From 52d4f34f054cd55a89efa581b6d26843ac72ceae Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sun, 30 Oct 2022 19:55:38 +0100
Subject: [PATCH] Kernel, libc: Implement umask()

---
 kernel/include/sys/Syscall.h    | 4 +++-
 kernel/include/thread/Task.h    | 2 ++
 kernel/src/sys/Syscall.cpp      | 1 +
 kernel/src/sys/stdio.cpp        | 9 ++++++++-
 libs/libc/include/sys/stat.h    | 4 +++-
 libs/libc/include/sys/syscall.h | 1 +
 libs/libc/src/sys/stat.cpp      | 4 ++--
 libs/libc/src/syscall.cpp       | 3 ++-
 8 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/kernel/include/sys/Syscall.h b/kernel/include/sys/Syscall.h
index d09e6ddc..94ffba07 100644
--- a/kernel/include/sys/Syscall.h
+++ b/kernel/include/sys/Syscall.h
@@ -30,6 +30,7 @@
 #define SYS_dup2 24
 #define SYS_setuid 25
 #define SYS_setgid 26
+#define SYS_umask 27
 
 struct stat;
 struct pstat;
@@ -67,4 +68,5 @@ void sys_getdents(Context* context, int fd, struct luna_dirent* buf, size_t coun
 void sys_stat(Context* context, const char* path, struct stat* buf);
 void sys_dup2(Context* context, int fd, int fd2);
 void sys_setuid(Context* context, int new_uid, int new_euid);
-void sys_setgid(Context* context, int new_gid, int new_egid);
\ No newline at end of file
+void sys_setgid(Context* context, int new_gid, int new_egid);
+void sys_umask(Context* context, mode_t cmask);
\ No newline at end of file
diff --git a/kernel/include/thread/Task.h b/kernel/include/thread/Task.h
index 60b16ebe..8faf4a8d 100644
--- a/kernel/include/thread/Task.h
+++ b/kernel/include/thread/Task.h
@@ -81,6 +81,8 @@ struct Task
 
     char name[128];
 
+    mode_t umask;
+
     BlockReason block_reason;
 
     union {
diff --git a/kernel/src/sys/Syscall.cpp b/kernel/src/sys/Syscall.cpp
index 357ab199..97cb07c2 100644
--- a/kernel/src/sys/Syscall.cpp
+++ b/kernel/src/sys/Syscall.cpp
@@ -40,6 +40,7 @@ void Syscall::entry(Context* context)
     case SYS_dup2: sys_dup2(context, (int)context->rdi, (int)context->rsi); break;
     case SYS_setuid: sys_setuid(context, (int)context->rdi, (int)context->rsi); break;
     case SYS_setgid: sys_setgid(context, (int)context->rdi, (int)context->rsi); break;
+    case SYS_umask: sys_umask(context, (mode_t)context->rdi); break;
     default: context->rax = -ENOSYS; break;
     }
     VMM::exit_syscall_context();
diff --git a/kernel/src/sys/stdio.cpp b/kernel/src/sys/stdio.cpp
index 6384cc5c..8cc05a74 100644
--- a/kernel/src/sys/stdio.cpp
+++ b/kernel/src/sys/stdio.cpp
@@ -333,7 +333,7 @@ void sys_mkdir(Context* context, const char* filename, mode_t mode)
 
     Task* current_task = Scheduler::current_task();
 
-    int rc = VFS::do_mkdir(kfilename, current_task->euid, current_task->egid, mode);
+    int rc = VFS::do_mkdir(kfilename, current_task->euid, current_task->egid, mode & (~current_task->umask));
 
     kfree(kfilename);
 
@@ -373,4 +373,11 @@ void sys_dup2(Context* context, int fd, int fd2)
     *file2 = *file1;
     kinfoln("dup2(): overwrote fd %d with fd %d", fd2, fd);
     context->rax = fd2;
+}
+
+void sys_umask(Context* context, mode_t cmask)
+{
+    Task* current_task = Scheduler::current_task();
+    context->rax = current_task->umask;
+    current_task->umask = cmask;
 }
\ No newline at end of file
diff --git a/libs/libc/include/sys/stat.h b/libs/libc/include/sys/stat.h
index 6602677d..b2480f84 100644
--- a/libs/libc/include/sys/stat.h
+++ b/libs/libc/include/sys/stat.h
@@ -64,7 +64,9 @@ extern "C"
     /* Returns information about the file pointed at path in buf. */
     int stat(const char* pathname, struct stat* buf);
 
-    mode_t umask(mode_t cmask);                   // Not implemented.
+    /* Changes the current process' file creation mask. */
+    mode_t umask(mode_t cmask);
+
     int chmod(const char* pathname, mode_t mode); // Not implemented.
 
 #ifdef __cplusplus
diff --git a/libs/libc/include/sys/syscall.h b/libs/libc/include/sys/syscall.h
index 1af1a0ad..f4699257 100644
--- a/libs/libc/include/sys/syscall.h
+++ b/libs/libc/include/sys/syscall.h
@@ -28,5 +28,6 @@
 #define SYS_dup2 24
 #define SYS_setuid 25
 #define SYS_setgid 26
+#define SYS_umask 27
 
 #endif
\ No newline at end of file
diff --git a/libs/libc/src/sys/stat.cpp b/libs/libc/src/sys/stat.cpp
index 936a72f9..7b9b96c1 100644
--- a/libs/libc/src/sys/stat.cpp
+++ b/libs/libc/src/sys/stat.cpp
@@ -20,9 +20,9 @@ extern "C"
         return (int)__lc_fast_syscall2(SYS_stat, path, buf);
     }
 
-    mode_t umask(mode_t)
+    mode_t umask(mode_t cmask)
     {
-        NOT_IMPLEMENTED("umask");
+        return (mode_t)__lc_fast_syscall1(SYS_umask, cmask);
     }
 
     int chmod(const char*, mode_t)
diff --git a/libs/libc/src/syscall.cpp b/libs/libc/src/syscall.cpp
index f835cbba..42602131 100644
--- a/libs/libc/src/syscall.cpp
+++ b/libs/libc/src/syscall.cpp
@@ -17,13 +17,14 @@ extern "C" long syscall(long number, ...)
     case SYS_exit:
     case SYS_getprocid:
     case SYS_close:
-    case SYS_mkdir:
+    case SYS_umask:
     case SYS_sleep: result = __luna_syscall1(number, va_arg(ap, arg)); break;
     case SYS_munmap:
     case SYS_execv:
     case SYS_access:
     case SYS_fstat:
     case SYS_stat:
+    case SYS_mkdir:
     case SYS_dup2:
     case SYS_clock_gettime:
     case SYS_setuid: