printcap.c File Reference

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

Go to the source code of this file.

Detailed Description

minimal example filesystem that prints out all capabilities supported by the kernel and then exits.

Compile with:

gcc -Wall printcap.c `pkg-config fuse3 --cflags --libs` -o printcap

Source code

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2017 Nikolaus Rath <Nikolaus@rath.org>
 
  This program can be distributed under the terms of the GNU GPLv2.
  See the file COPYING.
*/
 
#define FUSE_USE_VERSION 31
 
#include <fuse_lowlevel.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
 
struct fuse_session *se;
 
// Define a structure to hold capability information
struct cap_info {
        uint64_t flag;
        const char *name;
};
 
// Define an array of all capabilities
static const struct cap_info capabilities[] = {
    {FUSE_CAP_ASYNC_READ,               "FUSE_CAP_ASYNC_READ"},
    {FUSE_CAP_POSIX_LOCKS,              "FUSE_CAP_POSIX_LOCKS"},
    {FUSE_CAP_ATOMIC_O_TRUNC,           "FUSE_CAP_ATOMIC_O_TRUNC"},
    {FUSE_CAP_EXPORT_SUPPORT,           "FUSE_CAP_EXPORT_SUPPORT"},
    {FUSE_CAP_DONT_MASK,                "FUSE_CAP_DONT_MASK"},
    {FUSE_CAP_SPLICE_MOVE,              "FUSE_CAP_SPLICE_MOVE"},
    {FUSE_CAP_SPLICE_READ,              "FUSE_CAP_SPLICE_READ"},
    {FUSE_CAP_SPLICE_WRITE,             "FUSE_CAP_SPLICE_WRITE"},
    {FUSE_CAP_FLOCK_LOCKS,              "FUSE_CAP_FLOCK_LOCKS"},
    {FUSE_CAP_IOCTL_DIR,                "FUSE_CAP_IOCTL_DIR"},
    {FUSE_CAP_AUTO_INVAL_DATA,          "FUSE_CAP_AUTO_INVAL_DATA"},
    {FUSE_CAP_READDIRPLUS,              "FUSE_CAP_READDIRPLUS"},
    {FUSE_CAP_READDIRPLUS_AUTO,         "FUSE_CAP_READDIRPLUS_AUTO"},
    {FUSE_CAP_ASYNC_DIO,                "FUSE_CAP_ASYNC_DIO"},
    {FUSE_CAP_WRITEBACK_CACHE,          "FUSE_CAP_WRITEBACK_CACHE"},
    {FUSE_CAP_NO_OPEN_SUPPORT,          "FUSE_CAP_NO_OPEN_SUPPORT"},
    {FUSE_CAP_PARALLEL_DIROPS,          "FUSE_CAP_PARALLEL_DIROPS"},
    {FUSE_CAP_POSIX_ACL,                "FUSE_CAP_POSIX_ACL"},
    {FUSE_CAP_CACHE_SYMLINKS,           "FUSE_CAP_CACHE_SYMLINKS"},
    {FUSE_CAP_NO_OPENDIR_SUPPORT,       "FUSE_CAP_NO_OPENDIR_SUPPORT"},
    {FUSE_CAP_EXPLICIT_INVAL_DATA,      "FUSE_CAP_EXPLICIT_INVAL_DATA"},
    {FUSE_CAP_EXPIRE_ONLY,              "FUSE_CAP_EXPIRE_ONLY"},
    {FUSE_CAP_SETXATTR_EXT,             "FUSE_CAP_SETXATTR_EXT"},
    {FUSE_CAP_HANDLE_KILLPRIV,          "FUSE_CAP_HANDLE_KILLPRIV"},
    {FUSE_CAP_HANDLE_KILLPRIV_V2,       "FUSE_CAP_HANDLE_KILLPRIV_V2"},
    {FUSE_CAP_DIRECT_IO_ALLOW_MMAP,     "FUSE_CAP_DIRECT_IO_ALLOW_MMAP"},
    {FUSE_CAP_NO_EXPORT_SUPPORT,        "FUSE_CAP_NO_EXPORT_SUPPORT"},
    {FUSE_CAP_PASSTHROUGH,              "FUSE_CAP_PASSTHROUGH"},
    // Add any new capabilities here
    {0, NULL} // Sentinel to mark the end of the array
};
 
static void print_capabilities(struct fuse_conn_info *conn)
{
        printf("Capabilities:\n");
        for (const struct cap_info *cap = capabilities; cap->name != NULL; cap++) {
                if (fuse_get_feature_flag(conn, cap->flag)) {
                        printf("\t%s\n", cap->name);
                }
        }
}
 
static void pc_init(void *userdata, struct fuse_conn_info *conn)
{
        (void) userdata;
 
        printf("Protocol version: %d.%d\n", conn->proto_major,
               conn->proto_minor);
        print_capabilities(conn);
        fuse_session_exit(se);
}
 
 
static const struct fuse_lowlevel_ops pc_oper = {
        .init           = pc_init,
};
 
int main(int argc, char **argv)
{
        struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
        char *mountpoint;
        int ret = -1;
 
        mountpoint = strdup("/tmp/fuse_printcap_XXXXXX");
        if(mkdtemp(mountpoint) == NULL) {
                perror("mkdtemp");
                return 1;
        }
 
        printf("FUSE library version %s\n", fuse_pkgversion());
        fuse_lowlevel_version();
 
        se = fuse_session_new(&args, &pc_oper,
                              sizeof(pc_oper), NULL);
        if (se == NULL)
            goto err_out1;
 
        if (fuse_set_signal_handlers(se) != 0)
            goto err_out2;
 
        if (fuse_session_mount(se, mountpoint) != 0)
            goto err_out3;
 
        ret = fuse_session_loop(se);
 
        fuse_session_unmount(se);
err_out3:
        fuse_remove_signal_handlers(se);
err_out2:
        fuse_session_destroy(se);
err_out1:
        rmdir(mountpoint);
        free(mountpoint);
        fuse_opt_free_args(&args);
 
        return ret ? 1 : 0;
}

Definition in file printcap.c.