1 files changed, 73 insertions, 0 deletions
diff --git a/02_exercise/builtins.c b/02_exercise/builtins.c
new file mode 100644
index 0000000..ac655d8
--- /dev/null
+++ b/02_exercise/builtins.c
@@ -0,0 +1,73 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <wait.h>
+#include <stdlib.h>
+
+
+#include "array.h"
+#include "builtins.h"
+
+void handle(int sig) {
+    /* Do nothing. */
+}
+
+
+void builtin_wait(process p) {
+
+    struct sigaction handler;
+    handler.sa_handler = handle;
+    sigemptyset(&handler.sa_mask);
+    handler.sa_flags = 0;
+    bool error = false;
+    pid_t *pids;
+    arrayInit(pids);
+    size_t i = 1;
+    while (!error && p.argv[i] != NULL) {
+        char *end;
+        pid_t tmp = strtol(p.argv[i], &end, 10);
+        if (*end != '\0') {
+            fprintf(stderr, "Not a valid pid: %s", p.argv[i]);
+            error = true;
+            break;
+        }
+        arrayPush(pids) = tmp;
+        ++i;
+    }
+
+    if (!error) {
+        while (!arrayIsEmpty(pids)) {
+            int status;
+            pid_t current_pid = arrayPop(pids);
+            printf("Waiting for %ld...\n", (long)current_pid);
+            // install signal handler without SA_RESTART, so waitpid gets interrupted
+            sigaction(SIGINT, &handler, NULL);
+            if (waitpid(current_pid, &status, WUNTRACED) < 0) {
+                if (EINTR == errno) {
+                    // cancelled by ctrl-c
+                } else {
+                    perror("Could not wait on process");
+                }
+            } else {
+                printf("[%i] TERMINATED\n", current_pid);
+                if (WIFEXITED(status)) {
+                    printf("[%i] exited normally with status: %i\n", current_pid,
+                           WEXITSTATUS(status));
+                } else if (WIFSTOPPED(status)) {
+                    printf("[%i] was stopped by signal: %s\n", current_pid,
+                           strsignal(WSTOPSIG(status)));
+                } else if (WIFSIGNALED(status)) {
+                    printf("[%i] was terminated by signal: %s\n", current_pid,
+                           strsignal(WTERMSIG(status)));
+                } else {
+                    printf("[%i] exited (not sure why), exit status: %i\n", current_pid,
+                           WEXITSTATUS(status));
+                }
+            }
+            signal(SIGINT, SIG_DFL);
+        }
+    }
+
+    arrayRelease(pids);
+}
+\ No newline at end of file