Change types for source map offsets (#174)

* Improve strbuf guarantees

Introduce BUFSIZE_MAX macro and make sure that the strbuf implementation
can handle strings up to this size.

* Abort early if document size exceeds internal limit

* Change types for source map offsets

Switch to size_t for the public API, making the public headers
C89-compatible again.

Switch to bufsize_t internally, reducing memory usage and improving
performance on 32-bit platforms.

* Make parser return NULL on internal index overflow

Make S_parser_feed set an error and ignore subsequent chunks if the
total input document size exceeds an internal limit. Make
cmark_parser_finish return NULL if an error was encountered. Add
public API functions to retrieve error code and error message.

strbuf overflow in renderers and OOM in parser or renderers still
cause an abort.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/buffer.h b/src/buffer.h
index e878075..7f31a74 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -13,8 +13,28 @@
 extern "C" {
 #endif
 
+#ifndef CMARK_HUGE_DOCS
+
+// Maximum strbuf size without terminating NUL byte.
+#define BUFSIZE_MAX (INT32_MAX - 1)
+
 typedef int32_t bufsize_t;
 
+#else // CMARK_HUGE_DOCS
+
+// This is an untested proof of concept of how to handle multi-gigabyte
+// documents on 64-bit platforms at the expense of internal struct sizes.
+
+#ifdef PTRDIFF_MAX
+  #define BUFSIZE_MAX (PTRDIFF_MAX - 1)
+#else
+  #define BUFSIZE_MAX (ptrdiff_t)((size_t)-1 / 2)
+#endif
+
+typedef ptrdiff_t bufsize_t;
+
+#endif // CMARK_HUGE_DOCS
+
 typedef struct {
   cmark_mem *mem;
   unsigned char *ptr;