/* mycopy: copies its first command-line argument file to the second. */
/* This is Listing 17-4 in the text. */

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

FILE * file_open(char name[], char access_mode[]);
int fcopy(FILE *inf, FILE *outf);

main(int argc, char *argv[]) {
    FILE *inf, *outf;
    if (argc!=3) {                      /* Check command line */
        printf("You must supply source and destination filenames.\n");
        exit(EXIT_FAILURE);
    }
    inf = file_open(argv[1], "rb");     /* Try to open files */
    outf = file_open(argv[2], "wb");
    if (fcopy(inf, outf) != 0) {        /* Copy file */
        perror("Error writing file");   /* Error message on failure */
        fclose(inf); fclose(outf);
        exit(EXIT_FAILURE);
    }
    fclose(inf);  fclose(outf);
    return 0;
}

/***** fcopy: copies a file ******
 On entry: inf is open for binary input, outf for binary output.
 On exit:  Remaining data in inf is copied to outf; both files still open.
           Returns 0 for success, 1 for error transferring data.
*/
#define BUFMAX (4096)
int fcopy(FILE *inf, FILE *outf) {
    char buffer[BUFMAX];
    size_t num_read, num_written;
    while (
        num_read = fread(buffer, 1, BUFMAX, inf),
                           /*    ^ Note: chars always have size 1 */
        num_read > 0       /* The final block may be shorter than BUFMAX */
    ) {
        num_written = fwrite(buffer, 1, num_read, outf);
        if (num_written != num_read) {
            return 1;                           /* failure */
        }
    }
    if (ferror(inf)) {
        return 1;
    }
    return 0;                                   /* success */
}

/* The following #ifdef includes the file_open function; if you have
   it in a personal function library, you may wish to delete these lines
   and link the two files separately.
*/
#ifdef __cplusplus
    #include "lst10-7.cpp"    /* or maybe "lst10-7.cxx" */
#else
    #include "lst10-7.c"
#endif