http: compress: Add a couple of helper functions

This adds two helper function that will be used in subsequent commits.

nxt_http_comp_compress() does the actual compression.

nxt_http_comp_bound() returns the maximum compressed size for the given
size.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Author: ac000

src/nxt_http_compression.c

@@ -151,6 +151,36 @@ static void print_comp_config(size_t n)
     }
 }
 
+
+static ssize_t
+nxt_http_comp_compress(uint8_t *dst, size_t dst_size, const uint8_t *src,
+                       size_t src_size, bool last)
+{
+    nxt_http_comp_ctx_t               *ctx = &compressor_ctx;
+    nxt_http_comp_compressor_t        *compressor;
+    const nxt_http_comp_operations_t  *cops;
+
+    compressor = &enabled_compressors[ctx->idx];
+    cops = compressor->type->cops;
+
+    return cops->deflate(&ctx->ctx, src, src_size, dst, dst_size, last);
+}
+
+
+static size_t
+nxt_http_comp_bound(size_t size)
+{
+    nxt_http_comp_ctx_t               *ctx = &compressor_ctx;
+    nxt_http_comp_compressor_t        *compressor;
+    const nxt_http_comp_operations_t  *cops;
+
+    compressor = &enabled_compressors[ctx->idx];
+    cops = compressor->type->cops;
+
+    return cops->bound(&ctx->ctx, size);
+}
+
+
 bool
 nxt_http_comp_wants_compression(void)
 {