vasilito/RedBear-OS
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Impl AT_SYMLINK_NOFOLLOW and AT_EMPTY_PATH

Browse Source 
AT_SYMLINK_NOFOLLOW acts on the symlink itself rather than following it.

AT_EMPTY_PATH acts on the directory if path is empty.

Currently, this is implemented in fstatat itself but the code is general
enough to be refactored once we get the other *at functions. It could
likely just live in openat itself.
This commit is contained in:
Josh Megnauth
2025-09-10 01:49:21 -04:00
parent e1fa1ee7b7
commit 28901b1b62
3 changed files with 101 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/header/fcntl/redox.rs
+2
View File
@@ -30,3 +30,5 @@ pub const O_NDELAY: c_int = O_NONBLOCK;
// Flags for capability based "at" functions
pub const AT_FDCWD: c_int = -100;
pub const AT_SYMLINK_NOFOLLOW: c_int = 0x0200;
pub const AT_EMPTY_PATH: c_int = 0x4000;
src/platform/redox/mod.rs
+9 -13
View File
@@ -25,7 +25,7 @@ use crate::{
EBADF, EBADFD, EBADR, EINTR, EINVAL, EIO, ENAMETOOLONG, ENOENT, ENOMEM, ENOSYS,
EOPNOTSUPP, EPERM, ERANGE,
},
fcntl::{self, AT_FDCWD, O_RDONLY},
fcntl::{self, AT_EMPTY_PATH, AT_FDCWD, AT_SYMLINK_NOFOLLOW, O_NOFOLLOW, O_PATH, O_RDONLY},
limits,
sys_mman::{MAP_ANONYMOUS, MAP_FAILED, PROT_READ, PROT_WRITE},
sys_random,
@@ -292,19 +292,16 @@ impl Pal for Sys {
) -> Result<()> {
let path =
match CStr::from_nullable_ptr(path).and_then(|cs| str::from_utf8(cs.to_bytes()).ok()) {
// TODO: AT_EMPTY_PATH
Some(path) if !path.is_empty() => Ok(path),
None | Some(_) => Err(Errno(ENOENT)),
_ if flags & AT_EMPTY_PATH == AT_EMPTY_PATH => return Sys::fstat(fildes, buf),
_ => Err(Errno(ENOENT)),
}?;
// TODO: We need an AT_SYMLINK_NOFOLLOW constant for Redox. Unlike AT_FDCWD, it varies
// across OSes, so I don't want to define it here myself.
// O_NOFOLLOW may be incorrect too (see the rename.c unit test).
// let oflags = if flags & AT_SYMLINK_NOFOLLOW {
// O_RDONLY | O_NOFOLLOW
// } else {
// O_RDONLY
// };
let oflags = O_RDONLY;
let oflags = if flags & AT_SYMLINK_NOFOLLOW == AT_SYMLINK_NOFOLLOW {
O_RDONLY | O_PATH | O_NOFOLLOW
} else {
O_RDONLY
};
// Absolute paths are passed to fstat without processing.
// canonicalize_using_cwd checks that path is absolute so a third branch that does so here
@@ -328,7 +325,6 @@ impl Pal for Sys {
let path = CString::new(path).map_err(|_| Errno(ENOENT))?;
// TODO:
// * If AT_SYMLINK_NOFOLLOW is set, call lstat instead.
// * Switch open to openat.
let file = File::open(path.as_c_str().into(), oflags)?;
Sys::fstat(*file, buf)
tests/sys_stat/fstatat.c
+90 -15
View File
@@ -1,3 +1,5 @@
#define _GNU_SOURCE // Linux for CI
#include <assert.h>
#include <fcntl.h>
#include <limits.h>
@@ -49,7 +51,7 @@ static const char* mktestfile(
return path;
}
// Create a link, `dir/name`, to `target` and return its path.
// Create a symlink, `dir/name`, to `target` and return its path.
__attribute__((nonnull))
static const char* mktestlink(
const char dir[],
@@ -66,8 +68,8 @@ static const char* mktestlink(
strcat(path, "/");
strcat(path, name);
if (link(target, path) == -1) {
perror("link");
if (symlink(target, path) == -1) {
perror("symlink");
free(path);
return NULL;
}
@@ -81,14 +83,15 @@ static int run_test(
int flags,
const char name[],
const char path[],
size_t expected
size_t expected,
mode_t mode
) {
struct stat stat = {0};
if (fstatat(fd, name, &stat, flags) == -1) {
perror("fstatat");
return -1;
}
if ((size_t) stat.st_size != expected) {
fprintf(
stderr,
@@ -99,6 +102,32 @@ static int run_test(
);
return -1;
}
if ((stat.st_mode & S_IFMT) != mode) {
fprintf(
stderr,
"fstatat invalid mode\n\tFile: %s\n",
path
);
return -1;
}
// We create the temp dirs/files therefore we should own them.
uid_t uid = getuid();
gid_t gid = getgid();
if (stat.st_uid != uid || stat.st_gid != gid) {
fputs("fstatat invalid UID or GID", stderr);
fprintf(
stderr,
"\n\tExpected UID: %u\n\tActual UID: %u\n",
uid, stat.st_uid
);
fprintf(
stderr,
"\n\tExpected GID: %u\n\tActual GID: %u\n",
gid, stat.st_gid
);
}
return 0;
}
@@ -157,24 +186,37 @@ int main(void) {
// fstatat works (basic)
size_t len_cont_A = strlen(cont_A);
if (run_test(dir_a_fd, 0, name, file_A, len_cont_A) == -1) {
if (run_test(dir_a_fd, 0, name, file_A, len_cont_A, S_IFREG) == -1) {
goto close_dir_a_fd;
}
// fstatat follows symlinks (same dir)
if (run_test(dir_a_fd, 0, link_A_name, link_A, len_cont_A) == -1) {
if (run_test(dir_a_fd, 0, link_A_name, link_A, len_cont_A, S_IFREG) == -1) {
fprintf(stderr, "Context: link %s -> %s\n", link_A, file_A);
goto close_dir_a_fd;
}
// fstatat follows symlinks (to diff dir)
size_t len_cont_B = strlen(cont_B);
if (run_test(dir_a_fd, 0, link_B_name, link_B, len_cont_B) == -1) {
if (run_test(dir_a_fd, 0, link_B_name, link_B, len_cont_B, S_IFREG) == -1) {
fprintf(stderr, "Context: link %s -> %s\n", link_B, file_B);
goto close_dir_a_fd;
}
// TODO: AT_SYMLINK_NOFOLLOW (no Redox support)
// AT_SYMLINK_NOFOLLOW
if (
run_test(
dir_a_fd,
AT_SYMLINK_NOFOLLOW,
link_A_name,
link_A,
strlen(file_A),
S_IFLNK
) == -1
) {
fprintf(stderr, "Context: link %s (no follow)\n", link_A);
goto close_dir_a_fd;
}
// TODO: O_SEARCH (no Redox support)
@@ -188,7 +230,7 @@ int main(void) {
perror("chdir");
goto close_dir_a_fd;
}
if (run_test(AT_FDCWD, 0, name, "./", len_cont_A) == -1) {
if (run_test(AT_FDCWD, 0, name, "./", len_cont_A, S_IFREG) == -1) {
fputs("Context: AT_FDCWD\n", stderr);
goto close_dir_a_fd;
}
@@ -198,7 +240,7 @@ int main(void) {
}
// Absolute path
if (run_test(dir_a_fd, 0, file_A, file_A, len_cont_A) == -1) {
if (run_test(dir_a_fd, 0, file_A, file_A, len_cont_A, S_IFREG) == -1) {
fprintf(stderr, "Context: absolute path %s\n", file_A);
goto close_dir_a_fd;
}
@@ -228,7 +270,16 @@ int main(void) {
}
char rel_nested[sizeof(name) + 5] = "../";
strcat(rel_nested, name);
if (run_test(nested_fd, 0, rel_nested, rel_nested, len_cont_A) == -1) {
if (
run_test(
nested_fd,
0,
rel_nested,
rel_nested,
len_cont_A,
S_IFREG
) == -1
) {
fprintf(
stderr,
"Context: relative path from %s to ../%s\n",
@@ -240,13 +291,37 @@ int main(void) {
// TODO: AT_RESOLVE_BENEATH
// TODO: AT_EMPTY_PATH
// AT_EMPTY_PATH (empty path)
struct stat stat = {0};
if (fstatat(dir_a_fd, "", &stat, AT_EMPTY_PATH) == -1) {
fputs("Context: AT_EMPTY_PATH with empty path\n", stderr);
goto close_dir_a_fd;
}
if ((stat.st_mode & S_IFMT) != S_IFDIR) {
fputs("Context: AT_EMPTY_PATH should stat dir (empty path)\n", stderr);
goto close_dir_a_fd;
}
// AT_EMPTY_PATH (non-empty path)
if (
run_test(
dir_a_fd,
AT_EMPTY_PATH,
link_A_name,
link_A,
len_cont_A,
S_IFREG
) == -1
) {
fputs("Context: AT_EMPTY_PATH with path should stat path\n", stderr);
goto close_dir_a_fd;
}
// TODO: Swapped directories resolves correctly
// Failure conditions:
// Empty path
struct stat stat = {0};
// Empty path without AT_EMPTY_PATH
stat = (struct stat) {0};
if (fstatat(dir_a_fd, "", &stat, 0) == 0) {
fputs("Context: empty path should fail\n", stderr);
goto close_dir_a_fd;