libc: Add system()

apps/CMakeLists.txt

@@ -7,9 +7,11 @@ function(luna_app SOURCE_FILE APP_NAME)
 endfunction()
 
 luna_app(init.cpp init)
-luna_app(sh.cpp sh)
 luna_app(env.cpp env)
 
+luna_app(sh.cpp sh)
+target_link_libraries(sh PRIVATE os)
+
 luna_app(cat.cpp cat)
 target_link_libraries(cat PRIVATE os)
 

apps/sh.cpp

@@ -1,4 +1,5 @@
 #include <luna/Vector.h>
+#include <os/ArgumentParser.h>
 
 #include <errno.h>
 #include <stddef.h>
@@ -30,17 +31,56 @@ static Result<Vector<char*>> split_command_into_argv(const char* cmd)
     return result;
 }
 
-int main()
+[[noreturn]] static void execute_command(const char* command)
 {
+    Vector<char*> argv;
+    bool ok = split_command_into_argv(command).try_move_value_or_error(argv, errno);
+    if (!ok)
+    {
+        perror("failed to parse command");
+        exit(1);
+    }
+
+    if (argv[0] == NULL) exit(0);
+    execvp(argv[0], argv.data());
+    perror(argv[0]);
+    exit(1);
+}
+
+int main(int argc, char** argv)
+{
+    StringView file;
+    StringView command;
+
+    FILE* f;
+
+    os::ArgumentParser parser;
+    parser.add_positional_argument(file, "file"_sv, "-"_sv);
+    parser.add_value_argument(command, 'c', "command"_sv, true);
+    parser.parse(argc, argv);
+
+    if (!command.is_empty()) { execute_command(command.chars()); }
+
+    if (file == "-") f = stdin;
+    else
+    {
+        f = fopen(file.chars(), "r");
+        if (!f)
+        {
+            perror("fopen");
+            return 1;
+        }
+    }
+
     while (1)
     {
-        fputs("sh$ ", stdout);
+        if (file == "-") fputs("sh$ ", stdout);
 
-        char command[4096];
-        char* rc = fgets(command, sizeof(command), stdin);
+        char cmd[4096];
+        char* rc = fgets(cmd, sizeof(cmd), f);
         if (!rc) return 0;
 
-        if (strspn(command, " \n") == strlen(command)) continue;
+        if (strspn(cmd, " \n") == strlen(cmd)) continue;
 
         pid_t child = fork();
         if (child < 0)
@@ -49,21 +89,7 @@ int main()
             return 1;
         }
 
-        if (child == 0)
-        {
-            Vector<char*> argv;
-            bool ok = split_command_into_argv(command).try_move_value_or_error(argv, errno);
-            if (!ok)
-            {
-                perror("failed to parse command");
-                return 1;
-            }
-
-            if (argv[0] == NULL) return 0;
-            execvp(argv[0], argv.data());
-            perror(argv[0]);
-            return 1;
-        }
+        if (child == 0) { execute_command(cmd); }
 
         if (waitpid(child, NULL, 0) < 0)
         {

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;
+    }
 }