refactor

1 files changed, 141 insertions, 0 deletions

diff --git a/command/head.c b/command/head.c
new file mode 100644
index 0000000..c28a82c
--- /dev/null
+++ b/command/head.c
@@ -0,0 +1,141 @@
+#include "command.h"
+#include "lslib.h"
+
+#include <stdlib.h>
+
+static struct {
+    int count;
+    bool lines;
+    bool print_headers;
+    bool dont_print_headers;
+} flags;
+
+static void head_file_lines(FILE* file) {
+    size_t len = 0;
+    char* line = NULL;
+
+    int count = flags.count;
+    while(count > 0 && getline(&line, &len, file) != -1) {
+        printf("%s", line);
+        count--;
+    }
+
+    free(line);
+    fclose(file);
+}
+
+static void head_file_chars(FILE* file) {
+    char c;
+    int count = flags.count;
+    while(count > 0 && (c = getc(file)) != EOF) {
+        putchar(c);
+        count--;
+    }
+
+    fclose(file);
+}
+
+static void help(void) {
+    printf("Usage: head [OPTIONS] [FILE]...\n\n");
+    printf("Print first 10 lines of FILEs (or stdin)\n");
+    printf("With more than one FILE, precede each with a filename header.\n\n");
+    printf("\t-c [+]N[bkm]\tPrint first N bytes\n");
+	printf("\t-n N[bkm]\tPrint first N lines\n");
+	printf("\t\t\t(b:*512 k:*1024 m:*1024^2)\n");
+	printf("\t-q\t\tNever print headers\n");
+	printf("\t-v\t\tAlways print headers\n");
+}
+
+static void print_header(char* path, bool many) {
+    if (flags.dont_print_headers) return;
+    if (!many && !flags.print_headers) return;
+    if (streql("-", path)) {
+        printf("\n==> standard input <==\n");
+    } else {
+        printf("\n=>> %s <==\n", path);
+    }
+}
+
+static void head_file(char* path, bool many) {
+    FILE* file = get_file(path, "r");
+    print_header(path, many);
+    if (flags.lines) {
+        head_file_lines(file);
+    } else {
+        head_file_chars(file);
+    }
+}
+
+static int short_arg(char c, char* next) {
+    switch(c) {
+        case 'c': {
+            long int bkm;
+
+            flags.lines = false;
+            
+            check_arg(next);
+            bkm = get_blkm(next);
+            
+            if (bkm < 1) {
+                error("bkm cannot be less than 1");
+            }
+            
+            flags.count = bkm;
+            return ARG_USED;
+        }
+        case 'n': {
+            long int bkm;
+
+            flags.lines = true;
+            
+            check_arg(next);
+            bkm = get_blkm(next);
+            
+            if (bkm < 1) {
+                error("bkm cannot be less than 1");
+            }
+            
+            flags.count = bkm;
+            return ARG_USED;
+        }
+        case 'q':
+            flags.dont_print_headers = true;
+            break;
+        case 'v':
+            flags.print_headers = true;
+            break;
+        default:
+            return ARG_INVALID;
+    }
+    return ARG_UNUSED;
+}
+
+COMMAND(head) {
+
+    int start, count, i;
+
+    flags.count = 10;
+    flags.lines = true;
+    flags.print_headers = false;
+    flags.dont_print_headers = false;
+
+    start = parse_args(argc, argv, help, short_arg, NULL);
+
+    count = argc - start;
+
+    if (count < 1) {
+        head_file_lines(stdin);
+        return EXIT_SUCCESS;
+    }
+
+    if (count == 1) {
+        head_file(argv[start], false);
+        return EXIT_SUCCESS;
+    }
+    
+    for (i = 0; i < count; i++) {
+        head_file(argv[start + i], true);
+    }
+
+    return EXIT_SUCCESS;
+}