCH) || DEBUG(MAKE))
               debug_printf("%s modified %s...",
                   RANLIBMAG, Targ_FmtTime(tocModTime));
       return gn->youngestChild == NULL ||
              gn->youngestChild->mtime > tocModTime;
#else
       return false;
#endif
}

/*
* Decide if a node with the OP_LIB attribute is out-of-date.
* 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 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.
*/
bool
Arch_LibOODate(GNode *gn)
{

       if (gn->type & OP_PHONY)
               return true;
       if (!GNode_IsTarget(gn) && Lst_IsEmpty(&gn->children))
               return false;
       if ((!Lst_IsEmpty(&gn->children) && gn->youngestChild == NULL) ||
                  (gn->mtime > now) ||
                  (gn->youngestChild != NULL &&
                   gn->mtime < gn->youngestChild->mtime))
               return true;
       return RanlibOODate(gn);
}

/* Initialize the archives module. */
void
Arch_Init(void)
{
       Lst_Init(&archives);
}

#ifdef CLEANUP
/* Clean up the archives module. */
void
Arch_End(void)
{
       ArchListNode *ln;

       for (ln = archives.first; ln != NULL; ln = ln->next)
               ArchFree(ln->datum);
       Lst_Done(&archives);
}
#endif

bool
Arch_IsLib(GNode *gn)
{
       char buf[8];
       int fd;
       bool isLib;

       if ((fd = open(gn->path, O_RDONLY)) == -1)
               return false;
       isLib = read(fd, buf, sizeof buf) == sizeof buf
           && memcmp(buf, "!<arch>\n", sizeof buf) == 0;
       (void)close(fd);
       return isLib;
}