src/base/loader/image_file_data.cc

/*
 * Copyright (c) 2002-2004 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "base/loader/image_file_data.hh"

#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <zlib.h>

#include <cstdio>
#include <vector>

#include "base/logging.hh"

namespace Loader
{

static bool
hasGzipMagic(int fd)
{
    uint8_t buf[2] = {0};
    size_t sz = pread(fd, buf, 2, 0);
    panic_if(sz != 2, "Couldn't read magic bytes from object file");
    return ((buf[0] == 0x1f) && (buf[1] == 0x8b));
}

static int
doGzipLoad(int fd)
{
    const size_t blk_sz = 4096;

    gzFile fdz = gzdopen(fd, "rb");
    if (!fdz) {
        return -1;
    }

    size_t tmp_len = strlen(P_tmpdir);
    char *tmpnam = (char*) malloc(tmp_len + 20);
    strcpy(tmpnam, P_tmpdir);
    strcpy(tmpnam+tmp_len, "/gem5-gz-obj-XXXXXX"); // 19 chars
    fd = mkstemp(tmpnam); // repurposing fd variable for output
    if (fd < 0) {
        free(tmpnam);
        gzclose(fdz);
        return fd;
    }

    if (unlink(tmpnam) != 0)
        warn("couldn't remove temporary file %s\n", tmpnam);

    free(tmpnam);

    auto buf = new uint8_t[blk_sz];
    int r; // size of (r)emaining uncopied data in (buf)fer
    while ((r = gzread(fdz, buf, blk_sz)) > 0) {
        auto p = buf; // pointer into buffer
        while (r > 0) {
            auto sz = write(fd, p, r);
            assert(sz <= r);
            r -= sz;
            p += sz;
        }
    }
    delete[] buf;
    gzclose(fdz);
    if (r < 0) { // error
        close(fd);
        return -1;
    }
    assert(r == 0); // finished successfully
    return fd; // return fd to decompressed temporary file for mmap()'ing
}

ImageFileData::ImageFileData(const std::string &fname)
{
    _filename = fname;

    // Open the file.
    int fd = open(fname.c_str(), O_RDONLY);
    panic_if(fd < 0, "Failed to open file %s.\n", fname);

    // Decompress GZ files.
    if (hasGzipMagic(fd)) {
        fd = doGzipLoad(fd);
        panic_if(fd < 0, "Failed to unzip file %s.\n", fname);
    }

    // Find the length of the file by seeking to the end.
    off_t off = lseek(fd, 0, SEEK_END);
    fatal_if(off < 0, "Failed to determine size of file %s.\n", fname);
    _len = static_cast<size_t>(off);

    // Mmap the whole shebang.
    _data = (uint8_t *)mmap(NULL, _len, PROT_READ, MAP_SHARED, fd, 0);
    close(fd);

    panic_if(_data == MAP_FAILED, "Failed to mmap file %s.\n", fname);
}

ImageFileData::~ImageFileData()
{
    munmap((void *)_data, _len);
}

} // namespace Loader