cache: document negative ttls and add about ttl

We've long supported negative ttls, for infinite cache, except the
documentation incorrectly showed one of our defaults as being 5 and not
-1. As well, with a negative ttl, we were actually making the HTTP
expired header go backwards. This changes it to go ahead ten years
instead.

Further, we add an cache-about-ttl option to set a different ttl for
about pages, which are now increasingly being filtered through markdown
or just sent statically anyway.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/cgit.c b/cgit.c
index 950b878..a45ce1f 100644
--- a/cgit.c
+++ b/cgit.c
@@ -211,6 +211,8 @@ static void config_cb(const char *name, const char *value)
                 ctx.cfg.cache_static_ttl = atoi(value);
         else if (!strcmp(name, "cache-dynamic-ttl"))
                 ctx.cfg.cache_dynamic_ttl = atoi(value);
+        else if (!strcmp(name, "cache-about-ttl"))
+                ctx.cfg.cache_about_ttl = atoi(value);
         else if (!strcmp(name, "case-sensitive-sort"))
                 ctx.cfg.case_sensitive_sort = atoi(value);
         else if (!strcmp(name, "about-filter"))
@@ -351,12 +353,13 @@ static void prepare_context(struct cgit_context *ctx)
         ctx->cfg.agefile = "info/web/last-modified";
         ctx->cfg.nocache = 0;
         ctx->cfg.cache_size = 0;
-        ctx->cfg.cache_dynamic_ttl = 5;
         ctx->cfg.cache_max_create_time = 5;
-        ctx->cfg.cache_repo_ttl = 5;
         ctx->cfg.cache_root = CGIT_CACHE_ROOT;
+        ctx->cfg.cache_about_ttl = 15;
+        ctx->cfg.cache_repo_ttl = 5;
         ctx->cfg.cache_root_ttl = 5;
         ctx->cfg.cache_scanrc_ttl = 15;
+        ctx->cfg.cache_dynamic_ttl = 5;
         ctx->cfg.cache_static_ttl = -1;
         ctx->cfg.case_sensitive_sort = 1;
         ctx->cfg.branch_sort = 0;
@@ -922,6 +925,9 @@ static int calc_ttl()
         if (!ctx.qry.page)
                 return ctx.cfg.cache_repo_ttl;
 
+        if (!strcmp(ctx.qry.page, "about"))
+                return ctx.cfg.cache_about_ttl;
+
         if (ctx.qry.has_symref)
                 return ctx.cfg.cache_dynamic_ttl;
 
@@ -973,7 +979,10 @@ int main(int argc, const char **argv)
         }
 
         ttl = calc_ttl();
-        ctx.page.expires += ttl * 60;
+        if (ttl < 0)
+                ctx.page.expires += 10 * 365 * 24 * 60 * 60; /* 10 years */
+        else
+                ctx.page.expires += ttl * 60;
         if (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD"))
                 ctx.cfg.nocache = 1;
         if (ctx.cfg.nocache)