Stream: git-wasmtime

Topic: wasmtime / issue #8840 Fail to create link file with AT_S...

Wasmtime GitHub notifications bot (Jun 19 2024 at 10:22):

Userzxcvbvnm added the bug label to Issue #8840.

Wasmtime GitHub notifications bot (Jun 19 2024 at 10:22):

Userzxcvbvnm opened issue #8840:

Test Case

The c test case is:

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

int get_fd(const char *filename, int flags) {
    int fd = open(filename, flags);

    if (fd == -1) {
        printf("Get file descriptor of file %s failed!\n", filename);
        return -1;
    } else {
        printf("Get file descriptor of file %s succeed!\n", filename);
        return fd;
    }
}

void closebyfd(int fd) {
    if (close(fd) == -1) {
        printf("Close the file %d by descriptor failed!\n", fd);
    }
}


void path_link_00001_Nan21() {

    printf("Enter function path_link_00001_Nan21\n");



    int result = linkat(AT_FDCWD, "subdir_1/subdir_3/subfile_1", AT_FDCWD, "HARDLINKFILE", AT_SYMLINK_FOLLOW);

    if (result == -1) {
        printf("linkat failed");
    } else {
        printf("Hard link creation successful\n");
    }


}

int main() {
    printf("Enter function main\n");

    path_link_00001_Nan21();

    return 0;
}

Steps to Reproduce

(1)compile to wasm:./wasi-sdk-21.0/bin/clang --target=wasm32-unkown-wasi --sysroot=./wasi-sdk-21.0/share/wasi-sysroot test.c -o test.wasm

(2)Running wasm:
(Before run the Wasm file, file subdir_1/subdir_3/subfile_1 exists.)
wasmtime run --dir=. test.wasm

Expected Results

Successfully create the link file and print:

Enter function main
Enter function path_link_00001_Nan21
Hard link creation successful

This is what WAMR and WasmEdge do.

Actual Results

wasmtime prints:

Enter function main
Enter function path_link_00001_Nan21
linkat failed

However, with the parameter AT_SYMLINK_NOFOLLOW, wasmtime could cucceed, but with parameter AT_SYMLINK_FOLLOW, wasmtime fails.
The parameter AT_SYMLINK_FOLLOW means if the file subdir_1/subdir_3/subfile_1 is a softlink file, the file HARDLINKFILE is expected to points to the source file of subdir_1/subdir_3/subfile_1. In this case, subdir_1/subdir_3/subfile_1 is a not a softlink file, but, I think, in this way,it is expected that HARDLINKFILE points to subdir_1/subdir_3/subfile_1 directly.
I'm not sure whether this is a bug.

Versions and Environment

Wasmtime version or commit: 19.0.2
Operating system: Ubuntu 20.04
Architecture: x86_64

Wasmtime GitHub notifications bot (Jun 19 2024 at 10:56):

bjorn3 commented on issue #8840:

Looks like AT_SYMLINK_FOLLOW is explicitly denied: https://github.com/bytecodealliance/wasmtime/blob/95fee6f4bd0b96460dfc5411ff678d0b2967b772/crates/wasi/src/host/filesystem.rs#L483-L485 This is explicitly required by the wasi test suite: https://github.com/WebAssembly/wasi-testsuite/blob/2fec29ea6de1244c124f7fe3bfe9f2946113f66e/tests/rust/src/bin/path_link.rs#L177-L189 (seems to originate from https://github.com/bytecodealliance/wasmtime/commit/17f43d4cc347a54e34e7a0e65a34e5faef92919e) Wasmtime has been rejecting AT_SYMLINK_FOLLOW on path_link since https://github.com/bytecodealliance/wasmtime/commit/fded424e689dd5f5a3f3e1539f4bc2b36a6e324e.

Wasmtime GitHub notifications bot (Jun 26 2024 at 10:45):

Userzxcvbvnm edited issue #8840:

Test Case

The c test case is:

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

int get_fd(const char *filename, int flags) {
    int fd = open(filename, flags);

    if (fd == -1) {
        printf("Get file descriptor of file %s failed!\n", filename);
        return -1;
    } else {
        printf("Get file descriptor of file %s succeed!\n", filename);
        return fd;
    }
}

void closebyfd(int fd) {
    if (close(fd) == -1) {
        printf("Close the file %d by descriptor failed!\n", fd);
    }
}


void path_link_00001_Nan21() {

    printf("Enter function path_link_00001_Nan21\n");



    int result = linkat(AT_FDCWD, "subdir_1/subdir_3/subfile_1", AT_FDCWD, "HARDLINKFILE", AT_SYMLINK_FOLLOW);

    if (result == -1) {
        printf("linkat failed");
    } else {
        printf("Hard link creation successful\n");
    }


}

int main() {
    printf("Enter function main\n");

    path_link_00001_Nan21();

    return 0;
}

Steps to Reproduce

(1)compile to wasm:./wasi-sdk-21.0/bin/clang --target=wasm32-unkown-wasi --sysroot=./wasi-sdk-21.0/share/wasi-sysroot test.c -o test.wasm

(2)Running wasm:
(Before run the Wasm file, file subdir_1/subdir_3/subfile_1 exists.)
wasmtime run --dir=. test.wasm

Expected Results

Successfully create the link file and print:

Enter function main
Enter function path_link_00001_Nan21
Hard link creation successful

This is what WAMR and WasmEdge do.

Actual Results

wasmtime prints:

Enter function main
Enter function path_link_00001_Nan21
linkat failed

However, with the parameter AT_SYMLINK_NOFOLLOW, wasmtime could cucceed, but with parameter AT_SYMLINK_FOLLOW, wasmtime fails.
The parameter AT_SYMLINK_FOLLOW means if the file subdir_1/subdir_3/subfile_1 is a softlink file, the file HARDLINKFILE is expected to points to the source file of subdir_1/subdir_3/subfile_1. In this case, subdir_1/subdir_3/subfile_1 is a not a softlink file, but, I think, in this way,it is expected that HARDLINKFILE points to subdir_1/subdir_3/subfile_1 directly.
I'm not sure whether this is a bug.

Versions and Environment

Wasmtime version or commit: 19.0.2 and 13.0.1
Operating system: Ubuntu 20.04
Architecture: x86_64

Last updated: Nov 22 2024 at 17:03 UTC