libos: Add Process::exec

apps/sh.cpp

@@ -15,44 +15,17 @@
 
 using os::File;
 
-static Result<Vector<char*>> split_command_into_argv(StringView cmd, char** out)
+static Result<Vector<String>> split_command_into_args(StringView cmd)
 {
-    char* str = strdup(cmd.chars());
-
-    Vector<char*> result;
-
-    char* segment = strtok(str, " \n");
-    TRY(result.try_append(segment));
-
-    if (segment == NULL) return result;
-
-    for (;;)
-    {
-        segment = strtok(NULL, " \n");
-        TRY(result.try_append(segment));
-
-        if (segment == NULL) return result;
-    }
-
-    if (out) *out = str;
-
-    return result;
+    return cmd.split(" \n"_sv);
 }
 
-[[noreturn]] static void execute_command(StringView command)
+static Result<void> execute_command(StringView command)
 {
-    Vector<char*> argv;
-    bool ok = split_command_into_argv(command, nullptr).try_move_value_or_error(argv, errno);
-    if (!ok)
-    {
-        perror("failed to parse command");
-        exit(1);
-    }
+    auto args = TRY(split_command_into_args(command));
+    if (args.size() < 1) exit(0);
 
-    if (argv[0] == NULL) exit(0);
-    execvp(argv[0], argv.data());
-    perror(argv[0]);
-    exit(1);
+    return os::Process::exec(args[0].view(), args.slice());
 }
 
 Result<int> luna_main(int argc, char** argv)
@@ -68,7 +41,7 @@ Result<int> luna_main(int argc, char** argv)
     parser.add_value_argument(command, 'c', "command"_sv, true);
     parser.parse(argc, argv);
 
-    if (!command.is_empty()) execute_command(command);
+    if (!command.is_empty()) TRY(execute_command(command));
 
     if (path == "-")
     {
@@ -98,10 +71,10 @@ Result<int> luna_main(int argc, char** argv)
         {
             char* copy = nullptr;
 
-            auto args = TRY(split_command_into_argv(cmd.view(), &copy));
-            check("cd"_sv == args[0]);
+            auto args = TRY(split_command_into_args(cmd.view()));
+            check(args[0].view() == "cd");
 
-            if (args.size() == 2)
+            if (args.size() == 1)
             {
                 auto home = TRY(os::FileSystem::home_directory());
                 if (chdir(home.chars()) < 0) perror("cd");
@@ -109,14 +82,14 @@ Result<int> luna_main(int argc, char** argv)
                 continue;
             }
 
-            if (chdir(args[1]) < 0) perror("cd");
+            if (chdir(args[1].chars()) < 0) perror("cd");
             free(copy);
             continue;
         }
 
         pid_t child = TRY(os::Process::fork());
 
-        if (child == 0) { execute_command(cmd.view()); }
+        if (child == 0) { TRY(execute_command(cmd.view())); }
 
         if (waitpid(child, NULL, 0) < 0)
         {

libluna/include/luna/Slice.h

@@ -0,0 +1,52 @@
+#pragma once
+#include <luna/Types.h>
+
+template <typename T> class Slice
+{
+    typedef T* Iterator;
+    typedef const T* ConstIterator;
+
+  public:
+    Slice(T* data, usize size) : m_data(data), m_size(size)
+    {
+    }
+
+    const T* data() const
+    {
+        return m_data;
+    }
+
+    T* data()
+    {
+        return m_data;
+    }
+
+    usize size() const
+    {
+        return m_size;
+    }
+
+    Iterator begin()
+    {
+        return m_data;
+    }
+
+    ConstIterator begin() const
+    {
+        return m_data;
+    }
+
+    Iterator end()
+    {
+        return m_data + m_size;
+    }
+
+    ConstIterator end() const
+    {
+        return m_data + m_size;
+    }
+
+  private:
+    T* const m_data;
+    const usize m_size;
+};

libluna/include/luna/Vector.h

@@ -2,6 +2,7 @@
 #include <luna/Alloc.h>
 #include <luna/CString.h>
 #include <luna/Result.h>
+#include <luna/Slice.h>
 #include <luna/Types.h>
 
 template <typename T> class Vector
@@ -156,6 +157,18 @@ template <typename T> class Vector
         return m_data;
     }
 
+    Slice<T> slice()
+    {
+        return { m_data, m_size };
+    }
+
+    Slice<T> slice(usize index)
+    {
+        check(index < m_size);
+
+        return { m_data + index, m_size - index };
+    }
+
     usize capacity() const
     {
         return m_capacity;

libos/include/os/Process.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <luna/Result.h>
+#include <luna/String.h>
 #include <sys/types.h>
 
 namespace os
@@ -8,5 +9,7 @@ namespace os
     {
       public:
         static Result<pid_t> fork();
+
+        static Result<void> exec(StringView path, Slice<String> args, bool search_in_path = true);
     };
 }

libos/src/Process.cpp

@@ -1,4 +1,6 @@
 #include <os/Process.h>
+
+#include <errno.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
@@ -9,4 +11,17 @@ namespace os
         long rc = syscall(SYS_fork);
         return Result<pid_t>::from_syscall(rc);
     }
+
+    Result<void> Process::exec(StringView path, Slice<String> args, bool search_in_path)
+    {
+        Vector<const char*> argv;
+        for (const auto& arg : args) { TRY(argv.try_append(arg.chars())); }
+        TRY(argv.try_append(nullptr));
+
+        if (search_in_path) execvp(path.chars(), const_cast<char**>(argv.data()));
+        else
+            execv(path.chars(), const_cast<char**>(argv.data()));
+
+        return err(errno);
+    }
 }