Implement directory download as ZIP

Thanks to the fdzipstream library [1] and zlib [2], it is possible to
generate ZIP files on-the-fly, therefore requiring no extra disk space
usage and only a small amount of memory.

Unfortunately, as of the time of this writing fdzipstream is not
packaged by any distributions yet [3], so it had to be imported as a git
submodule as a workaround.

While libarchive [4] could be an interesting alternative, writing ZIP
files is only supported by very recent versions (>= 3.8.0), which are
still not packaged by many distributions [5], either.

Moreover, libarchive is a package with several dependencies other than
zlib and is significantly larger compared to fdzipstreams, so
fdzipstreams was ultimately considered a better fit for this purpose.

[1]: https://github.com/CTrabant/fdzipstream.git
[2]: http://zlib.net/
[3]: https://repology.org/projects/?search=fdzipstream
[4]: https://www.libarchive.org/
[5]: https://repology.org/project/libarchive/versions

1 files changed, 25 insertions, 1 deletions

diff --git a/page.c b/page.c
index af24e70..9d1ea8e 100644
--- a/page.c
+++ b/page.c
@@ -1,6 +1,7 @@
 #define _POSIX_C_SOURCE 200809L
 
 #include "page.h"
+#include "zip.h"
 #include <libweb/html.h>
 #include <libweb/http.h>
 #include <dynstr.h>
@@ -1812,6 +1813,21 @@ static bool preview(const struct page_resource *const pr)
     return false;
 }
 
+static bool download(const struct page_resource *const pr)
+{
+    for (size_t i = 0; i < pr->n_args; i++)
+    {
+        const struct http_arg *const a = &pr->args[i];
+
+        if (!strcmp(a->key, "download")
+            && (!strcmp(a->value, "1")
+                || !strcasecmp(a->value, "true")))
+            return true;
+    }
+
+    return false;
+}
+
 int page_resource(const struct page_resource *const pr)
 {
     int ret = -1;
@@ -1840,7 +1856,15 @@ int page_resource(const struct page_resource *const pr)
 
     if (S_ISDIR(m))
     {
-        if ((ret = list_dir(pr)))
+        if (download(pr))
+        {
+            if ((ret = zip(pr->res, pr->r)))
+            {
+                fprintf(stderr, "%s: zip_dir failed\n", __func__);
+                goto end;
+            }
+        }
+        else if ((ret = list_dir(pr)))
         {
             if (ret < 0)
             {