dan@prairie.UUCP (Daniel M. Frank) (01/20/87)
--------------- cpfix.c ---------------------------------- cut here ---
/* cpfix: repair damaged cpio archives.
* cpfix does its best to repair a cpio archive that has had
* extra bytes inserted, destroying sync. This happens with
* amazing regularity, especially when cpio is used to backup
* damaged file systems.
*
* There are two arguments. The first is the input file name,
* which may be `-' for stdin. The second is an explicit output
* filename.
*
* cpfix works only for binary cpio headers. It shouldn't be
* too hard to add an option for character headers.
*
* Operating Systems: known to work under SVR2, but probably
* fine under others. I hear that Sun did something
* funny to the header.
* Author: Daniel M. Frank (dan@prairie.uucp)
* Permissions: Permission is granted for distribution, without
* charge, of this program. Anyone who wants to
* sell it must ask my permission and grease my
* palm.
* cpfix is Copyright (C) 1987 by Daniel M. Frank.
*/
#include <stdio.h>
#include <sys/types.h>
struct Hdr {
short h_magic ,
h_dev ;
ushort h_ino,
h_mode,
h_uid,
h_gid;
short h_nlink,
h_rdev,
h_mtime[2],
h_namesize ;
ushort h_filesize[2] ;
};
main(argc, argv)
int argc ;
char **argv ;
{
char name[132] ;
struct Hdr header ;
int namesize ;
long filesize, fsadj, outpos, lastpos ;
FILE *inp, *outp ;
char buf[1024] ;
if (argv[1][0] == '-')
inp = stdin ;
else if ((inp = fopen(argv[1], "r")) == 0) {
perror("input file") ;
exit(1) ;
}
if ((outp = fopen(argv[2], "w")) == 0) {
perror("output file") ;
exit(1) ;
}
lastpos = 0 ;
while(1) {
outpos = ftell(outp) ; /* save current output position */
if (fread(&header, sizeof(header), 1, inp) != 1) {
perror("header read") ;
exit(1) ;
}
if (header.h_magic != 070707) {
printf("No magic - number was %o\n", header.h_magic) ;
fseek(outp, lastpos, 0) ; /* reset to last write postion */
outpos = lastpos ;
while(1) {
if (fread(&header, sizeof(header.h_magic), 1, inp) != 1) {
printf("Read failure during recovery scan\n") ;
exit(1) ;
}
if (header.h_magic == 070707) {
if (fread(&header.h_dev,
sizeof(header) - sizeof(header.h_magic),
1, inp) != 1) {
printf("Failure reading rest of header\n") ;
exit(1) ;
}
break ; /* leave while loop */
}
}
}
lastpos = outpos ;
namesize = (header.h_namesize + 1) & ~1 ;
if (fread(name, namesize, 1, inp) != 1) {
perror("name read") ;
exit(1) ;
}
if (fwrite(&header, sizeof(header), 1, outp) != 1) {
perror("header write") ;
exit(1) ;
}
if (fwrite(name, namesize, 1, outp) != 1) {
perror("name write") ;
exit(1) ;
}
if (strcmp(name, "TRAILER!!!") == 0) {
/* we have to adjust to a 512-byte boundary */
long adjust ;
outpos += sizeof(header) + namesize ;
adjust = ((outpos - 1) / 512 * 512 + 512) - outpos ;
if (adjust)
if (fwrite(buf, (int)adjust, 1, outp) != 1) {
perror("padding write") ;
exit(1) ;
}
printf("end of the archive!\n") ;
exit(0) ;
}
filesize = ((long)header.h_filesize[0] << 16) + header.h_filesize[1] ;
printf("file %s, size %ld\n", name, filesize) ;
fsadj = (filesize + 1) & ~1L ;
while (fsadj > 0) {
if (fread(buf, (fsadj > 1024 ? 1024 : (int)fsadj), 1, inp) != 1) {
perror("data read") ;
exit(1) ;
}
if (fwrite(buf, (fsadj > 1024 ? 1024 : (int)fsadj), 1, outp) != 1) {
perror("data write") ;
exit(1) ;
}
fsadj -= 1024 ;
}
}
}
--
Dan Frank
uucp: ... uwvax!prairie!dan
arpa: dan%caseus@spool.wisc.edu