// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <lzma.h>
#include <stdio.h>
#include <linux/compiler.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "compress.h"
#include "debug.h"
#include <string.h>
#include <unistd.h>
#include <internal/lib.h>

#define BUFSIZE 8192

static const char *lzma_strerror(lzma_ret ret)
{
        switch ((int) ret) {
        case LZMA_MEM_ERROR:
                return "Memory allocation failed";
        case LZMA_OPTIONS_ERROR:
                return "Unsupported decompressor flags";
        case LZMA_FORMAT_ERROR:
                return "The input is not in the .xz format";
        case LZMA_DATA_ERROR:
                return "Compressed file is corrupt";
        case LZMA_BUF_ERROR:
                return "Compressed file is truncated or otherwise corrupt";
        default:
                return "Unknown error, possibly a bug";
        }
}

int lzma_decompress_stream_to_file(FILE *infile, int output_fd)
{
        lzma_action action = LZMA_RUN;
        lzma_stream strm   = LZMA_STREAM_INIT;
        lzma_ret ret;
        int err = -1;

        u8 buf_in[BUFSIZE];
        u8 buf_out[BUFSIZE];

        ret = lzma_stream_decoder(&strm, UINT64_MAX, LZMA_CONCATENATED);
        if (ret != LZMA_OK) {
                pr_debug("lzma: lzma_stream_decoder failed %s (%d)\n", lzma_strerror(ret), ret);
                return err;
        }

        strm.next_in   = NULL;
        strm.avail_in  = 0;
        strm.next_out  = buf_out;
        strm.avail_out = sizeof(buf_out);

        while (1) {
                if (strm.avail_in == 0 && !feof(infile)) {
                        strm.next_in  = buf_in;
                        strm.avail_in = fread(buf_in, 1, sizeof(buf_in), infile);

                        if (ferror(infile)) {
                                pr_debug("lzma: read error: %m\n");
                                goto err_lzma_end;
                        }

                        if (feof(infile))
                                action = LZMA_FINISH;
                }

                ret = lzma_code(&strm, action);

                if (strm.avail_out == 0 || ret == LZMA_STREAM_END) {
                        ssize_t write_size = sizeof(buf_out) - strm.avail_out;

                        if (writen(output_fd, buf_out, write_size) != write_size) {
                                pr_debug("lzma: write error: %m\n");
                                goto err_lzma_end;
                        }

                        strm.next_out  = buf_out;
                        strm.avail_out = sizeof(buf_out);
                }

                if (ret != LZMA_OK) {
                        if (ret == LZMA_STREAM_END)
                                break;

                        pr_debug("lzma: failed %s\n", lzma_strerror(ret));
                        goto err_lzma_end;
                }
        }

        err = 0;
err_lzma_end:
        lzma_end(&strm);
        return err;
}

int lzma_decompress_to_file(const char *input, int output_fd)
{
        FILE *infile;
        int ret;

        infile = fopen(input, "rb");
        if (!infile) {
                pr_debug("lzma: fopen failed on %s: '%m'\n", input);
                return -1;
        }

        ret = lzma_decompress_stream_to_file(infile, output_fd);
        fclose(infile);
        return ret;
}

bool lzma_is_compressed(const char *input)
{
        int fd = open(input, O_RDONLY);
        const uint8_t magic[6] = { 0xFD, '7', 'z', 'X', 'Z', 0x00 };
        char buf[6] = { 0 };
        ssize_t rc;

        if (fd < 0)
                return false;

        rc = read(fd, buf, sizeof(buf));
        close(fd);
        return rc == sizeof(buf) ?
               memcmp(buf, magic, sizeof(buf)) == 0 : false;
}