使用mmap方式open一个文件hex2bin工具源码

#include
#include
#include
#include
#include

#define log_printf(msg...) fprintf(stderr, "hex2bin : "msg)

int inline hex2bin(char h4, char l4) {
    if (h4 >= 'a') h4 = h4 - 'a' + 'A';
    if (l4 >= 'a') l4 = l4 - 'a' + 'A';

    if (h4 >= 'A') h4 = h4 - 'A' + 10;
    else h4 = h4 - '0';
    if (l4 >= 'A') l4 = l4 - 'A' + 10;
    else l4 = l4 - '0';

    return ((h4 << 4) | l4);
}
int main(int argc, char *argv[])
{
    int fd;
    char *name;
    struct stat sb;
    char *data;
    int i;

    if (argc != 2) {
        log_printf("hex2bin filename!\nn");
        return 1;
    }
    name = argv[1];
    fd = open(name, O_RDWR);
    if (fd < 0) {
        log_printf("file %s is not exist\n", name);
        return 1;
    }

    if (fstat(fd, &sb)) {
        perror("fstat: ");
        return 1;
    }

    data = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);

    if (data == MAP_FAILED) {
        log_printf("mmap failed\n");
        return 1;
    }
    
    for (i = 0; i < sb.st_size;) {
        if ((data[i] == '\n') || (data[i] == '\r')) {
            ++i;
            continue;
        }
        fprintf(stdout, "%c", hex2bin(data[i], data[i+1]));
        i += 2;
    }
}

下面test.hex为含有十六进制字符数据的文件，比如里面内容为：
140f0f1011b5223d79587717ffd9ec3a
af65bb470269ecd7af01f68f1a2b7b78
007ee80e7e04d27f4af09b4a55bbe5da
e38a6863169abfba3e78406f98c457f7
然后gliethttp.bin就是十六进制对应的二进制数据了,可以使用ghex2软件查空二进制数据[luther.gliethttp]

luther@gliethttp:/vobs/tmp$ gcc hex2bin.c
luther@gliethttp:/vobs/tmp$ ./a.out test.hex > gliethttp.bin
luther@gliethttp:/vobs/tmp$ ghex2 gliethttp.bin