chown: Parse the owner and group properly

apps/chown.cpp

@@ -1,24 +1,78 @@
+#include <luna/String.h>
 #include <os/ArgumentParser.h>
+#include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
-int main(int argc, char** argv)
+Result<int> luna_main(int argc, char** argv)
 {
-    StringView user;
+    StringView user_and_group;
     StringView path;
 
     os::ArgumentParser parser;
     parser.add_description("Change the owner and group of a file."_sv);
-    parser.add_positional_argument(user, "user"_sv, true);
+    parser.add_positional_argument(user_and_group, "owner"_sv, true);
     parser.add_positional_argument(path, "path"_sv, true);
     parser.parse(argc, argv);
 
-    u32 id = (u32)strtoul(user.chars(), NULL, 0);
+    u32 uid = -1;
+    Option<u32> gid = -1;
 
-    if (chown(path.chars(), id, id) < 0)
+    auto names = TRY(user_and_group.split_once(':'));
+    if (names.size() > 1)
+    {
+        auto& group = names[1];
+        if (group.is_empty()) { gid = {}; }
+        else
+        {
+            auto rc = group.view().to_uint();
+            if (rc.has_value()) { gid = (u32)rc.value(); }
+            else
+            {
+                fprintf(stderr, "FIXME: read entry from group file to determine GID for group %s\n", group.chars());
+                return 1;
+            }
+        }
+    }
+    if (names.size() > 0)
+    {
+        auto& owner = names[0];
+        if (!owner.is_empty())
+        {
+            auto rc = owner.view().to_uint();
+            if (rc.has_value()) { uid = (u32)rc.value(); }
+            else
+            {
+                struct passwd* pw = getpwnam(owner.chars());
+                if (!pw)
+                {
+                    fprintf(stderr, "%s: unknown user %s!\n", argv[0], owner.chars());
+                    return 1;
+                }
+
+                uid = pw->pw_uid;
+            }
+
+            if (!gid.has_value())
+            {
+                struct passwd* pw = getpwuid(uid);
+                if (!pw)
+                {
+                    fprintf(stderr, "%s: unknown user id %u!\n", argv[0], uid);
+                    return 1;
+                }
+
+                gid = pw->pw_gid;
+            }
+        }
+    }
+
+    if (chown(path.chars(), uid, gid.value_or(-1)) < 0)
     {
         perror("chown");
         return 1;
     }
+
+    return 0;
 }

libluna/include/luna/String.h

@@ -27,6 +27,10 @@ class String
     Result<String> substring(usize begin, usize size) const;
 
     Result<Vector<String>> split(StringView delim) const;
+    Result<Vector<String>> split_once(char delim) const
+    {
+        return view().split_once(delim);
+    }
 
     static Result<String> format(const String& fmt, ...);
     static Result<String> format(StringView fmt, ...);

libluna/include/luna/StringView.h

@@ -41,6 +41,9 @@ class StringView
     bool operator==(StringView other) const;
 
     Result<Vector<String>> split(StringView delim) const;
+    Result<Vector<String>> split_once(char delim) const;
+
+    Result<usize> to_uint() const;
 
     Iterator begin() const
     {

libluna/src/StringView.cpp

@@ -1,4 +1,6 @@
 #include <luna/CString.h>
+#include <luna/NumberParsing.h>
+#include <luna/ScopeGuard.h>
 #include <luna/String.h>
 #include <luna/StringView.h>
 
@@ -62,9 +64,10 @@ Result<Vector<String>> StringView::split(StringView delim) const
     String str;
 
     char* copy = strndup(m_string, m_length);
+    auto guard = make_scope_guard([copy] { free_impl(copy); });
 
     char* segment = strtok(copy, delim.chars());
-    if (!segment) goto end;
+    if (!segment) return result;
 
     str = TRY(String::from_cstring(segment));
     TRY(result.try_append(move(str)));
@@ -72,14 +75,46 @@ Result<Vector<String>> StringView::split(StringView delim) const
     while (true)
     {
         segment = strtok(nullptr, delim.chars());
-        if (!segment) goto end;
+        if (!segment) return result;
 
         str = TRY(String::from_cstring(segment));
         TRY(result.try_append(move(str)));
     }
 
-end:
-    free_impl(copy);
+    return result;
+}
+
+Result<Vector<String>> StringView::split_once(char delim) const
+{
+    Vector<String> result;
+
+    char* copy = strndup(m_string, m_length);
+    auto guard = make_scope_guard([copy] { free_impl(copy); });
+
+    char* middle = strchr(copy, delim);
+    if (!middle)
+    {
+        auto str = TRY(String::from_cstring(copy));
+        TRY(result.try_append(move(str)));
+        return result;
+    }
+
+    *middle = '\0';
+
+    auto begin = TRY(String::from_cstring(copy));
+    auto end = TRY(String::from_cstring(middle + 1));
+
+    TRY(result.try_append(move(begin)));
+    TRY(result.try_append(move(end)));
+
+    return result;
+}
+
+Result<usize> StringView::to_uint() const
+{
+    const char* endptr = nullptr;
+    auto result = parse_unsigned_integer(m_string, &endptr, 0);
+    if (endptr == m_string) return err(EINVAL);
     return result;
 }