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#ifndef _GNU_SOURCE
#define _GNU_SOURCE /* O_DIRECT */
#endif
#include <dirent.h>
#include <errno.h>
#include <unistd.h>
/* TODO(ophestra): remove after 05ce67fea99ca09cd4b6625cff7aec9cc222dd5a reaches a release */
#include <sys/syscall.h>
#include "fuse-operations.h"
/* MUST_TRANSLATE_PATHNAME translates a userspace pathname to a relative pathname;
* the resulting address points to a constant string or part of pathname, it is never heap allocated. */
#define MUST_TRANSLATE_PATHNAME(pathname) \
do { \
if (pathname == NULL) \
return -EINVAL; \
while (*pathname == '/') \
pathname++; \
if (*pathname == '\0') \
pathname = "."; \
} while (0)
/* GET_CONTEXT_PRIV obtains fuse context and private data for the calling thread. */
#define GET_CONTEXT_PRIV(ctx, priv) \
do { \
ctx = fuse_get_context(); \
priv = ctx->private_data; \
} while (0)
/* impl_getattr modifies a struct stat from the kernel to present to userspace;
* impl_getattr returns a negative errno style error code. */
static int impl_getattr(struct fuse_context *ctx, struct stat *statbuf) {
/* allowlist of permitted types */
if (!S_ISDIR(statbuf->st_mode) && !S_ISREG(statbuf->st_mode) && !S_ISLNK(statbuf->st_mode)) {
return -ENOTRECOVERABLE; /* returning an errno causes all operations on the file to return EIO */
}
#define OVERRIDE_PERM(v) (statbuf->st_mode & ~0777) | (v & 0777)
if (S_ISDIR(statbuf->st_mode))
statbuf->st_mode = OVERRIDE_PERM(SHAREFS_PERM_DIR);
else if (S_ISREG(statbuf->st_mode))
statbuf->st_mode = OVERRIDE_PERM(SHAREFS_PERM_REG);
else
statbuf->st_mode = 0; /* should always be symlink in this case */
statbuf->st_uid = ctx->uid;
statbuf->st_gid = SHAREFS_MEDIA_RW_ID;
statbuf->st_ctim = statbuf->st_mtim;
statbuf->st_nlink = 1;
return 0;
}
/* fuse_operations implementation */
int sharefs_getattr(const char *pathname, struct stat *statbuf, struct fuse_file_info *fi) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)fi;
if (fstatat(priv->dirfd, pathname, statbuf, AT_SYMLINK_NOFOLLOW) == -1)
return -errno;
return impl_getattr(ctx, statbuf);
}
int sharefs_readdir(const char *pathname, void *buf, fuse_fill_dir_t filler, off_t offset, struct fuse_file_info *fi, enum fuse_readdir_flags flags) {
int fd;
DIR *dp;
struct stat st;
int ret = 0;
struct dirent *de;
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)offset;
(void)fi;
if ((fd = openat(priv->dirfd, pathname, O_RDONLY | O_DIRECTORY | O_CLOEXEC)) == -1)
return -errno;
if ((dp = fdopendir(fd)) == NULL) {
close(fd);
return -errno;
}
errno = 0; /* for the next readdir call */
while ((de = readdir(dp)) != NULL) {
if (flags & FUSE_READDIR_PLUS) {
if (fstatat(dirfd(dp), de->d_name, &st, AT_SYMLINK_NOFOLLOW) == -1) {
ret = -errno;
break;
}
if ((ret = impl_getattr(ctx, &st)) < 0)
break;
errno = 0;
ret = filler(buf, de->d_name, &st, 0, FUSE_FILL_DIR_PLUS);
} else
ret = filler(buf, de->d_name, NULL, 0, 0);
if (ret != 0) {
ret = errno != 0 ? -errno : -EIO; /* filler */
break;
}
errno = 0; /* for the next readdir call */
}
if (ret == 0 && errno != 0)
ret = -errno; /* readdir */
closedir(dp);
return ret;
}
int sharefs_mkdir(const char *pathname, mode_t mode) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)mode;
if (mkdirat(priv->dirfd, pathname, SHAREFS_PERM_DIR) == -1)
return -errno;
return 0;
}
int sharefs_unlink(const char *pathname) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
if (unlinkat(priv->dirfd, pathname, 0) == -1)
return -errno;
return 0;
}
int sharefs_rmdir(const char *pathname) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
if (unlinkat(priv->dirfd, pathname, AT_REMOVEDIR) == -1)
return -errno;
return 0;
}
int sharefs_rename(const char *oldpath, const char *newpath, unsigned int flags) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(oldpath);
MUST_TRANSLATE_PATHNAME(newpath);
/* TODO(ophestra): replace with wrapper after 05ce67fea99ca09cd4b6625cff7aec9cc222dd5a reaches a release */
if (syscall(__NR_renameat2, priv->dirfd, oldpath, priv->dirfd, newpath, flags) == -1)
return -errno;
return 0;
}
int sharefs_truncate(const char *pathname, off_t length, struct fuse_file_info *fi) {
int fd;
int ret;
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)fi;
if ((fd = openat(priv->dirfd, pathname, O_WRONLY | O_CLOEXEC)) == -1)
return -errno;
if ((ret = ftruncate(fd, length)) == -1)
ret = -errno;
close(fd);
return ret;
}
int sharefs_utimens(const char *pathname, const struct timespec times[2], struct fuse_file_info *fi) {
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)fi;
if (utimensat(priv->dirfd, pathname, times, AT_SYMLINK_NOFOLLOW) == -1)
return -errno;
return 0;
}
int sharefs_create(const char *pathname, mode_t mode, struct fuse_file_info *fi) {
int fd;
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
(void)mode;
if ((fd = openat(priv->dirfd, pathname, fi->flags & ~SHAREFS_FORBIDDEN_FLAGS, SHAREFS_PERM_REG)) == -1)
return -errno;
fi->fh = fd;
return 0;
}
int sharefs_open(const char *pathname, struct fuse_file_info *fi) {
int fd;
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
if ((fd = openat(priv->dirfd, pathname, fi->flags & ~SHAREFS_FORBIDDEN_FLAGS)) == -1)
return -errno;
fi->fh = fd;
return 0;
}
int sharefs_read(const char *pathname, char *buf, size_t count, off_t offset, struct fuse_file_info *fi) {
int ret;
(void)pathname;
if ((ret = pread(fi->fh, buf, count, offset)) == -1)
return -errno;
return ret;
}
int sharefs_write(const char *pathname, const char *buf, size_t count, off_t offset, struct fuse_file_info *fi) {
int ret;
(void)pathname;
if ((ret = pwrite(fi->fh, buf, count, offset)) == -1)
return -errno;
return ret;
}
int sharefs_statfs(const char *pathname, struct statvfs *statbuf) {
int fd;
int ret;
struct fuse_context *ctx;
struct sharefs_private *priv;
GET_CONTEXT_PRIV(ctx, priv);
MUST_TRANSLATE_PATHNAME(pathname);
if ((fd = openat(priv->dirfd, pathname, O_RDONLY | O_CLOEXEC)) == -1)
return -errno;
if ((ret = fstatvfs(fd, statbuf)) == -1)
ret = -errno;
close(fd);
return ret;
}
int sharefs_release(const char *pathname, struct fuse_file_info *fi) {
(void)pathname;
return close(fi->fh);
}
int sharefs_fsync(const char *pathname, int datasync, struct fuse_file_info *fi) {
(void)pathname;
if (datasync ? fdatasync(fi->fh) : fsync(fi->fh) == -1)
return -errno;
return 0;
}
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