Manifest read() should remove 512 byte limit for Manifest main attributes
Comments
EVALUATION
Agreed. Looks like it should be relatively easy to fix.
We should replace the fixed length buffer in Manifest.java:
// Line buffer
byte[] lbuf = new byte[512];
with an unbounded length data structure.
###@###.### 2003-06-19
The Jar File Specification makes it clear that
lines in the Manifest file must be a maximum of 72 bytes long,
with provision for line continuation. Java APIs like
Manifest.write correctly generate such line continuations.
Keeping this in mind, there is no reason why the implementation
need accept any input lines longer than 72 bytes. The fact that
it accepts even 512 bytes is generous. There is no bug in
the current implementation. I have re-classified this bug as RFE.
However, the specification is poor. This kind of
restriction (RFC822) was intended as an interchange file format
for ancient computer systems. Today we should design all
file formats to never have such arbitrary length restrictions.
Because the jar file format is an interchange format between
different Java implementations, the old format must be
supported for years, if not decades. The default must
remain to generate Manifest files with the 72byte limit,
and the limit must continue to be documented, so that
tools that generate Manifests programmatically can continue
to generate portable jar files.
Nevertheless, the spec should be changed so that all future
implementations have no line length limit. Perhaps 20 years
after this is implemented, we can abandon compatibility with
old Java implemenations and by default generate new jar files
with long lines.
###@###.### 2003-08-07
07-08-2003
WORK AROUND
Use the Manifest.write method to generate manifest files instead
of writing them "by hand". For example, this code:
public static void main (String[] args) throws Exception {
Manifest m = new Manifest();
Attributes a = m.getMainAttributes();
a.put(Attributes.Name.MANIFEST_VERSION, "3.14");
a.put(Attributes.Name.CLASS_PATH,
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath1 " +
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath2 " +
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath3 " +
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath4 " +
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath5 " +
"/some/very/long/paaaaaaaaaaaaaaaaaaaaaaaaaath6");
m.write(System.out);
generates an output file with 72-byte lines and continuation lines.
###@###.### 2003-08-07