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/*
* Functions for extracting tar archives.
* Bruce Perens, April-May 1995
* Copyright (C) 1995 Bruce Perens
* This is free software under the GNU General Public License.
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include "tarfn.h"
struct TarHeader {
char Name[100];
char Mode[8];
char UserID[8];
char GroupID[8];
char Size[12];
char ModificationTime[12];
char Checksum[8];
char LinkFlag;
char LinkName[100];
char MagicNumber[8];
char UserName[32];
char GroupName[32];
char MajorDevice[8];
char MinorDevice[8];
};
typedef struct TarHeader TarHeader;
static const unsigned int TarChecksumOffset
= (unsigned int)&(((TarHeader *)0)->Checksum);
/* Octal-ASCII-to-long */
static long
OtoL(const char * s, int size)
{
int n = 0;
while ( *s == ' ' ) {
s++;
size--;
}
while ( --size >= 0 && *s >= '0' && *s <= '7' )
n = (n * 010) + (*s++ - '0');
return n;
}
static int
DecodeTarHeader(char * block, TarInfo * d)
{
TarHeader * h = (TarHeader *)block;
unsigned char * s = (unsigned char *)block;
struct passwd * passwd = 0;
struct group * group = 0;
unsigned int i;
long sum;
long checksum;
if ( *h->UserName )
passwd = getpwnam(h->UserName);
if ( *h->GroupName )
group = getgrnam(h->GroupName);
d->Name = h->Name;
d->LinkName = h->LinkName;
d->Mode = (mode_t)OtoL(h->Mode, sizeof(h->Mode));
d->Size = (size_t)OtoL(h->Size, sizeof(h->Size));
d->ModTime = (time_t)OtoL(h->ModificationTime
,sizeof(h->ModificationTime));
d->Device = ((OtoL(h->MajorDevice, sizeof(h->MajorDevice)) & 0xff) << 8)
| (OtoL(h->MinorDevice, sizeof(h->MinorDevice)) & 0xff);
checksum = OtoL(h->Checksum, sizeof(h->Checksum));
d->UserID = (uid_t)OtoL(h->UserID, sizeof(h->UserID));
d->GroupID = (gid_t)OtoL(h->GroupID, sizeof(h->GroupID));
d->Type = (TarFileType)h->LinkFlag;
if ( passwd )
d->UserID = passwd->pw_uid;
if ( group )
d->GroupID = group->gr_gid;
sum = ' ' * sizeof(h->Checksum);/* Treat checksum field as all blank */
for ( i = TarChecksumOffset; i > 0; i-- )
sum += *s++;
s += sizeof(h->Checksum); /* Skip the real checksum field */
for ( i = (512 - TarChecksumOffset - sizeof(h->Checksum)); i > 0; i-- )
sum += *s++;
return ( sum == checksum );
}
extern int
TarExtractor(
void * userData
,const TarFunctions * functions)
{
int status;
char buffer[512];
TarInfo h;
h.UserData = userData;
while ( (status = functions->Read(userData, buffer, 512)) == 512 ) {
int nameLength;
if ( !DecodeTarHeader(buffer, &h) ) {
if ( h.Name[0] == '\0' ) {
return 0; /* End of tape */
} else {
errno = 0; /* Indicates broken tarfile */
return -1; /* Header checksum error */
}
}
if ( h.Name[0] == '\0' ) {
errno = 0; /* Indicates broken tarfile */
return -1; /* Bad header data */
}
nameLength = strlen(h.Name);
switch ( h.Type ) {
case NormalFile0:
case NormalFile1:
/* Compatibility with pre-ANSI ustar */
if ( h.Name[nameLength - 1] != '/' ) {
status = (*functions->ExtractFile)(&h);
break;
}
/* Else, Fall Through */
case Directory:
h.Name[nameLength - 1] = '\0';
status = (*functions->MakeDirectory)(&h);
break;
case HardLink:
status = (*functions->MakeHardLink)(&h);
break;
case SymbolicLink:
status = (*functions->MakeSymbolicLink)(&h);
break;
case CharacterDevice:
case BlockDevice:
case FIFO:
status = (*functions->MakeSpecialFile)(&h);
break;
default:
errno = 0; /* Indicates broken tarfile */
return -1; /* Bad header field */
}
if ( status != 0 )
return status; /* Pass on status from coroutine */
}
if ( status > 0 ) { /* Read partial header record */
errno = 0; /* Indicates broken tarfile */
return -1;
} else {
return status; /* Whatever I/O function returned */
}
}
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