Implement file previews

When using HTTP "Content-Disposition: attachment;", users are forced to
download files in order to use them, whereas others might prefer to open
them in the browser.

Therefore, now that URL parameters are supported by http.h, previews can
be forced by adding "preview=1" or "preview=true" (case-insensitive) as
a URL parameters. Any other parameters are ignored by slcl.

For users, a "Preview" link has been added next to the "Share" button
for each file.

1 files changed, 83 insertions, 18 deletions

diff --git a/page.c b/page.c
index e731177..6c67484 100644
--- a/page.c
+++ b/page.c
@@ -16,6 +16,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <time.h>
 
 #define PROJECT_NAME "slcl"
@@ -243,11 +244,50 @@ end:
     return ret;
 }
 
+static int prepare_preview(struct html_node *const n,
+    const struct stat *const sb, const char *const dir, const char *const name)
+{
+    int ret = -1;
+    struct html_node *a;
+    struct dynstr d;
+
+    dynstr_init(&d);
+
+    if (!S_ISREG(sb->st_mode))
+        return 0;
+    else if (!(a = html_node_add_child(n, "a")))
+    {
+        fprintf(stderr, "%s: html_node_add_child form failed\n", __func__);
+        goto end;
+    }
+    else if (dynstr_append(&d, "%s%s?preview=1", dir, name))
+    {
+        fprintf(stderr, "%s: dynstr_append failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_add_attr(a, "href", d.str))
+    {
+        fprintf(stderr, "%s: html_node_add_attr failed\n", __func__);
+        goto end;
+    }
+    else if (html_node_set_value(a, "Preview"))
+    {
+        fprintf(stderr, "%s: html_node_set_value value failed\n", __func__);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    dynstr_free(&d);
+    return ret;
+}
+
 static int add_element(struct html_node *const n, const char *const dir,
     const char *const res, const char *const name)
 {
     int ret = -1;
-    enum {NAME, SIZE, DATE, SHARE, COLUMNS};
+    enum {NAME, SIZE, DATE, SHARE, PREVIEW, COLUMNS};
     struct html_node *tr, *td[COLUMNS];
     struct dynstr path;
     const char *const sep = res[strlen(res) - 1] != '/' ? "/" : "";
@@ -301,6 +341,11 @@ static int add_element(struct html_node *const n, const char *const dir,
         fprintf(stderr, "%s: prepare_date failed\n", __func__);
         goto end;
     }
+    else if (prepare_preview(td[PREVIEW], &sb, dir, name))
+    {
+        fprintf(stderr, "%s: prepare_date failed\n", __func__);
+        goto end;
+    }
 
     ret = 0;
 
@@ -867,13 +912,12 @@ end:
     return ret;
 }
 
-static int list_dir(struct http_response *const r, const char *const dir,
-    const char *const root, const char *const res,
-    const struct page_quota *const q)
+static int list_dir(const struct page_resource *const pr)
 {
     int ret = -1;
     struct dynstr out;
-    struct html_node *table, *const html = resource_layout(dir, q, &table);
+    struct html_node *table,
+        *const html = resource_layout(pr->dir, pr->q, &table);
 
     dynstr_init(&out);
 
@@ -882,7 +926,7 @@ static int list_dir(struct http_response *const r, const char *const dir,
         fprintf(stderr, "%s: resource_layout failed\n", __func__);
         goto end;
     }
-    else if (add_elements(root, res, dir, table))
+    else if (add_elements(pr->root, pr->res, pr->dir, table))
     {
         fprintf(stderr, "%s: read_elements failed\n", __func__);
         goto end;
@@ -898,7 +942,7 @@ static int list_dir(struct http_response *const r, const char *const dir,
         goto end;
     }
 
-    *r = (const struct http_response)
+    *pr->r = (const struct http_response)
     {
         .status = HTTP_STATUS_OK,
         .buf.rw = out.str,
@@ -906,7 +950,7 @@ static int list_dir(struct http_response *const r, const char *const dir,
         .free = free
     };
 
-    if (http_response_add_header(r, "Content-Type", "text/html"))
+    if (http_response_add_header(pr->r, "Content-Type", "text/html"))
     {
         fprintf(stderr, "%s: http_response_add_header failed\n", __func__);
         goto end;
@@ -924,7 +968,7 @@ end:
 }
 
 static int serve_file(struct http_response *const r,
-    const struct stat *const sb, const char *const res)
+    const struct stat *const sb, const char *const res, const bool preview)
 {
     int ret = -1;
     FILE *const f = fopen(res, "rb");
@@ -949,6 +993,14 @@ static int serve_file(struct http_response *const r,
         fprintf(stderr, "%s: basename(3) failed\n", __func__);
         goto end;
     }
+    else if (preview)
+    {
+        if (dynstr_append(&d, "inline"))
+        {
+            fprintf(stderr, "%s: dynstr_append inline failed\n", __func__);
+            goto end;
+        }
+    }
     else if (dynstr_append(&d, "attachment; filename=\"%s\"", bn))
     {
         fprintf(stderr, "%s: dynstr_append attachment failed\n", __func__);
@@ -1007,19 +1059,32 @@ static int page_not_found(struct http_response *const r)
     return 0;
 }
 
-int page_resource(struct http_response *const r, const char *const dir,
-    const char *const root, const char *const res,
-    const struct page_quota *const q)
+static bool preview(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, "preview")
+            && (!strcmp(a->value, "1")
+                || !strcasecmp(a->value, "true")))
+            return true;
+    }
+
+    return false;
+}
+
+int page_resource(const struct page_resource *const pr)
 {
     struct stat sb;
 
-    if (stat(res, &sb))
+    if (stat(pr->res, &sb))
     {
         fprintf(stderr, "%s: stat(2) %s: %s\n",
-            __func__, res, strerror(errno));
+            __func__, pr->res, strerror(errno));
 
         if (errno == ENOENT)
-            return page_not_found(r);
+            return page_not_found(pr->r);
         else
             return -1;
     }
@@ -1027,9 +1092,9 @@ int page_resource(struct http_response *const r, const char *const dir,
     const mode_t m = sb.st_mode;
 
     if (S_ISDIR(m))
-        return list_dir(r, dir, root, res, q);
+        return list_dir(pr);
     else if (S_ISREG(m))
-        return serve_file(r, &sb, res);
+        return serve_file(pr->r, &sb, pr->res, preview(pr));
 
     fprintf(stderr, "%s: unexpected st_mode %jd\n", __func__, (intmax_t)m);
     return -1;
@@ -1101,7 +1166,7 @@ int page_public(struct http_response *const r, const char *const res)
         fprintf(stderr, "%s: resolve_link failed\n", __func__);
         goto end;
     }
-    else if (serve_file(r, &sb, path))
+    else if (serve_file(r, &sb, path, false))
     {
         fprintf(stderr, "%s: serve_file failed\n", __func__);
         goto end;