added tail and head

8 files changed, 384 insertions, 50 deletions

diff --git a/readme.md b/readme.md
index 3440299..8308f19 100644
--- a/readme.md
+++ b/readme.md
@@ -4,7 +4,7 @@
 A terrible busybox/gnu coreutils clone.
 
 Currently the only supported commands are: 
-`dd`, `cat`, `yes`, `echo`, `printf`, `id`, `groups`, `ls`, `tail`
+`dd`, `cat`, `yes`, `echo`, `printf`, `id`, `groups`, `ls`, `tail`, `head`
  
 ## How to
 
diff --git a/src/command.h b/src/command.h
index 939886d..0b7b8ad 100644
--- a/src/command.h
+++ b/src/command.h
@@ -18,3 +18,4 @@ COMMAND_EMPTY(groups);
 COMMAND_EMPTY(user_id);
 COMMAND(ls);
 COMMAND(tail);
+COMMAND(head);
diff --git a/src/commands/head.c b/src/commands/head.c
new file mode 100644
index 0000000..446a9e6
--- /dev/null
+++ b/src/commands/head.c
@@ -0,0 +1,145 @@
+#include "../command.h"
+
+#include <stdio.h>
+#include <string.h>
+
+struct Flags {
+    int count;
+    bool lines;
+    bool print_headers;
+    bool dont_print_headers;
+};
+
+static void head_file_lines(FILE* file, struct Flags* flags) {
+    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, struct Flags* flags) {
+    char c;
+    int count = flags->count;
+    while(count > 0 && (c = getc(file)) != EOF) {
+        putchar(c);
+        count--;
+    }
+
+    fclose(file);
+}
+
+static void help() {
+    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");
+    exit(EXIT_SUCCESS);
+}
+
+static char* next_arg(int argc, char** argv, int index) {
+    if (index >= argc) {
+        error("error: expected another argument after option");
+    }
+    return argv[index];
+}
+
+static void print_header(char* path, struct Flags* flags, 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, struct Flags* flags, bool many) {
+    FILE* file = get_file(path, "r");
+    print_header(path, flags, many);
+    if (flags->lines) {
+        head_file_lines(file, flags);
+    } else {
+        head_file_chars(file, flags);
+    }
+}
+
+COMMAND(head) {
+    struct Flags flags;
+    flags.count = 10;
+    flags.lines = true;
+    flags.print_headers = false;
+    flags.dont_print_headers = false;
+
+    int start = 0;
+    for (int i = 0; i < argc; i++) { 
+        if (!prefix("-", argv[i])) break;
+        if (streql(argv[0], "--help")) help();
+        start++;
+        int i_s = i;
+        for (size_t j = 1; j < strlen(argv[i_s]); j++) {
+            char c = argv[i_s][j];
+            switch(c) {
+                case 'c': {
+                    start++;
+                    flags.lines = false;
+                    char* arg = next_arg(argc, argv, ++i);
+                    long int bkm = get_blkm(arg);
+                    if (bkm < 1) {
+                        error("error: bkm cannot be less than 1");
+                    }
+                    flags.count = bkm;
+                    break;
+                }
+                case 'n': {
+                    start++;
+                    flags.lines = true;
+                    char* arg = next_arg(argc, argv, ++i);
+                    long int bkm = get_blkm(arg);
+                    if (bkm < 1) {
+                        error("error: bkm cannot be less than 1");
+                    }
+                    flags.count = bkm;
+                    break;
+                }
+                case 'q':
+                    flags.dont_print_headers = true;
+                    break;
+                case 'v':
+                    flags.print_headers = true;
+                    break;
+                default: {
+                    error("error: unknown option -%c", c);
+                }
+            }
+        }
+    }
+
+    int count = argc - start;
+
+    if (count < 1) {
+        head_file_lines(stdin, &flags);
+        return EXIT_SUCCESS;
+    }
+
+    if (count == 1) {
+        head_file(argv[start], &flags, false);
+        return EXIT_SUCCESS;
+    }
+
+    for (int i = 0; i < count; i++) {
+        head_file(argv[start + i], &flags, true);
+    }
+
+    return EXIT_SUCCESS;
+}
diff --git a/src/commands/ls.c b/src/commands/ls.c
index d31c143..b0b00a5 100644
--- a/src/commands/ls.c
+++ b/src/commands/ls.c
@@ -25,6 +25,7 @@ struct Flags {
     bool more_info;
     bool one_column;
     bool recurse;
+    bool colored;
 };
 
 struct FileInfo {
@@ -34,10 +35,11 @@ struct FileInfo {
     struct group* grp;
     char size[5];
     char date[13];
-    struct dirent* file;
+    char name[PATH_MAX];
     bool set_uid;
     bool set_gid;
     bool exec;
+    unsigned char type;
 };
 
 struct FileListInfo {
@@ -61,14 +63,17 @@ static DIR* get_directory(char* path) {
     return d;
 }
 
-static void append_path(char buf[PATH_MAX], const char* dir_path, const struct dirent* file) {
+static void append_path(char buf[PATH_MAX], const char* dir_path, const char* file_path) {
     size_t dir_len = strlen(dir_path);
+    size_t file_len = strlen(file_path);
+
     memcpy(buf, dir_path, dir_len);
     if (buf[dir_len-1] != '/') {
         buf[dir_len] = '/';
         dir_len++;
     }
-    memcpy(buf + dir_len, file->d_name, strlen(file->d_name) + 1);
+    memcpy(buf + dir_len, file_path, file_len);
+    buf[dir_len + file_len] = '\0';
 }
 
 static bool get_file_info(struct dirent* file, const char* dir_path, struct FileInfo* info) {
@@ -77,17 +82,20 @@ static bool get_file_info(struct dirent* file, const char* dir_path, struct File
     gid_t gid = getgid();
 
     char buf[PATH_MAX];
-    append_path(buf, dir_path, file);
+    append_path(buf, dir_path, file->d_name);
         
     struct stat s;
+    memset(&s, 0, sizeof(struct stat));
+
     if (stat(buf, &s) < 0) {
-        printf("\x1b[0merror: failed to read file '%s': %s\n", buf, strerror(errno));
+        // printf("\x1b[0merror: failed to read file '%s': %s\n", buf, strerror(errno));
         return false;
     }
 
     info->set_uid = false;
     info->set_gid = false;
     info->exec = false;
+    info->name[0] = '\0';
 
     if (file->d_type == DT_DIR) 
         info->mode[0] = 'd';
@@ -137,8 +145,10 @@ static bool get_file_info(struct dirent* file, const char* dir_path, struct File
 
     info->usr = getpwuid(s.st_uid);
     info->grp = getgrgid(s.st_gid);
-    info->file = file;
     info->links = s.st_nlink;
+    info->type = file->d_type;
+
+    strcpy(info->name, file->d_name);
 
     print_file_size(s.st_size, info->size);
     print_date_time(s.st_mtim.tv_sec + s.st_mtim.tv_nsec / 1000000, info->date);
@@ -147,9 +157,9 @@ static bool get_file_info(struct dirent* file, const char* dir_path, struct File
 
 static char* get_file_color(struct FileInfo* info) {
     char* color;
-    if (info->file->d_type == DT_DIR) {
+    if (info->type == DT_DIR) {
         color = DIR_COLOR;
-    } else if (info->file->d_type == DT_LNK) {
+    } else if (info->type == DT_LNK) {
         color = LINK_COLOR;
     } else {
         if (info->set_uid) {
@@ -171,6 +181,7 @@ static void list_files(struct FileInfo* files, int file_len, struct FileListInfo
 
     if (!isatty(1)) {
         flags->one_column = true;
+        flags->colored = false;
     }
 
     char* color;
@@ -179,7 +190,6 @@ static void list_files(struct FileInfo* files, int file_len, struct FileListInfo
 
     for (int i = 0; i < file_len; i++) {
         struct FileInfo finfo = files[i];
-        if (strlen(finfo.file->d_name) < 1) continue;
         color = get_file_color(&finfo);
         if (flags->more_info) {
             printf("%s %*d %*s %*s %*s %s %s%s\x1b[0m", 
@@ -193,12 +203,12 @@ static void list_files(struct FileInfo* files, int file_len, struct FileListInfo
                 info.max_size,
                 finfo.size, 
                 finfo.date,
-                color,
-                finfo.file->d_name
+                flags->colored ? color : FILE_COLOR,
+                finfo.name
             );
-            if (finfo.file->d_type == DT_LNK) {
+            if (finfo.type == DT_LNK) {
                 char path[PATH_MAX];
-                append_path(path, dir_path, finfo.file);
+                append_path(path, dir_path, finfo.name);
 
                 char lnk[PATH_MAX];
                 if (readlink(path, lnk, PATH_MAX) < 0) {
@@ -211,13 +221,13 @@ static void list_files(struct FileInfo* files, int file_len, struct FileListInfo
                 putchar('\n');
             }
         } else if (flags->one_column) {
-            printf("%s%s\x1b[0m\n", color, finfo.file->d_name);
+            printf("%s%s\x1b[0m\n", color, finfo.name);
         } else {
             if (info.total_len > w.ws_col) {
                 if (i != 0 && i % row_count == 0) putchar('\n');
-                printf("%s%*s\x1b[0m", color, column_width, finfo.file->d_name);
+                printf("%s%*s\x1b[0m", flags->colored ? color : FILE_COLOR, -column_width, finfo.name);
             } else {
-                printf("%s%s\x1b[0m  ", color, finfo.file->d_name);
+                printf("%s%s\x1b[0m  ", flags->colored ? color : FILE_COLOR, finfo.name);
             }
         }
     }
@@ -318,7 +328,7 @@ static bool recurse_directory(char* path, struct Flags* flags) {
         if (!flags->hidden && prefix(".", file->d_name)) continue;
         if (is_dot_dir(file->d_name)) continue;
         char buf[PATH_MAX];
-        append_path(buf, path, file);
+        append_path(buf, path, file->d_name);
         recurse_directory(buf, flags);
     }
 
@@ -374,11 +384,17 @@ COMMAND(ls) {
     flags.hide_dot = false;
     flags.one_column = false;
     flags.recurse = false;
+    flags.colored = false;
+
     int start = 0;
     for (int i = 0; i < argc; i++) {
         if (!prefix("-", argv[i])) break;
         if (streql("--help", argv[i])) help();
         start++;
+        if (streql("--color=auto", argv[i]) || streql("--color=yes", argv[i])) {
+            flags.colored = true;
+            continue;
+        }
         for (size_t j = 1; j < strlen(argv[i]); j++) {
             char c = argv[i][j];
             switch (c) {
diff --git a/src/commands/tail.c b/src/commands/tail.c
index 04f7f42..24d7b1f 100644
--- a/src/commands/tail.c
+++ b/src/commands/tail.c
@@ -2,19 +2,31 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <sys/select.h>
 #include <sys/stat.h>
+#include <unistd.h>
 
-static void tail_file(FILE* file) {
-    char* ring[10];
-    memset(ring, 0, sizeof(char*) * 10);
+struct Flags {
+    bool lines;
+    int count;
+    bool print_headers;
+    bool dont_print_headers;
+    bool print_as_grow;
+    int grow_wait;
+};
 
-    int ring_len[10];
+static size_t tail_file_lines(FILE* file, unsigned int count, size_t skip) {
+    char* ring[count];
+    memset(ring, 0, sizeof(char*) * count);
+
+    int ring_len[count];
     
     int index = 0;
-    int size = 0;
+    unsigned int size = 0;
 
     int read;
-    size_t len = 0;
+    fseek(file, skip, SEEK_SET);
+    size_t len = skip;
     char* line = NULL;
     while ((read = getline(&line, &len, file)) != -1) {
 
@@ -23,57 +35,189 @@ static void tail_file(FILE* file) {
         ring_len[index] = read;
 
         index++;
-        index %= 10;
-        if (size < 10) size++;
+        index %= count;
+        if (size < count) size++;
 
         line = NULL;
     }
 
-    index += 10 - size;
-    index %= 10;
+    index += count - size;
+    index %= count;
     
-    for (int i = 0; i < size; i++) {
+    for (unsigned int i = 0; i < size; i++) {
         fwrite(ring[index], ring_len[index], 1, stdout);
         free(ring[index]);
         index += 1;
-        index %= 10;
+        index %= count;
     }
 
     free(line);
     fclose(file);
+
+    return len;
+}
+
+static size_t tail_file_chars(FILE* file, unsigned int count, size_t skip) {
+    char ring[count];
+    memset(ring, 0, count);
+
+    int index = 0;
+    unsigned int size = 0;
+
+    fseek(file, skip, SEEK_SET);
+    int read = skip;
+    int c;
+    while((c = getc(file)) != EOF) {
+        ring[index] = c;
+        index++;
+        read++;
+        index %= count;
+        if (size < count) size++;
+    }
+
+    index += count - size;
+    index %= count;
+
+    for (unsigned int i = 0; i < size; i++) {
+        putchar(ring[index]);
+        index += 1;
+        index %= count;
+    }
+
+    fclose(file);
+
+    return read;
 }
 
 static void help() {
-    printf("Usage: tail [FILE]...\n\n");
+    printf("Usage: tail [OPTIONS] [FILE]...\n\n");
     printf("Print last 10 lines of FILEs (or stdin) to.\n");
-    printf("With more than one FILE, precede each with a filename header.\n");
+    printf("With more than one FILE, precede each with a filename header.\n\n");
+    printf("\t-c [+]N[bkm]\tPrint last N bytes\n");
+	printf("\t-n N[bkm]\tPrint last 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");
+	printf("\t-f\t\tPrint data as file grows\n");
+	printf("\t-s SECONDS\tWait SECONDS between reads with -f\n");
     exit(EXIT_SUCCESS);
 }
 
+static char* next_arg(int argc, char** argv, int index) {
+    if (index >= argc) {
+        error("error: expected another argument after option");
+    }
+    return argv[index];
+}
+
+static void print_header(char* path, struct Flags* flags, 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 tail_file(char* path, struct Flags* flags, bool many) {
+    FILE* file = get_file(path, "r");
+    print_header(path, flags, many);
+    
+    size_t skip = 0;
+    while (true) {
+        if (flags->lines) {
+            skip = tail_file_lines(file, flags->count, skip);
+        } else {
+            skip = tail_file_chars(file, flags->count, skip);
+        }
+        if (!flags->print_as_grow) break;
+        sleep(flags->grow_wait);
+        get_file(path, "r");
+    };
+}
+
 COMMAND(tail) {
-    if (argc < 1) {
-        tail_file(stdin);
-        return EXIT_SUCCESS;
+
+    struct Flags flags;
+    flags.count = 10;
+    flags.dont_print_headers = false;
+    flags.print_headers = false;
+    flags.lines = true;
+    flags.print_as_grow = false;
+    flags.grow_wait = 10;
+
+    int start = 0;
+    for (int i = 0; i < argc; i++) { 
+        if (!prefix("-", argv[i])) break;
+        if (streql(argv[0], "--help")) help();
+        start++;
+        int i_s = i;
+        for (size_t j = 1; j < strlen(argv[i_s]); j++) {
+            char c = argv[i_s][j];
+            switch(c) {
+                case 'c': {
+                    start++;
+                    flags.lines = false;
+                    char* arg = next_arg(argc, argv, ++i);
+                    long int bkm = get_blkm(arg);
+                    if (bkm < 1) {
+                        error("error: bkm cannot be less than 1");
+                    }
+                    flags.count = bkm;
+                    break;
+                }
+                case 'n': {
+                    start++;
+                    flags.lines = true;
+                    char* arg = next_arg(argc, argv, ++i);
+                    long int bkm = get_blkm(arg);
+                    if (bkm < 1) {
+                        error("error: bkm cannot be less than 1");
+                    }
+                    flags.count = bkm;
+                    break;
+                }
+                case 'q':
+                    flags.dont_print_headers = true;
+                    break;
+                case 'v':
+                    flags.print_headers = true;
+                    break;
+                case 'f':
+                    flags.print_as_grow = true;
+                    break;
+                case 's': {
+                    start++;
+                    char* arg = next_arg(argc, argv, ++i);
+                    long int sec = get_number(arg);
+                    if (sec < 1) {
+                        error("error: wait seconds cannot be less than 1");
+                    }
+                    flags.grow_wait = sec;
+                    break;
+                }
+                default: {
+                    error("error: unknown option -%c", c);
+                }
+            }
+        }
     }
 
-    if (streql(argv[0], "--help")) help();
+    int count = argc - start;
 
-    if (argc == 1) {
-        FILE* file = get_file(argv[0], "r");
-        tail_file(file);
+    if (count < 1) {
+        tail_file_lines(stdin, 10, 0);
         return EXIT_SUCCESS;
     }
 
-    for (int i = 0; i < argc; i++) {
-        FILE* file;
-        if (streql("-", argv[i])) {
-            file = stdin;
-        } else {
-            file = get_file_s(argv[i], "r");
-            if (file == NULL) continue;
-        }
-        printf("\n==> %s <==\n", argv[i]);
-        tail_file(file);
+    if (count == 1) {
+        tail_file(argv[start], &flags, false);
+        return EXIT_SUCCESS;
+    }
+
+    for (int i = 0; i < count; i++) {
+        tail_file(argv[start + i], &flags, true);
     }
 
     return EXIT_SUCCESS;
diff --git a/src/main.c b/src/main.c
index ce89210..72e1531 100644
--- a/src/main.c
+++ b/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, echo, printf, id, groups, ls, tail\n");
+            printf("\tdd, cat, yes, echo, printf, id, groups, ls, tail, head\n");
             return EXIT_SUCCESS;
         }
         argc--;
@@ -52,6 +52,8 @@ int main (ARGUMENTS) {
         return ls(NEXT_ARGS);
     } else if (streql(cmd, "tail")) {
         return tail(NEXT_ARGS);
+    } else if (streql(cmd, "head")) {
+        return head(NEXT_ARGS);
     } else {
         error("error: invalid command %s", cmd);
     }
diff --git a/src/shared.c b/src/shared.c
index 8d0dcca..240e364 100644
--- a/src/shared.c
+++ b/src/shared.c
@@ -34,6 +34,7 @@ FILE* get_file_s(const char* path, const char* type) {
 }
 
 FILE* get_file(const char* path, const char* type) {
+    if (streql("-", path)) return stdin;
     FILE* file = get_file_s(path, type);
     if (file == NULL) exit(EXIT_FAILURE);
     return file;
@@ -48,6 +49,30 @@ long int get_number(const char* text) {
     return n;
 }
 
+long int get_blkm(const char* text) {
+    char* end;
+    long int n = strtol(text, &end, 10);
+    if (text == end) {
+        error("error: %s is not a valid bkm", text);
+    }
+    if (*end == '\0') return n;
+    switch (*end) {
+        case 'K':
+        case 'k':
+            return n * 1024;
+        case 'B':
+        case 'b':
+            return n * 512;
+        case 'M':
+        case 'm':
+            return n * 1024 * 1204;
+        default:
+            error("error: invalid bkm type %c", *end);
+    }
+    // shouldnt get here anyways
+    return 0;
+}
+
 bool streql(const char* a, const char* b) {
     if (*a != *b) return false;
     int n = 0;
diff --git a/src/shared.h b/src/shared.h
index 251a993..a542ba6 100644
--- a/src/shared.h
+++ b/src/shared.h
@@ -10,6 +10,7 @@ void error(const char* format, ...);
 FILE* get_file_s(const char* path, const char* type);
 FILE* get_file(const char* path, const char* type);
 long int get_number(const char* text);
+long int get_blkm(const char* text);
 
 bool streql(const char* a, const char* b);
 bool prefix(const char* pre, const char* str);