Advanced users may use the Firehose file to backup the QCN (Qualcomm Calibration Network) file for baseband repair (fixing IMEI null issues) or to flash custom recoveries like TWRP.
OPPO service centers use a signed MSM tool. If you find the "OPPO A57 MSM Download Tool" (often named CPH1701_11_A.14_MSM_8937.rar), it contains the Firehose embedded. You simply: oppo a57 firehose file
Unpack the OTA Oppo_A57_CPH1701_*.zip → Look inside firmware-update/ for a file named prog_emmc_firehose_*.mbn or *.elf. Most Oppo OTAs do not include it – it’s stripped. Advanced users may use the Firehose file to