copy.c

copy.c

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <unistd.h>

#define BUF_SIZE 4096


int main(int argc, char* argv[]) {
    int inputFd, outputFd, tmpFd;
    ssize_t numIn, numOut;
    char buffer[BUF_SIZE];
    off_t begin=0, end=0;
    long long fileSize, blockSize, pos=0;

    FILE* stream;
    char tmpStr[] = "tmp_XXXXXX";
    mktemp(tmpStr);
    printf("%s\n", tmpStr);
    stream = fopen(tmpStr, "w+");       /*權限為600，只有owner才可以讀寫*/
    if (stream == NULL)
        perror("error: ");
    tmpFd = fileno(stream);
    inputFd = open (argv [1], O_RDONLY);
    outputFd = open(tmpFd, O_WRONLY | O_CREAT, S_IRUSR| S_IWUSR);
    ftruncate(outputFd, 0);

    fileSize = lseek(inputFd, 0, SEEK_END);
    lseek(inputFd, 0, SEEK_SET);

        while (1) {
                pos = lseek(inputFd, pos, SEEK_DATA);
                begin = pos;
                pos = lseek(inputFd, pos, SEEK_HOLE);
                end = pos;
                blockSize=end-begin;
                lseek(inputFd, begin, SEEK_SET);
                lseek(outputFd, begin, SEEK_SET);
                while((numIn = read (inputFd, buffer, BUF_SIZE)) > 0) {
                        numOut = write (outputFd, buffer, (ssize_t) numIn);
                        if (numIn != numOut) perror("numIn != numOut");
                        blockSize-=numIn;
                        if (blockSize == 0) break;
                }
                if (lseek(outputFd, 0, SEEK_CUR) == fileSize) break;
    }
    close (inputFd);
    close (outputFd);

    return (EXIT_SUCCESS);
}