libc: Add system()

libc/include/stdlib.h

@@ -100,7 +100,8 @@ extern "C"
     /* Exit the program abnormally, without performing any registered cleanup actions. */
     __noreturn void _Exit(int status);
 
-    int system(const char*);
+    /* Execute a shell command. */
+    int system(const char* cmd);
 
     /* Get the value of an environment variable. */
     char* getenv(const char* key);

libc/include/sys/wait.h

@@ -6,6 +6,9 @@
 #include <bits/waitpid.h>
 #include <sys/types.h>
 
+#define WIFEXITED(ret) ((ret) | 0)
+#define WEXITSTATUS(ret) ((ret)&0xff)
+
 #ifdef __cplusplus
 extern "C"
 {

libc/src/stdlib.cpp

@@ -6,6 +6,7 @@
 #include <luna/Utf8.h>
 #include <stdlib.h>
 #include <sys/syscall.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 template <typename ArgT, typename ResultT> static inline ResultT __generic_div(ArgT a, ArgT b)
@@ -175,4 +176,28 @@ extern "C"
     {
         free_impl(ptr);
     }
+
+    int system(const char* cmd)
+    {
+        if (!cmd)
+        {
+            // FIXME: Check if there is a shell available in the system.
+            errno = ENOTSUP;
+            return -1;
+        }
+
+        pid_t child = fork();
+        if (child == 0)
+        {
+            execl("/bin/sh", "sh", "-c", cmd, NULL);
+            _Exit(127);
+        }
+
+        if (child < 0) return -1;
+
+        int status;
+        waitpid(child, &status, 0);
+
+        return status;
+    }
 }