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March 1, 2012 15:51
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/* | |
Big Brother File System | |
The point of this FUSE filesystem is to provide an introduction to | |
FUSE. It was my first FUSE filesystem as I got to know the | |
software; hopefully, the comments in this code will help people who | |
follow later to get a gentler introduction. | |
This might be called a no-op filesystem: it doesn't impose | |
filesystem semantics on top of any other existing structure. It | |
simply reports the requests that come in, and passes them to an | |
underlying filesystem. The information is saved in a logfile named | |
bbfs.log, in the directory from which you run bbfs. | |
gcc -Wall `pkg-config fuse --cflags --libs` -o bbfs bbfs.c | |
*/ | |
#include "params.h" | |
#include <ctype.h> | |
#include <dirent.h> | |
#include <errno.h> | |
#include <fcntl.h> | |
#include <fuse.h> | |
#include <libgen.h> | |
#include <limits.h> | |
#include <stdlib.h> | |
#include <stdio.h> | |
#include <string.h> | |
#include <unistd.h> | |
#include <sys/types.h> | |
#include <sys/xattr.h> | |
#include "log.h" | |
// Report errors to logfile and give -errno to caller | |
static int bb_error(char *str) | |
{ | |
int ret = -errno; | |
log_msg(" ERROR %s: %s\n", str, strerror(errno)); | |
return ret; | |
} | |
// Check whether the given user is permitted to perform the given operation on the given | |
// All the paths I see are relative to the root of the mounted | |
// filesystem. In order to get to the underlying filesystem, I need to | |
// have the mountpoint. I'll save it away early on in main(), and then | |
// whenever I need a path for something I'll call this to construct | |
// it. | |
static void bb_fullpath(char fpath[PATH_MAX], const char *path) | |
{ | |
strcpy(fpath, BB_DATA->rootdir); | |
strncat(fpath, path, PATH_MAX); // ridiculously long paths will | |
// break here | |
log_msg(" bb_fullpath: rootdir = \"%s\", path = \"%s\", fpath = \"%s\"\n", | |
BB_DATA->rootdir, path, fpath); | |
} | |
/////////////////////////////////////////////////////////// | |
// | |
// Prototypes for all these functions, and the C-style comments, | |
// come indirectly from /usr/include/fuse.h | |
// | |
/** Get file attributes. | |
* | |
* Similar to stat(). The 'st_dev' and 'st_blksize' fields are | |
* ignored. The 'st_ino' field is ignored except if the 'use_ino' | |
* mount option is given. | |
*/ | |
int bb_getattr(const char *path, struct stat *statbuf) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_getattr(path=\"%s\", statbuf=0x%08x)\n", | |
path, statbuf); | |
bb_fullpath(fpath, path); | |
retstat = lstat(fpath, statbuf); | |
if (retstat != 0) | |
retstat = bb_error("bb_getattr lstat"); | |
log_stat(statbuf); | |
return retstat; | |
} | |
/** Read the target of a symbolic link | |
* | |
* The buffer should be filled with a null terminated string. The | |
* buffer size argument includes the space for the terminating | |
* null character. If the linkname is too long to fit in the | |
* buffer, it should be truncated. The return value should be 0 | |
* for success. | |
*/ | |
// Note the system readlink() will truncate and lose the terminating | |
// null. So, the size passed to to the system readlink() must be one | |
// less than the size passed to bb_readlink() | |
// bb_readlink() code by Bernardo F Costa (thanks!) | |
int bb_readlink(const char *path, char *link, size_t size) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("bb_readlink(path=\"%s\", link=\"%s\", size=%d)\n", | |
path, link, size); | |
bb_fullpath(fpath, path); | |
retstat = readlink(fpath, link, size - 1); | |
if (retstat < 0) | |
retstat = bb_error("bb_readlink readlink"); | |
else { | |
link[retstat] = '\0'; | |
retstat = 0; | |
} | |
return retstat; | |
} | |
/** Create a file node | |
* | |
* There is no create() operation, mknod() will be called for | |
* creation of all non-directory, non-symlink nodes. | |
*/ | |
// shouldn't that comment be "if" there is no.... ? | |
int bb_mknod(const char *path, mode_t mode, dev_t dev) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_mknod(path=\"%s\", mode=0%3o, dev=%lld)\n", | |
path, mode, dev); | |
bb_fullpath(fpath, path); | |
// On Linux this could just be 'mknod(path, mode, rdev)' but this | |
// is more portable | |
if (S_ISREG(mode)) { | |
retstat = open(fpath, O_CREAT | O_EXCL | O_WRONLY, mode); | |
if (retstat < 0) | |
retstat = bb_error("bb_mknod open"); | |
else { | |
retstat = close(retstat); | |
if (retstat < 0) | |
retstat = bb_error("bb_mknod close"); | |
} | |
} else | |
if (S_ISFIFO(mode)) { | |
retstat = mkfifo(fpath, mode); | |
if (retstat < 0) | |
retstat = bb_error("bb_mknod mkfifo"); | |
} else { | |
retstat = mknod(fpath, mode, dev); | |
if (retstat < 0) | |
retstat = bb_error("bb_mknod mknod"); | |
} | |
return retstat; | |
} | |
/** Create a directory */ | |
int bb_mkdir(const char *path, mode_t mode) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_mkdir(path=\"%s\", mode=0%3o)\n", | |
path, mode); | |
bb_fullpath(fpath, path); | |
retstat = mkdir(fpath, mode); | |
if (retstat < 0) | |
retstat = bb_error("bb_mkdir mkdir"); | |
return retstat; | |
} | |
/** Remove a file */ | |
int bb_unlink(const char *path) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("bb_unlink(path=\"%s\")\n", | |
path); | |
bb_fullpath(fpath, path); | |
retstat = unlink(fpath); | |
if (retstat < 0) | |
retstat = bb_error("bb_unlink unlink"); | |
return retstat; | |
} | |
/** Remove a directory */ | |
int bb_rmdir(const char *path) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("bb_rmdir(path=\"%s\")\n", | |
path); | |
bb_fullpath(fpath, path); | |
retstat = rmdir(fpath); | |
if (retstat < 0) | |
retstat = bb_error("bb_rmdir rmdir"); | |
return retstat; | |
} | |
/** Create a symbolic link */ | |
// The parameters here are a little bit confusing, but do correspond | |
// to the symlink() system call. The 'path' is where the link points, | |
// while the 'link' is the link itself. So we need to leave the path | |
// unaltered, but insert the link into the mounted directory. | |
int bb_symlink(const char *path, const char *link) | |
{ | |
int retstat = 0; | |
char flink[PATH_MAX]; | |
log_msg("\nbb_symlink(path=\"%s\", link=\"%s\")\n", | |
path, link); | |
bb_fullpath(flink, link); | |
retstat = symlink(path, flink); | |
if (retstat < 0) | |
retstat = bb_error("bb_symlink symlink"); | |
return retstat; | |
} | |
/** Rename a file */ | |
// both path and newpath are fs-relative | |
int bb_rename(const char *path, const char *newpath) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
char fnewpath[PATH_MAX]; | |
log_msg("\nbb_rename(fpath=\"%s\", newpath=\"%s\")\n", | |
path, newpath); | |
bb_fullpath(fpath, path); | |
bb_fullpath(fnewpath, newpath); | |
retstat = rename(fpath, fnewpath); | |
if (retstat < 0) | |
retstat = bb_error("bb_rename rename"); | |
return retstat; | |
} | |
/** Create a hard link to a file */ | |
int bb_link(const char *path, const char *newpath) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX], fnewpath[PATH_MAX]; | |
log_msg("\nbb_link(path=\"%s\", newpath=\"%s\")\n", | |
path, newpath); | |
bb_fullpath(fpath, path); | |
bb_fullpath(fnewpath, newpath); | |
retstat = link(fpath, fnewpath); | |
if (retstat < 0) | |
retstat = bb_error("bb_link link"); | |
return retstat; | |
} | |
/** Change the permission bits of a file */ | |
int bb_chmod(const char *path, mode_t mode) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_chmod(fpath=\"%s\", mode=0%03o)\n", | |
path, mode); | |
bb_fullpath(fpath, path); | |
retstat = chmod(fpath, mode); | |
if (retstat < 0) | |
retstat = bb_error("bb_chmod chmod"); | |
return retstat; | |
} | |
/** Change the owner and group of a file */ | |
int bb_chown(const char *path, uid_t uid, gid_t gid) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_chown(path=\"%s\", uid=%d, gid=%d)\n", | |
path, uid, gid); | |
bb_fullpath(fpath, path); | |
retstat = chown(fpath, uid, gid); | |
if (retstat < 0) | |
retstat = bb_error("bb_chown chown"); | |
return retstat; | |
} | |
/** Change the size of a file */ | |
int bb_truncate(const char *path, off_t newsize) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_truncate(path=\"%s\", newsize=%lld)\n", | |
path, newsize); | |
bb_fullpath(fpath, path); | |
retstat = truncate(fpath, newsize); | |
if (retstat < 0) | |
bb_error("bb_truncate truncate"); | |
return retstat; | |
} | |
/** Change the access and/or modification times of a file */ | |
/* note -- I'll want to change this as soon as 2.6 is in debian testing */ | |
int bb_utime(const char *path, struct utimbuf *ubuf) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_utime(path=\"%s\", ubuf=0x%08x)\n", | |
path, ubuf); | |
bb_fullpath(fpath, path); | |
retstat = utime(fpath, ubuf); | |
if (retstat < 0) | |
retstat = bb_error("bb_utime utime"); | |
return retstat; | |
} | |
/** File open operation | |
* | |
* No creation, or truncation flags (O_CREAT, O_EXCL, O_TRUNC) | |
* will be passed to open(). Open should check if the operation | |
* is permitted for the given flags. Optionally open may also | |
* return an arbitrary filehandle in the fuse_file_info structure, | |
* which will be passed to all file operations. | |
* | |
* Changed in version 2.2 | |
*/ | |
int bb_open(const char *path, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
int fd; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_open(path\"%s\", fi=0x%08x)\n", | |
path, fi); | |
bb_fullpath(fpath, path); | |
fd = open(fpath, fi->flags); | |
if (fd < 0) | |
retstat = bb_error("bb_open open"); | |
fi->fh = fd; | |
log_fi(fi); | |
return retstat; | |
} | |
/** Read data from an open file | |
* | |
* Read should return exactly the number of bytes requested except | |
* on EOF or error, otherwise the rest of the data will be | |
* substituted with zeroes. An exception to this is when the | |
* 'direct_io' mount option is specified, in which case the return | |
* value of the read system call will reflect the return value of | |
* this operation. | |
* | |
* Changed in version 2.2 | |
*/ | |
// I don't fully understand the documentation above -- it doesn't | |
// match the documentation for the read() system call which says it | |
// can return with anything up to the amount of data requested. nor | |
// with the fusexmp code which returns the amount of data also | |
// returned by read. | |
int bb_read(const char *path, char *buf, size_t size, off_t offset, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_read(path=\"%s\", buf=0x%08x, size=%d, offset=%lld, fi=0x%08x)\n", | |
path, buf, size, offset, fi); | |
// no need to get fpath on this one, since I work from fi->fh not the path | |
log_fi(fi); | |
retstat = pread(fi->fh, buf, size, offset); | |
if (retstat < 0) | |
retstat = bb_error("bb_read read"); | |
return retstat; | |
} | |
/** Write data to an open file | |
* | |
* Write should return exactly the number of bytes requested | |
* except on error. An exception to this is when the 'direct_io' | |
* mount option is specified (see read operation). | |
* | |
* Changed in version 2.2 | |
*/ | |
// As with read(), the documentation above is inconsistent with the | |
// documentation for the write() system call. | |
int bb_write(const char *path, const char *buf, size_t size, off_t offset, | |
struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_write(path=\"%s\", buf=0x%08x, size=%d, offset=%lld, fi=0x%08x)\n", | |
path, buf, size, offset, fi | |
); | |
// no need to get fpath on this one, since I work from fi->fh not the path | |
log_fi(fi); | |
retstat = pwrite(fi->fh, buf, size, offset); | |
if (retstat < 0) | |
retstat = bb_error("bb_write pwrite"); | |
return retstat; | |
} | |
/** Get file system statistics | |
* | |
* The 'f_frsize', 'f_favail', 'f_fsid' and 'f_flag' fields are ignored | |
* | |
* Replaced 'struct statfs' parameter with 'struct statvfs' in | |
* version 2.5 | |
*/ | |
int bb_statfs(const char *path, struct statvfs *statv) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_statfs(path=\"%s\", statv=0x%08x)\n", | |
path, statv); | |
bb_fullpath(fpath, path); | |
// get stats for underlying filesystem | |
retstat = statvfs(fpath, statv); | |
if (retstat < 0) | |
retstat = bb_error("bb_statfs statvfs"); | |
log_statvfs(statv); | |
return retstat; | |
} | |
/** Possibly flush cached data | |
* | |
* BIG NOTE: This is not equivalent to fsync(). It's not a | |
* request to sync dirty data. | |
* | |
* Flush is called on each close() of a file descriptor. So if a | |
* filesystem wants to return write errors in close() and the file | |
* has cached dirty data, this is a good place to write back data | |
* and return any errors. Since many applications ignore close() | |
* errors this is not always useful. | |
* | |
* NOTE: The flush() method may be called more than once for each | |
* open(). This happens if more than one file descriptor refers | |
* to an opened file due to dup(), dup2() or fork() calls. It is | |
* not possible to determine if a flush is final, so each flush | |
* should be treated equally. Multiple write-flush sequences are | |
* relatively rare, so this shouldn't be a problem. | |
* | |
* Filesystems shouldn't assume that flush will always be called | |
* after some writes, or that if will be called at all. | |
* | |
* Changed in version 2.2 | |
*/ | |
int bb_flush(const char *path, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_flush(path=\"%s\", fi=0x%08x)\n", path, fi); | |
// no need to get fpath on this one, since I work from fi->fh not the path | |
log_fi(fi); | |
return retstat; | |
} | |
/** Release an open file | |
* | |
* Release is called when there are no more references to an open | |
* file: all file descriptors are closed and all memory mappings | |
* are unmapped. | |
* | |
* For every open() call there will be exactly one release() call | |
* with the same flags and file descriptor. It is possible to | |
* have a file opened more than once, in which case only the last | |
* release will mean, that no more reads/writes will happen on the | |
* file. The return value of release is ignored. | |
* | |
* Changed in version 2.2 | |
*/ | |
int bb_release(const char *path, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_release(path=\"%s\", fi=0x%08x)\n", | |
path, fi); | |
log_fi(fi); | |
// We need to close the file. Had we allocated any resources | |
// (buffers etc) we'd need to free them here as well. | |
retstat = close(fi->fh); | |
return retstat; | |
} | |
/** Synchronize file contents | |
* | |
* If the datasync parameter is non-zero, then only the user data | |
* should be flushed, not the meta data. | |
* | |
* Changed in version 2.2 | |
*/ | |
int bb_fsync(const char *path, int datasync, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_fsync(path=\"%s\", datasync=%d, fi=0x%08x)\n", | |
path, datasync, fi); | |
log_fi(fi); | |
if (datasync) | |
retstat = fdatasync(fi->fh); | |
else | |
retstat = fsync(fi->fh); | |
if (retstat < 0) | |
bb_error("bb_fsync fsync"); | |
return retstat; | |
} | |
/** Set extended attributes */ | |
int bb_setxattr(const char *path, const char *name, const char *value, size_t size, int flags) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_setxattr(path=\"%s\", name=\"%s\", value=\"%s\", size=%d, flags=0x%08x)\n", | |
path, name, value, size, flags); | |
bb_fullpath(fpath, path); | |
retstat = lsetxattr(fpath, name, value, size, flags); | |
if (retstat < 0) | |
retstat = bb_error("bb_setxattr lsetxattr"); | |
return retstat; | |
} | |
/** Get extended attributes */ | |
int bb_getxattr(const char *path, const char *name, char *value, size_t size) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_getxattr(path = \"%s\", name = \"%s\", value = 0x%08x, size = %d)\n", | |
path, name, value, size); | |
bb_fullpath(fpath, path); | |
retstat = lgetxattr(fpath, name, value, size); | |
if (retstat < 0) | |
retstat = bb_error("bb_getxattr lgetxattr"); | |
else | |
log_msg(" value = \"%s\"\n", value); | |
return retstat; | |
} | |
/** List extended attributes */ | |
int bb_listxattr(const char *path, char *list, size_t size) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
char *ptr; | |
log_msg("bb_listxattr(path=\"%s\", list=0x%08x, size=%d)\n", | |
path, list, size | |
); | |
bb_fullpath(fpath, path); | |
retstat = llistxattr(fpath, list, size); | |
if (retstat < 0) | |
retstat = bb_error("bb_listxattr llistxattr"); | |
log_msg(" returned attributes (length %d):\n", retstat); | |
for (ptr = list; ptr < list + retstat; ptr += strlen(ptr)+1) | |
log_msg(" \"%s\"\n", ptr); | |
return retstat; | |
} | |
/** Remove extended attributes */ | |
int bb_removexattr(const char *path, const char *name) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_removexattr(path=\"%s\", name=\"%s\")\n", | |
path, name); | |
bb_fullpath(fpath, path); | |
retstat = lremovexattr(fpath, name); | |
if (retstat < 0) | |
retstat = bb_error("bb_removexattr lrmovexattr"); | |
return retstat; | |
} | |
/** Open directory | |
* | |
* This method should check if the open operation is permitted for | |
* this directory | |
* | |
* Introduced in version 2.3 | |
*/ | |
int bb_opendir(const char *path, struct fuse_file_info *fi) | |
{ | |
DIR *dp; | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_opendir(path=\"%s\", fi=0x%08x)\n", | |
path, fi); | |
bb_fullpath(fpath, path); | |
dp = opendir(fpath); | |
if (dp == NULL) | |
retstat = bb_error("bb_opendir opendir"); | |
fi->fh = (intptr_t) dp; | |
log_fi(fi); | |
return retstat; | |
} | |
/** Read directory | |
* | |
* This supersedes the old getdir() interface. New applications | |
* should use this. | |
* | |
* The filesystem may choose between two modes of operation: | |
* | |
* 1) The readdir implementation ignores the offset parameter, and | |
* passes zero to the filler function's offset. The filler | |
* function will not return '1' (unless an error happens), so the | |
* whole directory is read in a single readdir operation. This | |
* works just like the old getdir() method. | |
* | |
* 2) The readdir implementation keeps track of the offsets of the | |
* directory entries. It uses the offset parameter and always | |
* passes non-zero offset to the filler function. When the buffer | |
* is full (or an error happens) the filler function will return | |
* '1'. | |
* | |
* Introduced in version 2.3 | |
*/ | |
int bb_readdir(const char *path, void *buf, fuse_fill_dir_t filler, off_t offset, | |
struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
DIR *dp; | |
struct dirent *de; | |
log_msg("\nbb_readdir(path=\"%s\", buf=0x%08x, filler=0x%08x, offset=%lld, fi=0x%08x)\n", | |
path, buf, filler, offset, fi); | |
// once again, no need for fullpath -- but note that I need to cast fi->fh | |
dp = (DIR *) (uintptr_t) fi->fh; | |
// Every directory contains at least two entries: . and .. If my | |
// first call to the system readdir() returns NULL I've got an | |
// error; near as I can tell, that's the only condition under | |
// which I can get an error from readdir() | |
de = readdir(dp); | |
if (de == 0) { | |
retstat = bb_error("bb_readdir readdir"); | |
return retstat; | |
} | |
// This will copy the entire directory into the buffer. The loop exits | |
// when either the system readdir() returns NULL, or filler() | |
// returns something non-zero. The first case just means I've | |
// read the whole directory; the second means the buffer is full. | |
do { | |
log_msg("calling filler with name %s\n", de->d_name); | |
if (filler(buf, de->d_name, NULL, 0) != 0) { | |
log_msg(" ERROR bb_readdir filler: buffer full"); | |
return -ENOMEM; | |
} | |
} while ((de = readdir(dp)) != NULL); | |
log_fi(fi); | |
return retstat; | |
} | |
/** Release directory | |
* | |
* Introduced in version 2.3 | |
*/ | |
int bb_releasedir(const char *path, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_releasedir(path=\"%s\", fi=0x%08x)\n", | |
path, fi); | |
log_fi(fi); | |
closedir((DIR *) (uintptr_t) fi->fh); | |
return retstat; | |
} | |
/** Synchronize directory contents | |
* | |
* If the datasync parameter is non-zero, then only the user data | |
* should be flushed, not the meta data | |
* | |
* Introduced in version 2.3 | |
*/ | |
// when exactly is this called? when a user calls fsync and it | |
// happens to be a directory? ??? | |
int bb_fsyncdir(const char *path, int datasync, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_fsyncdir(path=\"%s\", datasync=%d, fi=0x%08x)\n", | |
path, datasync, fi); | |
log_fi(fi); | |
return retstat; | |
} | |
/** | |
* Initialize filesystem | |
* | |
* The return value will passed in the private_data field of | |
* fuse_context to all file operations and as a parameter to the | |
* destroy() method. | |
* | |
* Introduced in version 2.3 | |
* Changed in version 2.6 | |
*/ | |
// Undocumented but extraordinarily useful fact: the fuse_context is | |
// set up before this function is called, and | |
// fuse_get_context()->private_data returns the user_data passed to | |
// fuse_main(). Really seems like either it should be a third | |
// parameter coming in here, or else the fact should be documented | |
// (and this might as well return void, as it did in older versions of | |
// FUSE). | |
void *bb_init(struct fuse_conn_info *conn) | |
{ | |
log_msg("\nbb_init()\n"); | |
return BB_DATA; | |
} | |
/** | |
* Clean up filesystem | |
* | |
* Called on filesystem exit. | |
* | |
* Introduced in version 2.3 | |
*/ | |
void bb_destroy(void *userdata) | |
{ | |
log_msg("\nbb_destroy(userdata=0x%08x)\n", userdata); | |
} | |
/** | |
* Check file access permissions | |
* | |
* This will be called for the access() system call. If the | |
* 'default_permissions' mount option is given, this method is not | |
* called. | |
* | |
* This method is not called under Linux kernel versions 2.4.x | |
* | |
* Introduced in version 2.5 | |
*/ | |
int bb_access(const char *path, int mask) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
log_msg("\nbb_access(path=\"%s\", mask=0%o)\n", | |
path, mask); | |
bb_fullpath(fpath, path); | |
retstat = access(fpath, mask); | |
if (retstat < 0) | |
retstat = bb_error("bb_access access"); | |
return retstat; | |
} | |
/** | |
* Create and open a file | |
* | |
* If the file does not exist, first create it with the specified | |
* mode, and then open it. | |
* | |
* If this method is not implemented or under Linux kernel | |
* versions earlier than 2.6.15, the mknod() and open() methods | |
* will be called instead. | |
* | |
* Introduced in version 2.5 | |
*/ | |
int bb_create(const char *path, mode_t mode, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
char fpath[PATH_MAX]; | |
int fd; | |
log_msg("\nbb_create(path=\"%s\", mode=0%03o, fi=0x%08x)\n", | |
path, mode, fi); | |
bb_fullpath(fpath, path); | |
fd = creat(fpath, mode); | |
if (fd < 0) | |
retstat = bb_error("bb_create creat"); | |
fi->fh = fd; | |
log_fi(fi); | |
return retstat; | |
} | |
/** | |
* Change the size of an open file | |
* | |
* This method is called instead of the truncate() method if the | |
* truncation was invoked from an ftruncate() system call. | |
* | |
* If this method is not implemented or under Linux kernel | |
* versions earlier than 2.6.15, the truncate() method will be | |
* called instead. | |
* | |
* Introduced in version 2.5 | |
*/ | |
int bb_ftruncate(const char *path, off_t offset, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_ftruncate(path=\"%s\", offset=%lld, fi=0x%08x)\n", | |
path, offset, fi); | |
log_fi(fi); | |
retstat = ftruncate(fi->fh, offset); | |
if (retstat < 0) | |
retstat = bb_error("bb_ftruncate ftruncate"); | |
return retstat; | |
} | |
/** | |
* Get attributes from an open file | |
* | |
* This method is called instead of the getattr() method if the | |
* file information is available. | |
* | |
* Currently this is only called after the create() method if that | |
* is implemented (see above). Later it may be called for | |
* invocations of fstat() too. | |
* | |
* Introduced in version 2.5 | |
*/ | |
// Since it's currently only called after bb_create(), and bb_create() | |
// opens the file, I ought to be able to just use the fd and ignore | |
// the path... | |
int bb_fgetattr(const char *path, struct stat *statbuf, struct fuse_file_info *fi) | |
{ | |
int retstat = 0; | |
log_msg("\nbb_fgetattr(path=\"%s\", statbuf=0x%08x, fi=0x%08x)\n", | |
path, statbuf, fi); | |
log_fi(fi); | |
retstat = fstat(fi->fh, statbuf); | |
if (retstat < 0) | |
retstat = bb_error("bb_fgetattr fstat"); | |
log_stat(statbuf); | |
return retstat; | |
} | |
struct fuse_operations bb_oper = { | |
.getattr = bb_getattr, | |
.readlink = bb_readlink, | |
// no .getdir -- that's deprecated | |
.getdir = NULL, | |
.mknod = bb_mknod, | |
.mkdir = bb_mkdir, | |
.unlink = bb_unlink, | |
.rmdir = bb_rmdir, | |
.symlink = bb_symlink, | |
.rename = bb_rename, | |
.link = bb_link, | |
.chmod = bb_chmod, | |
.chown = bb_chown, | |
.truncate = bb_truncate, | |
.utime = bb_utime, | |
.open = bb_open, | |
.read = bb_read, | |
.write = bb_write, | |
/** Just a placeholder, don't set */ // huh??? | |
.statfs = bb_statfs, | |
.flush = bb_flush, | |
.release = bb_release, | |
.fsync = bb_fsync, | |
.setxattr = bb_setxattr, | |
.getxattr = bb_getxattr, | |
.listxattr = bb_listxattr, | |
.removexattr = bb_removexattr, | |
.opendir = bb_opendir, | |
.readdir = bb_readdir, | |
.releasedir = bb_releasedir, | |
.fsyncdir = bb_fsyncdir, | |
.init = bb_init, | |
.destroy = bb_destroy, | |
.access = bb_access, | |
.create = bb_create, | |
.ftruncate = bb_ftruncate, | |
.fgetattr = bb_fgetattr | |
}; | |
void bb_usage() | |
{ | |
fprintf(stderr, "usage: bbfs rootDir mountPoint\n"); | |
abort(); | |
} | |
int main(int argc, char *argv[]) | |
{ | |
int i; | |
int fuse_stat; | |
struct bb_state *bb_data; | |
// bbfs doesn't do any access checking on its own (the comment | |
// blocks in fuse.h mention some of the functions that need | |
// accesses checked -- but note there are other functions, like | |
// chown(), that also need checking!). Since running bbfs as root | |
// will therefore open Metrodome-sized holes in the system | |
// security, we'll check if root is trying to mount the filesystem | |
// and refuse if it is. The somewhat smaller hole of an ordinary | |
// user doing it with the allow_other flag is still there because | |
// I don't want to parse the options string. | |
if ((getuid() == 0) || (geteuid() == 0)) { | |
fprintf(stderr, "Running BBFS as root opens unnacceptable security holes\n"); | |
return 1; | |
} | |
bb_data = calloc(sizeof(struct bb_state), 1); | |
if (bb_data == NULL) { | |
perror("main calloc"); | |
abort(); | |
} | |
bb_data->logfile = log_open(); | |
// libfuse is able to do most of the command line parsing; all I | |
// need to do is to extract the rootdir; this will be the first | |
// non-option passed in. I'm using the GNU non-standard extension | |
// and having realpath malloc the space for the path | |
// the string. | |
for (i = 1; (i < argc) && (argv[i][0] == '-'); i++) | |
if (argv[i][1] == 'o') i++; // -o takes a parameter; need to | |
// skip it too. This doesn't | |
// handle "squashed" parameters | |
if ((argc - i) != 2) bb_usage(); | |
bb_data->rootdir = realpath(argv[i], NULL); | |
argv[i] = argv[i+1]; | |
argc--; | |
fprintf(stderr, "about to call fuse_main\n"); | |
fuse_stat = fuse_main(argc, argv, &bb_oper, bb_data); | |
fprintf(stderr, "fuse_main returned %d\n", fuse_stat); | |
return fuse_stat; | |
} |
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