{"record":{"id":"a3563e9d15083bd3","repo":"lionsoul2014/ip2region","slug":"failed-to-allocate-memory-for-db-path","errorCode":null,"errorMessage":"failed to allocate memory for db_path","messagePattern":"failed to allocate memory for db_path","errorType":"console","errorClass":null,"httpStatus":null,"severity":"critical","filePath":"binding/nginx/src/ngx_http_ip2region_module.c","lineNumber":97,"sourceCode":"\n\n// 用于初始化带版本校验的搜索器的辅助函数\nstatic char *\nngx_http_ip2region_init_searcher(ngx_conf_t *cf, char *db_name,\n    char *cache_policy, xdb_version_t *expected_version, const char *directive_name)\n{\n    ip2region_searcher_t       *ip2region_searcher;\n    int                         err;\n    char                       *db_path;\n    size_t                      len;\n\n    if(ngx_http_ip2region_is_absolute_path(db_name) == NGX_OK) {\n        db_path = db_name;\n    } else { // relative path to conf directory\n        len = ngx_cycle->conf_prefix.len + strlen(db_name) + 1;\n        db_path = malloc(len);\n        if (db_path == NULL) {\n            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,\n                               \"failed to allocate memory for db_path\");\n            return NGX_CONF_ERROR;\n        }\n        memset(db_path, '\\0', len);\n        memcpy(db_path, ngx_cycle->conf_prefix.data, ngx_cycle->conf_prefix.len);\n        strcat(db_path, db_name);\n    }\n\n    ip2region_searcher = ngx_palloc(cf->pool, sizeof(ip2region_searcher_t));\n\n    if(ip2region_searcher == NULL) {\n        if(ngx_http_ip2region_is_absolute_path(db_name) != NGX_OK) {\n            free(db_path);\n        }\n        return NGX_CONF_ERROR;\n    }\n\n    ip2region_searcher->v_index = NULL;","sourceCodeStart":79,"sourceCodeEnd":115,"githubUrl":"https://github.com/lionsoul2014/ip2region/blob/c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1/binding/nginx/src/ngx_http_ip2region_module.c#L79-L115","documentation":"In the nginx module's init, when the xdb path is relative it is joined onto the conf prefix; the malloc for that combined path failed, so nginx logs this EMERG message and aborts configuration parsing. It indicates host memory exhaustion (or an absurdly long path) at config-load time.","triggerScenarios":"ngx_http_ip2region_init_searcher with a relative db_name whose conf_prefix + name length makes malloc return NULL — typically under severe memory pressure or with a path exceeding practical limits.","commonSituations":"Host with exhausted memory during nginx start/reload, extremely long prefix/path combination, restricted container memory limits.","solutions":["Free host memory or raise the container/memory limit and reload nginx","Shorten the configured db path or use an absolute path (avoids the concatenation entirely)","Check conf_prefix length; move xdb files closer to the conf root","Check system logs (dmesg/OOM killer) if the failure recurs at startup"],"exampleFix":"# before\nip2region_db ip2region/../very/long/path/to/region.v6.xdb;\n# after\nip2region_db /var/lib/ip2region/region.v6.xdb;  # absolute path, no malloc join","handlingStrategy":"validation","validationCode":"/* C: check path length before init */\nif (strlen(ngx_cycle->conf_prefix.data) + strlen(db_name) + 1 > 4096) {\n    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, \"ip2region db path too long\");\n    return NGX_CONF_ERROR;\n}","typeGuard":null,"tryCatchPattern":"/* caller of init already returns NGX_CONF_ERROR; verify at startup */\nnginx -t 2>&1 | grep 'failed to allocate memory for db_path' && free -m","preventionTips":["Use absolute paths to skip the malloc-and-join path entirely","Keep xdb paths short and near the conf prefix","Ensure adequate host memory before nginx start/reload","Run nginx -t after config changes to catch this before production reload"],"tags":["c","nginx","out-of-memory","config-load"],"backgroundTag":"out-of-memory","analyzedSha":"c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1","analyzedAt":"2026-09-02T16:58:39.988Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-09T21:17:11.164Z"}