Kernel, libc: Add stat()

kernel/include/sys/Syscall.h

@@ -25,6 +25,7 @@
 #define SYS_fstat 20
 #define SYS_pstat 21
 #define SYS_getdents 22
+#define SYS_stat 23
 
 struct stat;
 struct pstat;
@@ -57,4 +58,5 @@ void sys_waitpid(Context* context, long pid, int* wstatus, int options);
 void sys_access(Context* context, const char* path, int amode);
 void sys_fstat(Context* context, int fd, struct stat* buf);
 void sys_pstat(Context* context, long pid, struct pstat* buf);
-void sys_getdents(Context* context, int fd, struct luna_dirent* buf, size_t count);
+void sys_getdents(Context* context, int fd, struct luna_dirent* buf, size_t count);
+void sys_stat(Context* context, const char* path, struct stat* buf);

kernel/src/sys/stat.cpp

@@ -1,6 +1,7 @@
 #include "fs/VFS.h"
 #include "interrupts/Context.h"
 #include "std/errno.h"
+#include "std/stdlib.h"
 #include "sys/UserMemory.h"
 #include "thread/Scheduler.h"
 
@@ -15,6 +16,21 @@ struct stat // FIXME: This struct is quite stubbed out.
     off_t st_size;
 };
 
+void do_stat(Context* context, VFS::Node* node, struct stat* buf)
+{
+    struct stat* kstat = obtain_user_ref(buf);
+    if (!kstat)
+    {
+        context->rax = -EFAULT; // FIXME: The manual doesn't say fstat can return EFAULT, but it seems logical here...
+        return;
+    }
+    kstat->st_ino = node->inode;
+    kstat->st_mode = (mode_t)node->type;
+    kstat->st_size = node->length;
+    release_user_ref(kstat);
+    context->rax = 0;
+}
+
 void sys_fstat(Context* context, int fd, struct stat* buf)
 {
     Task* current_task = Scheduler::current_task();
@@ -29,16 +45,24 @@ void sys_fstat(Context* context, int fd, struct stat* buf)
         context->rax = -EBADF;
         return;
     }
-    struct stat* kstat = obtain_user_ref(buf);
-    if (!kstat)
+    VFS::Node* node = file.node();
+    return do_stat(context, node, buf);
+}
+
+void sys_stat(Context* context, const char* path, struct stat* buf)
+{
+    char* kpath = strdup_from_user(path);
+    if (!kpath)
     {
-        context->rax = -EFAULT; // FIXME: The manual doesn't say fstat can return EFAULT, but it seems logical here...
+        context->rax = -EFAULT;
         return;
     }
-    VFS::Node* node = file.node();
-    kstat->st_ino = node->inode;
-    kstat->st_mode = (mode_t)node->type;
-    kstat->st_size = node->length;
-    release_user_ref(kstat);
-    context->rax = 0;
+    VFS::Node* node = VFS::resolve_path(kpath);
+    kfree(kpath);
+    if (!node)
+    {
+        context->rax = -ENOENT;
+        return;
+    }
+    return do_stat(context, node, buf);
 }

libs/libc/include/sys/stat.h

@@ -25,6 +25,9 @@ extern "C"
     /* Returns information about the file pointed to by fd in buf. */
     int fstat(int fd, struct stat* buf);
 
+    /* Returns information about the file pointed at path in buf. */
+    int stat(const char* pathname, struct stat* buf);
+
 #ifdef __cplusplus
 }
 #endif

libs/libc/include/sys/syscall.h

@@ -24,5 +24,6 @@
 #define SYS_fstat 20
 #define SYS_pstat 21
 #define SYS_getdents 22
+#define SYS_stat 23
 
 #endif

libs/libc/src/sys/stat.cpp

@@ -13,4 +13,9 @@ extern "C"
     {
         return (int)syscall(SYS_fstat, fd, buf);
     }
+
+    int stat(const char* path, struct stat* buf)
+    {
+        return (int)syscall(SYS_stat, path, buf);
+    }
 }

libs/libc/src/syscall.cpp

@@ -24,6 +24,7 @@ extern "C" long syscall(long number, ...)
     case SYS_munmap:
     case SYS_access:
     case SYS_fstat:
+    case SYS_stat:
     case SYS_pstat:
     case SYS_open: {
         arg arg0 = va_arg(ap, arg);