Switch to reading content streams on the fly during interpretation.

Previously, before interpreting a pages content stream we would
load it entirely into a buffer. Then we would interpret that
buffer. This has a cost in memory use.

Here, we update the code to read from a stream on the fly.

This has required changes in various different parts of the code.

Firstly, we have removed all use of the FILE lock - as stream
reads can now safely be interrupted by resource (or object) reads
from elsewhere in the file, the file lock becomes a very hard
thing to maintain, and doesn't actually benefit us at all. The
choices were to either use a recursive lock, or to remove it
entirely; I opted for the latter.

The file lock enum value remains as a placeholder for future use in
extendable data streams.

Secondly, we add a new 'concat' filter that concatenates a series of
streams together into one, optionally putting whitespace between each
stream (as the pdf parser requires this).

Finally, we change page/xobject/pattern content streams to work
on the fly, but we leave type3 glyphs using buffers (as presumably
these will be run repeatedly).

1 files changed, 0 insertions, 1 deletions

diff --git a/scripts/cmapdump.c b/scripts/cmapdump.c
index 57cfe54b..53247339 100644
--- a/scripts/cmapdump.c
+++ b/scripts/cmapdump.c
@@ -85,7 +85,6 @@ main(int argc, char **argv)
 		clean(name);
 
 		fi = fz_open_file(ctx, argv[i]);
-		fz_lock_stream(fi);
 		cmap = pdf_load_cmap(ctx, fi);
 		fz_close(fi);