wasmtime / issue #7347 Create directory error? · git-wasmtime

Stream: git-wasmtime

Topic: wasmtime / issue #7347 Create directory error?

Wasmtime GitHub notifications bot (Oct 24 2023 at 15:21):

orangeC23 added the bug label to Issue #7347.

Wasmtime GitHub notifications bot (Oct 24 2023 at 15:22):

orangeC23 opened issue #7347:

Steps to Reproduce

(1) The cfile is :

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>

int path_create_directory(int fd, const char *base_directory, const char *new_directory, mode_t right){
    printf("Enter path_create_directory.\n");

    if (mkdirat(fd, new_directory, right) == -1) {
        perror("Error creating new directory");
        close(fd);
        return 1;
    }

    printf("Directory '%s' created under '%s'\n", new_directory, base_directory);
    printf("Leave path_create_directory.\n");
    return fd;
}

int snapshot(int myfd){
    printf("Enter snapshot\n");

    struct stat file_info;
    if (fstat(myfd, &file_info) == -1) {
        perror("Error getting file attributes");
        close(myfd);
        return 1;
    }

    printf("File Size: %lld bytes \n", (long long)file_info.st_size);

    if (close(myfd) == -1) {
        perror("Error closing file");
        return 1;
    }

    printf("Leave snapshot\n");
}

int get_fd(const char* file_name, int open_style){
    int fd = open(file_name, open_style);
    if (fd == -1) {
        perror("Failed to open the file");
        return 1;
    }

    return fd;
}


int path_create_directoryZOyjKVxmtB (int fd, const char *base_directory){
    const char *new_directory = "newdir";
    mode_t right = 0200;
    return path_create_directory(fd, base_directory, new_directory, right);
}

int main() {
    const char* file_name = "Data/mydir";
    int open_style= O_RDONLY;
    int fd = get_fd(file_name, open_style);
    path_create_directoryZOyjKVxmtB(fd, file_name);
    snapshot(fd);
    return 0;
}

(2)compile the c file into wasm: ./wasi-sdk-16.0/bin/clang --target=wasm32-unkown-wasi --sysroot=./wasi-sdk-16.0/share/wasi-sysroot createdir.c -o createdir.wasm
(3)exeute open.wasm
wasmtime run --dir=./Data createdir.wasm
The permission of Data/mydir is 0700, user1 create the Data/mydir directory before and user1 execute the Wasm file.

Expected Results

Using gcc createdir.c -o createdir and ./createdir to execute get the following result:

Enter path_create_directory.
Directory 'newdir' created under 'Data/mydir'
Leave path_create_directory.
Enter snapshot
File Size: 4096 bytes
Leave snapshot

And using 'ls -al' to check the newdir, the result is -w-------,this is the same as the C source code setting "0200".

Actual Results

wasmtime also prints:

Enter path_create_directory.
Directory 'newdir' created under 'Data/mydir'
Leave path_create_directory.
Enter snapshot
File Size: 4096 bytes
Leave snapshot

However, using 'ls -al' to check the newdir, the result is drwxr-xr-x, which is different from the C source code setting "0200".
I'm not sure whether this could be a bug. Maybe a bug or something different?
Thanks a lot !

Versions and Environment

wasmtime 13.0.0
Operating system: Ubuntu 20.04

Architecture: x86_64

Wasmtime GitHub notifications bot (Oct 24 2023 at 15:38):

bjorn3 commented on issue #7347:

Wasi doesn't have a way to get or set permissions for files and directories. Creating a directory is literally path_create_directory(fd: fd, path: string) -> Result<(), errno>. It has a permission system called "rights", but those only apply not file descriptors, not the stored files.

Wasmtime GitHub notifications bot (Oct 24 2023 at 16:04):

pchickey commented on issue #7347:

@bjorn3 is correct - WASI doesn't specify any sort of behavior for the permissions of files and directories on the host filesystem, and none of the WASI Preview 1 functions expose any way to view, set, or change permissions. So, each implementation is free to behave however they see fit with regard to permissions.