update readme

.gitignore

@@ -1,2 +1,3 @@
 *.exe
 **/.DS_Store
+bin/

README.md

@@ -1,22 +1,24 @@
 # memory allocator
 
-it allocates memory *(in gibibytes (GiB))*
+it allocates memory
 
 ## how to use
 
-- run the executable
-- enter how many gibibytes you want (max is how many gibibytes of memory you have)
-- confirm (y)
-- wait for the program to allocate the memory
-- your memory is allocated
-- press any key or CTRL+C to free the memory and exit the program
-- ???
-- profit
+```
+usage: allocatememory -b <bytes> [-o <output file>] [-s]
+
+OPTIONS
+  -h    displays help
+  -b    number of bytes to allocate (e.g. 1024, 1g, 64K)
+  -o    file to output to
+  -s    run silently (requires -b and -o)
+  -w    disable warnings ("i know what i'm doing!")
+```
 
 ## how to compile
 
-- get a c compiler (i use gcc)
-- `gcc -o ./allocatememory.exe ./main.c`
+- get a c compiler (i use gcc or clang)
+- `gcc -o ./allocatememory -O2 ./main.c`
 - ???
 - profit
 

main.c

@@ -1,47 +1,211 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
+#include <unistd.h>
+#include <errno.h>
+#include <ctype.h>
+#include <string.h>
 
-int main() {
+#define BYTES_GIVEN     1
+#define OUTPUT_FILE     2
+#define SILENT          4
+#define BYPASS_WARN     8
 
-    long long unsigned int size = 0;
+#define KiB (unsigned long long int) 0x400
+#define MiB (unsigned long long int) 0x100000
+#define GiB (unsigned long long int) 0x40000000
+#define TiB (unsigned long long int) 0x10000000000
 
-    printf("please enter the number of bytes (GiB) you would like to allocate (i.e. 4 = 4GiB):\n> ");
-    int digit = 0;
-    while (1) {
-        char input = getchar();
-        if (input == '\n') break;
-        if (input < '0' || input > '9') continue;
+#define LOADS TiB * 9999
 
-        char number = input - 48;
-        if (digit > 0) number = number * 10 * digit;
-        if (input == '0') number = 10 * digit;
+void print_help();
+unsigned char* get_shorthand(unsigned long long int size);
+void adjust_by_denomination(unsigned long long int* size, char denomination);
+unsigned long long int* allocate_heap(unsigned long long int size, char silent);
+void save_heap(unsigned long long int* heap, unsigned long long int size, char* filename, char silent);
 
-        size = size + number;
-        digit++;
+int main(int argc, char* argv[]) {
+
+        unsigned char flags = 0;
+        unsigned long long int size = 0;
+        unsigned char* filename = NULL;
+        unsigned char denominator = 0;
+
+        int arg;
+        while ((arg = getopt(argc, argv, "hb:o:sw")) != -1) {
+                switch (arg) {
+                        case 'h':
+                                print_help();
+                                exit(0);
+                        case 'b':
+                                size = strtoull(optarg, NULL, 10);
+                                if (errno == EINVAL) {
+                                        fprintf(stderr, "argument -b used with invalid value '%s'!\n", optarg);
+                                        exit(0);
+                                }
+                                if (errno == ERANGE) {
+                                        fprintf(stderr, "byte argument ''%s' out of range!\n", optarg);
+                                        exit(0);
+                                }
+                                denominator = optarg[strlen(optarg) - 1];
+                                flags |= BYTES_GIVEN;
+                                break;
+                        case 'o':
+                                filename = optarg;
+                                flags |= OUTPUT_FILE;
+                                break;
+                        case 's':
+                                if (size == 0 || filename == NULL) {
+                                        fprintf(stderr, "cannot run silently without -b and -o set!\n");
+                                        print_help();
+                                }
+                                flags |= SILENT;
+                                break;
+                        case 'w':
+                                flags |= BYPASS_WARN;
+                                break;
+                        case '?':
+                                if (optopt == 'b' || optopt == 'o')
+                                        fprintf(stderr, "argument -%c requires an argument!\n", optopt);
+                                else if (isprint(optopt))
+                                        fprintf(stderr, "unknown argument '-%c'.\n", optopt);
+                                else
+                                        fprintf(stderr, "unknown argument character '\\x%x'.\n", optopt);
+                                exit(1);
+                        default:
+                                exit(1);
+                }
         }
 
-    size = size * 1024 * 1024 * 1024;
+        if (!(flags & BYTES_GIVEN)) {
+                fprintf(stderr, "argument -b is required!\n", optopt);
+                print_help();
+                exit(1);
+        }
 
-    printf("you are about to allocate %llu bytes of heap memory. are you sure? (y/n)\n> ", size);
+        adjust_by_denomination(&size, denominator);
 
-    char input = getchar();
-    if (input != 'y') return 0;
+        // even if the user doesn't specify a denomination, it still would be nice to display a truncated amount if available.
+        unsigned char* shorthand = get_shorthand(size);
+        if (!(flags & SILENT) && !(flags & BYPASS_WARN)) {
+                if (shorthand) {
+                        printf("you are about to allocate %s (%llu bytes) of heap memory. are you sure? (y/N)\n> ", shorthand, size);
+                } else {
+                        printf("you are about to allocate %llu byte%c of heap memory. are you sure? (y/N)\n> ", size, size == 1 ? 0 : 's');
+                }
+
+                unsigned char input = getchar();
+                if (input != 'y') exit(0);
                 while (getchar() != '\n');
-
-    printf("please wait...\n");
-    char* wtf = (char*) malloc(size * sizeof(char));
-
-    for (long long unsigned int i = 0; i < size; i++) {
-        wtf[i] = 255;
         }
 
-    printf("%llu bytes of heap memory has been allocated. you are insane.\n", size);
-    printf("press any key to release this memory, or CTRL+C to exit the program.\n");
+        unsigned long long int* heap = allocate_heap(size, flags & SILENT);
+        if (filename != NULL) save_heap(heap, size, filename, flags & SILENT);
 
+        if (!(flags & SILENT)) {
+                if (shorthand) {
+                        printf("%s (%llu bytes) of heap memory has been allocated. you are insane.\n", shorthand, size);
+                } else {
+                        printf("%llu byte%c of heap memory ha%s been allocated. you are insane.\n", size, size == 1 ? 0 : 's', size == 1 ? "s" : "ve");
+                }
+                free(shorthand);
+
+                printf("press ENTER to release this memory, or CTRL+C to exit the program.\n");
                 getchar();
+                free(heap);
+                exit(0);
+        }
 
-    free(wtf);
-
+        free(heap);
         return 0;
 
 }
+
+void print_help() {
+        printf("usage: allocatememory -b <bytes> [-o <output file>] [-s]\n\n");
+        printf("OPTIONS\n");
+        printf("  -h\tdisplays help\n");
+        printf("  -b\tnumber of bytes to allocate (e.g. 1024, 1g, 64K)\n");
+        printf("  -o\tfile to output to\n");
+        printf("  -s\trun silently (requires -b and -o)\n");
+        printf("  -w\tdisable warnings (\"i know what i'm doing!\")\n");
+        exit(0);
+}
+
+unsigned char* get_shorthand(unsigned long long int size) {
+        if (size < KiB) return 0;
+
+        if (size > LOADS) {
+                return ">9999 TiB";
+        }
+
+        unsigned char* buffer = malloc(sizeof(char) * 12);
+
+        if (size >= TiB) {
+                snprintf(buffer, 12, "%.2f TiB", (float) size / TiB);
+                return buffer;
+        }
+        if (size >= GiB) {
+                snprintf(buffer, 12, "%.2f GiB", (float) size / GiB);
+                return buffer;
+        }
+        if (size >= MiB) {
+                snprintf(buffer, 12, "%.2f MiB", (float) size / MiB);
+                return buffer;
+        }
+        if (size >= KiB) {
+                snprintf(buffer, 12, "%.2f KiB", (float) size / KiB);
+                return buffer;
+        }
+
+        return 0;
+}
+
+void adjust_by_denomination(unsigned long long int* size, char denomination) {
+        if (denomination >= 'a' && denomination <= 'z') denomination -= 32;
+        switch (denomination) {
+                case 'K':
+                        *size *= KiB;
+                        return;
+                case 'M':
+                        *size *= MiB;
+                        return;
+                case 'G':
+                        *size *= GiB;
+                        return;
+                case 'T':
+                        *size *= TiB;
+                        return;
+        }
+}
+
+unsigned long long int* allocate_heap(unsigned long long int size, char silent) {
+        if (!silent) {
+                printf("please wait.");
+                fflush(stdout);
+        }
+
+        unsigned long long int* heap = (unsigned long long int*) malloc(size);
+
+        for (unsigned long long int i = 0; i < size / sizeof(long long int); i++) {
+                heap[i] = i;
+                if (!silent && i > 0 && i % (1024 * 1024 * 1024 / sizeof(long long int)) == 0) {
+                        printf(".");
+                        fflush(stdout);
+                }
+        }
+        if (!silent) printf("\n");
+
+        return heap;
+}
+
+void save_heap(unsigned long long int* heap, unsigned long long int size, char* filename, char silent) {
+        FILE* file = fopen(filename, "wb");
+        if (file == NULL) {
+                printf("failed to open %s!", filename);
+                exit(1);
+        }
+        fwrite(heap, sizeof(char), size, file);
+        fputs("\n", file);
+        fclose(file);
+}