新人課題cat masatora

cat/masatora-cat.c

@@ -0,0 +1,178 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <stdarg.h>
+
+#define E_NOT_FOUND 0
+#define E_DIRECTORY 1
+#define E_PERMISSION 2
+#define E_INVALID_ARG 3
+
+typedef struct options {
+    int number;
+} Options;
+
+void print(int file, Options options);
+void itoa(int n, char s[]);
+void reverse(char s[]);
+void error(int e_type, char *name);
+
+int main(int argc, char *argv[])
+{
+    int file, c;
+    int number = 0;
+    Options options = { 0 };
+    struct stat stduf;
+
+    // 引数がない場合は標準入力から読み込んで出力
+    if (argc > 1) {
+        while (--argc > 0 && (*++argv)[0] == '-') {
+            //引数がハイフンだけだった場合は標準入力から読み込んで出力
+            if (*++argv[0] == NULL) {
+                print(0, options);
+                return 0;
+            }
+            while ((c = *argv[0]++)) {
+                switch (c) {
+                    case 'n':
+                        options.number = 1;
+                        break;
+                    default:
+                        // cat -[invalid arguments]とした場合、エラーメッセージには一番最初の不正なオプションのみを表示する
+                        // (例) cat -aho の場合、cat: illegal option -- a
+                        argv[0]--;
+                        (*argv)[1] = '\0';
+                        error(E_INVALID_ARG, *argv);
+                        return 1;
+                }
+            }
+        }
+
+        // オプションだけ指定した場合は標準入力から読み込んで出力
+        if (argc > 0) {
+            while (*argv) {
+                stat(*argv, &stduf);
+                if ((stduf.st_mode & S_IFMT) == S_IFDIR) {
+                    error(E_DIRECTORY, *argv);
+                    break;
+                }
+                if (access(*argv, F_OK) != 0) {
+                    error(E_NOT_FOUND, *argv);
+                    break;
+                } else {
+                    if (access(*argv, R_OK) != 0) {
+                        error(E_PERMISSION, *argv);
+                        break;
+                    }
+                }
+
+                file = open(*argv, O_RDONLY, 0);
+                print(file, options);
+                close(file);
+                argv++;
+            }
+        } else
+            print(0, options);
+    } else
+        print(0, options);
+    return 0;
+}
+
+#define BUFSIZE 1000
+#define MAXSIZE 1000
+
+void print(int file, Options options)
+{
+    // -nオプション
+    if (options.number) {
+        char c;
+        int n, i = 0, lc = 1;
+        char line[MAXSIZE], lc_char[10];
+
+        while ((n = read(file, &c, 1)) == 1) {
+            line[i] = c;
+            i++;
+            if (c == '\n') {
+                itoa(lc++, lc_char);
+                line[i] = '\0';
+
+                write(1, "     ", strlen("     "));
+                write(1, lc_char, strlen(lc_char));
+                write(1, "  ", strlen("  "));
+                write(1, line, strlen(line));
+
+                i = 0;
+            }
+        }
+    } else {
+        char buf[BUFSIZE];
+        int n;
+
+        while ((n = read(file, buf, BUFSIZE)) > 0)
+            write(1, buf, n);
+    }
+
+
+}
+
+void itoa(int n, char s[])
+{
+    int i, sign;
+
+    if ((sign = n) < 0)
+        n = -n;
+    i = 0;
+    do {
+        s[i++] = n % 10 + '0';
+    } while ((n /= 10) > 0);
+
+    if (sign < 0)
+        s[i++] = '-';
+    s[i] = '\0';
+    reverse(s);
+}
+
+void reverse(char s[])
+{
+    int c, i, j;
+
+    for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
+        c = s[i];
+        s[i] = s[j];
+        s[j] = c;
+    }
+}
+
+#define ERROR_MSG_SIZE 256
+
+void error(int e_type, char *name)
+{
+    char error_msg[ERROR_MSG_SIZE];
+
+    strcpy(error_msg, "cat: ");
+    switch (e_type) {
+        case E_NOT_FOUND:
+            strcat(error_msg, name);
+            strcat(error_msg, ": No such file or directory");
+            break;
+        case E_DIRECTORY:
+            strcat(error_msg, name);
+            strcat(error_msg, ": Is a directory");
+            break;
+        case E_PERMISSION:
+            strcat(error_msg, name);
+            strcat(error_msg, ": Permission denied");
+            break;
+        case E_INVALID_ARG:
+            strcat(error_msg, "illegal option -- ");
+            strcat(error_msg, name);
+            strcat(error_msg, "\nusage: cat [-n] [file ...]");
+            break;
+        default:
+            break;
+    }
+    strcat(error_msg, "\n");
+
+    write(2, error_msg, strlen(error_msg));
+}