Shell-III releaseshell-III

Added the ability to run programs in the background.
Added tokens for future releases.

1 files changed, 99 insertions, 11 deletions

diff --git a/shell.c b/shell.c
index a1b5b29..c03b62b 100644
--- a/shell.c
+++ b/shell.c
@@ -15,12 +15,21 @@ enum {
     double_quotes   = '"'
 };
 
+/* two-letter tokens */
+enum {
+    append          = '>' + 1,
+    and             = '&' + 1,
+    or              = '|' + 1
+};
+
 struct param_type {
     int is_word;
     int escape_sequences;
     unsigned int double_quotes_counter;
     char stored_symbol;
     int empty_word_flag;
+    int tokens;
+    int wrong_command;
 };
 
 static void show_invitation()
@@ -40,10 +49,12 @@ static void init_params(struct param_type *params, enum modes *current_mode)
     params->double_quotes_counter = 0;
     params->stored_symbol = ' ';
     params->empty_word_flag = 0;
+    params->tokens = 0;
+    params->wrong_command = 0;
     *current_mode = word_separation;
 }
 
-static void prepare_new_line(struct param_type *params,
+static void reset_params(struct param_type *params,
                              enum modes *current_mode,
                              struct queue *word_chain,
                              struct dynamic_array *tmp_word)
@@ -64,6 +75,50 @@ static int check_separation(int ch, struct param_type params)
             !params.escape_sequences;
 }
 
+static int single_tokens(int ch)
+{
+    return ch == '<' || ch == ';' || ch == '(' || ch == ')';
+}
+
+static void clean_input_buffer()
+{
+    int ch;
+    while((ch = getchar() != new_line))
+    {}
+}
+
+static void double_tokens_and_fg(int ch, struct param_type *params)
+{
+    int next_ch;
+    next_ch = getchar();
+    ungetc(next_ch, stdin);
+    if(ch == '>' && next_ch == '>')
+        params->tokens = append;
+    else if(ch == '|' && next_ch == '|')
+        params->tokens = or;
+    else if(ch == '&' && next_ch == '&')
+        params->tokens = and;
+    else if(ch == '&') {
+        while((ch = getchar()) != new_line) {
+            if(ch != whitespace && ch != tab) {
+                fprintf(stderr, "incorrect command\n");
+                params->wrong_command = 1;
+                return;
+            }
+        }
+        params->tokens = '&';
+    }
+}
+
+static int check_tokens(int ch, struct param_type *params)
+{
+    if(single_tokens(ch))
+        params->tokens = ch;
+    else
+        double_tokens_and_fg(ch, params);
+    return params->tokens;
+}
+
 static int ignore_spaces(int ch, struct param_type params)
 {
     return (ch == whitespace || ch == tab) && !params.escape_sequences;
@@ -87,7 +142,7 @@ static void add_word(struct queue *word_chain,
     char *word = malloc(tmp_word->last_element_index+1);
     dynarr_copy_array(tmp_word, word);
     queue_push(word_chain, word);
-    tmp_word->last_element_index = -1;
+    dynarr_drop_word(tmp_word);
     params->is_word = 0;
 }
 
@@ -151,9 +206,22 @@ static void clean_up_memory(struct queue *word_chain, char **cmdline)
     free(cmdline);
 }
 
-static void run_external_program(struct queue *word_chain)
+static void clean_up_zombie_process()
+{
+    int pid;
+    do {
+        pid = wait4(-1, NULL, WNOHANG, NULL);
+    } while(pid > 0);
+}
+
+static void run_external_program(struct queue *word_chain,
+                                 struct param_type *params)
 {
-    int pid, result;
+    int pid, wait_pid, result;
+    if(word_chain->first == NULL) {
+        fprintf(stderr, "empty command\n");
+        return;
+    }
     char **cmdline = create_cmdline(word_chain,
                                     queue_get_word_count(word_chain));
     if(check_cd(cmdline[0])) {
@@ -173,12 +241,20 @@ static void run_external_program(struct queue *word_chain)
             exit(1);
         }
         /* parent process */
-        wait(&result);
+
         clean_up_memory(word_chain, cmdline);
+
+        /* waiting for forground process */
+        if(params->tokens != '&') {
+            do {
+                wait_pid = wait(&result);
+            } while(wait_pid != pid);
+        } else
+            clean_up_zombie_process();
     }
 }
 
-static void new_line_processing(struct param_type *params,
+static void command_processing(struct param_type *params,
                                 enum modes *current_mode,
                                 struct queue *word_chain,
                                 struct dynamic_array *tmp_word)
@@ -186,7 +262,7 @@ static void new_line_processing(struct param_type *params,
     /* and odd number of double quotes  */
     if(!is_double_quotes_pair(*params)) {
         print_error();
-        prepare_new_line(params, current_mode, word_chain, tmp_word);
+        reset_params(params, current_mode, word_chain, tmp_word);
         show_invitation();
         return;
     }
@@ -195,12 +271,13 @@ static void new_line_processing(struct param_type *params,
             dynarr_push_back(tmp_word, '\0');
         add_word(word_chain, tmp_word, params);
     }
-    run_external_program(word_chain);
+    run_external_program(word_chain, params);
+    if(params->tokens == '&' || params->tokens == 0)
+        show_invitation();
+    reset_params(params, current_mode, word_chain, tmp_word);
 #if 0
     print_line(word_chain);
 #endif
-    prepare_new_line(params, current_mode, word_chain, tmp_word);
-    show_invitation();
 }
 
 static int is_empty_word(int ch, struct param_type params)
@@ -232,6 +309,16 @@ static void word_separation_processing(int ch, struct param_type *params,
         params->escape_sequences = 1;
         return;
     }
+    if(check_tokens(ch, params)) {
+        command_processing(params, current_mode, word_chain, tmp_word);
+        return;
+    }
+    if(params->wrong_command) {
+        clean_input_buffer();
+        reset_params(params, current_mode, word_chain, tmp_word);
+        show_invitation();
+        return;
+    }
     if(check_separation(ch, *params)) {
         add_word(word_chain, tmp_word, params);
         params->is_word = 0;
@@ -305,8 +392,9 @@ int main()
     init_params(&params, &current_mode);
     show_invitation();
     while((ch = getchar()) != EOF) {
+        clean_up_zombie_process();
         if(ch == new_line)
-            new_line_processing(&params, &current_mode, &word_chain,
+            command_processing(&params, &current_mode, &word_chain,
                                 &tmp_word);
         else if(current_mode == word_separation)
             word_separation_processing(ch, &params, &current_mode, &word_chain,