1 files changed, 449 insertions, 0 deletions
diff --git a/libc-bottom-half/sources/posix.c b/libc-bottom-half/sources/posix.c
new file mode 100644
index 0000000..35dd99b
--- /dev/null
+++ b/libc-bottom-half/sources/posix.c
@@ -0,0 +1,449 @@
+//! POSIX-like functions supporting absolute path arguments, implemented in
+//! terms of `__wasilibc_find_relpath` and `*at`-style functions.
+
+#include <errno.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <utime.h>
+#include <wasi/libc.h>
+#include <wasi/libc-find-relpath.h>
+#include <wasi/libc-nocwd.h>
+
+static int find_relpath2(
+    const char *path,
+    char **relative,
+    size_t *relative_len
+) {
+    // See comments in `preopens.c` for what this trick is doing.
+    const char *abs;
+    if (__wasilibc_find_relpath_alloc)
+        return __wasilibc_find_relpath_alloc(path, &abs, relative, relative_len, 1);
+    return __wasilibc_find_relpath(path, &abs, relative, *relative_len);
+}
+
+// Helper to call `__wasilibc_find_relpath` and return an already-managed
+// pointer for the `relative` path. This function is not reentrant since the
+// `relative` pointer will point to static data that cannot be reused until
+// `relative` is no longer used.
+static int find_relpath(const char *path, char **relative) {
+    static __thread char *relative_buf = NULL;
+    static __thread size_t relative_buf_len = 0;
+    int fd = find_relpath2(path, &relative_buf, &relative_buf_len);
+    // find_relpath2 can update relative_buf, so assign it after the call
+    *relative = relative_buf;
+    return fd;
+}
+
+// same as `find_relpath`, but uses another set of static variables to cache
+static int find_relpath_alt(const char *path, char **relative) {
+    static __thread char *relative_buf = NULL;
+    static __thread size_t relative_buf_len = 0;
+    int fd = find_relpath2(path, &relative_buf, &relative_buf_len);
+    // find_relpath2 can update relative_buf, so assign it after the call
+    *relative = relative_buf;
+    return fd;
+}
+
+int open(const char *path, int oflag, ...) {
+    // WASI libc's `openat` ignores the mode argument, so call a special
+    // entrypoint which avoids the varargs calling convention.
+    return __wasilibc_open_nomode(path, oflag);
+}
+
+// See the documentation in libc.h
+int __wasilibc_open_nomode(const char *path, int oflag) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_openat_nomode(dirfd, relative_path, oflag);
+}
+
+int access(const char *path, int amode) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_faccessat(dirfd, relative_path, amode, 0);
+}
+
+ssize_t readlink(
+    const char *restrict path,
+    char *restrict buf,
+    size_t bufsize)
+{
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_readlinkat(dirfd, relative_path, buf, bufsize);
+}
+
+int stat(const char *restrict path, struct stat *restrict buf) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_fstatat(dirfd, relative_path, buf, 0);
+}
+
+int lstat(const char *restrict path, struct stat *restrict buf) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_fstatat(dirfd, relative_path, buf, AT_SYMLINK_NOFOLLOW);
+}
+
+int utime(const char *path, const struct utimbuf *times) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_utimensat(
+             dirfd, relative_path,
+                     times ? ((struct timespec [2]) {
+                                 { .tv_sec = times->actime },
+                                 { .tv_sec = times->modtime }
+                             })
+                           : NULL,
+                     0);
+}
+
+int utimes(const char *path, const struct timeval times[2]) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_utimensat(
+             dirfd, relative_path,
+                     times ? ((struct timespec [2]) {
+                                 { .tv_sec = times[0].tv_sec,
+				   .tv_nsec = times[0].tv_usec * 1000 },
+                                 { .tv_sec = times[1].tv_sec,
+				   .tv_nsec = times[1].tv_usec * 1000 },
+                             })
+                           : NULL,
+                     0);
+}
+
+int unlink(const char *path) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    // `unlinkat` imports `__wasi_path_remove_directory` even when
+    // `AT_REMOVEDIR` isn't passed. Instead, use a specialized function which
+    // just imports `__wasi_path_unlink_file`.
+    return __wasilibc_nocwd___wasilibc_unlinkat(dirfd, relative_path);
+}
+
+int rmdir(const char *path) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd___wasilibc_rmdirat(dirfd, relative_path);
+}
+
+int remove(const char *path) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    // First try to remove it as a file.
+    int r = __wasilibc_nocwd___wasilibc_unlinkat(dirfd, relative_path);
+    if (r != 0 && (errno == EISDIR || errno == ENOTCAPABLE)) {
+        // That failed, but it might be a directory.
+        r = __wasilibc_nocwd___wasilibc_rmdirat(dirfd, relative_path);
+
+        // If it isn't a directory, we lack capabilities to remove it as a file.
+        if (errno == ENOTDIR)
+            errno = ENOTCAPABLE;
+    }
+    return r;
+}
+
+int mkdir(const char *path, mode_t mode) {
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_mkdirat_nomode(dirfd, relative_path);
+}
+
+DIR *opendir(const char *dirname) {
+    char *relative_path;
+    int dirfd = find_relpath(dirname, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return NULL;
+    }
+
+    return __wasilibc_nocwd_opendirat(dirfd, relative_path);
+}
+
+int scandir(
+    const char *restrict dir,
+    struct dirent ***restrict namelist,
+    int (*filter)(const struct dirent *),
+    int (*compar)(const struct dirent **, const struct dirent **)
+) {
+    char *relative_path;
+    int dirfd = find_relpath(dir, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_scandirat(dirfd, relative_path, namelist, filter, compar);
+}
+
+int symlink(const char *target, const char *linkpath) {
+    char *relative_path;
+    int dirfd = find_relpath(linkpath, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_symlinkat(target, dirfd, relative_path);
+}
+
+int link(const char *old, const char *new) {
+    char *old_relative_path;
+    int old_dirfd = find_relpath_alt(old, &old_relative_path);
+
+    if (old_dirfd != -1) {
+        char *new_relative_path;
+        int new_dirfd = find_relpath(new, &new_relative_path);
+
+        if (new_dirfd != -1)
+            return __wasilibc_nocwd_linkat(old_dirfd, old_relative_path,
+                                           new_dirfd, new_relative_path, 0);
+    }
+
+    // We couldn't find a preopen for it; indicate that we lack capabilities.
+    errno = ENOTCAPABLE;
+    return -1;
+}
+
+int rename(const char *old, const char *new) {
+    char *old_relative_path;
+    int old_dirfd = find_relpath_alt(old, &old_relative_path);
+
+    if (old_dirfd != -1) {
+        char *new_relative_path;
+        int new_dirfd = find_relpath(new, &new_relative_path);
+
+        if (new_dirfd != -1)
+            return __wasilibc_nocwd_renameat(old_dirfd, old_relative_path,
+                                             new_dirfd, new_relative_path);
+    }
+
+    // We couldn't find a preopen for it; indicate that we lack capabilities.
+    errno = ENOTCAPABLE;
+    return -1;
+}
+
+// Like `access`, but with `faccessat`'s flags argument.
+int
+__wasilibc_access(const char *path, int mode, int flags)
+{
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_faccessat(dirfd, relative_path,
+                                      mode, flags);
+}
+
+// Like `utimensat`, but without the `at` part.
+int
+__wasilibc_utimens(const char *path, const struct timespec times[2], int flags)
+{
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_utimensat(dirfd, relative_path,
+                                      times, flags);
+}
+
+// Like `stat`, but with `fstatat`'s flags argument.
+int
+__wasilibc_stat(const char *__restrict path, struct stat *__restrict st, int flags)
+{
+    char *relative_path;
+    int dirfd = find_relpath(path, &relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_fstatat(dirfd, relative_path, st, flags);
+}
+
+// Like `link`, but with `linkat`'s flags argument.
+int
+__wasilibc_link(const char *oldpath, const char *newpath, int flags)
+{
+    char *old_relative_path;
+    char *new_relative_path;
+    int old_dirfd = find_relpath(oldpath, &old_relative_path);
+    int new_dirfd = find_relpath(newpath, &new_relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (old_dirfd == -1 || new_dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_linkat(old_dirfd, old_relative_path,
+                                   new_dirfd, new_relative_path,
+                                   flags);
+}
+
+// Like `__wasilibc_link`, but oldpath is relative to olddirfd.
+int
+__wasilibc_link_oldat(int olddirfd, const char *oldpath, const char *newpath, int flags)
+{
+    char *new_relative_path;
+    int new_dirfd = find_relpath(newpath, &new_relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (new_dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_linkat(olddirfd, oldpath,
+                                   new_dirfd, new_relative_path,
+                                   flags);
+}
+
+// Like `__wasilibc_link`, but newpath is relative to newdirfd.
+int
+__wasilibc_link_newat(const char *oldpath, int newdirfd, const char *newpath, int flags)
+{
+    char *old_relative_path;
+    int old_dirfd = find_relpath(oldpath, &old_relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (old_dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_linkat(old_dirfd, old_relative_path,
+                                   newdirfd, newpath,
+                                   flags);
+}
+
+// Like `rename`, but from is relative to fromdirfd.
+int
+__wasilibc_rename_oldat(int fromdirfd, const char *from, const char *to)
+{
+    char *to_relative_path;
+    int to_dirfd = find_relpath(to, &to_relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (to_dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_renameat(fromdirfd, from, to_dirfd, to_relative_path);
+}
+
+// Like `rename`, but to is relative to todirfd.
+int
+__wasilibc_rename_newat(const char *from, int todirfd, const char *to)
+{
+    char *from_relative_path;
+    int from_dirfd = find_relpath(from, &from_relative_path);
+
+    // If we can't find a preopen for it, indicate that we lack capabilities.
+    if (from_dirfd == -1) {
+        errno = ENOTCAPABLE;
+        return -1;
+    }
+
+    return __wasilibc_nocwd_renameat(from_dirfd, from_relative_path, todirfd, to);
+}