1 files changed, 121 insertions, 0 deletions
diff --git a/03_exercise/srv/shell.c b/03_exercise/srv/shell.c
new file mode 100644
index 0000000..a32fc5f
--- /dev/null
+++ b/03_exercise/srv/shell.c
@@ -0,0 +1,121 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <wait.h>
+#include <errno.h>
+
+#include "array.h"
+#include "process.h"
+#include "prompt_utils.h"
+#include "builtins.h"
+
+#define BUF_SIZE 256
+
+process *processes;
+
+const char * const get_current_dir_name();
+
+void signal_handler(int signal) {
+    if (signal == SIGINT) {
+        for (size_t i = 0; i < arrayLen(processes); ++i) {
+            pid_t pid = processes[i].pid;
+            if (pid != 0) {
+                kill(pid, SIGINT);
+            }
+        }
+    }
+}
+
+int shell(int in_fd) {
+    setvbuf(stderr, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+
+    dup2(in_fd, 1);
+    dup2(in_fd, 2);
+
+    // I don't think the shell should exit on SIG_TERM
+    if (signal(SIGINT, SIG_IGN) == SIG_ERR) {
+        perror("Couldn't ignore sigterm");
+        exit(errno);
+    }
+
+    printf("Welcome! Available built-ins are:\n"
+           "cd: `cd <path>` - if no path is given, return to the current dir\n"
+           "wait: `wait pid1 ... pidN` - wait on the processes and report their exit conditions\n"
+           "fg: `fg pid` - pulls a process from the background back in the foreground\n"
+           "\n"
+           "You can put processes in the background using `&`\n"
+           "And with `|` you can pipe the output from one process to the input of another\n"
+    );
+
+    char const *const original_wd = get_current_dir_name();
+
+    bool done = false;
+    while (!done) {
+        char line[BUF_SIZE];
+
+        for (int i = 0; i < BUF_SIZE; ++i) {
+            read(in_fd, line + i, 1);
+            if (line[i] == '\n') {
+                line[i] = 0;
+                break;
+            }
+        }
+
+        if (strspn(line, " \n\t") == strlen(line)) {
+            // skip empty lines - empty being just spaces or tabs
+            continue;
+        }
+
+        processes = NULL;
+        parse_line(line, &processes);
+
+        if (strcmp(processes[0].argv[0], "cd") == 0) {
+            if (arrayLen(processes) != 1) {
+                perror("Can't chain cd with other processes");
+            }
+            int ret;
+            switch (arrayLen(processes[0].argv)) {
+                case 3:
+                    ret = chdir(processes[0].argv[1]);
+                    break;
+                case 2:
+                    ret = chdir(original_wd);
+                    break;
+                default:
+                    fprintf(stderr, "usage: cd <path>\n");
+                    fflush(stderr);
+                    ret = -1;
+            }
+
+            if (ret)
+                printf("[%i] ", ret);
+
+        } else if (strcmp(processes[0].argv[0], "exit") == 0) {
+            done = true;
+        } else if (strcmp(processes[0].argv[0], "wait") == 0) {
+            builtin_wait(processes[0], false);
+        } else if (strcmp(processes[0].argv[0], "fg") == 0) {
+            // same behaviour as wait, just bind to shell again (i.e. terminate process on ctrl-c)
+            builtin_wait(processes[0], true);
+        } else {
+            if (arrayLen(processes) != 0 && processes[arrayLen(processes) - 1].blocking) {
+                signal(SIGINT, signal_handler);
+            }
+            for (size_t i = 0; i < arrayLen(processes); ++i) {
+                int ret = exec_command(processes[i]);
+                if (ret)
+                    printf("[%i] ", ret);
+            }
+            signal(SIGINT, SIG_IGN);
+        }
+
+        free_processes(&processes);
+    }
+
+    free((void *) original_wd);
+
+    return 0;
+}