/**
* @file
* @brief Untar an Image
* @ingroup libmisc_untar_img Untar Image
* FIXME:
* 1. Symbolic links are not created.
* 2. Untar_FromMemory uses FILE *fp.
* 3. How to determine end of archive?
*/
/*
* Written by: Jake Janovetz <janovetz@tempest.ece.uiuc.edu>
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/param.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <rtems/untar.h>
#include <rtems/bspIo.h>
/*
* TAR file format:
* Offset Length Contents
* 0 100 bytes File name ('\0' terminated, 99 maxmum length)
* 100 8 bytes File mode (in octal ascii)
* 108 8 bytes User ID (in octal ascii)
* 116 8 bytes Group ID (in octal ascii)
* 124 12 bytes File size (s) (in octal ascii)
* 136 12 bytes Modify time (in octal ascii)
* 148 8 bytes Header checksum (in octal ascii)
* 156 1 bytes Link flag
* 157 100 bytes Linkname ('\0' terminated, 99 maxmum length)
* 257 8 bytes Magic PAX ("ustar\0" + 2 bytes padding)
* 257 8 bytes Magic GNU tar ("ustar \0")
* 265 32 bytes User name ('\0' terminated, 31 maxmum length)
* 297 32 bytes Group name ('\0' terminated, 31 maxmum length)
* 329 8 bytes Major device ID (in octal ascii)
* 337 8 bytes Minor device ID (in octal ascii)
* 345 155 bytes Prefix
* 512 (s+p)bytes File contents (s+p) := (((s) + 511) & ~511),
* round up to 512 bytes
*
* Checksum:
* int i, sum;
* char* header = tar_header_pointer;
* sum = 0;
* for(i = 0; i < 512; i++)
* sum += 0xFF & header[i];
*/
#define MAX_NAME_FIELD_SIZE 99
/*
* This converts octal ASCII number representations into an
* unsigned long. Only support 32-bit numbers for now.
*/
unsigned long
_rtems_octal2ulong(
const char *octascii,
size_t len
)
{
size_t i;
unsigned long num;
num = 0;
for (i=0; i < len; i++) {
if ((octascii[i] < '0') || (octascii[i] > '9')) {
continue;
}
num = num * 8 + ((unsigned long)(octascii[i] - '0'));
}
return(num);
}
/*
* Function: Untar_FromMemory
*
* Description:
*
* This is a simple subroutine used to rip links, directories, and
* files out of a block of memory.
*
*
* Inputs:
*
* void * tar_buf - Pointer to TAR buffer.
* size_t size - Length of TAR buffer.
*
*
* Output:
*
* int - UNTAR_SUCCESSFUL (0) on successful completion.
* UNTAR_INVALID_CHECKSUM for an invalid header checksum.
* UNTAR_INVALID_HEADER for an invalid header.
*
*/
int
Untar_FromMemory(
void *tar_buf,
size_t size
)
{
FILE *fp;
const char *tar_ptr = (const char *)tar_buf;
const char *bufr;
size_t n;
char fname[100];
char linkname[100];
int sum;
int hdr_chksum;
int retval;
unsigned long ptr;
unsigned long i;
unsigned long nblocks;
unsigned long file_size;
unsigned char linkflag;
ptr = 0;
while (1) {
if (ptr + 512 > size) {
retval = UNTAR_SUCCESSFUL;
break;
}
/* Read the header */
bufr = &tar_ptr[ptr];
ptr += 512;
if (strncmp(&bufr[257], "ustar", 5)) {
retval = UNTAR_SUCCESSFUL;
break;
}
strncpy(fname, bufr, MAX_NAME_FIELD_SIZE);
fname[MAX_NAME_FIELD_SIZE] = '\0';
linkflag = bufr[156];
file_size = _rtems_octal2ulong(&bufr[124], 12);
/*
* Compute the TAR checksum and check with the value in
* the archive. The checksum is computed over the entire
* header, but the checksum field is substituted with blanks.
*/
hdr_chksum = _rtems_octal2ulong(&bufr[148], 8);
sum = _rtems_tar_header_checksum(bufr);
if (sum != hdr_chksum) {
retval = UNTAR_INVALID_CHECKSUM;
break;
}
/*
* We've decoded the header, now figure out what it contains and
* do something with it.
*/
if (linkflag == SYMTYPE) {
strncpy(linkname, &bufr[157], MAX_NAME_FIELD_SIZE);
linkname[MAX_NAME_FIELD_SIZE] = '\0';
symlink(linkname, fname);
} else if (linkflag == REGTYPE) {
nblocks = (((file_size) + 511) & ~511) / 512;
if ((fp = fopen(fname, "w")) == NULL) {
printk("Untar: failed to create file %s\n", fname);
ptr += 512 * nblocks;
} else {
unsigned long sizeToGo = file_size;
size_t len;
/*
* Read out the data. There are nblocks of data where nblocks
* is the file_size rounded to the nearest 512-byte boundary.
*/
for (i=0; i<nblocks; i++) {
len = ((sizeToGo < 512L)?(sizeToGo):(512L));
n = fwrite(&tar_ptr[ptr], 1, len, fp);
if (n != len) {
printk("untar: Error during write\n");
retval = UNTAR_FAIL;
break;
}
ptr += 512;
sizeToGo -= n;
}
fclose(fp);
}
} else if (linkflag == DIRTYPE) {
if ( mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) != 0 ) {
if (errno == EEXIST) {
struct stat stat_buf;
if ( stat(fname, &stat_buf) == 0 ) {
if ( S_ISDIR(stat_buf.st_mode) ) {
continue;
} else {
if ( unlink(fname) != -1 ) {
if ( mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) == 0 )
continue;
}
}
}
}
printk("Untar: failed to create directory %s\n", fname);
retval = UNTAR_FAIL;
break;
}
}
}
return(retval);
}
/*
* Function: Untar_FromFile
*
* Description:
*
* This is a simple subroutine used to rip links, directories, and
* files out of a TAR file.
*
* Inputs:
*
* const char *tar_name - TAR filename.
*
* Output:
*
* int - UNTAR_SUCCESSFUL (0) on successful completion.
* UNTAR_INVALID_CHECKSUM for an invalid header checksum.
* UNTAR_INVALID_HEADER for an invalid header.
*/
int
Untar_FromFile(
const char *tar_name
)
{
int fd;
char *bufr;
ssize_t n;
char fname[100];
char linkname[100];
int sum;
int hdr_chksum;
int retval;
unsigned long i;
unsigned long nblocks;
unsigned long size;
unsigned char linkflag;
retval = UNTAR_SUCCESSFUL;
if ((fd = open(tar_name, O_RDONLY)) < 0) {
return UNTAR_FAIL;
}
bufr = (char *)malloc(512);
if (bufr == NULL) {
close(fd);
return(UNTAR_FAIL);
}
while (1) {
/* Read the header */
/* If the header read fails, we just consider it the end of the tarfile. */
if ((n = read(fd, bufr, 512)) != 512) {
break;
}
if (strncmp(&bufr[257], "ustar", 5)) {
break;
}
strncpy(fname, bufr, MAX_NAME_FIELD_SIZE);
fname[MAX_NAME_FIELD_SIZE] = '\0';
linkflag = bufr[156];
size = _rtems_octal2ulong(&bufr[124], 12);
/*
* Compute the TAR checksum and check with the value in
* the archive. The checksum is computed over the entire
* header, but the checksum field is substituted with blanks.
*/
hdr_chksum = _rtems_octal2ulong(&bufr[148], 8);
sum = _rtems_tar_header_checksum(bufr);
if (sum != hdr_chksum) {
retval = UNTAR_INVALID_CHECKSUM;
break;
}
/*
* We've decoded the header, now figure out what it contains and
* do something with it.
*/
if (linkflag == SYMTYPE) {
strncpy(linkname, &bufr[157], MAX_NAME_FIELD_SIZE);
linkname[MAX_NAME_FIELD_SIZE] = '\0';
symlink(linkname,fname);
} else if (linkflag == REGTYPE) {
int out_fd;
/*
* Read out the data. There are nblocks of data where nblocks
* is the size rounded to the nearest 512-byte boundary.
*/
nblocks = (((size) + 511) & ~511) / 512;
if ((out_fd = creat(fname, 0644)) == -1) {
(void) lseek(fd, SEEK_CUR, 512 * nblocks);
} else {
for (i=0; i<nblocks; i++) {
n = read(fd, bufr, 512);
n = MIN(n, size - i*512);
(void) write(out_fd, bufr, n);
}
close(out_fd);
}
} else if (linkflag == DIRTYPE) {
if ( mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) != 0 ) {
if (errno == EEXIST) {
struct stat stat_buf;
if ( stat(fname, &stat_buf) == 0 ) {
if ( S_ISDIR(stat_buf.st_mode) ) {
continue;
} else {
if ( unlink(fname) != -1 ) {
if ( mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) == 0 )
continue;
}
}
}
}
}
}
}
free(bufr);
close(fd);
return(retval);
}
/*
* Compute the TAR checksum and check with the value in
* the archive. The checksum is computed over the entire
* header, but the checksum field is substituted with blanks.
*/
int
_rtems_tar_header_checksum(
const char *bufr
)
{
int i, sum;
sum = 0;
for (i=0; i<512; i++) {
if ((i >= 148) && (i < 156))
sum += 0xff & ' ';
else
sum += 0xff & bufr[i];
}
return(sum);
}