lzma.c

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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <lzma.h>
#include <stdio.h>
#include <linux/compiler.h>
#include "compress.h"
#include "util.h"
#include "debug.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_to_file(const char *input, 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];
    FILE *infile;

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

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

    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_err("lzma: read error: %s\n", strerror(errno));
                goto err_fclose;
            }

            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_err("lzma: write error: %s\n", strerror(errno));
                goto err_fclose;
            }

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

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

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

    err = 0;
err_fclose:
    fclose(infile);
    return err;
}