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sltar.c
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sltar.c
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/* sltar - a simple tar
* © 2014 Enno Boland <g s01 de>
*
* See LICENSE for further informations
*/
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <ftw.h>
#include <grp.h>
#include <pwd.h>
enum Header {
NAME = 0, MODE = 100, UID = 108, GID = 116, SIZE = 124, MTIME = 136,
CHK = 148, TYPE = 156, LINK = 157, MAGIC = 257, VERS = 263, UNAME = 265,
GNAME = 297, MAJ = 329, MIN = 337, END = 512
};
enum Type {
REG = '0', HARDLINK = '1', SYMLINK = '2', CHARDEV = '3', BLOCKDEV = '4',
DIRECTORY = '5', FIFO = '6'
};
void chksum(const char b[END], char *chk) {
unsigned sum = 0, i;
for(i = 0; i<END; i++)
sum += (i >= CHK && i < CHK+8) ? ' ' : b[i];
snprintf(chk, 8, "%.7o", sum);
}
int c_file(const char* path, const struct stat* st, int type) {
int l = END;
char b[END] = { 0 };
FILE *f = NULL;
struct passwd *pw = getpwuid(st->st_uid);
struct group *gr = getgrgid(st->st_gid);
memset(b+SIZE, '0', 12);
strcpy(b+MAGIC, "ustar");
strcpy(b+VERS, "00");
snprintf(b+NAME, 100, "%s", path);
snprintf(b+MODE, 8, "%.7o", (unsigned)st->st_mode&0777);
snprintf(b+UID, 8, "%.7o", (unsigned)st->st_uid);
snprintf(b+GID, 8, "%.7o", (unsigned)st->st_gid);
snprintf(b+MTIME,12, "%.11o", (unsigned)st->st_mtime);
snprintf(b+UNAME, 32, "%s", pw->pw_name);
snprintf(b+GNAME, 32, "%s", gr->gr_name);
mode_t mode = st->st_mode;
if(S_ISREG(mode)) {
b[TYPE] = REG;
snprintf(b+SIZE, 12, "%.11o", (unsigned)st->st_size);
f = fopen(path, "r");
} else if(S_ISDIR(mode)) {
b[TYPE] = DIRECTORY;
} else if(S_ISLNK(mode)) {
b[TYPE] = SYMLINK;
readlink(path, b+LINK, 99);
} else if(S_ISCHR(mode)) {
b[TYPE] = CHARDEV;
snprintf(b+MAJ, 8, "%.7o", (unsigned)major(st->st_dev));
snprintf(b+MIN, 8, "%.7o", (unsigned)minor(st->st_dev));
} else if(S_ISBLK(mode)) {
b[TYPE] = BLOCKDEV;
snprintf(b+MAJ, 8, "%.7o", (unsigned)major(st->st_dev));
snprintf(b+MIN, 8, "%.7o", (unsigned)minor(st->st_dev));
} else if(S_ISFIFO(mode)) {
b[TYPE] = FIFO;
}
chksum(b, b+CHK);
if(!f) return 0;
do {
if(l<END)
memset(b + l, 0, END - l);
fwrite(b, END, 1, stdout);
} while((l = fread(b, 1, END, f)) > 0);
fclose(f);
return 0;
}
int x(char *fname, int l, char b[END]){
static char lname[101] = {0}, chk[8] = {0};
int r = 0;
FILE *f = NULL;
memcpy(lname, b+LINK, 100);
unlink(fname);
switch(b[TYPE]) {
case REG:
r = !(f = fopen(fname, "w")) ||
chmod(fname,strtoul(b + MODE, 0, 8));
break;
case HARDLINK:
r = link(lname,fname);
break;
case SYMLINK:
r = symlink(lname,fname);
break;
case DIRECTORY:
r = mkdir(fname,(mode_t) strtoull(b + MODE,0,8));
break;
case CHARDEV:
case BLOCKDEV:
r = mknod(fname, (b[TYPE] == CHARDEV ?
S_IFCHR : S_IFBLK) | strtoul(b + MODE,0,8),
makedev(strtoul(b + MAJ,0,8),
strtoul(b + MIN,0,8)));
break;
case FIFO:
r = mknod(fname, S_IFIFO | strtoul(b + MODE, 0, 8), 0);
break;
default:
fprintf(stderr,"%s: unsupported filetype %c\n", fname, b[TYPE]);
}
if(r || (getuid() == 0 && chown(fname, strtoul(b + UID, 0, 8),
strtoul(b + GID, 0, 8))))
perror(fname);
chksum(b, chk);
if(strncmp(b+CHK, chk, 8))
fprintf(stderr, "%s: chksum failed\n", fname);
for(; l > 0; l -= END){
fread(b, END, 1, stdin);
if(f) fwrite(b, MIN(l, 512), 1, f);
}
if(f) fclose(f);
return 0;
}
int t(char *fname, int l, char b[END]){
puts(fname);
for(; l > 0; l -= END)
fread(b, END, 1, stdin);
return 0;
}
int tar(int (*fn)(char*, int, char[END])) {
int l;
char b[END], fname[101] = { 0 };
while(fread(b, END, 1, stdin)){
if(*b == '\0')
break;
memcpy(fname, b, 100);
l = strtol(b+SIZE, 0, 8);
fn(fname, l, b);
}
return EXIT_SUCCESS;
}
int c(char *p) {
static struct stat st;
if(lstat(p, &st))
perror(p);
else if(S_ISDIR(st.st_mode))
return ftw(p, c_file, 1024);
else
return c_file(p, &st, 0);
return 1;
}
void usage() {
fputs("sltar-" VERSION " - simple tar\n"
"Usage: sltar [tx]\n"
" sltar c PATH ...\n", stderr);
exit(EXIT_FAILURE);
}
int main(int argc, char *argv[]) {
if(argc < 2 || strlen(argv[1]) != 1)
usage();
switch(argv[1][0]) {
case 'c':
if(argc < 3) usage();
while(argc-- >= 3)
if(c(argv[argc])) return EXIT_FAILURE;
return EXIT_SUCCESS;
case 'x':
if(argc == 2) return tar(x);
case 't':
if(argc == 2) return tar(t);
default:
usage();
}
return EXIT_FAILURE;
}