From 580a94bc44bcea61bf1b07abf24c1b00e43a1d64 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 10 Feb 2020 19:32:40 +0100
Subject: [PATCH] Kernel+LibC: Merge sys$stat() and sys$lstat()

There is now only one sys$stat() instead of two separate syscalls.
---
 Kernel/Process.cpp        | 30 +++++++-----------------------
 Kernel/Process.h          |  3 +--
 Kernel/Syscall.h          |  7 ++++++-
 Libraries/LibC/unistd.cpp | 17 +++++++++--------
 4 files changed, 23 insertions(+), 34 deletions(-)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 6ee08c341ac170..5755cd1ab4a6fb 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -1783,41 +1783,25 @@ int Process::sys$fstat(int fd, stat* statbuf)
     return description->fstat(*statbuf);
 }
 
-int Process::sys$lstat(const char* user_path, size_t path_length, stat* user_statbuf)
+int Process::sys$stat(const Syscall::SC_stat_params* user_params)
 {
     REQUIRE_PROMISE(rpath);
-    if (!validate_write_typed(user_statbuf))
+    Syscall::SC_stat_params params;
+    if (!validate_read_and_copy_typed(&params, user_params))
         return -EFAULT;
-    auto path = get_syscall_path_argument(user_path, path_length);
-    if (path.is_error())
-        return path.error();
-    auto metadata_or_error = VFS::the().lookup_metadata(path.value(), current_directory(), O_NOFOLLOW_NOERROR);
-    if (metadata_or_error.is_error())
-        return metadata_or_error.error();
-    stat statbuf;
-    auto result = metadata_or_error.value().stat(statbuf);
-    if (result.is_error())
-        return result;
-    copy_to_user(user_statbuf, &statbuf);
-    return 0;
-}
-
-int Process::sys$stat(const char* user_path, size_t path_length, stat* user_statbuf)
-{
-    REQUIRE_PROMISE(rpath);
-    if (!validate_write_typed(user_statbuf))
+    if (!validate_write_typed(params.statbuf))
         return -EFAULT;
-    auto path = get_syscall_path_argument(user_path, path_length);
+    auto path = get_syscall_path_argument(params.path);
     if (path.is_error())
         return path.error();
-    auto metadata_or_error = VFS::the().lookup_metadata(path.value(), current_directory());
+    auto metadata_or_error = VFS::the().lookup_metadata(path.value(), current_directory(), params.follow_symlinks ? 0 : O_NOFOLLOW_NOERROR);
     if (metadata_or_error.is_error())
         return metadata_or_error.error();
     stat statbuf;
     auto result = metadata_or_error.value().stat(statbuf);
     if (result.is_error())
         return result;
-    copy_to_user(user_statbuf, &statbuf);
+    copy_to_user(params.statbuf, &statbuf);
     return 0;
 }
 
diff --git a/Kernel/Process.h b/Kernel/Process.h
index e9156e42096fff..01c7c5d3f668f9 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -195,8 +195,7 @@ class Process : public InlineLinkedListNode<Process>
     ssize_t sys$write(int fd, const u8*, ssize_t);
     ssize_t sys$writev(int fd, const struct iovec* iov, int iov_count);
     int sys$fstat(int fd, stat*);
-    int sys$lstat(const char*, size_t, stat*);
-    int sys$stat(const char*, size_t, stat*);
+    int sys$stat(const Syscall::SC_stat_params*);
     int sys$lseek(int fd, off_t, int whence);
     int sys$kill(pid_t pid, int sig);
     [[noreturn]] void sys$exit(int status);
diff --git a/Kernel/Syscall.h b/Kernel/Syscall.h
index 41392023da3b5d..75e8cf79908ad1 100644
--- a/Kernel/Syscall.h
+++ b/Kernel/Syscall.h
@@ -56,7 +56,6 @@ typedef u32 socklen_t;
     __ENUMERATE_SYSCALL(mmap)                       \
     __ENUMERATE_SYSCALL(munmap)                     \
     __ENUMERATE_SYSCALL(get_dir_entries)            \
-    __ENUMERATE_SYSCALL(lstat)                      \
     __ENUMERATE_SYSCALL(getcwd)                     \
     __ENUMERATE_SYSCALL(gettimeofday)               \
     __ENUMERATE_SYSCALL(gethostname)                \
@@ -413,6 +412,12 @@ struct SC_waitid_params {
     int options;
 };
 
+struct SC_stat_params {
+    StringArgument path;
+    struct stat* statbuf;
+    bool follow_symlinks;
+};
+
 void initialize();
 int sync();
 
diff --git a/Libraries/LibC/unistd.cpp b/Libraries/LibC/unistd.cpp
index 4a1d6b1e466224..81769a2996d3b8 100644
--- a/Libraries/LibC/unistd.cpp
+++ b/Libraries/LibC/unistd.cpp
@@ -278,24 +278,25 @@ int close(int fd)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-int lstat(const char* path, struct stat* statbuf)
+static int do_stat(const char* path, struct stat* statbuf, bool follow_symlinks)
 {
     if (!path) {
         errno = EFAULT;
         return -1;
     }
-    int rc = syscall(SC_lstat, path, strlen(path), statbuf);
+    Syscall::SC_stat_params params { { path, strlen(path) }, statbuf, follow_symlinks };
+    int rc = syscall(SC_stat, &params);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int lstat(const char* path, struct stat* statbuf)
+{
+    return do_stat(path, statbuf, false);
+}
+
 int stat(const char* path, struct stat* statbuf)
 {
-    if (!path) {
-        errno = EFAULT;
-        return -1;
-    }
-    int rc = syscall(SC_stat, path, strlen(path), statbuf);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
+    return do_stat(path, statbuf, true);
 }
 
 int fstat(int fd, struct stat* statbuf)