kernel+libc: Add stat() + fstat()

kernel/CMakeLists.txt

@@ -34,6 +34,7 @@ set(SOURCES
     src/sys/mknod.cpp
     src/sys/waitpid.cpp
     src/sys/getdents.cpp
+    src/sys/stat.cpp
     src/fs/VFS.cpp
     src/fs/tmpfs/FileSystem.cpp
     src/fs/devices/DeviceRegistry.cpp

kernel/src/sys/stat.cpp

@@ -0,0 +1,60 @@
+#include "memory/MemoryManager.h"
+#include "sys/Syscall.h"
+#include "thread/Scheduler.h"
+#include <bits/modes.h>
+#include <bits/struct_stat.h>
+
+static mode_t make_mode(mode_t mode, VFS::InodeType type)
+{
+    mode_t result = mode;
+
+    switch (type)
+    {
+    case VFS::InodeType::RegularFile: result |= S_IFREG; break;
+    case VFS::InodeType::Directory: result |= S_IFDIR; break;
+    case VFS::InodeType::Device: result |= S_IFCHR; break;
+    default: break;
+    }
+
+    return result;
+}
+
+static Result<u64> do_stat(SharedPtr<VFS::Inode> inode, stat* st)
+{
+    stat kstat;
+
+    kstat.st_ino = inode->inode_number();
+    kstat.st_mode = make_mode(inode->mode(), inode->type());
+    kstat.st_nlink = 1; // FIXME: Count hard links to files.
+    kstat.st_uid = inode->uid();
+    kstat.st_gid = inode->gid();
+    kstat.st_size = inode->size();
+
+    if (!MemoryManager::copy_to_user_typed(st, &kstat)) return err(EFAULT);
+
+    return 0;
+}
+
+Result<u64> sys_stat(Registers*, SyscallArgs args)
+{
+    auto path = TRY(MemoryManager::strdup_from_user(args[0]));
+    stat* st = (stat*)args[1];
+
+    Thread* current = Scheduler::current();
+
+    auto inode = TRY(VFS::resolve_path(path.chars(), current->auth));
+
+    return do_stat(inode, st);
+}
+
+Result<u64> sys_fstat(Registers*, SyscallArgs args)
+{
+    int fd = (int)args[0];
+    stat* st = (stat*)args[1];
+
+    Thread* current = Scheduler::current();
+
+    auto descriptor = *TRY(current->resolve_fd(fd));
+
+    return do_stat(descriptor.inode, st);
+}

libc/include/bits/modes.h

@@ -6,6 +6,11 @@
 #define S_IFMT 070000
 #define S_IFREG 000000
 #define S_IFDIR 040000
+#define S_IFCHR 050000
+
+#define S_ISREG(mode) ((mode)&S_IFMT == S_IFREG)
+#define S_ISDIR(mode) ((mode)&S_IFMT == S_IFDIR)
+#define S_ISCHR(mode) ((mode)&S_IFMT == S_IFCHR)
 
 #define S_IRWXU 0700
 #define S_IRUSR 0400
@@ -23,7 +28,4 @@
 #define S_ISGID 02000
 #define S_ISVTX 01000
 
-#define S_ISREG(m) ((m & S_IFMT) == S_IFREG)
-#define S_ISDIR(m) ((m & S_IFMT) == S_IFDIR)
-
 #endif

libc/include/bits/struct_stat.h

@@ -0,0 +1,18 @@
+/* bits/struct_stat.h: The stat structure. */
+
+#ifndef _BITS_STRUCT_STAT_H
+#define _BITS_STRUCT_STAT_H
+
+#include <sys/types.h>
+
+struct stat
+{
+    ino_t st_ino;
+    mode_t st_mode;
+    nlink_t st_nlink;
+    uid_t st_uid;
+    gid_t st_gid;
+    off_t st_size;
+};
+
+#endif

libc/include/sys/stat.h

@@ -4,6 +4,7 @@
 #define _SYS_STAT_H
 
 #include <bits/modes.h>
+#include <bits/struct_stat.h>
 #include <sys/types.h>
 
 #ifdef __cplusplus
@@ -17,6 +18,17 @@ extern "C"
     /* Create a special file. */
     int mknod(const char* path, mode_t mode, dev_t dev);
 
+#pragma GCC push_options
+#pragma GCC diagnostic ignored "-Wshadow"
+
+    /* Retrieve information about a file. */
+    int stat(const char* path, struct stat* st);
+
+#pragma GCC pop_options
+
+    /* Retrieve information about a file. */
+    int fstat(int fd, struct stat* st);
+
 #ifdef __cplusplus
 }
 #endif

libc/include/sys/types.h

@@ -18,6 +18,7 @@ typedef __u64_t dev_t;
 typedef __u64_t ino_t;
 typedef __u32_t uid_t;
 typedef __u32_t gid_t;
+typedef __u64_t nlink_t;
 
 typedef off_t fpos_t;
 

libc/src/sys/stat.cpp

@@ -16,4 +16,16 @@ extern "C"
         long rc = syscall(SYS_mknod, path, mode, dev);
         __errno_return(rc, int);
     }
+
+    int stat(const char* path, struct stat* st)
+    {
+        long rc = syscall(SYS_stat, path, st);
+        __errno_return(rc, int);
+    }
+
+    int fstat(int fd, struct stat* st)
+    {
+        long rc = syscall(SYS_fstat, fd, st);
+        __errno_return(rc, int);
+    }
 }

libluna/include/luna/Syscall.h

@@ -4,7 +4,7 @@
     _e(exit) _e(clock_gettime) _e(mmap) _e(munmap) _e(usleep) _e(open) _e(close) _e(read) _e(getpid) _e(write)         \
         _e(lseek) _e(mkdir) _e(execve) _e(mknod) _e(fork) _e(waitpid) _e(getppid) _e(fcntl) _e(getdents) _e(getuid)    \
             _e(geteuid) _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(chmod) _e(chown)       \
-                _e(ioctl)
+                _e(ioctl) _e(stat) _e(fstat)
 
 enum Syscalls
 {