tar.c File Reference

#include "c.h"
#include <sys/stat.h>
#include "pgtar.h"

Include dependency graph for tar.c:

Go to the source code of this file.

Functions
void	print_tar_number (char *s, int len, uint64 val)
uint64	read_tar_number (const char *s, int len)
int	tarChecksum (const char *header)
bool	isValidTarHeader (const char *header)
enum tarError	tarCreateHeader (char *h, const char *filename, const char *linktarget, pgoff_t size, mode_t mode, uid_t uid, gid_t gid, time_t mtime)

Function Documentation

isValidTarHeader()

bool isValidTarHeader

(

const char *

header

)

Definition at line 112 of file tar.c.

{
    int         sum;
    int         chk = tarChecksum(header);
 
    sum = read_tar_number(&header[TAR_OFFSET_CHECKSUM], 8);
 
    if (sum != chk)
        return false;
 
    /* POSIX tar format */
    if (memcmp(&header[TAR_OFFSET_MAGIC], "ustar\0", 6) == 0 &&
        memcmp(&header[TAR_OFFSET_VERSION], "00", 2) == 0)
        return true;
    /* GNU tar format */
    if (memcmp(&header[TAR_OFFSET_MAGIC], "ustar  \0", 8) == 0)
        return true;
    /* not-quite-POSIX format written by pre-9.3 pg_dump */
    if (memcmp(&header[TAR_OFFSET_MAGIC], "ustar00\0", 8) == 0)
        return true;
 
    return false;
}

References fb(), read_tar_number(), TAR_OFFSET_CHECKSUM, TAR_OFFSET_MAGIC, TAR_OFFSET_VERSION, and tarChecksum().

Referenced by _discoverArchiveFormat(), and astreamer_tar_header().

print_tar_number()

void print_tar_number	(	char *	s,
		int	len,
		uint64	val
	)

Definition at line 22 of file tar.c.

{
    if (val < (((uint64) 1) << ((len - 1) * 3)))
    {
        /* Use octal with trailing space */
        s[--len] = ' ';
        while (len)
        {
            s[--len] = (val & 7) + '0';
            val >>= 3;
        }
    }
    else
    {
        /* Use base-256 with leading \200 */
        s[0] = '\200';
        while (len > 1)
        {
            s[--len] = (val & 255);
            val >>= 8;
        }
    }
}

References len, and val.

Referenced by tar_close(), and tarCreateHeader().

read_tar_number()

uint64 read_tar_number	(	const char *	s,
		int	len
	)

Definition at line 58 of file tar.c.

{
    uint64      result = 0;
 
    if (*s == '\200')
    {
        /* base-256 */
        while (--len)
        {
            result <<= 8;
            result |= (unsigned char) (*++s);
        }
    }
    else
    {
        /* octal */
        while (len-- && *s >= '0' && *s <= '7')
        {
            result <<= 3;
            result |= (*s - '0');
            s++;
        }
    }
    return result;
}

References fb(), len, and result.

Referenced by _tarGetHeader(), astreamer_tar_header(), and isValidTarHeader().

tarChecksum()

int tarChecksum

(

const char *

header

)

Definition at line 90 of file tar.c.

{
    int         i,
                sum;
 
    /*
     * Per POSIX, the checksum is the simple sum of all bytes in the header,
     * treating the bytes as unsigned, and treating the checksum field (at
     * offset TAR_OFFSET_CHECKSUM) as though it contained 8 spaces.
     */
    sum = 8 * ' ';              /* presumed value for checksum field */
    for (i = 0; i < TAR_BLOCK_SIZE; i++)
        if (i < TAR_OFFSET_CHECKSUM || i >= TAR_OFFSET_CHECKSUM + 8)
            sum += 0xFF & header[i];
    return sum;
}

References fb(), i, TAR_BLOCK_SIZE, and TAR_OFFSET_CHECKSUM.

Referenced by _tarGetHeader(), isValidTarHeader(), tar_close(), and tarCreateHeader().

tarCreateHeader()

enum tarError tarCreateHeader	(	char *	h,
		const char *	filename,
		const char *	linktarget,
		pgoff_t	size,
		mode_t	mode,
		uid_t	uid,
		gid_t	gid,
		time_t	mtime
	)

Definition at line 143 of file tar.c.

{
    if (strlen(filename) > 99)
        return TAR_NAME_TOO_LONG;
 
    if (linktarget && strlen(linktarget) > 99)
        return TAR_SYMLINK_TOO_LONG;
 
    memset(h, 0, TAR_BLOCK_SIZE);
 
    /* Name 100 */
    strlcpy(&h[TAR_OFFSET_NAME], filename, 100);
    if (linktarget != NULL || S_ISDIR(mode))
    {
        /*
         * We only support symbolic links to directories, and this is
         * indicated in the tar format by adding a slash at the end of the
         * name, the same as for regular directories.
         */
        int         flen = strlen(filename);
 
        flen = Min(flen, 99);
        h[flen] = '/';
        h[flen + 1] = '\0';
    }
 
    /* Mode 8 - this doesn't include the file type bits (S_IFMT)  */
    print_tar_number(&h[TAR_OFFSET_MODE], 8, (mode & 07777));
 
    /* User ID 8 */
    print_tar_number(&h[TAR_OFFSET_UID], 8, uid);
 
    /* Group 8 */
    print_tar_number(&h[TAR_OFFSET_GID], 8, gid);
 
    /* File size 12 */
    if (linktarget != NULL || S_ISDIR(mode))
        /* Symbolic link or directory has size zero */
        print_tar_number(&h[TAR_OFFSET_SIZE], 12, 0);
    else
        print_tar_number(&h[TAR_OFFSET_SIZE], 12, size);
 
    /* Mod Time 12 */
    print_tar_number(&h[TAR_OFFSET_MTIME], 12, mtime);
 
    /* Checksum 8 cannot be calculated until we've filled all other fields */
 
    if (linktarget != NULL)
    {
        /* Type - Symbolic link */
        h[TAR_OFFSET_TYPEFLAG] = TAR_FILETYPE_SYMLINK;
        /* Link Name 100 */
        strlcpy(&h[TAR_OFFSET_LINKNAME], linktarget, 100);
    }
    else if (S_ISDIR(mode))
    {
        /* Type - directory */
        h[TAR_OFFSET_TYPEFLAG] = TAR_FILETYPE_DIRECTORY;
    }
    else
    {
        /* Type - regular file */
        h[TAR_OFFSET_TYPEFLAG] = TAR_FILETYPE_PLAIN;
    }
 
    /* Magic 6 */
    strcpy(&h[TAR_OFFSET_MAGIC], "ustar");
 
    /* Version 2 */
    memcpy(&h[TAR_OFFSET_VERSION], "00", 2);
 
    /* User 32 */
    /* XXX: Do we need to care about setting correct username? */
    strlcpy(&h[TAR_OFFSET_UNAME], "postgres", 32);
 
    /* Group 32 */
    /* XXX: Do we need to care about setting correct group name? */
    strlcpy(&h[TAR_OFFSET_GNAME], "postgres", 32);
 
    /* Major Dev 8 */
    print_tar_number(&h[TAR_OFFSET_DEVMAJOR], 8, 0);
 
    /* Minor Dev 8 */
    print_tar_number(&h[TAR_OFFSET_DEVMINOR], 8, 0);
 
    /* Prefix 155 - not used, leave as nulls */
 
    /* Finally, compute and insert the checksum */
    print_tar_number(&h[TAR_OFFSET_CHECKSUM], 8, tarChecksum(h));
 
    return TAR_OK;
}

References fb(), filename, memcpy(), Min, mode, print_tar_number(), S_ISDIR, strlcpy(), TAR_BLOCK_SIZE, TAR_FILETYPE_DIRECTORY, TAR_FILETYPE_PLAIN, TAR_FILETYPE_SYMLINK, TAR_NAME_TOO_LONG, TAR_OFFSET_CHECKSUM, TAR_OFFSET_DEVMAJOR, TAR_OFFSET_DEVMINOR, TAR_OFFSET_GID, TAR_OFFSET_GNAME, TAR_OFFSET_LINKNAME, TAR_OFFSET_MAGIC, TAR_OFFSET_MODE, TAR_OFFSET_MTIME, TAR_OFFSET_NAME, TAR_OFFSET_SIZE, TAR_OFFSET_TYPEFLAG, TAR_OFFSET_UID, TAR_OFFSET_UNAME, TAR_OFFSET_VERSION, TAR_OK, TAR_SYMLINK_TOO_LONG, and tarChecksum().

Referenced by _tarWriteHeader(), _tarWriteHeader(), astreamer_tar_archiver_content(), and tar_open_for_write().