Upstream: fixed proxy_no_cache when caching errors. Caching errors, notably intercepted errors and internally generated 502/504 errors, as well as handling of cache revalidation with 304, did not take into account u->conf->no_cache predicates configured. As a result, an error might be cached even if configuration explicitly says not to. Fix is to check u->conf->no_cache in these cases. To simplify usage in multiple places, checking u->conf->no_cache is now done in a separate function. As a minor optimization, u->conf->no_cache is only checked if u->cacheable is set. As a side effect, this change also fixes caching errors after proxy_cache_bypass. Also, during cache revalidation u->cacheable is now tested, so 304 responses which disable caching won't extend cacheability of stored responses. Additionally, when caching internally generated 502/504 errors u->cacheable is now explicitly updated from u->headers_in.no_cache and u->headers_in.expired, restoring the behaviour before 8041:0784ab86ad08 (1.23.0) when an error happens while reading the response headers. Reported by Kirill A. Korinsky, https://freenginx.org/pipermail/nginx/2024-April/000082.html

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


ngx_list_t *
ngx_list_create(ngx_pool_t *pool, ngx_uint_t n, size_t size)
{
    ngx_list_t  *list;

    list = ngx_palloc(pool, sizeof(ngx_list_t));
    if (list == NULL) {
        return NULL;
    }

    if (ngx_list_init(list, pool, n, size) != NGX_OK) {
        return NULL;
    }

    return list;
}


void *
ngx_list_push(ngx_list_t *l)
{
    void             *elt;
    ngx_list_part_t  *last;

    last = l->last;

    if (last->nelts == l->nalloc) {

        /* the last part is full, allocate a new list part */

        last = ngx_palloc(l->pool, sizeof(ngx_list_part_t));
        if (last == NULL) {
            return NULL;
        }

        last->elts = ngx_palloc(l->pool, l->nalloc * l->size);
        if (last->elts == NULL) {
            return NULL;
        }

        last->nelts = 0;
        last->next = NULL;

        l->last->next = last;
        l->last = last;
    }

    elt = (char *) last->elts + l->size * last->nelts;
    last->nelts++;

    return elt;
}