Cat

src/cat/cat.1

@@ -1 +1 @@
-\" TODO
+\" TODO

src/cat/cat.c

@@ -1,6 +1,331 @@
+#include <ctype.h>
+#include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
-int main(void) {
-  printf("Hello, World!\n");
+#define NAME "cat (canoutils)"
+#define VERSION "1.0.0"
+#define AUTHOR "Akos Szijgyarto (SzAkos04)"
+
+#include "version_info.h"
+
+#define print_help()                                                           \
+  do {                                                                         \
+    printf("Usage: cat [OPTION]... [FILE]...\n");                              \
+    printf("Concatenate FILE(s) to standard output.\n");                       \
+    printf("\n");                                                              \
+    printf("With no FILE, or when FILE is -, read standard input.\n");         \
+    printf("\n");                                                              \
+    printf("  -A, --show-all           equivalent to -vET\n");                 \
+    printf("  -b, --number-nonblank    number nonempty output lines, "         \
+           "overrides -n\n");                                                  \
+    printf("  -e                       equivalent to -vE\n");                  \
+    printf("  -E, --show-ends          display $ at end of each line\n");      \
+    printf("  -n, --number             number all output lines\n");            \
+    printf(                                                                    \
+        "  -s, --squeeze-blank      suppress repeated empty output lines\n");  \
+    printf("  -t                       equivalent to -vT\n");                  \
+    printf("  -T, --show-tabs          display TAB characters as ^I\n");       \
+    /* TODO: If done, remove the note */                                       \
+    printf("  -u                       (ignored) --NOTE:  not yet "            \
+           "implemented\n");                                                   \
+    printf("  -v, --show-nonprinting   use ^ and M- notation, except for LFD " \
+           "and TAB\n");                                                       \
+    printf("      --help        display this help and exit\n");                \
+    printf("      --version     output version information and exit\n");       \
+    printf("\n");                                                              \
+    printf("Examples:\n");                                                     \
+    printf("  cat f - g  Output f's contents, then standard input, then g's "  \
+           "contents.\n");                                                     \
+    printf("  cat        Copy standard input to standard output.\n");          \
+  } while (0)
+
+#define print_incorrect_args()                                                 \
+  do {                                                                         \
+    printf("incorrect arguments\n");                                           \
+    printf("see `cat --help`\n");                                              \
+  } while (0)
+
+#define assert_argc(argc, n)                                                   \
+  do {                                                                         \
+    if (argc != n) {                                                           \
+      print_incorrect_args();                                                  \
+      exit(EXIT_FAILURE);                                                      \
+    }                                                                          \
+  } while (0)
+
+#define BUF_MAX 65535  // max length of a buffer in bytes
+#define ARGS_LEN 32767 // max length of the arguments in bytes
+
+typedef enum {
+  NumberNonblank = (1 << 0),  // number nonempty output lines, overrides -n
+  ShowEnds = (1 << 1),        // display $ at end of each line
+  Number = (1 << 2),          // number all output lines
+  SqueezeBlank = (1 << 3),    // suppress repeated empty output lines
+  ShowTabs = (1 << 4),        // display TAB characters as ^I
+  ShowNonprinting = (1 << 5), // use ^ and M- notation, except for LFD and TAB
+} Flag;
+
+static const char FLAGLIST[] = "bEnsTv";
+
+int cat(int filec, char **paths, unsigned int flags);
+int print_buffer(char *buf, unsigned int flags);
+int print_stdin(unsigned int flags);
+
+inline __attribute__((const)) int stridx(const char *str, char c);
+
+void free_paths(int filec, char **paths);
+
+int main(int argc, char **argv) {
+  if (argc < 2) {
+    // print stdin
+    return (print_stdin(0) == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+  }
+
+  int filec = 0; // file count
+  char **paths = (char **)malloc((argc - 1) * sizeof(char *));
+  if (!paths) {
+    perror("could not allocate memory");
+    return EXIT_FAILURE;
+  }
+
+  unsigned int flags = 0;
+
+  // parse arguments
+  for (int i = 1; i < argc; ++i) {
+    int len = strlen(argv[i]);
+    if (len > 1 && argv[i][0] == '-') {
+      for (int j = 1; j < len; ++j) {
+        switch (argv[i][j]) {
+        // flags that are multiple flags in one
+        case 'A':
+          flags |= ShowNonprinting | ShowEnds | ShowTabs;
+          break;
+        case 'b':
+          flags &= ~Number;
+          flags |= NumberNonblank;
+          break;
+        case 'e':
+          flags |= ShowNonprinting | ShowEnds;
+          break;
+        case 'n':
+          flags &= ~NumberNonblank;
+          flags |= Number;
+          break;
+        case 't':
+          flags |= ShowNonprinting | ShowTabs;
+          break;
+        case '-':
+          if (!strcmp(argv[i], "--show-all")) {
+            flags |= ShowNonprinting | ShowEnds | ShowTabs;
+          } else if (!strcmp(argv[i], "--number-nonblank")) {
+            flags |= 1 << (stridx(FLAGLIST, 'b'));
+          } else if (!strcmp(argv[i], "--show-ends")) {
+            flags |= 1 << (stridx(FLAGLIST, 'E'));
+          } else if (!strcmp(argv[i], "--number")) {
+            flags |= 1 << (stridx(FLAGLIST, 'n'));
+          } else if (!strcmp(argv[i], "--squeeze-blank")) {
+            flags |= 1 << (stridx(FLAGLIST, 's'));
+          } else if (!strcmp(argv[i], "--show-tabs")) {
+            flags |= 1 << (stridx(FLAGLIST, 'T'));
+          } else if (!strcmp(argv[i], "--show-nonprinting")) {
+            flags |= 1 << (stridx(FLAGLIST, 'v'));
+          } else if (!strcmp(argv[i], "--help")) {
+            print_help();
+            free_paths(filec, paths);
+            return EXIT_SUCCESS;
+          } else if (!strcmp(argv[i], "--version")) {
+            print_version();
+            free_paths(filec, paths);
+            return EXIT_SUCCESS;
+          }
+          break;
+        default: {
+          int flag = stridx(FLAGLIST, argv[i][j]);
+          if (flag < 0) {
+            fprintf(stderr, "cat: invalid option `-%c`\n", argv[i][j]);
+            fprintf(stderr, "Try 'cat --help' for more information.\n");
+            free_paths(filec, paths);
+            return EXIT_FAILURE;
+          }
+          flags |= 1 << (flag);
+          break;
+        }
+        }
+      }
+    } else {
+      // check if the file is accessible
+      if (access(argv[i], F_OK | R_OK) != 0 && strcmp(argv[i], "-") != 0) {
+        fprintf(stderr, "cat: file `%s` not found\n", argv[i]);
+        free_paths(filec, paths);
+        return EXIT_FAILURE;
+      }
+
+      paths[filec] = (char *)malloc(ARGS_LEN * sizeof(char));
+      if (!paths[filec]) {
+        perror("could not allocate memory");
+        free_paths(filec, paths);
+        return EXIT_FAILURE;
+      }
+
+      strcpy(paths[filec], argv[i]);
+      filec++;
+    }
+  }
+
+  paths = (char **)realloc(paths, filec * sizeof(char *));
+  if (!paths) {
+    perror("could not allocate memory");
+    return EXIT_FAILURE;
+  }
+
+  if (cat(filec, paths, flags) != 0) {
+    free_paths(filec, paths);
+    return EXIT_FAILURE;
+  }
+
+  free_paths(filec, paths);
+  return EXIT_SUCCESS;
+}
+
+int cat(int filec, char **paths, unsigned int flags) {
+  // print stdin
+  if (filec == 0 || !paths) {
+    return print_stdin(flags);
+  }
+
+  for (int i = 0; i < filec; ++i) {
+    // print stdin
+    if (!strcmp(paths[i], "-")) {
+      if (print_stdin(flags) != 0) {
+        return 1;
+      }
+
+      continue;
+    }
+
+    // read file
+    FILE *infile = fopen(paths[i], "r");
+    if (!infile) {
+      perror("could not open file");
+      return 1;
+    }
+
+    // get the size of the file
+    fseek(infile, 0, SEEK_END);
+    long file_size = ftell(infile);
+    fseek(infile, 0, SEEK_SET);
+
+    char buf[file_size + 1];
+
+    // read the file into the buffer
+    size_t files_read = fread(buf, sizeof(char), file_size, infile);
+    if (files_read != (size_t)file_size) {
+      fprintf(stderr, "cat: could not read file\n");
+      fclose(infile);
+      return 1;
+    }
+    buf[file_size] = '\0'; // make sure the string is null terminated
+
+    fclose(infile);
+
+    if (print_buffer(buf, flags) != 0) {
+      return 1;
+    }
+  }
   return 0;
-}
+}
+
+#define BEFORE_NUMBER 6 // number of spaces before line numbers
+
+int print_buffer(char *buf, unsigned int flags) {
+  int lines = 1;
+  if ((flags & Number)) {
+    // print number before the first line
+    printf("%*d  ", BEFORE_NUMBER, lines);
+  }
+  if ((flags & NumberNonblank)) {
+    if (buf[0] != '\n' && buf[1] != '\0') {
+      // print number before the first line
+      printf("%*d  ", BEFORE_NUMBER, lines);
+    }
+  }
+  int len = strlen(buf);
+  for (int i = 0; i < len; ++i) {
+    // higher priority
+    // NOTE: not the prettiest code, but it works
+    if ((flags & SqueezeBlank) && buf[i] == '\n') {
+      // skip over consecutive '\n' characters
+      if (i + 1 < len && buf[i + 1] == '\n') {
+        // if the consecutive '\n' characters are over
+        if (i + 2 < len && buf[i + 2] != '\n') {
+          if ((flags & Number)) {
+            printf("\n%*d  ", BEFORE_NUMBER, ++lines);
+          } else {
+            putchar('\n');
+          }
+        }
+        continue;
+      }
+    }
+
+    if ((flags & NumberNonblank) && buf[i] == '\n' && buf[i + 1] != '\n' &&
+        buf[i + 1] != '\0') {
+      printf("\n%*d  ", BEFORE_NUMBER, ++lines);
+      continue;
+    }
+    if ((flags & ShowEnds) && buf[i] == '\n') {
+      putchar('$');
+    }
+    if ((flags & Number) && buf[i] == '\n' && buf[i + 1] != '\0') {
+      printf("\n%*d  ", BEFORE_NUMBER, ++lines);
+      continue;
+    }
+    if ((flags & ShowTabs) && buf[i] == '\t') {
+      printf("^I");
+      continue;
+    }
+    if ((flags & ShowNonprinting) && !isprint(buf[i]) && buf[i] != 9 &&
+        buf[i] != 10) {
+      if (buf[i] & 0x80) {
+        // meta (M-) notation for characters with the eighth bit set
+        printf("M-");
+        char printable_char = buf[i] & 0x7F; // clear the eighth bit
+        printf("^%c", '@' + printable_char);
+      } else {
+        // regular non-printable character notation
+        printf("^%c", '@' + buf[i]);
+      }
+      continue;
+    }
+
+    putchar(buf[i]);
+  }
+
+  return 0;
+}
+
+int print_stdin(unsigned int flags) {
+  char buf[BUF_MAX];
+  while (fgets(buf, BUF_MAX, stdin)) {
+    if (print_buffer(buf, flags) != 0) {
+      return 1;
+    }
+  }
+
+  return 0;
+}
+
+inline __attribute__((const)) int stridx(const char *str, char c) {
+  const char *p = strchr(str, c);
+  return (p) ? (int)(p - str) : -1;
+}
+
+void free_paths(int filec, char **paths) {
+  for (int i = 0; i < filec; i++) {
+    free(paths[i]);
+  }
+  free(paths);
+}