AT_FDCWD support

Makefile

@@ -191,6 +191,10 @@ override WASM_CFLAGS += --target=$(TARGET_TRIPLE)
 # WebAssembly floating-point match doesn't trap.
 # TODO: Add -fno-signaling-nans when the compiler supports it.
 override WASM_CFLAGS += -fno-trapping-math
+# We should have proper declarations for everything.
+override WASM_CFLAGS += \
+    -Werror=missing-declarations \
+    -Werror=implicit-function-declaration \
 
 # Configure support for threads.
 ifeq ($(THREAD_MODEL), single)

expected/wasm32-wasi/defined-symbols.txt

@@ -249,13 +249,34 @@ __uflow
 __unlist_locked_file
 __uselocale
 __utc
+__wasilibc_access
 __wasilibc_fd_renumber
 __wasilibc_find_relpath
 __wasilibc_init_preopen
+__wasilibc_link
+__wasilibc_link_newat
+__wasilibc_link_oldat
+__wasilibc_nocwd___wasilibc_rmdirat
+__wasilibc_nocwd___wasilibc_unlinkat
+__wasilibc_nocwd_faccessat
+__wasilibc_nocwd_fstatat
+__wasilibc_nocwd_linkat
+__wasilibc_nocwd_mkdirat
+__wasilibc_nocwd_openat
+__wasilibc_nocwd_opendirat
+__wasilibc_nocwd_readlinkat
+__wasilibc_nocwd_renameat
+__wasilibc_nocwd_scandirat
+__wasilibc_nocwd_symlinkat
+__wasilibc_nocwd_utimensat
 __wasilibc_register_preopened_fd
+__wasilibc_rename_newat
+__wasilibc_rename_oldat
 __wasilibc_rmdirat
+__wasilibc_stat
 __wasilibc_tell
 __wasilibc_unlinkat
+__wasilibc_utimens
 __wcscoll_l
 __wcsftime_l
 __wcsxfrm_l

expected/wasm32-wasi/include-all.c

@@ -170,6 +170,7 @@
 #include <values.h>
 #include <wasi/core.h>
 #include <wasi/libc-find-relpath.h>
+#include <wasi/libc-nocwd.h>
 #include <wasi/libc.h>
 #include <wchar.h>
 #include <wctype.h>

expected/wasm32-wasi/predefined-macros.txt

@@ -46,6 +46,7 @@
 #define ARG_MAX 131072
 #define ARMAG "!<arch>\n"
 #define AT_EACCESS (0x0)
+#define AT_FDCWD (-2)
 #define AT_REMOVEDIR (0x4)
 #define AT_SYMLINK_FOLLOW (0x2)
 #define AT_SYMLINK_NOFOLLOW (0x1)
@@ -3098,6 +3099,7 @@
 #define __wasi_core_h 
 #define __wasi_libc_find_relpath_h 
 #define __wasi_libc_h 
+#define __wasi_libc_nocwd_h 
 #define __wasilibc___errno_values_h 
 #define __wasilibc___fd_set_h 
 #define __wasilibc___function___isatty_h 

libc-bottom-half/cloudlibc/src/libc/dirent/opendirat.c

@@ -6,10 +6,22 @@
 #include <fcntl.h>
 #include <stddef.h>
 #include <unistd.h>
+#ifdef __wasilibc_unmodified_upstream // Use WASI libc's nocwd functions.
+#else
+#include <wasi/libc-nocwd.h>
+#endif
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 DIR *opendirat(int dir, const char *dirname) {
+#else
+DIR *__wasilibc_nocwd_opendirat(int dir, const char *dirname) {
+#endif
   // Open directory.
+#ifdef __wasilibc_unmodified_upstream // Call the nocwd function directly.
   int fd = openat(dir, dirname, O_RDONLY | O_NONBLOCK | O_DIRECTORY);
+#else
+  int fd = __wasilibc_nocwd_openat(dir, dirname, O_RDONLY | O_NONBLOCK | O_DIRECTORY, 0);
+#endif
   if (fd == -1)
     return NULL;
 

libc-bottom-half/cloudlibc/src/libc/dirent/scandirat.c

@@ -9,22 +9,36 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#ifdef __wasilibc_unmodified_upstream // Use WASI libc's nocwd functions.
+#else
+#include <wasi/libc-nocwd.h>
+#endif
 
 #include "dirent_impl.h"
 
 static int sel_true(const struct dirent *de) {
   return 1;
 }
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int scandirat(int dirfd, const char *dir, struct dirent ***namelist,
               int (*sel)(const struct dirent *),
               int (*compar)(const struct dirent **, const struct dirent **)) {
+#else
+int __wasilibc_nocwd_scandirat(int dirfd, const char *dir, struct dirent ***namelist,
+                               int (*sel)(const struct dirent *),
+                               int (*compar)(const struct dirent **, const struct dirent **)) {
+#endif
   // Match all files if no select function is provided.
   if (sel == NULL)
     sel = sel_true;
 
   // Open the directory.
+#ifdef __wasilibc_unmodified_upstream // Call the nocwd function directly.
   int fd = openat(dirfd, dir, O_RDONLY | O_NONBLOCK | O_DIRECTORY);
+#else
+  int fd = __wasilibc_nocwd_openat(dirfd, dir, O_RDONLY | O_NONBLOCK | O_DIRECTORY, 0);
+#endif
   if (fd == -1)
     return -1;
 

libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c

@@ -21,7 +21,11 @@ static_assert(O_DIRECTORY >> 12 == __WASI_O_DIRECTORY, "Value mismatch");
 static_assert(O_EXCL >> 12 == __WASI_O_EXCL, "Value mismatch");
 static_assert(O_TRUNC >> 12 == __WASI_O_TRUNC, "Value mismatch");
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int openat(int fd, const char *path, int oflag, ...) {
+#else
+int __wasilibc_nocwd_openat(int fd, const char *path, int oflag, mode_t mode) {
+#endif
   // Compute rights corresponding with the access modes provided.
   // Attempt to obtain all rights, except the ones that contradict the
   // access mode provided to openat().

libc-bottom-half/cloudlibc/src/libc/stdio/renameat.c

@@ -9,7 +9,11 @@
 #include <stdio.h>
 #include <string.h>
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int renameat(int oldfd, const char *old, int newfd, const char *new) {
+#else
+int __wasilibc_nocwd_renameat(int oldfd, const char *old, int newfd, const char *new) {
+#endif
 #ifdef __wasilibc_unmodified_upstream
   __wasi_errno_t error = __wasi_file_rename(oldfd, old, strlen(old),
 #else

libc-bottom-half/cloudlibc/src/libc/sys/stat/fstatat.c

@@ -13,8 +13,13 @@
 
 #include "stat_impl.h"
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int fstatat(int fd, const char *restrict path, struct stat *restrict buf,
             int flag) {
+#else
+int __wasilibc_nocwd_fstatat(int fd, const char *restrict path, struct stat *restrict buf,
+                             int flag) {
+#endif
   // Create lookup properties.
 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t
   __wasi_lookup_t lookup = {.fd = fd, .flags = 0};

libc-bottom-half/cloudlibc/src/libc/sys/stat/mkdirat.c

@@ -10,10 +10,10 @@
 #include <errno.h>
 #include <string.h>
 
-#ifdef __wasilibc_unmodified_upstream
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support, and don't use varargs
 int mkdirat(int fd, const char *path, ...) {
 #else
-int mkdirat(int fd, const char *path, mode_t mode) {
+int __wasilibc_nocwd_mkdirat(int fd, const char *path, mode_t mode) {
 #endif
 #ifdef __wasilibc_unmodified_upstream // __wasi_path_create_directory
   __wasi_errno_t error = __wasi_file_create(

libc-bottom-half/cloudlibc/src/libc/sys/stat/utimensat.c

@@ -13,8 +13,13 @@
 
 #include "stat_impl.h"
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int utimensat(int fd, const char *path, const struct timespec times[2],
               int flag) {
+#else
+int __wasilibc_nocwd_utimensat(int fd, const char *path, const struct timespec times[2],
+                               int flag) {
+#endif
   // Convert timestamps and extract NOW/OMIT flags.
 #ifdef __wasilibc_unmodified_upstream // fstat
   __wasi_filestat_t fs;

libc-bottom-half/cloudlibc/src/libc/unistd/__wasilibc_rmdirat.c

@@ -4,7 +4,7 @@
 #include <errno.h>
 #include <string.h>
 
-int __wasilibc_rmdirat(int fd, const char *path) {
+int __wasilibc_nocwd___wasilibc_rmdirat(int fd, const char *path) {
     size_t path_len = strlen(path);
     __wasi_errno_t error = __wasi_path_remove_directory(fd, path, path_len);
     if (error != 0) {

libc-bottom-half/cloudlibc/src/libc/unistd/__wasilibc_unlinkat.c

@@ -4,7 +4,7 @@
 #include <errno.h>
 #include <string.h>
 
-int __wasilibc_unlinkat(int fd, const char *path) {
+int __wasilibc_nocwd___wasilibc_unlinkat(int fd, const char *path) {
     size_t path_len = strlen(path);
     __wasi_errno_t error = __wasi_path_unlink_file(fd, path, path_len);
     if (error != 0) {

libc-bottom-half/cloudlibc/src/libc/unistd/faccessat.c

@@ -10,7 +10,11 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int faccessat(int fd, const char *path, int amode, int flag) {
+#else
+int __wasilibc_nocwd_faccessat(int fd, const char *path, int amode, int flag) {
+#endif
   // Validate function parameters.
   if ((amode & ~(F_OK | R_OK | W_OK | X_OK)) != 0 ||
       (flag & ~AT_EACCESS) != 0) {

libc-bottom-half/cloudlibc/src/libc/unistd/linkat.c

@@ -10,7 +10,11 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int linkat(int fd1, const char *path1, int fd2, const char *path2, int flag) {
+#else
+int __wasilibc_nocwd_linkat(int fd1, const char *path1, int fd2, const char *path2, int flag) {
+#endif
   // Create lookup properties.
 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t
   __wasi_lookup_t lookup1 = {.fd = fd1, .flags = 0};

libc-bottom-half/cloudlibc/src/libc/unistd/readlinkat.c

@@ -9,8 +9,13 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 ssize_t readlinkat(int fd, const char *restrict path, char *restrict buf,
                    size_t bufsize) {
+#else
+ssize_t __wasilibc_nocwd_readlinkat(int fd, const char *restrict path, char *restrict buf,
+                                    size_t bufsize) {
+#endif
   size_t bufused;
 #ifdef __wasilibc_unmodified_upstream
   __wasi_errno_t error = __wasi_file_readlink(fd, path, strlen(path),

libc-bottom-half/cloudlibc/src/libc/unistd/symlinkat.c

@@ -9,7 +9,11 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifdef __wasilibc_unmodified_upstream // Rename for AT_FDCWD support
 int symlinkat(const char *path1, int fd, const char *path2) {
+#else
+int __wasilibc_nocwd_symlinkat(const char *path1, int fd, const char *path2) {
+#endif
   __wasi_errno_t error =
 #ifdef __wasilibc_unmodified_upstream
       __wasi_file_symlink(path1, strlen(path1), fd, path2, strlen(path2));

libc-bottom-half/headers/private/stdio.h

@@ -1,2 +1,3 @@
 #include <_/cdefs.h>
 int snprintf(char *str, size_t size, const char *format, ...);
+int rename(const char *oldpath, const char *newpath);

libc-bottom-half/headers/public/__header_fcntl.h

@@ -51,6 +51,12 @@
 
 #define FD_CLOEXEC (1)
 
+#define AT_FDCWD            (-2)
+/*
+ * WASI doesn't make a distinction between the "real UID" and the
+ * "effective UID", so AT_EACCESS is 0 because it doesn't change
+ * anything.
+ */
 #define AT_EACCESS          (0x0)
 #define AT_SYMLINK_NOFOLLOW (0x1)
 #define AT_SYMLINK_FOLLOW   (0x2)

libc-bottom-half/headers/public/wasi/libc-nocwd.h

@@ -0,0 +1,60 @@
+#ifndef __wasi_libc_nocwd_h
+#define __wasi_libc_nocwd_h
+
+/*
+ * In order to support AT_FDCWD, we need to wrap the *at functions to handle
+ * it by calling back into the non-at versions which perform libpreopen
+ * queries. These __wasilibc_nocwd_* forms are the underlying calls which
+ * assume AT_FDCWD has already been resolved.
+ */
+
+#define __need_size_t
+#include <stddef.h>
+#include <__typedef_ssize_t.h>
+#include <__typedef_mode_t.h>
+#include <__typedef_DIR.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct timespec;
+struct stat;
+struct dirent;
+
+int __wasilibc_nocwd___wasilibc_unlinkat(int, const char *)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd___wasilibc_rmdirat(int, const char *)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_linkat(int, const char *, int, const char *, int)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_symlinkat(const char *, int, const char *)
+    __attribute__((__warn_unused_result__));
+ssize_t __wasilibc_nocwd_readlinkat(int, const char *__restrict, char *__restrict, size_t)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_unlinkat(int, const char *, int)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_faccessat(int, const char *, int, int)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_renameat(int, const char *, int, const char *)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_openat(int, const char *, int, mode_t)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_fstatat(int, const char *__restrict, struct stat *__restrict, int)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_mkdirat(int, const char *, mode_t)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_utimensat(int, const char *, const struct timespec [2], int)
+    __attribute__((__warn_unused_result__));
+DIR *__wasilibc_nocwd_opendirat(int, const char *)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_nocwd_scandirat(int, const char *, struct dirent ***,
+                               int (*)(const struct dirent *),
+                               int (*)(const struct dirent **, const struct dirent **))
+    __attribute__((__warn_unused_result__));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc-bottom-half/headers/public/wasi/libc.h

@@ -2,17 +2,44 @@
 #define __wasi_libc_h
 
 #include <__typedef_off_t.h>
+#include <__struct_timespec.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+struct stat;
+struct timespec;
+
 void __wasilibc_init_preopen(void);
-int __wasilibc_register_preopened_fd(int fd, const char *path);
-int __wasilibc_fd_renumber(int fd, int newfd);
-int __wasilibc_unlinkat(int fd, const char *path);
-int __wasilibc_rmdirat(int fd, const char *path);
-off_t __wasilibc_tell(int fd);
+int __wasilibc_register_preopened_fd(int fd, const char *path)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_fd_renumber(int fd, int newfd)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_unlinkat(int fd, const char *path)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_rmdirat(int fd, const char *path)
+    __attribute__((__warn_unused_result__));
+off_t __wasilibc_tell(int fd)
+    __attribute__((__warn_unused_result__));
+
+/* Non-`at` forms of various `*at` functions. */
+int __wasilibc_access(const char *pathname, int mode, int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_stat(const char *__restrict pathname, struct stat *__restrict statbuf, int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_utimens(const char *pathname, const struct timespec times[2], int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_link(const char *oldpath, const char *newpath, int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_link_oldat(int olddirfd, const char *oldpath, const char *newpath, int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_link_newat(const char *oldpath, int newdirfd, const char *newpath, int flags)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_rename_oldat(int olddirfd, const char *oldpath, const char *newpath)
+    __attribute__((__warn_unused_result__));
+int __wasilibc_rename_newat(const char *oldpath, int newdirfd, const char *newpath)
+    __attribute__((__warn_unused_result__));
 
 #ifdef __cplusplus
 }