sbase/tar.c

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6.8 KiB
C
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/* See LICENSE file for copyright and license details. */
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <stdbool.h>
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#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
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#include <limits.h>
#include <grp.h>
#include <pwd.h>
#include "util.h"
typedef struct Header Header;
struct Header {
char name[100];
char mode[8];
char uid[8];
char gid[8];
char size[12];
char mtime[12];
char chksum[8];
char type;
char link[100];
char magic[6];
char version[2];
char uname[32];
char gname[32];
char major[8];
char minor[8];
char prefix[155];
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};
enum {
Blksiz = 512
};
enum Type {
REG = '0', AREG = '\0', HARDLINK = '1', SYMLINK = '2', CHARDEV = '3',
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BLOCKDEV = '4', DIRECTORY = '5', FIFO = '6'
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};
static void putoctal(char *, unsigned, int);
static int archive(const char *);
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static int unarchive(char *, int, char[Blksiz]);
static int print(char *, int , char[Blksiz]);
static void c(const char *);
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static void xt(int (*)(char*, int, char[Blksiz]));
static FILE *tarfile;
static ino_t tarinode;
static dev_t tardev;
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static bool mflag = false;
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static void
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usage(void)
{
eprintf("usage: tar [-f tarfile] [-C dir] [-]x[m]|t\n"
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" tar [-f tarfile] [-C dir] [-]c dir\n"
" tar [-C dir] cf tarfile dir\n"
" tar [-C dir] x[m]|tf tarfile\n");
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}
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int
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main(int argc, char *argv[])
{
struct stat st;
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char *file = NULL, *dir = ".", *ap;
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char mode = '\0';
ARGBEGIN {
case 'x':
case 'c':
case 't':
if(mode)
usage();
mode = ARGC();
break;
case 'C':
dir = EARGF(usage());
break;
case 'f':
file = EARGF(usage());
break;
case 'm':
mflag = true;
break;
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default:
usage();
} ARGEND;
if(!mode) {
if(argc < 1)
usage();
for(ap = argv[0]; *ap; ap++) {
switch(*ap) {
case 'x':
case 'c':
case 't':
if(mode)
usage();
mode = *ap;
break;
case 'f':
if(argc < 2)
usage();
argc--, argv++;
file = argv[0];
break;
case 'C':
if(argc < 2)
usage();
argc--, argv++;
dir = argv[0];
break;
case 'm':
mflag = true;
break;
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default:
usage();
}
}
argc--, argv++;
}
if(!mode || argc != (mode == 'c'))
usage();
if(file) {
tarfile = fopen(file, (mode == 'c') ? "wb" : "rb");
if(!tarfile)
eprintf("tar: open '%s':", file);
if (lstat(file, &st) < 0)
eprintf("tar: stat '%s':", file);
tarinode = st.st_ino;
tardev = st.st_dev;
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} else {
tarfile = (mode == 'c') ? stdout : stdin;
}
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chdir(dir);
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if(mode == 'c') {
c(argv[0]);
} else {
xt((mode == 'x') ? unarchive : print);
}
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return 0;
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}
static void
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putoctal(char *dst, unsigned num, int n)
{
snprintf(dst, n, "%.*o", n-1, num);
}
static int
archive(const char* path)
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{
unsigned char b[Blksiz];
unsigned chksum;
int l, x;
Header *h = (void*)b;
FILE *f = NULL;
struct stat st;
struct passwd *pw;
struct group *gr;
mode_t mode;
lstat(path, &st);
if (st.st_ino == tarinode && st.st_dev == tardev) {
fprintf(stderr, "ignoring '%s'\n", path);
return 0;
}
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pw = getpwuid(st.st_uid);
gr = getgrgid(st.st_gid);
memset(b, 0, sizeof b);
snprintf(h->name, sizeof h->name, "%s", path);
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putoctal(h->mode, (unsigned)st.st_mode&0777, sizeof h->mode);
putoctal(h->uid, (unsigned)st.st_uid, sizeof h->uid);
putoctal(h->gid, (unsigned)st.st_gid, sizeof h->gid);
putoctal(h->size, 0, sizeof h->size);
putoctal(h->mtime, (unsigned)st.st_mtime, sizeof h->mtime);
memcpy(h->magic, "ustar", sizeof h->magic);
memcpy(h->version, "00", sizeof h->version);
snprintf(h->uname, sizeof h->uname, "%s", pw ? pw->pw_name : "");
snprintf(h->gname, sizeof h->gname, "%s", gr ? gr->gr_name : "");
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mode = st.st_mode;
if(S_ISREG(mode)) {
h->type = REG;
putoctal(h->size, (unsigned)st.st_size, sizeof h->size);
f = fopen(path, "r");
} else if(S_ISDIR(mode)) {
h->type = DIRECTORY;
} else if(S_ISLNK(mode)) {
h->type = SYMLINK;
readlink(path, h->link, (sizeof h->link)-1);
} else if(S_ISCHR(mode) || S_ISBLK(mode)) {
h->type = S_ISCHR(mode) ? CHARDEV : BLOCKDEV;
#if defined(major) && defined(minor)
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putoctal(h->major, (unsigned)major(st.st_dev), sizeof h->major);
putoctal(h->minor, (unsigned)minor(st.st_dev), sizeof h->minor);
#else
return 0;
#endif
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} else if(S_ISFIFO(mode)) {
h->type = FIFO;
}
memset(h->chksum, ' ', sizeof h->chksum);
for(x = 0, chksum = 0; x < sizeof *h; x++)
chksum += b[x];
putoctal(h->chksum, chksum, sizeof h->chksum);
fwrite(b, Blksiz, 1, tarfile);
if(!f)
return 0;
while((l = fread(b, 1, Blksiz, f)) > 0) {
if(l < Blksiz)
memset(b+l, 0, Blksiz-l);
fwrite(b, Blksiz, 1, tarfile);
}
fclose(f);
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return 0;
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}
static int
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unarchive(char *fname, int l, char b[Blksiz])
{
char lname[101];
FILE *f = NULL;
unsigned long mode, major, minor, type, mtime;
struct timeval times[2];
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Header *h = (void*)b;
if(!mflag)
mtime = strtoul(h->mtime, 0, 8);
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unlink(fname);
switch(h->type) {
case REG:
case AREG:
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mode = strtoul(h->mode, 0, 8);
if(!(f = fopen(fname, "w")) || chmod(fname, mode))
perror(fname);
break;
case HARDLINK:
case SYMLINK:
snprintf(lname, sizeof lname, "%s", h->link);
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if(!((h->type == HARDLINK) ? link : symlink)(lname, fname))
perror(fname);
break;
case DIRECTORY:
mode = strtoul(h->mode, 0, 8);
if(mkdir(fname, (mode_t)mode))
perror(fname);
break;
case CHARDEV:
case BLOCKDEV:
#ifdef makedev
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mode = strtoul(h->mode, 0, 8);
major = strtoul(h->major, 0, 8);
minor = strtoul(h->mode, 0, 8);
type = (h->type == CHARDEV) ? S_IFCHR : S_IFBLK;
if(mknod(fname, type | mode, makedev(major, minor)))
perror(fname);
#endif
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break;
case FIFO:
mode = strtoul(h->mode, 0, 8);
if(mknod(fname, S_IFIFO | mode, 0))
perror(fname);
break;
default:
fprintf(stderr, "usupported tarfiletype %c\n", h->type);
}
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if(getuid() == 0 && chown(fname, strtoul(h->uid, 0, 8),
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strtoul(h->gid, 0, 8)))
perror(fname);
for(; l > 0; l -= Blksiz) {
fread(b, Blksiz, 1, tarfile);
if(f)
fwrite(b, MIN(l, 512), 1, f);
}
if(f)
fclose(f);
if(!mflag) {
times[0].tv_sec = times[1].tv_sec = mtime;
times[0].tv_usec = times[1].tv_usec = 0;
if(utimes(fname, times))
perror(fname);
}
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return 0;
}
static int
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print(char * fname, int l, char b[Blksiz])
{
puts(fname);
for(; l > 0; l -= Blksiz)
fread(b, Blksiz, 1, tarfile);
return 0;
}
static void
c(const char * path)
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{
archive(path);
recurse(path, c);
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}
static void
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xt(int (*fn)(char*, int, char[Blksiz]))
{
char b[Blksiz], fname[257], *s;
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Header *h = (void*)b;
while(fread(b, Blksiz, 1, tarfile) && h->name[0] != '\0') {
s = fname;
if (h->prefix[0] != '\0')
s += sprintf(s, "%.*s/", (int)sizeof h->prefix, h->prefix);
sprintf(s, "%.*s", (int)sizeof h->name, h->name);
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fn(fname, strtol(h->size, 0, 8), b);
}
}