Implemented cksum

.gitignore

@@ -76,6 +76,7 @@ src/rm/rm
 src/rmdir/rmdir
 src/sh/sh
 src/sleep/sleep
+src/cksum/cksum
 
 bin/
 

Makefile

@@ -25,6 +25,7 @@ BINS += mv
 BINS += chmod
 BINS += sh
 BINS += sleep
+BINS += cksum
 
 BINARIES := $(foreach b, $(BINS), src/$b/$b)
 BINS-COPY := $(foreach b, $(BINS), bin/$b)

src/cksum/Makefile

@@ -0,0 +1,5 @@
+OUT := cksum
+
+SRC := cksum.c
+
+include ../shared.mk

src/cksum/cksum.1

@@ -0,0 +1 @@
+\" TODO

src/cksum/cksum.c

@@ -0,0 +1,149 @@
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define NAME "cksum (canoutils)"
+#define VERSION "0.0.1"
+#define AUTHOR "cospplredman"
+
+#include "cgetopt.h"
+#include "version_info.h"
+
+static const char usage[] = {"Usage: cksum [Option]... [File]...\n"
+                             "  --version   version information\n"
+                             "  --help      display this help and exit\n"
+                             "  --raw       output raw crc\n"
+                             "  --tag       default output style\n"};
+
+// flags
+static int output_format = 't';
+
+static struct option long_options[] = {
+    {"version", no_argument, NULL, 'v'},
+    {"help", no_argument, NULL, 'h'},
+    {"raw", no_argument, NULL, 'r'},
+    {"tag", no_argument, NULL, 't'},
+};
+
+static const uint32_t crc32_ = 0x04c11db7;
+
+static uint32_t crc32(FILE *file, size_t *octets) {
+  uint32_t remainder = 0;
+  uint8_t difference = 0;
+
+  size_t length = 0;
+
+  /* calculate crc of file contents */
+  int cur_char;
+  while ((cur_char = getc(file)) != EOF) {
+    remainder = (remainder << 8) ^ (difference & 0xff) ^ cur_char;
+    difference = 0;
+    for (int i = 31; i > 23; i--) {
+      if (remainder & (1 << i)) {
+        remainder ^= (1 << i) | (crc32_ >> (32 - i));
+        difference ^= crc32_ << (i - 24);
+      }
+    }
+    length++;
+  }
+
+  *octets = length;
+
+  /* calculate crc of file contents + length of files in bytes */
+  while (length) {
+    cur_char = (length & 0xff);
+    length >>= 8;
+
+    remainder = (remainder << 8) ^ (difference & 0xff) ^ cur_char;
+    difference = 0;
+    for (int i = 31; i > 23; i--) {
+      if (remainder & (1 << i)) {
+        remainder ^= (1 << i) | (crc32_ >> (32 - i));
+        difference ^= crc32_ << (i - 24);
+      }
+    }
+  }
+
+  /* work through the remaining 3 bytes  */
+  for (int j = 0; j < 3; j++) {
+    remainder = (remainder << 8) ^ (difference & 0xff);
+    difference = 0;
+    for (int i = 31; i > 23; i--) {
+      if (remainder & (1 << i)) {
+        remainder ^= (1 << i) | (crc32_ >> (32 - i));
+        difference ^= crc32_ << (i - 24);
+      }
+    }
+  }
+
+  return ~((remainder << 8) | (difference & 0xff));
+}
+
+static void crc_print(char *filename, uint32_t crc, size_t octets) {
+  switch (output_format) {
+  case 't':
+    if (filename == NULL)
+      printf("%u %lu\n", crc, octets);
+    else
+      printf("%u %lu %s\n", crc, octets, filename);
+    break;
+  case 'r':
+    printf("%c%c%c%c", (crc >> 24) & 255, (crc >> 16) & 255, (crc >> 8) & 255,
+           crc & 255);
+    break;
+  }
+}
+
+int main(int argc, char **argv) {
+
+  int opt, option_index;
+  while ((opt = getopt_long(argc, argv, "", long_options, &option_index)) !=
+         -1) {
+    switch (opt) {
+    case 0:
+      break;
+    case 'v':
+      print_version();
+      return EXIT_SUCCESS;
+      break;
+    case 'h':
+      printf("%s\n", usage);
+      return EXIT_SUCCESS;
+    case 'r':
+      output_format = 'r';
+      break;
+    case 't':
+      output_format = 't';
+      break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  int index = 0;
+  size_t octets;
+  uint32_t crc;
+
+  if (argc < 1) {
+    crc = crc32(stdin, &octets);
+    crc_print(NULL, crc, octets);
+    return EXIT_SUCCESS;
+  }
+
+  for (; index < argc; index++) {
+    FILE *file = fopen(argv[index], "r+");
+
+    if (file == NULL) {
+      fprintf(stderr, "cksum: %s: %s\n", argv[index], strerror(errno));
+      continue;
+    }
+
+    crc = crc32(file, &octets);
+    crc_print(argv[index], crc, octets);
+
+    fclose(file);
+  }
+}

utils.txt

@@ -22,3 +22,4 @@ pwd
 rm
 rmdir
 sleep
+cksum