/*
* Searches for the ZIP64 end of central directory (END) header. The
* contents of the ZIP64 END header will be read and placed in end64buf.
* Returns the file position of the ZIP64 END header, otherwise returns
* -1 if the END header was not found or an error occurred.
*
* The ZIP format specifies the "position" of each related record as
* ...
* [central directory]
* [zip64 end of central directory record]
* [zip64 end of central directory locator]
* [end of central directory record]
*
* The offset of zip64 end locator can be calculated from endpos as
* "endpos - ZIP64_LOCHDR".
* The "offset" of zip64 end record is stored in zip64 end locator.
*/
static jlong
findEND64(jzfile *zip, void *end64buf, jlong endpos)
{
char loc64[ZIP64_LOCHDR];
jlong end64pos;
if (readFullyAt(zip->zfd, loc64, ZIP64_LOCHDR, endpos - ZIP64_LOCHDR) == -1) {
return -1; // end64 locator not found
}
end64pos = ZIP64_LOCOFF(loc64);
if (readFullyAt(zip->zfd, end64buf, ZIP64_ENDHDR, end64pos) == -1) {
return -1; // end64 record not found
}
return end64pos;
}
/*
* Computes and positions at the start of the CEN header, ie. the central
* directory, this will also return the offset if there is a zip file comment
* at the end of the archive, for most cases this would be 0.
*/
static jlong
compute_cen(int fd, Byte *bp)
{
int bytes;
Byte *p;
jlong base_offset;
jlong offset;
char buffer[MINREAD];
p = buffer;
/*
* Read the END Header, which is the starting point for ZIP files.
* (Clearly designed to make writing a zip file easier than reading
* one. Now isn't that precious...)
*/
if ((base_offset = find_end(fd, bp)) == -1) {
return (-1);
}
p = bp;
/*
* There is a historical, but undocumented, ability to allow for
* additional "stuff" to be prepended to the zip/jar file. It seems
* that this has been used to prepend an actual java launcher
* executable to the jar on Windows. Although this is just another
* form of statically linking a small piece of the JVM to the
* application, we choose to continue to support it. Note that no
* guarantees have been made (or should be made) to the customer that
* this will continue to work.
*
* Therefore, calculate the base offset of the zip file (within the
* expanded file) by assuming that the central directory is followed
* immediately by the end record.
*/
if (zip64_present) {
if ((offset = ZIP64_LOCOFF(p)) < (jlong)0) {
return -1;
}
if (JLI_Lseek(fd, offset, SEEK_SET) < (jlong) 0) {
return (-1);
}
if ((bytes = read(fd, buffer, MINREAD)) < 0) {
return (-1);
}
if (GETSIG(buffer) != ZIP64_ENDSIG) {
return -1;
}
if ((offset = ZIP64_ENDOFF(buffer)) < (jlong)0) {
return -1;
}
if (JLI_Lseek(fd, offset, SEEK_SET) < (jlong)0) {
return (-1);
}
p = buffer;
base_offset = base_offset - ZIP64_ENDSIZ(p) - ZIP64_ENDOFF(p) - ZIP64_ENDHDR;
} else {
base_offset = base_offset - ENDSIZ(p) - ENDOFF(p);
/*
* The END Header indicates the start of the Central Directory
* Headers. Remember that the desired Central Directory Header (CEN)
* will almost always be the second one and the first one is a small
* directory entry ("META-INF/"). Keep the code optimized for
* that case.
*
* Seek to the beginning of the Central Directory.
*/
if (JLI_Lseek(fd, base_offset + ENDOFF(p), SEEK_SET) < (jlong) 0) {
return (-1);
}
}
return base_offset;
}
