api/io: readlinkat

arch/amd64/syscall.c

@@ -59,6 +59,7 @@ void *syscall_table[256] = {
     [SYSCALL_NR_UNLINKAT] =         sys_unlinkat,
     [SYSCALL_NR_READDIR] =          sys_readdir,
     [SYSCALL_NR_CHMOD] =            sys_chmod,
+    [SYSCALL_NR_READLINKAT] =       sys_readlinkat,
     [SYSCALL_NR_CHOWN] =            sys_chown,
     [SYSCALL_NR_MKNOD] =            sys_mknod,
 

fs/ram.c

@@ -122,9 +122,9 @@ int ram_vnode_bset_resize(struct vnode *vn, size_t size) {
             _assert(block_start <= block_index);
 
             for (size_t i = block_start; i < block_index; ++i) {
-                _assert(priv->bpa_l1[l1_index]);
-                mm_phys_free_page(MM_PHYS(priv->bpa_l1[l1_index]));
-                priv->bpa_l1[l1_index] = NULL;
+                _assert(priv->bpa_l1[i]);
+                mm_phys_free_page(MM_PHYS(priv->bpa_l1[i]));
+                priv->bpa_l1[i] = NULL;
             }
         }
         // TODO: handle L2

fs/vfs_ops.c

@@ -545,6 +545,38 @@ int vfs_fstatat(struct vfs_ioctx *ctx, struct vnode *at, const char *path, struc
     return node->op->stat(node, st);
 }
 
+ssize_t vfs_readlinkat(struct vfs_ioctx *ctx,
+                       struct vnode *at,
+                       const char *restrict pathname,
+                       char *restrict buf,
+                       size_t lim) {
+    struct vnode *node;
+    int res;
+
+    _assert(pathname);
+    _assert(ctx);
+    _assert(buf);
+
+    if (!at) {
+        at = ctx->cwd_vnode;
+    }
+
+    if ((res = vfs_find(ctx, at, pathname, AT_SYMLINK_NOFOLLOW, &node)) != 0) {
+        return res;
+    }
+
+    if (node->type != VN_LNK) {
+        return -EINVAL;
+    }
+
+    if (!node->op || !node->op->readlink) {
+        kerror("readlink() not implemented for node\n");
+        return -EINVAL;
+    }
+
+    return node->op->readlink(node, buf, lim);
+}
+
 int vfs_ftruncate(struct vfs_ioctx *ctx, struct vnode *node, off_t length) {
     _assert(ctx);
     _assert(node);

include/fs/node.h

@@ -57,7 +57,7 @@ struct vnode_operations {
     int (*chmod) (struct vnode *node, mode_t mode);
     int (*chown) (struct vnode *node, uid_t uid, gid_t gid);
 
-    int (*readlink) (struct vnode *at, char *buf, size_t lim);
+    ssize_t (*readlink) (struct vnode *at, char *buf, size_t lim);
 
     ssize_t (*read) (struct ofile *fd, void *buf, size_t count);
     ssize_t (*write) (struct ofile *fd, const void *buf, size_t count);

include/fs/vfs.h

@@ -46,6 +46,11 @@ int vfs_openat(struct vfs_ioctx *ctx,
                struct vnode *at,
                const char *path,
                int flags, int mode);
+ssize_t vfs_readlinkat(struct vfs_ioctx *ctx,
+                       struct vnode *at,
+                       const char *restrict pathname,
+                       char *restrict buf,
+                       size_t lim);
 void vfs_close(struct vfs_ioctx *ctx, struct ofile *fd);
 int vfs_readdir(struct vfs_ioctx *ctx, struct ofile *fd, struct dirent *ent);
 int vfs_unlinkat(struct vfs_ioctx *ctx, struct vnode *at, const char *pathname, int flags);

include/sys/sys_file.h

@@ -25,3 +25,4 @@ int sys_chmod(const char *path, mode_t mode);
 int sys_chown(const char *path, uid_t uid, gid_t gid);
 off_t sys_lseek(int fd, off_t offset, int whence);
 int sys_mknod(const char *filename, int mode, unsigned int dev);
+ssize_t sys_readlinkat(int dfd, const char *restrict pathname, char *restrict buf, size_t lim);

include/user/syscall.h

@@ -24,6 +24,7 @@
 #define SYSCALL_NR_UNLINKAT         87
 #define SYSCALL_NR_READDIR          89
 #define SYSCALL_NR_CHMOD            90
+#define SYSCALL_NR_READLINKAT       91
 #define SYSCALL_NR_CHOWN            92
 #define SYSCALL_NR_MKNOD            133
 

sys/sys_file.c

@@ -253,6 +253,20 @@ int sys_faccessat(int dfd, const char *pathname, int mode, int flags) {
     return vfs_faccessat(get_ioctx(), at, pathname, mode, flags);
 }
 
+ssize_t sys_readlinkat(int dfd, const char *restrict pathname, char *restrict buf, size_t lim) {
+    userptr_check(pathname);
+    userptr_check(buf);
+
+    struct vnode *at;
+    int res;
+
+    if ((res = get_at_vnode(dfd, &at, 0)) != 0) {
+        return res;
+    }
+
+    return vfs_readlinkat(get_ioctx(), at, pathname, buf, lim);
+}
+
 int sys_pipe(int *filedes) {
     userptr_check(filedes);
     struct process *proc = thread_self->proc;

sys/wait.c

@@ -160,7 +160,7 @@ int sys_waitpid(pid_t pid, int *status, int flags) {
     struct process *proc_self = thr->proc;
     _assert(proc_self);
 
-    struct process *chld;
+    struct process *chld = NULL;
     struct io_notify *notify;
     int res;