From c2ed59710a65ab32dae521cfe1a36e2ddf33fbd4 Mon Sep 17 00:00:00 2001
From: Tulio A M Mendes <tadryanom@hotmail.com>
Date: Wed, 11 Feb 2026 19:46:34 -0300
Subject: [PATCH] feat: permissions support (uid/gid/mode, chmod, chown,
 getuid, getgid)

- include/fs.h: added uid, gid, mode fields to fs_node_t
- include/process.h: added uid, gid fields to struct process
- include/stat.h: added st_uid, st_gid to struct stat, permission bit defines
- include/syscall.h: added SYSCALL_CHMOD(50), SYSCALL_CHOWN(51), SYSCALL_GETUID(52), SYSCALL_GETGID(53)
- src/kernel/syscall.c: chmod_impl, chown_impl, getuid/getgid dispatch; stat_from_node now populates uid/gid/mode
- user/init.c: updated struct stat to match kernel layout
- cppcheck clean, 19/19 smoke tests pass
---
 include/fs.h         |  3 +++
 include/process.h    |  2 ++
 include/stat.h       | 15 +++++++++++
 include/syscall.h    |  5 ++++
 src/kernel/syscall.c | 59 +++++++++++++++++++++++++++++++++++++++++++-
 user/init.c          |  2 ++
 6 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/include/fs.h b/include/fs.h
index de7825f4..fe8a8bcf 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -23,6 +23,9 @@ typedef struct fs_node {
     uint32_t flags;
     uint32_t inode;
     uint32_t length;
+    uint32_t uid;
+    uint32_t gid;
+    uint32_t mode;
     
     // Function pointers for operations (Polymorphism in C)
     uint32_t (*read)(struct fs_node* node, uint32_t offset, uint32_t size, uint8_t* buffer);
diff --git a/include/process.h b/include/process.h
index 3328cff4..7fc64f8f 100644
--- a/include/process.h
+++ b/include/process.h
@@ -39,6 +39,8 @@ struct process {
     uint32_t parent_pid;
     uint32_t session_id;
     uint32_t pgrp_id;
+    uint32_t uid;
+    uint32_t gid;
     uintptr_t sp;
     uintptr_t addr_space;
     uint32_t* kernel_stack;
diff --git a/include/stat.h b/include/stat.h
index 6dc89d18..5ea55d6b 100644
--- a/include/stat.h
+++ b/include/stat.h
@@ -17,10 +17,25 @@
 #define S_IFDIR 0040000
 #define S_IFCHR 0020000
 
+#define S_IRWXU 00700
+#define S_IRUSR 00400
+#define S_IWUSR 00200
+#define S_IXUSR 00100
+#define S_IRWXG 00070
+#define S_IRGRP 00040
+#define S_IWGRP 00020
+#define S_IXGRP 00010
+#define S_IRWXO 00007
+#define S_IROTH 00004
+#define S_IWOTH 00002
+#define S_IXOTH 00001
+
 struct stat {
     uint32_t st_ino;
     uint32_t st_mode;
     uint32_t st_nlink;
+    uint32_t st_uid;
+    uint32_t st_gid;
     uint32_t st_size;
 };
 
diff --git a/include/syscall.h b/include/syscall.h
index dc997f3e..f31cd327 100644
--- a/include/syscall.h
+++ b/include/syscall.h
@@ -76,6 +76,11 @@ enum {
     SYSCALL_SHMAT  = 47,
     SYSCALL_SHMDT  = 48,
     SYSCALL_SHMCTL = 49,
+
+    SYSCALL_CHMOD  = 50,
+    SYSCALL_CHOWN  = 51,
+    SYSCALL_GETUID = 52,
+    SYSCALL_GETGID = 53,
 };
 
 #endif
diff --git a/src/kernel/syscall.c b/src/kernel/syscall.c
index 135165ac..5991f6ad 100644
--- a/src/kernel/syscall.c
+++ b/src/kernel/syscall.c
@@ -536,11 +536,14 @@ static int stat_from_node(const fs_node_t* node, struct stat* st) {
     st->st_ino = node->inode;
     st->st_nlink = 1;
     st->st_size = node->length;
+    st->st_uid = node->uid;
+    st->st_gid = node->gid;
 
-    uint32_t mode = 0;
+    uint32_t mode = node->mode & 07777;
     if (node->flags == FS_DIRECTORY) mode |= S_IFDIR;
     else if (node->flags == FS_CHARDEVICE) mode |= S_IFCHR;
     else mode |= S_IFREG;
+    if ((mode & 07777) == 0) mode |= 0755;
     st->st_mode = mode;
     return 0;
 }
@@ -1615,6 +1618,35 @@ static uintptr_t syscall_brk_impl(uintptr_t addr) {
     return addr;
 }
 
+static int syscall_chmod_impl(const char* user_path, uint32_t mode) {
+    if (!user_path) return -EFAULT;
+
+    char path[128];
+    int prc = path_resolve_user(user_path, path, sizeof(path));
+    if (prc < 0) return prc;
+
+    fs_node_t* node = vfs_lookup(path);
+    if (!node) return -ENOENT;
+
+    node->mode = mode & 07777;
+    return 0;
+}
+
+static int syscall_chown_impl(const char* user_path, uint32_t uid, uint32_t gid) {
+    if (!user_path) return -EFAULT;
+
+    char path[128];
+    int prc = path_resolve_user(user_path, path, sizeof(path));
+    if (prc < 0) return prc;
+
+    fs_node_t* node = vfs_lookup(path);
+    if (!node) return -ENOENT;
+
+    node->uid = uid;
+    node->gid = gid;
+    return 0;
+}
+
 void syscall_handler(struct registers* regs) {
     uint32_t syscall_no = regs->eax;
 
@@ -1997,6 +2029,31 @@ void syscall_handler(struct registers* regs) {
         return;
     }
 
+    if (syscall_no == SYSCALL_CHMOD) {
+        const char* path = (const char*)regs->ebx;
+        uint32_t mode = regs->ecx;
+        regs->eax = (uint32_t)syscall_chmod_impl(path, mode);
+        return;
+    }
+
+    if (syscall_no == SYSCALL_CHOWN) {
+        const char* path = (const char*)regs->ebx;
+        uint32_t uid = regs->ecx;
+        uint32_t gid = regs->edx;
+        regs->eax = (uint32_t)syscall_chown_impl(path, uid, gid);
+        return;
+    }
+
+    if (syscall_no == SYSCALL_GETUID) {
+        regs->eax = current_process ? current_process->uid : 0;
+        return;
+    }
+
+    if (syscall_no == SYSCALL_GETGID) {
+        regs->eax = current_process ? current_process->gid : 0;
+        return;
+    }
+
     regs->eax = (uint32_t)-ENOSYS;
 }
 
diff --git a/user/init.c b/user/init.c
index b6c2ca4e..7e2fb085 100644
--- a/user/init.c
+++ b/user/init.c
@@ -168,6 +168,8 @@ struct stat {
     uint32_t st_ino;
     uint32_t st_mode;
     uint32_t st_nlink;
+    uint32_t st_uid;
+    uint32_t st_gid;
     uint32_t st_size;
 };
 
-- 
2.43.0