add echo and pritnf

readme.md

@@ -4,7 +4,7 @@
 A terrible busybox/gnu coreutils clone.
 
 Currently the only supported commands are: 
-`dd`, `cat`, `yes`
+`dd`, `cat`, `yes`, `echo`, `printf`
  
 ## How to
 

src/command.h

@@ -11,3 +11,5 @@
 COMMAND(dd);
 COMMAND(cat);
 COMMAND(yes);
+COMMAND(echo);
+COMMAND(print);

src/commands/echo.c

@@ -0,0 +1,103 @@
+#include "../command.h"
+
+#include <stdio.h>
+#include <string.h>
+
+static void print_with_escape_codes(const char* str) {
+    
+    size_t index = 0;
+    while (true) {
+        char c = str[index];
+        index++;
+
+        if (c == '\0') break;
+        if (c != '\\') {
+            putchar(c);
+            continue;
+        }
+
+        char n = str[index];
+        index++;
+
+        switch (n) {
+            case '\\':
+                putchar('\\');
+                break;
+            case 'b':
+                putchar('\b');
+                break;
+            case 'c':
+                exit(EXIT_SUCCESS);
+            case 'n':
+                putchar('\n');
+                break;
+            case 'r':
+                putchar('\r');
+                break;
+            case 't':
+                putchar('\t');
+                break;
+            case 'v':
+                putchar('\v');
+                break;
+            default:
+                putchar(c);
+                putchar(n);
+        }
+    }
+}
+
+COMMAND(echo) {
+
+    if (argc < 1) {
+        return EXIT_SUCCESS;
+    }
+
+    bool escape_codes = false;
+    bool newline = true;
+
+    int start = 0;
+
+    if (prefix("-", argv[0])) {
+
+        start = 1;
+
+        for (size_t i = 0; i < strlen(argv[0] + 1); i++) {
+            char c = argv[0][i + 1];
+            switch (c) {
+                case 'e':
+                    escape_codes = true;
+                    break;
+                case 'E':
+                    escape_codes = false;
+                    break;
+                case 'n':
+                    newline = false;
+                    break;
+                default:
+                    escape_codes = false;
+                    newline = true;
+                    start = 0;
+                    break;
+            }
+        }
+    }
+
+    for (int i = start; i < argc; i++) {
+         if (escape_codes) {
+            print_with_escape_codes(argv[i]);
+        } else {
+            printf("%s", argv[i]);
+        }
+
+        if (i + 1 != argc) {
+            putchar(' ');
+        }
+    } 
+
+    if (newline) {
+        putchar('\n');
+    }
+
+    return EXIT_SUCCESS;
+}

src/commands/printf.c

@@ -0,0 +1,118 @@
+#include "../command.h"
+#include <stdlib.h>
+
+static long cast_long(const char* arg) {
+    char* end;
+    long l = strtol(arg, &end, 10);
+    if (end == arg) {
+        return 0;
+    } else {
+        return l;
+    }
+}
+
+static double cast_double(const char* arg) {
+    char* end;
+    double d = strtod(arg, &end);
+    if (end == arg) {
+        return 0.0;
+    } else {
+        return d;
+    }
+}
+
+#define NUMBER(name, type, arg) \
+    long l = cast_long(arg); \
+    type* t = (type*) &l; \
+    type name = *t;
+
+static void handle_percent(char n, const char* arg) {
+    switch (n) {
+        case 'd':
+        case 'z': {
+            NUMBER(i, int, arg)
+            printf("%d", i);
+            break;
+        }
+        case 'u': {
+            NUMBER(u, unsigned int, arg);
+            printf("%u", u);
+            break;
+        }
+        case 'f': {
+            double d = cast_double(arg);
+            printf("%lf", d);
+            break;
+        }
+        case 'c': {
+            putchar(arg[0]);
+            break;
+        }
+        case 's': {
+            printf("%s", arg);
+            break;
+        }
+        default: {
+            putchar('%');
+            putchar(n);
+        }
+    }
+}
+
+static void handle_slash(char n) {
+    switch (n) {
+        case 'n':
+            putchar('\n');
+            break;
+        case 't':
+            putchar('\t');
+            break;
+        case 'v':
+            putchar('\v');
+            break;
+        case 'b':
+            putchar('\b');
+            break;
+        default:
+            putchar('\\');
+            putchar(n);
+    }
+}
+
+COMMAND(print) {
+    if (argc < 1) {
+        error("usage: printf FORMAT [ARG]...\n");
+    }
+
+    size_t index = 0;
+    int arg_index = 0;
+
+    while (true) {
+        char c = argv[0][index];
+        index++;
+
+        if (c == '\0') break;
+        if (c != '%' && c != '\\') {
+            putchar(c);
+            continue;
+        }
+
+        char n = argv[0][index];
+        index++;
+
+        char* arg = NULL;
+        if (arg_index < argc) {
+            arg = argv[arg_index + 1];
+        }
+
+        if (c == '%') {
+            handle_percent(n, arg);
+        } else {
+            handle_slash(n);
+        }
+
+        arg_index++;
+    }
+
+    return EXIT_SUCCESS;
+}

src/main.c

@@ -20,7 +20,7 @@ int main (ARGUMENTS) {
         if (argc < 2) {
             printf("usage: lazysphere [function [arguments]...]\n\n");
             printf("currently defined functions:\n");
-            printf("\tdd, cat, yes\n");
+            printf("\tdd, cat, yes, echo, printf\n");
             return EXIT_SUCCESS;
         }
         argc--;
@@ -40,6 +40,10 @@ int main (ARGUMENTS) {
         return cat(NEXT_ARGS);
     } else if (streql(cmd, "yes")) {
         return yes(NEXT_ARGS);
+    } else if (streql(cmd, "echo")) {
+        return echo(NEXT_ARGS);
+    } else if (streql(cmd, "printf")) {
+        return print(NEXT_ARGS);
     } else {
         error("error: invalid command %s", cmd);
     }