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/*
 * ar - portable (ascii) format version
 */
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <mach.h>
#include <ar.h>

/*
 *      The algorithm uses up to 3 temp files.  The "pivot member" is the
 *      archive member specified by and a, b, or i option.  The temp files are
 *      astart - contains existing members up to and including the pivot member.
 *      amiddle - contains new files moved or inserted behind the pivot.
 *      aend - contains the existing members that follow the pivot member.
 *      When all members have been processed, function 'install' streams the
 *      temp files, in order, back into the archive.
 */

typedef struct  Arsymref
{
        char    *name;
        int     type;
        int     len;
        vlong   offset;
        struct  Arsymref *next;
} Arsymref;

typedef struct  Armember        /* Temp file entry - one per archive member */
{
        struct Armember *next;
        struct ar_hdr   hdr;
        long            size;
        long            date;
        void            *member;
} Armember;

typedef struct Arfile           /* Temp file control block - one per tempfile */
{
        int     paged;          /* set when some data paged to disk */
        char    *fname;         /* paging file name */
        int     fd;             /* paging file descriptor */
        vlong   size;
        Armember *head;         /* head of member chain */
        Armember *tail;         /* tail of member chain */
        Arsymref *sym;          /* head of defined symbol chain */
} Arfile;

typedef struct Hashchain
{
        char    *name;
        struct Hashchain *next;
} Hashchain;

#define NHASH   1024

/*
 *      macro to portably read/write archive header.
 *      'cmd' is read/write/Bread/Bwrite, etc.
 */
#define HEADER_IO(cmd, f, h)    cmd(f, h.name, sizeof(h.name)) != sizeof(h.name)\
                                || cmd(f, h.date, sizeof(h.date)) != sizeof(h.date)\
                                || cmd(f, h.uid, sizeof(h.uid)) != sizeof(h.uid)\
                                || cmd(f, h.gid, sizeof(h.gid)) != sizeof(h.gid)\
                                || cmd(f, h.mode, sizeof(h.mode)) != sizeof(h.mode)\
                                || cmd(f, h.size, sizeof(h.size)) != sizeof(h.size)\
                                || cmd(f, h.fmag, sizeof(h.fmag)) != sizeof(h.fmag)

                /* constants and flags */
char    *man =          "mrxtdpq";
char    *opt =          "uvnbailo";
char    artemp[] =      "/tmp/vXXXXX";
char    movtemp[] =     "/tmp/v1XXXXX";
char    tailtemp[] =    "/tmp/v2XXXXX";
char    symdef[] =      "__.SYMDEF";

int     aflag;                          /* command line flags */
int     bflag;
int     cflag;
int     oflag;
int     uflag;
int     vflag;

Arfile *astart, *amiddle, *aend;        /* Temp file control block pointers */
int     allobj = 1;                     /* set when all members are object files of the same type */
int     symdefsize;                     /* size of symdef file */
int     dupfound;                       /* flag for duplicate symbol */
Hashchain       *hash[NHASH];           /* hash table of text symbols */
        
#define ARNAMESIZE      sizeof(astart->tail->hdr.name)

char    poname[ARNAMESIZE+1];           /* name of pivot member */
char    *file;                          /* current file or member being worked on */
Biobuf  bout;
Biobuf bar;

void    arcopy(Biobuf*, Arfile*, Armember*);
int     arcreate(char*);
void    arfree(Arfile*);
void    arinsert(Arfile*, Armember*);
char    *armalloc(int);
void    armove(Biobuf*, Arfile*, Armember*);
void    arread(Biobuf*, Armember*, int);
void    arstream(int, Arfile*);
int     arwrite(int, Armember*);
int     bamatch(char*, char*);
int     duplicate(char*);
Armember *getdir(Biobuf*);
int     getspace(void);
void    install(char*, Arfile*, Arfile*, Arfile*, int);
void    longt(Armember*);
int     match(int, char**);
void    mesg(int, char*);
Arfile  *newtempfile(char*);
Armember *newmember(void);
void    objsym(Sym*, void*);
int     openar(char*, int, int);
int     page(Arfile*);
void    pmode(long);
void    rl(int);
void    scanobj(Biobuf*, Arfile*, long);
void    select(int*, long);
void    setcom(void(*)(char*, int, char**));
void    skip(Biobuf*, vlong);
int     symcomp(void*, void*);
void    trim(char*, char*, int);
void    usage(void);
void    wrerr(void);
void    wrsym(Biobuf*, long, Arsymref*);

void    rcmd(char*, int, char**);               /* command processing */
void    dcmd(char*, int, char**);
void    xcmd(char*, int, char**);
void    tcmd(char*, int, char**);
void    pcmd(char*, int, char**);
void    mcmd(char*, int, char**);
void    qcmd(char*, int, char**);
void    (*comfun)(char*, int, char**);

void
main(int argc, char *argv[])
{
        char *cp;

        Binit(&bout, 1, OWRITE);
        if(argc < 3)
                usage();
        for (cp = argv[1]; *cp; cp++) {
                switch(*cp) {
                case 'a':       aflag = 1;      break;
                case 'b':       bflag = 1;      break;
                case 'c':       cflag = 1;      break;
                case 'd':       setcom(dcmd);   break;
                case 'i':       bflag = 1;      break;
                case 'l':
                                strcpy(artemp, "vXXXXX");
                                strcpy(movtemp, "v1XXXXX");
                                strcpy(tailtemp, "v2XXXXX");
                                break;
                case 'm':       setcom(mcmd);   break;
                case 'o':       oflag = 1;      break;
                case 'p':       setcom(pcmd);   break;
                case 'q':       setcom(qcmd);   break;
                case 'r':       setcom(rcmd);   break;
                case 't':       setcom(tcmd);   break;
                case 'u':       uflag = 1;      break;
                case 'v':       vflag = 1;      break;
                case 'x':       setcom(xcmd);   break;
                default:
                        fprint(2, "ar: bad option `%c'\n", *cp);
                        exits("error");
                }
        }
        if (aflag && bflag) {
                fprint(2, "ar: only one of 'a' and 'b' can be specified\n");
                usage();
        }
        if(aflag || bflag) {
                trim(argv[2], poname, sizeof(poname));
                argv++;
                argc--;
                if(argc < 3)
                        usage();
        }
        if(comfun == 0) {
                if(uflag == 0) {
                        fprint(2, "ar: one of [%s] must be specified\n", man);
                        usage();
                }
                setcom(rcmd);
        }
        cp = argv[2];
        argc -= 3;
        argv += 3;
        (*comfun)(cp, argc, argv);      /* do the command */
        cp = 0;
        while (argc--) {
                if (*argv) {
                        fprint(2, "ar: %s not found\n", *argv);
                        cp = "error";
                }
                argv++;
        }
        exits(cp);
}
/*
 *      select a command
 */
void
setcom(void (*fun)(char *, int, char**))
{

        if(comfun != 0) {
                fprint(2, "ar: only one of [%s] allowed\n", man);
                usage();
        }
        comfun = fun;
}
/*
 *      perform the 'r' and 'u' commands
 */
void
rcmd(char *arname, int count, char **files)
{
        int fd;
        int i;
        Arfile *ap;
        Armember *bp;
        Dir *d;
        Biobuf *bfile;

        fd = openar(arname, ORDWR, 1);
        if (fd >= 0) {
                Binit(&bar, fd, OREAD);
                Bseek(&bar,seek(fd,0,1), 1);
        }
        astart = newtempfile(artemp);
        ap = astart;
        aend = 0;
        for(i = 0; fd >= 0; i++) {
                bp = getdir(&bar);
                if (!bp)
                        break;
                if (bamatch(file, poname)) {            /* check for pivot */
                        aend = newtempfile(tailtemp);
                        ap = aend;
                }
                        /* pitch symdef file */
                if (i == 0 && strcmp(file, symdef) == 0) {
                        skip(&bar, bp->size);
                        continue;
                }
                if (count && !match(count, files)) {
                        scanobj(&bar, ap, bp->size);
                        arcopy(&bar, ap, bp);
                        continue;
                }
                bfile = Bopen(file, OREAD);
                if (!bfile) {
                        if (count != 0)
                                fprint(2, "ar: cannot open %s\n", file);
                        scanobj(&bar, ap, bp->size);
                        arcopy(&bar, ap, bp);
                        continue;
                }
                d = dirfstat(Bfildes(bfile));
                if(d == nil)
                        fprint(2, "ar: cannot stat %s: %r\n", file);
                if (uflag && (d==nil || d->mtime <= bp->date)) {
                        scanobj(&bar, ap, bp->size);
                        arcopy(&bar, ap, bp);
                        Bterm(bfile);
                        free(d);
                        continue;
                }
                mesg('r', file);
                skip(&bar, bp->size);
                scanobj(bfile, ap, d->length);
                free(d);
                armove(bfile, ap, bp);
                Bterm(bfile);
        }
        if(fd >= 0)
                close(fd);
                /* copy in remaining files named on command line */
        for (i = 0; i < count; i++) {
                file = files[i];
                if(file == 0)
                        continue;
                files[i] = 0;
                bfile = Bopen(file, OREAD);
                if (!bfile)
                        fprint(2, "ar: %s cannot open\n", file);
                else {
                        mesg('a', file);
                        d = dirfstat(Bfildes(bfile));
                        if (d == nil)
                                fprint(2, "can't stat %s\n", file);
                        else {
                                scanobj(bfile, astart, d->length);
                                armove(bfile, astart, newmember());
                                free(d);
                        }
                        Bterm(bfile);
                }
        }
        if(fd < 0 && !cflag)
                install(arname, astart, 0, aend, 1);    /* issue 'creating' msg */
        else
                install(arname, astart, 0, aend, 0);
}

void
dcmd(char *arname, int count, char **files)
{
        Armember *bp;
        int fd, i;

        if (!count)
                return;
        fd = openar(arname, ORDWR, 0);
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        astart = newtempfile(artemp);
        for (i = 0; bp = getdir(&bar); i++) {
                if(match(count, files)) {
                        mesg('d', file);
                        skip(&bar, bp->size);
                        if (strcmp(file, symdef) == 0)
                                allobj = 0;
                } else if (i == 0 && strcmp(file, symdef) == 0)
                                skip(&bar, bp->size);
                else {
                        scanobj(&bar, astart, bp->size);
                        arcopy(&bar, astart, bp);
                }
        }
        close(fd);
        install(arname, astart, 0, 0, 0);
}

void
xcmd(char *arname, int count, char **files)
{
        int fd, f, mode, i;
        Armember *bp;
        Dir dx;

        fd = openar(arname, OREAD, 0);
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        i = 0;
        while (bp = getdir(&bar)) {
                if(count == 0 || match(count, files)) {
                        mode = strtoul(bp->hdr.mode, 0, 8) & 0777;
                        f = create(file, OWRITE, mode);
                        if(f < 0) {
                                fprint(2, "ar: %s cannot create\n", file);
                                skip(&bar, bp->size);
                        } else {
                                mesg('x', file);
                                arcopy(&bar, 0, bp);
                                if (write(f, bp->member, bp->size) < 0)
                                        wrerr();
                                if(oflag) {
                                        nulldir(&dx);
                                        dx.atime = bp->date;
                                        dx.mtime = bp->date;
                                        if(dirwstat(file, &dx) < 0)
                                                perror(file);
                                }
                                free(bp->member);
                                close(f);
                        }
                        free(bp);
                        if (count && ++i >= count)
                                break;
                } else {
                        skip(&bar, bp->size);
                        free(bp);
                }
        }
        close(fd);
}
void
pcmd(char *arname, int count, char **files)
{
        int fd;
        Armember *bp;

        fd = openar(arname, OREAD, 0);
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        while(bp = getdir(&bar)) {
                if(count == 0 || match(count, files)) {
                        if(vflag)
                                print("\n<%s>\n\n", file);
                        arcopy(&bar, 0, bp);
                        if (write(1, bp->member, bp->size) < 0)
                                wrerr();
                } else
                        skip(&bar, bp->size);
                free(bp);
        }
        close(fd);
}
void
mcmd(char *arname, int count, char **files)
{
        int fd, i;
        Arfile *ap;
        Armember *bp;

        if (count == 0)
                return;
        fd = openar(arname, ORDWR, 0);
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        astart = newtempfile(artemp);
        amiddle = newtempfile(movtemp);
        aend = 0;
        ap = astart;
        for (i = 0; bp = getdir(&bar); i++) {
                if (bamatch(file, poname)) {
                        aend = newtempfile(tailtemp);
                        ap = aend;
                }
                if(match(count, files)) {
                        mesg('m', file);
                        scanobj(&bar, amiddle, bp->size);
                        arcopy(&bar, amiddle, bp);
                } else
                        /*
                         * pitch the symdef file if it is at the beginning
                         * of the archive and we aren't inserting in front
                         * of it (ap == astart).
                         */
                if (ap == astart && i == 0 && strcmp(file, symdef) == 0)
                        skip(&bar, bp->size);
                else {
                        scanobj(&bar, ap, bp->size);
                        arcopy(&bar, ap, bp);
                }
        }
        close(fd);
        if (poname[0] && aend == 0)
                fprint(2, "ar: %s not found - files moved to end.\n", poname);
        install(arname, astart, amiddle, aend, 0);
}
void
tcmd(char *arname, int count, char **files)
{
        int fd;
        Armember *bp;
        char name[ARNAMESIZE+1];

        fd = openar(arname, OREAD, 0);
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        while(bp = getdir(&bar)) {
                if(count == 0 || match(count, files)) {
                        if(vflag)
                                longt(bp);
                        trim(file, name, ARNAMESIZE);
                        Bprint(&bout, "%s\n", name);
                }
                skip(&bar, bp->size);
                free(bp);
        }
        close(fd);
}
void
qcmd(char *arname, int count, char **files)
{
        int fd, i;
        Armember *bp;
        Biobuf *bfile;

        if(aflag || bflag) {
                fprint(2, "ar: abi not allowed with q\n");
                exits("error");
        }
        fd = openar(arname, ORDWR, 1);
        if (fd < 0) {
                if(!cflag)
                        fprint(2, "ar: creating %s\n", arname);
                fd = arcreate(arname);
        }
        Binit(&bar, fd, OREAD);
        Bseek(&bar,seek(fd,0,1), 1);
        /* leave note group behind when writing archive; i.e. sidestep interrupts */
        rfork(RFNOTEG);
        Bseek(&bar, 0, 2);
        bp = newmember();
        for(i=0; i<count && files[i]; i++) {
                file = files[i];
                files[i] = 0;
                bfile = Bopen(file, OREAD);
                if(!bfile)
                        fprint(2, "ar: %s cannot open\n", file);
                else {
                        mesg('q', file);
                        armove(bfile, 0, bp);
                        if (!arwrite(fd, bp))
                                wrerr();
                        free(bp->member);
                        bp->member = 0;
                        Bterm(bfile);
                }
        }
        free(bp);
        close(fd);
}

/*
 *      extract the symbol references from an object file
 */
void
scanobj(Biobuf *b, Arfile *ap, long size)
{
        int obj;
        vlong offset;
        Dir *d;
        static int lastobj = -1;

        if (!allobj)                    /* non-object file encountered */
                return;
        offset = Boffset(b);
        obj = objtype(b, 0);
        if (obj < 0) {                  /* not an object file */
                allobj = 0;
                d = dirfstat(Bfildes(b));
                if (d != nil && d->length == 0)
                        fprint(2, "ar: zero length file %s\n", file);
                free(d);
                Bseek(b, offset, 0);
                return;
        }
        if (lastobj >= 0 && obj != lastobj) {
                fprint(2, "ar: inconsistent object file %s\n", file);
                allobj = 0;
                Bseek(b, offset, 0);
                return;
        }
        lastobj = obj;
        if (!readar(b, obj, offset+size, 0)) {
                fprint(2, "ar: invalid symbol reference in file %s\n", file);
                allobj = 0;
                Bseek(b, offset, 0);
                return;
        }
        Bseek(b, offset, 0);
        objtraverse(objsym, ap);
}

/*
 *      add text and data symbols to the symbol list
 */
void
objsym(Sym *s, void *p)
{
        int n;
        Arsymref *as;
        Arfile *ap;

        if (s->type != 'T' &&  s->type != 'D')
                return;
        ap = (Arfile*)p;
        as = (Arsymref*)armalloc(sizeof(Arsymref));
        as->offset = ap->size;
        n = strlen(s->name);
        as->name = armalloc(n+1);
        strcpy(as->name, s->name);
        if(s->type == 'T' && duplicate(as->name)) {
                dupfound = 1;
                fprint(2, "duplicate text symbol: %s\n", as->name);
                free(as->name);
                free(as);
                return;
        }
        as->type = s->type;
        symdefsize += 4+(n+1)+1;
        as->len = n;
        as->next = ap->sym;
        ap->sym = as;
}

/*
 *      Check the symbol table for duplicate text symbols
 */
int
duplicate(char *name)
{
        Hashchain *p;
        char *cp;
        int h;

        h = 0;
        for(cp = name; *cp; h += *cp++)
                h *= 1119;
        if(h < 0)
                h = ~h;
        h %= NHASH;

        for(p = hash[h]; p; p = p->next)
                if(strcmp(p->name, name) == 0)
                        return 1;
        p = (Hashchain*) armalloc(sizeof(Hashchain));
        p->next = hash[h];
        p->name = name;
        hash[h] = p;
        return 0;
}

/*
 *      open an archive and validate its header
 */
int
openar(char *arname, int mode, int errok)
{
        int fd;
        char mbuf[SARMAG];

        fd = open(arname, mode);
        if(fd >= 0){
                if(read(fd, mbuf, SARMAG) != SARMAG || strncmp(mbuf, ARMAG, SARMAG)) {
                        fprint(2, "ar: %s not in archive format\n", arname);
                        exits("error");
                }
        }else if(!errok){
                fprint(2, "ar: cannot open %s: %r\n", arname);
                exits("error");
        }
        return fd;
}

/*
 *      create an archive and set its header
 */
int
arcreate(char *arname)
{
        int fd;

        fd = create(arname, OWRITE, 0664);
        if(fd < 0){
                fprint(2, "ar: cannot create %s: %r\n", arname);
                exits("error");
        }
        if(write(fd, ARMAG, SARMAG) != SARMAG)
                wrerr();
        return fd;
}

/*
 *              error handling
 */
void
wrerr(void)
{
        perror("ar: write error");
        exits("error");
}

void
rderr(void)
{
        perror("ar: read error");
        exits("error");
}

void
phaseerr(int offset)
{
        fprint(2, "ar: phase error at offset %d\n", offset);
        exits("error");
}

void
usage(void)
{
        fprint(2, "usage: ar [%s][%s] archive files ...\n", opt, man);
        exits("error");
}

/*
 *      read the header for the next archive member
 */
Armember *
getdir(Biobuf *b)
{
        Armember *bp;
        char *cp;
        static char name[ARNAMESIZE+1];

        bp = newmember();
        if(HEADER_IO(Bread, b, bp->hdr)) {
                free(bp);
                return 0;
        }
        if(strncmp(bp->hdr.fmag, ARFMAG, sizeof(bp->hdr.fmag)) != 0)
                phaseerr(Boffset(b));
        strncpy(name, bp->hdr.name, sizeof(bp->hdr.name));
        cp = name+sizeof(name)-1;
        *cp = '\0';
        /* skip trailing spaces and (gnu-produced) slashes */
        while(*--cp == ' ' || *cp == '/')
                ;
        cp[1] = '\0';
        file = name;
        bp->date = strtol(bp->hdr.date, 0, 0);
        bp->size = strtol(bp->hdr.size, 0, 0);
        return bp;
}

/*
 *      Copy the file referenced by fd to the temp file
 */
void
armove(Biobuf *b, Arfile *ap, Armember *bp)
{
        char *cp;
        Dir *d;

        d = dirfstat(Bfildes(b));
        if (d == nil) {
                fprint(2, "ar: cannot stat %s\n", file);
                return;
        }
        trim(file, bp->hdr.name, sizeof(bp->hdr.name));
        for (cp = strchr(bp->hdr.name, 0);              /* blank pad on right */
                cp < bp->hdr.name+sizeof(bp->hdr.name); cp++)
                        *cp = ' ';
        sprint(bp->hdr.date, "%-12ld", d->mtime);
        sprint(bp->hdr.uid, "%-6d", 0);
        sprint(bp->hdr.gid, "%-6d", 0);
        sprint(bp->hdr.mode, "%-8lo", d->mode);
        sprint(bp->hdr.size, "%-10lld", d->length);
        strncpy(bp->hdr.fmag, ARFMAG, 2);
        bp->size = d->length;
        arread(b, bp, bp->size);
        if (d->length&0x01)
                d->length++;
        if (ap) {
                arinsert(ap, bp);
                ap->size += d->length+SAR_HDR;
        }
        free(d);
}

/*
 *      Copy the archive member at the current offset into the temp file.
 */
void
arcopy(Biobuf *b, Arfile *ap, Armember *bp)
{
        long n;

        n = bp->size;
        if (n & 01)
                n++;
        arread(b, bp, n);
        if (ap) {
                arinsert(ap, bp);
                ap->size += n+SAR_HDR;
        }
}

/*
 *      Skip an archive member
 */
void
skip(Biobuf *bp, vlong len)
{
        if (len & 01)
                len++;
        Bseek(bp, len, 1);
}

/*
 *      Stream the three temp files to an archive
 */
void
install(char *arname, Arfile *astart, Arfile *amiddle, Arfile *aend, int createflag)
{
        int fd;

        if(allobj && dupfound) {
                fprint(2, "%s not changed\n", arname);
                return;
        }
        /* leave note group behind when copying back; i.e. sidestep interrupts */
        rfork(RFNOTEG);

        if(createflag)
                fprint(2, "ar: creating %s\n", arname);
        fd = arcreate(arname);

        if(allobj)
                rl(fd);

        if (astart) {
                arstream(fd, astart);
                arfree(astart);
        }
        if (amiddle) {
                arstream(fd, amiddle);
                arfree(amiddle);
        }
        if (aend) {
                arstream(fd, aend);
                arfree(aend);
        }
        close(fd);
}

void
rl(int fd)
{

        Biobuf b;
        char *cp;
        struct ar_hdr a;
        long len;

        Binit(&b, fd, OWRITE);
        Bseek(&b,seek(fd,0,1), 0);

        len = symdefsize;
        if(len&01)
                len++;
        sprint(a.date, "%-12ld", time(0));
        sprint(a.uid, "%-6d", 0);
        sprint(a.gid, "%-6d", 0);
        sprint(a.mode, "%-8lo", 0644L);
        sprint(a.size, "%-10ld", len);
        strncpy(a.fmag, ARFMAG, 2);
        strcpy(a.name, symdef);
        for (cp = strchr(a.name, 0);            /* blank pad on right */
                cp < a.name+sizeof(a.name); cp++)
                        *cp = ' ';
        if(HEADER_IO(Bwrite, &b, a))
                        wrerr();

        len += Boffset(&b);
        if (astart) {
                wrsym(&b, len, astart->sym);
                len += astart->size;
        }
        if(amiddle) {
                wrsym(&b, len, amiddle->sym);
                len += amiddle->size;
        }
        if(aend)
                wrsym(&b, len, aend->sym);

        if(symdefsize&0x01)
                Bputc(&b, 0);
        Bterm(&b);
}

/*
 *      Write the defined symbols to the symdef file
 */
void
wrsym(Biobuf *bp, long offset, Arsymref *as)
{
        int off;

        while(as) {
                Bputc(bp, as->type);
                off = as->offset+offset;
                Bputc(bp, off);
                Bputc(bp, off>>8);
                Bputc(bp, off>>16);
                Bputc(bp, off>>24);
                if (Bwrite(bp, as->name, as->len+1) != as->len+1)
                        wrerr();
                as = as->next;
        }
}

/*
 *      Check if the archive member matches an entry on the command line.
 */
int
match(int count, char **files)
{
        int i;
        char name[ARNAMESIZE+1];

        for(i=0; i<count; i++) {
                if(files[i] == 0)
                        continue;
                trim(files[i], name, ARNAMESIZE);
                if(strncmp(name, file, ARNAMESIZE) == 0) {
                        file = files[i];
                        files[i] = 0;
                        return 1;
                }
        }
        return 0;
}

/*
 *      compare the current member to the name of the pivot member
 */
int
bamatch(char *file, char *pivot)
{
        static int state = 0;

        switch(state)
        {
        case 0:                  /* looking for position file */
                if (aflag) {
                        if (strncmp(file, pivot, ARNAMESIZE) == 0)
                                state = 1;
                } else if (bflag) {
                        if (strncmp(file, pivot, ARNAMESIZE) == 0) {
                                state = 2;      /* found */
                                return 1;
                        }
                }
                break;
        case 1:                 /* found - after previous file */
                state = 2;
                return 1;
        case 2:                 /* already found position file */
                break;
        }
        return 0;
}

/*
 *      output a message, if 'v' option was specified
 */
void
mesg(int c, char *file)
{

        if(vflag)
                Bprint(&bout, "%c - %s\n", c, file);
}

/*
 *      isolate file name by stripping leading directories and trailing slashes
 */
void
trim(char *s, char *buf, int n)
{
        char *p;

        for(;;) {
                p = strrchr(s, '/');
                if (!p) {               /* no slash in name */
                        strncpy(buf, s, n);
                        return;
                }
                if (p[1] != 0) {        /* p+1 is first char of file name */
                        strncpy(buf, p+1, n);
                        return;
                }
                *p = 0;                 /* strip trailing slash */
        }
}

/*
 *      utilities for printing long form of 't' command
 */
#define SUID    04000
#define SGID    02000
#define ROWN    0400
#define WOWN    0200
#define XOWN    0100
#define RGRP    040
#define WGRP    020
#define XGRP    010
#define ROTH    04
#define WOTH    02
#define XOTH    01
#define STXT    01000

void
longt(Armember *bp)
{
        char *cp;

        pmode(strtoul(bp->hdr.mode, 0, 8));
        Bprint(&bout, "%3ld/%1ld", strtol(bp->hdr.uid, 0, 0), strtol(bp->hdr.gid, 0, 0));
        Bprint(&bout, "%7ld", bp->size);
        cp = ctime(bp->date);
        Bprint(&bout, " %-12.12s %-4.4s ", cp+4, cp+24);
}

int     m1[] = { 1, ROWN, 'r', '-' };
int     m2[] = { 1, WOWN, 'w', '-' };
int     m3[] = { 2, SUID, 's', XOWN, 'x', '-' };
int     m4[] = { 1, RGRP, 'r', '-' };
int     m5[] = { 1, WGRP, 'w', '-' };
int     m6[] = { 2, SGID, 's', XGRP, 'x', '-' };
int     m7[] = { 1, ROTH, 'r', '-' };
int     m8[] = { 1, WOTH, 'w', '-' };
int     m9[] = { 2, STXT, 't', XOTH, 'x', '-' };

int     *m[] = { m1, m2, m3, m4, m5, m6, m7, m8, m9};

void
pmode(long mode)
{
        int **mp;

        for(mp = &m[0]; mp < &m[9];)
                select(*mp++, mode);
}

void
select(int *ap, long mode)
{
        int n;

        n = *ap++;
        while(--n>=0 && (mode&*ap++)==0)
                ap++;
        Bputc(&bout, *ap);
}

/*
 *      Temp file I/O subsystem.  We attempt to cache all three temp files in
 *      core.  When we run out of memory we spill to disk.
 *      The I/O model assumes that temp files:
 *              1) are only written on the end
 *              2) are only read from the beginning
 *              3) are only read after all writing is complete.
 *      The architecture uses one control block per temp file.  Each control
 *      block anchors a chain of buffers, each containing an archive member.
 */
Arfile *
newtempfile(char *name)         /* allocate a file control block */
{
        Arfile *ap;

        ap = (Arfile *) armalloc(sizeof(Arfile));
        ap->fname = name;
        return ap;
}

Armember *
newmember(void)                 /* allocate a member buffer */
{
        return (Armember *)armalloc(sizeof(Armember));
}

void
arread(Biobuf *b, Armember *bp, int n)  /* read an image into a member buffer */
{
        int i;

        bp->member = armalloc(n);
        i = Bread(b, bp->member, n);
        if (i < 0) {
                free(bp->member);
                bp->member = 0;
                rderr();
        }
}

/*
 * insert a member buffer into the member chain
 */
void
arinsert(Arfile *ap, Armember *bp)
{
        bp->next = 0;
        if (!ap->tail)
                ap->head = bp;
        else
                ap->tail->next = bp;
        ap->tail = bp;
}

/*
 *      stream the members in a temp file to the file referenced by 'fd'.
 */
void
arstream(int fd, Arfile *ap)
{
        Armember *bp;
        int i;
        char buf[8192];

        if (ap->paged) {                /* copy from disk */
                seek(ap->fd, 0, 0);
                for (;;) {
                        i = read(ap->fd, buf, sizeof(buf));
                        if (i < 0)
                                rderr();
                        if (i == 0)
                                break;
                        if (write(fd, buf, i) != i)
                                wrerr();
                }
                close(ap->fd);
                ap->paged = 0;
        }
                /* dump the in-core buffers */
        for (bp = ap->head; bp; bp = bp->next) {
                if (!arwrite(fd, bp))
                        wrerr();
        }
}

/*
 *      write a member to 'fd'.
 */
int
arwrite(int fd, Armember *bp)
{
        int len;

        if(HEADER_IO(write, fd, bp->hdr))
                return 0;
        len = bp->size;
        if (len & 01)
                len++;
        if (write(fd, bp->member, len) != len)
                return 0;
        return 1;
}

/*
 *      Spill a member to a disk copy of a temp file
 */
int
page(Arfile *ap)
{
        Armember *bp;

        bp = ap->head;
        if (!ap->paged) {               /* not yet paged - create file */
                ap->fname = mktemp(ap->fname);
                ap->fd = create(ap->fname, ORDWR|ORCLOSE, 0600);
                if (ap->fd < 0) {
                        fprint(2,"ar: can't create temp file\n");
                        return 0;
                }
                ap->paged = 1;
        }
        if (!arwrite(ap->fd, bp))       /* write member and free buffer block */
                return 0;
        ap->head = bp->next;
        if (ap->tail == bp)
                ap->tail = bp->next;
        free(bp->member);
        free(bp);
        return 1;
}

/*
 *      try to reclaim space by paging.  we try to spill the start, middle,
 *      and end files, in that order.  there is no particular reason for the
 *      ordering.
 */
int
getspace(void)
{
        if (astart && astart->head && page(astart))
                        return 1;
        if (amiddle && amiddle->head && page(amiddle))
                        return 1;
        if (aend && aend->head && page(aend))
                        return 1;
        return 0;
}

void
arfree(Arfile *ap)              /* free a member buffer */
{
        Armember *bp, *next;

        for (bp = ap->head; bp; bp = next) {
                next = bp->next;
                if (bp->member)
                        free(bp->member);
                free(bp);
        }
        free(ap);
}

/*
 *      allocate space for a control block or member buffer.  if the malloc
 *      fails we try to reclaim space by spilling previously allocated
 *      member buffers.
 */
char *
armalloc(int n)
{
        char *cp;

        do {
                cp = malloc(n);
                if (cp) {
                        memset(cp, 0, n);
                        return cp;
                }
        } while (getspace());
        fprint(2, "ar: out of memory\n");
        exits("malloc");
        return 0;
}