ref: fc4bfd57d261e5c99c5d4367adf5c72e8c7e6496
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; return x = egetc(), x |= egetc()<<8; } static ulong rd3211() { ulong x; return x = egetc()<<16, x |= egetc()<<24, x |= egetc(), x |= egetc()<<8; } /* 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("not octal"); x = x<<3 | 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; } static HdrReader * rdmagic(void) { uchar buf[6]; 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(); if(memcmp(buf, "070707", 6) == 0) return rdsysiii; sysfatal("Out of phase--get MERT help"); return nil; } 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 && (Bseek(tape, 0, 1) & 1)) 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; }