80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/**
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* file: dd.c
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* command: dd
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* author: Tyler Murphy
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*/
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#include "command.h"
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#include "lslib.h"
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#include <stdlib.h>
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/**
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* Help function for dd
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*/
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static void help(void) {
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printf("Usage: dd [if=FILE] [of=FILE] [bs=N] [count=N]\n\n");
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printf("Copy a file with converting and formatting\n\n");
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printf("\tif=FILE\t\tRead from FILE instead of stdin\n");
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printf("\tof=FILE\t\tWrite to FILE instead of stdout\n");
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printf("\tbs=N\t\tRead and write N bytes at a time\n");
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printf("\tcount=N\t\tCopy only N input blocks\n");
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}
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/**
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* Copys a file with converting and formatting
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*/
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COMMAND(dd_main) {
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FILE* in_file = stdin; /* the file to copy from */
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FILE* out_file = stdout; /* the file to copy to */
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int bs = 1024; /* the default bs */
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int count = -1; /* amount of bs's to copy, if negative go until EOF */
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int i;
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char* buffer; /* buffer to hold copy data */
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size_t read;
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/* parse arguments and only check for --help */
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parse_help(argc, argv, help);
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/* dd doesnt use standard arguments, parse though each argument and match each arg */
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for (i = 0; i < argc; i++) {
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if (prefix("if=", argv[i])) { /* sets the input file */
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char* path = argv[i] + 3; /* get data after = */
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in_file = get_file(path, "rb");
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} else if (prefix("of=", argv[i])) { /* sets the output file */
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char* path = argv[i] + 3; /* get data after = */
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out_file = get_file(path, "wb");
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} else if (prefix("bs=", argv[i])) { /* sets the blocksize */
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char* str = argv[i] + 3; /* get data after = */
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bs = get_blkm(str);
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if (bs < 1) { /* cannot have a negative bs */
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error("block size must be greater than 0");
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}
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} else if (prefix("count=", argv[i])) { /* sets the count of bs to do */
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char* str = argv[i] + 6; /* get data after = */
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count = get_number(str);
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if (count < 1) {
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error("count must be greather than 0");
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}
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} else { /* error and exit since arg is invalid */
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error("unkown option %s", argv[i]);
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}
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}
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/* allocate buffer of set bs */
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buffer = xalloc(bs);
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/* read data until EOF from and to buf */
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while ((read = fread(buffer, 1, bs, in_file)) != 0) {
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fwrite(buffer, 1, read, out_file);
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if (--count, count == 0) break;
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}
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/* cleanup */
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free(buffer);
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fclose(in_file);
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fclose(out_file);
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return EXIT_SUCCESS;
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}
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