carray - Print a binary file as a C array

carray.c

/*
 * Print the contents of a binary file as a C array.
 *
 * SPDX License Identifier: MIT
 * (C) 2017 Jon Szymaniak <[email protected]>
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

static const char usage[] =
    "Usage: %s <binary file> [type] [name]\n"
    "\n"
    "Prints the contents of <binary file> as a C array, of type [type] and \n"
    "named [name], to stdout.Each input byte will be a separate array \n"
    "element. The defaults are: type=char, name=data\n"
    "\n"
    "Example:\n"
    "   $ carray myfile.bin uint8_t mydata\n"
    "\n";


static const char header[] = "static const %s %s[] = {";
static const char footer[] = "\n};\n\nstatic const size_t %s_len = %zd;\n\n";

int main(int argc, char *argv[])
{
    const char default_name[] = "data";
    const char default_type[] = "uint8_t";

    const char *type = default_type;
    const char *name = default_name;

    FILE *in;
    size_t addr, n_read, col, i;
    unsigned char buf[64 * 1024];


    if (argc < 2 || argc > 5) {
        fprintf(stderr, usage, argv[0]);
        return EXIT_FAILURE;
    }

    if (argc >= 3) {
        type = argv[2];
    }

    if (argc >= 4) {
        name = argv[3];
    }

    in = fopen(argv[1], "rb");
    if (!in) {
        fprintf(stderr, "Failed to open %s: %s\n", argv[1], strerror(errno));
        return EXIT_FAILURE;
    }

    printf(header, type, name);

    addr = col = 0;
    n_read = fread(buf, 1, sizeof(buf), in);
    while (n_read) {
        for (i = 0; i < n_read; i++, addr++) {
            const unsigned char b = buf[addr];
            switch (col) {
                case 0:
                    printf("\n    /* %08x */      0x%02x",
                            (unsigned int) addr, b);
                    break;

                case 4:
                    printf(",    0x%02x", b);
                    break;

                case 7:
                    printf(", 0x%02x,", b);
                    break;

                default:
                    printf(", 0x%02x", b);

            }

            col = (col + 1) & 0x7;
        }

        n_read = fread(buf, 1, sizeof(buf), in);
    }

    printf(footer, name, addr);
    fclose(in);
    return 0;
}

man xxd