Add process scheduler, pipes, and separate terminal from shell

src/user/app/shell/shell.c

@@ -0,0 +1,126 @@
+#include "src/lib/memory.h"
+#include "src/lib/string.h"
+#include "src/lib/util.h"
+#include "src/user/syscall.h"
+
+static void help(uint8_t argc, char **argv);
+static void cd(uint8_t argc, char **argv);
+
+#define PATH "/bin/"
+
+#define PRINT_S(s) write(1, s, sizeof(s) - 1);
+#define PRINT_D(s) write(1, s, string_length(s));
+
+typedef void (*app_t)(uint8_t argc, char **argv);
+
+typedef struct {
+  const char *name;
+  app_t app;
+} app_entry_t;
+
+static app_entry_t builtins[] = {
+    {"help", help},
+    {"cd", cd},
+};
+
+static void help(uint8_t argc, __attribute__((unused)) char **argv) {
+  if (argc > 1) {
+    PRINT_S("help: expects no arguments");
+    return;
+  }
+
+  PRINT_S("Available commands:\n");
+  for (uint64_t i = 0; i < sizeof(builtins) / sizeof(app_entry_t); i++) {
+    PRINT_D(builtins[i].name);
+    PRINT_S("\n");
+  }
+}
+
+static void cd(uint8_t argc, char **argv) {
+  if (argc != 2) {
+    PRINT_S("cd: requires a single path\n");
+    return;
+  }
+
+  if (chdir(argv[1]) == (uint64_t)-1) {
+    PRINT_S("cd: path does not exist\n");
+  }
+}
+
+static void print_prompt() {
+  char path[256];
+  uint8_t pl = getcwd(256, path);
+  char *components[16];
+  uint8_t cl = string_split(path, '/', 16, components);
+
+  PRINT_S("[")
+  PRINT_D(pl == 1 ? "/" : components[cl - 1]);
+  PRINT_S("]$ ");
+}
+
+static void execute(char *command) {
+  char *argv[16];
+  uint8_t argc = (uint8_t)string_split(command, ' ', 16, argv);
+
+  PRINT_S("\n");
+
+  if (string_equal(command, "^C")) {
+    print_prompt();
+    return;
+  }
+
+  if (string_equal(command, "^D")) {
+    exit(EXIT_CODE_OK);
+  }
+
+  uint8_t i;
+  for (i = 0; i < sizeof(builtins) / sizeof(app_entry_t); i++) {
+    if (string_equal(argv[0], builtins[i].name)) {
+      builtins[i].app(argc, argv);
+      break;
+    }
+  }
+  if (i == sizeof(builtins) / sizeof(app_entry_t)) {
+    uint64_t size = sizeof(PATH) + string_length(argv[0]) + 1;
+    char *path = memory_allocate(size);
+    memory_copy(PATH, sizeof(PATH), path);
+    memory_copy(argv[0], size - sizeof(PATH), path + sizeof(PATH) - 1);
+    uint64_t pid = spawn(path, argc, (const char **)argv);
+    memory_free(path);
+
+    if (pid == EXIT_CODE_NOT_FOUND) {
+      PRINT_S("shell: program not found\n");
+    } else {
+      waitpid(pid);
+    }
+  }
+  print_prompt();
+}
+
+uint64_t main() {
+  PRINT_D("Welcome to FreywarOS v" VERSION "!\n\n");
+
+  print_prompt();
+
+  char line[256];
+  uint64_t offset;
+
+  char chunk[64];
+  uint64_t received;
+
+  while (1) {
+    if ((received = read(0, sizeof(chunk), chunk))) {
+      for (uint64_t i = 0; i < received; i++) {
+        if (chunk[i] == '\n') {
+          line[offset] = '\0';
+          execute(line);
+          offset = 0;
+        } else if (offset < 255) {
+          line[offset++] = chunk[i];
+        }
+      }
+    }
+  }
+
+  return 0;
+}