ref: f73fb96cb2c0136b019540b6ac0d76be57ea7d49
dir: /sys/src/cmd/tapefs/cpiofs.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "tapefs.h"
/*
* File system for cpio tapes (read-only)
*/
union hblock {
char tbuf[Maxbuf];
} dblock;
typedef void HdrReader(Fileinf *);
Biobuf *tape;
static void
addrfatal(char *fmt, va_list arg)
{
char buf[1024];
vseprint(buf, buf+sizeof(buf), fmt, arg);
fprint(2, "%s: %#llx: %s\n", argv0, Bseek(tape, 0, 1), buf);
exits(buf);
}
static int
egetc(void)
{
int c;
if((c = Bgetc(tape)) == Beof)
sysfatal("unexpected eof");
if(c < 0)
sysfatal("read error: %r");
return c;
}
static ushort
rd16le()
{
ushort x;
x = egetc();
x |= egetc()<<8;
return x;
}
static ulong
rd3211()
{
ulong x;
x = egetc()<<16;
x |= egetc()<<24;
x |= egetc();
x |= egetc()<<8;
return x;
}
/* sysvr3 and sysvr4 skip records with names longer than 256. pwb 1.0,
32V, sysiii, sysvr1, and sysvr2 overrun their 256 byte buffer */
static void
rdpwb(Fileinf *f, ushort (*rd16)(void), ulong (*rd32)(void))
{
int namesz, n;
static char buf[256];
rd16(); /* dev */
rd16(); /* ino */
f->mode = rd16();
f->uid = rd16();
f->gid = rd16();
rd16(); /* nlink */
rd16(); /* rdev */
f->mdate = rd32();
namesz = rd16();
f->size = rd32();
/* namesz include the trailing nul */
if(namesz == 0)
sysfatal("name too small");
if(namesz > sizeof(buf))
sysfatal("name too big");
if((n = Bread(tape, buf, namesz)) < 0)
sysfatal("read error: %r");
if(n < namesz)
sysfatal("unexpected eof");
if(buf[n-1] != '\0')
sysfatal("no nul after file name");
if((n = strlen(buf)) != namesz-1)
sysfatal("mismatched name length: saw %d; expected %d", n, namesz-1);
f->name = buf;
/* skip padding */
if(Bseek(tape, 0, 1) & 1)
egetc();
}
static void
rdpwb11(Fileinf *f)
{
rdpwb(f, rd16le, rd3211);
}
static vlong
rdasc(int n)
{
vlong x;
int y;
for(x = 0; n > 0; n--) {
if((y = egetc() - '0') & ~7)
sysfatal("rdasc:%#c not octal", y);
x = x<<3 | y;
}
return x;
}
static vlong
rdascx(int n)
{
vlong x;
int y;
for(x = 0; n > 0; n--) {
y = egetc();
if ((y >= '0') && (y <= '9')){
x = x << 4 | (y - '0');
continue;
}
if ((y >= 'a') && (y <= 'f')){
x = x << 4 | 10 + (y - 'a');
continue;
}
if ((y >= 'A') && (y <= 'F')){
x = x << 4 | 10 + (y - 'A');
continue;
}
sysfatal("rdascx:%#x:not hex", y);
}
return x;
}
/* sysvr3 and sysvr4 skip records with names longer than 256. sysiii,
sysvr1, and sysvr2 overrun their 256 byte buffer */
static void
rdsysiii(Fileinf *f)
{
int namesz, n;
static char buf[256];
rdasc(6); /* dev */
rdasc(6); /* ino */
f->mode = rdasc(6);
f->uid = rdasc(6);
f->gid = rdasc(6);
rdasc(6); /* nlink */
rdasc(6); /* rdev */
f->mdate = rdasc(11);
namesz = rdasc(6);
f->size = rdasc(11);
/* namesz includes the trailing nul */
if(namesz == 0)
sysfatal("name too small");
if(namesz > sizeof (buf))
sysfatal("name too big");
if((n = Bread(tape, buf, namesz)) < 0)
sysfatal("read error: %r");
if(n < namesz)
sysfatal("unexpected eof");
if(buf[n-1] != '\0')
sysfatal("no nul after file name");
if((n = strlen(buf)) != namesz-1)
sysfatal("mismatched name length: saw %d; expected %d", n, namesz-1);
f->name = buf;
}
/*
struct cpio_newc_header {
char c_magic[6];
char c_ino[8];
char c_mode[8];
char c_uid[8];
char c_gid[8];
char c_nlink[8];
char c_mtime[8];
char c_filesize[8];
char c_devmajor[8];
char c_devminor[8];
char c_rdevmajor[8];
char c_rdevminor[8];
char c_namesize[8];
char c_check[8];
};
*/
static void
rdnewc(Fileinf *f)
{
int namesz, n;
static char buf[256];
rdascx(8); /* ino */
f->mode = rdascx(8);
f->uid = rdascx(8);
f->gid = rdascx(8);
rdascx(8); /* nlink */
f->mdate = rdascx(8);
f->size = rdascx(8);
rdascx(8); //devmajor
rdascx(8); //devminor
rdascx(8); //rdevmajor
rdascx(8); //rdevminor
namesz = rdascx(8);
rdascx(8); // checksum
/* namesz includes the trailing nul */
if(namesz == 0)
sysfatal("name too small");
if(namesz > sizeof (buf))
sysfatal("name too big");
if((n = Bread(tape, buf, namesz)) < 0)
sysfatal("read error: %r");
if(n < namesz)
sysfatal("unexpected eof");
if(buf[n-1] != '\0')
sysfatal("no nul after file name");
if((n = strlen(buf)) != namesz-1)
sysfatal("mismatched name length: saw %d; expected %d", n, namesz-1);
f->name = buf;
if((Bseek(tape, 0, 1) & 3)) {
int skip = 4-(Bseek(tape, 0, 1) & 3);
for(int i = 0; i < skip; i++)
egetc();
}
}
static HdrReader *
rdmagic(void)
{
uchar buf[8];
buf[0] = egetc();
buf[1] = egetc();
if(buf[0] == 0xc7 && buf[1] == 0x71)
return rdpwb11;
buf[2] = egetc();
buf[3] = egetc();
buf[4] = egetc();
buf[5] = egetc();
buf[6] = 0;
if(memcmp(buf, "070707", 6) == 0)
return rdsysiii;
if(memcmp(buf, "070701", 6) == 0)
return rdnewc;
for(int i = 0; i < 6; i++)
print("%#x,", buf[i]);
sysfatal("Out of phase(%s)--get MERT help", buf);
}
void
populate(char *name)
{
HdrReader *rdhdr, *prevhdr;
Fileinf f;
/* the tape buffer may not be the ideal size for scanning the
record headers */
if((tape = Bopen(name, OREAD)) == nil)
sysfatal("Can't open argument file");
extern void (*_sysfatal)(char *, va_list);
_sysfatal = addrfatal;
prevhdr = nil;
replete = 1;
for(;;) {
/* sysiii and sysv implementations don't allow
multiple header types within a single tape, so we
won't either */
rdhdr = rdmagic();
if(prevhdr != nil && rdhdr != prevhdr)
sysfatal("mixed headers");
rdhdr(&f);
while(f.name[0] == '/')
f.name++;
if(f.name[0] == '\0')
sysfatal("nameless record");
if(strcmp(f.name, "TRAILER!!!") == 0)
break;
switch(f.mode & 0170000) {
case 0040000:
f.mode = DMDIR | f.mode&0777;
break;
case 0100000: /* normal file */
case 0120000: /* symlink */
f.mode &= 0777;
break;
default: /* sockets, pipes, devices */
f.mode = 0;
break;
}
f.addr = Bseek(tape, 0, 1);
poppath(f, 1);
Bseek(tape, f.size, 1);
/* skip padding */
if(((rdhdr == rdpwb11)||(rdhdr == rdnewc)) && (Bseek(tape, 0, 1) & 1))
egetc();
/* sleazy alignment hack. Who needs a for loop? */
if(rdhdr == rdnewc && (Bseek(tape, 0, 1) & 2)) {
egetc();
egetc();
}
}
}
void
dotrunc(Ram *r)
{
USED(r);
}
void
docreate(Ram *r)
{
USED(r);
}
char *
doread(Ram *r, vlong off, long cnt)
{
Bseek(tape, r->addr+off, 0);
if (cnt>sizeof(dblock.tbuf))
sysfatal("read too big");
Bread(tape, dblock.tbuf, cnt);
return dblock.tbuf;
}
void
popdir(Ram *r)
{
USED(r);
}
void
dowrite(Ram *r, char *buf, long off, long cnt)
{
USED(r); USED(buf); USED(off); USED(cnt);
}
int
dopermw(Ram *r)
{
USED(r);
return 0;
}