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@@ -1,90 +1,174 @@
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+/*
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+ * File system for tar archives (read-only)
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+ */
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+
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#include <u.h>
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#include <libc.h>
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#include <auth.h>
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#include <fcall.h>
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#include "tapefs.h"
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+/* fundamental constants */
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+enum {
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+ Tblock = 512,
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+ Namsiz = 100,
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+ Maxpfx = 155, /* from POSIX */
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+ Maxname = Namsiz + 1 + Maxpfx,
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+ Binsize = 0x80, /* flag in size[0], from gnu: positive binary size */
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+ Binnegsz = 0xff, /* flag in size[0]: negative binary size */
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+};
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+
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+/* POSIX link flags */
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+enum {
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+ LF_PLAIN1 = '\0',
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+ LF_PLAIN2 = '0',
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+ LF_LINK = '1',
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+ LF_SYMLINK1 = '2',
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+ LF_SYMLINK2 = 's', /* 4BSD used this */
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+ LF_CHR = '3',
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+ LF_BLK = '4',
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+ LF_DIR = '5',
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+ LF_FIFO = '6',
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+ LF_CONTIG = '7',
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+ /* 'A' - 'Z' are reserved for custom implementations */
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+};
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+
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+typedef union {
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+ char dummy[Tblock];
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+ char tbuf[Maxbuf];
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+ struct Header {
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+ char name[Namsiz];
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+ char mode[8];
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+ char uid[8];
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+ char gid[8];
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+ char size[12];
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+ char mtime[12];
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+ char chksum[8];
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+ char linkflag;
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+ char linkname[Namsiz];
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+
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+ /* rest are defined by POSIX's ustar format; see p1003.2b */
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+ char magic[6]; /* "ustar" */
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+ char version[2];
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+ char uname[32];
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+ char gname[32];
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+ char devmajor[8];
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+ char devminor[8];
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+ char prefix[Maxpfx]; /* if non-null, path= prefix "/" name */
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+ };
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+} Hdr;
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+
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+Hdr dblock;
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+int tapefile;
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+
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+int checksum(void);
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+
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+static int
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+isustar(Hdr *hp)
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+{
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+ return strcmp(hp->magic, "ustar") == 0;
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+}
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+
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/*
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- * File system for tar tapes (read-only)
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+ * s is at most n bytes long, but need not be NUL-terminated.
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+ * if shorter than n bytes, all bytes after the first NUL must also
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+ * be NUL.
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*/
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+static int
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+strnlen(char *s, int n)
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+{
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+ return s[n - 1] != '\0'? n: strlen(s);
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+}
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-#define TBLOCK 512
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-#define NBLOCK 40 /* maximum blocksize */
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-#define DBLOCK 20 /* default blocksize */
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-#define TNAMSIZ 100
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-
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-union hblock {
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- char dummy[TBLOCK];
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- char tbuf[Maxbuf];
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- struct header {
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- char name[TNAMSIZ];
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- char mode[8];
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- char uid[8];
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- char gid[8];
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- char size[12];
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- char mtime[12];
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- char chksum[8];
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- char linkflag;
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- char linkname[TNAMSIZ];
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- } dbuf;
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-} dblock;
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-
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-int tapefile;
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-int checksum(void);
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+/* set fullname from header */
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+static char *
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+tarname(Hdr *hp)
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+{
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+ int pfxlen, namlen;
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+ static char fullname[Maxname+1];
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+
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+ namlen = strnlen(hp->name, sizeof hp->name);
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+ if (hp->prefix[0] == '\0' || !isustar(hp)) { /* old-style name? */
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+ memmove(fullname, hp->name, namlen);
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+ fullname[namlen] = '\0';
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+ return fullname;
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+ }
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+
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+ /* posix name: name is in two pieces */
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+ pfxlen = strnlen(hp->prefix, sizeof hp->prefix);
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+ memmove(fullname, hp->prefix, pfxlen);
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+ fullname[pfxlen] = '/';
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+ memmove(fullname + pfxlen + 1, hp->name, namlen);
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+ fullname[pfxlen + 1 + namlen] = '\0';
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+ return fullname;
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+}
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void
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populate(char *name)
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{
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- long blkno, isabs, chksum, linkflg;
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+ long chksum, linkflg;
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+ vlong blkno;
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+ char *fname;
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Fileinf f;
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+ Hdr *hp;
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tapefile = open(name, OREAD);
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- if (tapefile<0)
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+ if (tapefile < 0)
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error("Can't open argument file");
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replete = 1;
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- for (blkno = 0;;) {
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- seek(tapefile, TBLOCK*blkno, 0);
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- if (read(tapefile, dblock.dummy, sizeof(dblock.dummy))<sizeof(dblock.dummy))
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+ hp = &dblock;
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+ for (blkno = 0; ; blkno++) {
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+ seek(tapefile, Tblock*blkno, 0);
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+ if (readn(tapefile, hp->dummy, sizeof hp->dummy) < sizeof hp->dummy)
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break;
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- if (dblock.dbuf.name[0]=='\0')
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+ fname = tarname(hp);
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+ if (fname[0] == '\0')
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break;
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- f.addr = blkno+1;
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- f.mode = strtoul(dblock.dbuf.mode, 0, 8);
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- f.uid = strtoul(dblock.dbuf.uid, 0, 8);
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- f.gid = strtoul(dblock.dbuf.gid, 0, 8);
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- if((uchar)dblock.dbuf.size[0] == 0x80)
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- f.size = b8byte(dblock.dbuf.size+3);
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+
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+ /* crack header */
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+ f.addr = blkno + 1;
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+ f.mode = strtoul(hp->mode, 0, 8);
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+ f.uid = strtoul(hp->uid, 0, 8);
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+ f.gid = strtoul(hp->gid, 0, 8);
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+ if((uchar)hp->size[0] == 0x80)
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+ f.size = b8byte(hp->size+3);
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else
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- f.size = strtoull(dblock.dbuf.size, 0, 8);
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- f.mdate = strtoul(dblock.dbuf.mtime, 0, 8);
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- chksum = strtoul(dblock.dbuf.chksum, 0, 8);
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+ f.size = strtoull(hp->size, 0, 8);
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+ f.mdate = strtoul(hp->mtime, 0, 8);
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+ chksum = strtoul(hp->chksum, 0, 8);
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/* the mode test is ugly but sometimes necessary */
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- if (dblock.dbuf.linkflag == '5'
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- || (f.mode&0170000) == 040000
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- || strrchr(dblock.dbuf.name, '\0')[-1] == '/'){
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+ if (hp->linkflag == LF_DIR || (f.mode&0170000) == 040000 ||
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+ strrchr(fname, '\0')[-1] == '/'){
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f.mode |= DMDIR;
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f.size = 0;
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}
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- f.mode &= DMDIR|0777;
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- linkflg = dblock.dbuf.linkflag=='s' || dblock.dbuf.linkflag=='1';
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- isabs = dblock.dbuf.name[0]=='/';
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+ f.mode &= DMDIR | 0777;
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+
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+ /* make file name safe and canonical */
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+ while (fname[0] == '/') /* don't allow absolute paths */
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+ ++fname;
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+ cleanname(fname);
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+
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+ /* reject links */
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+ linkflg = hp->linkflag == LF_SYMLINK1 ||
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+ hp->linkflag == LF_SYMLINK2 || hp->linkflag == LF_LINK;
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if (chksum != checksum()){
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- fprint(1, "bad checksum on %.28s\n", dblock.dbuf.name);
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+ fprint(2, "%s: bad checksum on %.28s at offset %lld\n",
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+ argv0, fname, Tblock*blkno);
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exits("checksum");
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}
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if (linkflg) {
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- /*fprint(2, "link %s->%s skipped\n", dblock.dbuf.name,
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- dblock.dbuf.linkname);*/
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+ /*fprint(2, "link %s->%s skipped\n", fname, hp->linkname);*/
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f.size = 0;
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- blkno += 1;
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- continue;
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+ } else {
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+ /* accept this file */
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+ f.name = fname;
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+ if (f.name[0] == '\0')
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+ fprint(2, "%s: null name skipped\n", argv0);
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+ else
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+ poppath(f, 1);
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+ blkno += (f.size + Tblock - 1)/Tblock;
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}
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- f.name = dblock.dbuf.name+isabs;
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- if (f.name[0]=='\0')
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- fprint(1, "null name skipped\n");
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- else
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- poppath(f, 1);
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- blkno += 1 + (f.size+TBLOCK-1)/TBLOCK;
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}
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}
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@@ -103,10 +187,14 @@ docreate(Ram *r)
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char *
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doread(Ram *r, vlong off, long cnt)
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{
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- seek(tapefile, TBLOCK*r->addr+off, 0);
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- if (cnt>sizeof(dblock.tbuf))
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+ int n;
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+
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+ seek(tapefile, Tblock*r->addr + off, 0);
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+ if (cnt > sizeof dblock.tbuf)
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error("read too big");
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- read(tapefile, dblock.tbuf, cnt);
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+ n = readn(tapefile, dblock.tbuf, cnt);
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+ if (n != cnt)
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+ memset(dblock.tbuf + n, 0, cnt - n);
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return dblock.tbuf;
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}
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@@ -130,15 +218,15 @@ dopermw(Ram *r)
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}
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int
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-checksum()
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+checksum(void)
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{
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- int i;
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- char *cp;
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+ int i, n;
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+ uchar *cp;
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- for (cp = dblock.dbuf.chksum; cp < &dblock.dbuf.chksum[sizeof(dblock.dbuf.chksum)]; cp++)
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- *cp = ' ';
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+ memset(dblock.chksum, ' ', sizeof dblock.chksum);
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+ cp = (uchar *)dblock.dummy;
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i = 0;
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- for (cp = dblock.dummy; cp < &dblock.dummy[TBLOCK]; cp++)
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- i += *cp&0xff;
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- return(i);
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+ for (n = Tblock; n-- > 0; )
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+ i += *cp++;
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+ return i;
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}
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David du Colombier