// write up to buflen bytes into buf, starting at the given offset in the file.
// return the number of bytes written on success.
// return negative on failure.
ssize_t fskit_write( struct fskit_core* core, struct fskit_file_handle* fh, char const* buf, size_t buflen, off_t offset ) {
fskit_file_handle_rlock( fh );
// sanity check
if( (fh->flags & (O_RDWR | O_WRONLY)) == 0 ) {
fskit_file_handle_unlock( fh );
return -EBADF;
}
ssize_t num_written = fskit_run_user_write( core, fh->path, fh->fent, buf, buflen, offset, fh->app_data );
if( num_written >= 0 ) {
// update metadata
fskit_entry_wlock( fh->fent );
fskit_entry_set_mtime( fh->fent, NULL );
fskit_entry_set_atime( fh->fent, NULL );
fh->fent->size = ((unsigned)(offset + buflen) > fh->fent->size ? offset + buflen : fh->fent->size);
fskit_entry_unlock( fh->fent );
}
fskit_file_handle_unlock( fh );
return num_written;
}
// i/o continuation, called with the same locks held as the trunc()
static int fskit_trunc_cont( struct fskit_core* core, struct fskit_entry* fent, off_t new_size, ssize_t trunc_rc ) {
if( trunc_rc == 0 ) {
// update metadata
fskit_entry_set_mtime( fent, NULL );
fskit_entry_set_atime( fent, NULL );
fent->size = new_size;
}
return 0;
}
// continuation for successful write
// fent must be write-locked
int fskit_write_cont( struct fskit_core* core, struct fskit_entry* fent, off_t offset, ssize_t num_written ) {
if( num_written >= 0 ) {
fskit_entry_set_mtime( fent, NULL );
fskit_entry_set_atime( fent, NULL );
off_t size_delta = 0;
if( offset + num_written > fent->size ) {
size_delta = (offset + num_written) - fent->size;
}
fent->size += size_delta;
}
return 0;
}
// create/open a file, with the given flags and (if creating) mode
// on success, return a file handle to the created/opened file.
// on failure, return NULL and set *err to the appropriate errno
struct fskit_file_handle* fskit_open_ex( struct fskit_core* core, char const* _path, uint64_t user, uint64_t group, int flags, mode_t mode, void* cls, int* err ) {
if( fskit_check_flags( flags ) != 0 ) {
*err = -EINVAL;
return NULL;
}
int rc = 0;
char* path = strdup(_path);
if( path == NULL ) {
*err = -ENOMEM;
return NULL;
}
fskit_sanitize_path( path );
size_t basename_len = fskit_basename_len( path );
if( basename_len > FSKIT_FILESYSTEM_NAMEMAX ) {
free( path );
*err = -ENAMETOOLONG;
return NULL;
}
void* handle_data = NULL;
// resolve the parent of this child (and write-lock it)
char* path_dirname = fskit_dirname( path, NULL );
char path_basename[FSKIT_FILESYSTEM_NAMEMAX + 1];
memset( path_basename, 0, FSKIT_FILESYSTEM_NAMEMAX + 1 );
fskit_basename( path, path_basename );
struct fskit_file_handle* ret = NULL;
// write-lock parent--we need to ensure that the child does not disappear on us between attaching it and routing the user-given callback
struct fskit_entry* parent = fskit_entry_resolve_path( core, path_dirname, user, group, true, err );
if( parent == NULL ) {
fskit_safe_free( path_dirname );
fskit_safe_free( path );
// err is set appropriately
return NULL;
}
fskit_safe_free( path_dirname );
rc = fskit_do_parent_check( parent, flags, user, group );
if( rc != 0 ) {
// can't perform this operation
fskit_entry_unlock( parent );
fskit_safe_free( path );
*err = rc;
return NULL;
}
// resolve the child (which may be in the process of being deleted)
struct fskit_entry* child = fskit_entry_set_find_name( parent->children, path_basename );
bool created = false;
if( flags & O_CREAT ) {
if( child != NULL ) {
fskit_entry_wlock( child );
// it might have been marked for garbage-collection
rc = fskit_entry_try_garbage_collect( core, path, parent, child );
if( rc >= 0 ) {
if( rc == 0 ) {
// not destroyed, but no longer attached
fskit_entry_unlock( child );
}
// safe to create
child = NULL;
}
else {
// can't garbage-collect--child still exists
fskit_entry_unlock( parent );
fskit_entry_unlock( child );
fskit_safe_free( path );
if( rc == -EEXIST ) {
*err = -EEXIST;
return NULL;
}
else {
// shouldn't happen
fskit_error("BUG: fskit_entry_try_garbage_collect(%s) rc = %d\n", path, rc );
*err = -EIO;
}
return NULL;
}
}
if( child == NULL ) {
// can create!
// NOTE: do *not* lock child--it has to be unlocked for running user-given routes
rc = fskit_do_create( core, parent, path, mode, user, group, cls, &child, &handle_data );
if( rc != 0 ) {
fskit_entry_unlock( parent );
fskit_safe_free( path );
*err = rc;
return NULL;
}
// created!
created = true;
}
}
else if( child == NULL ) {
// not found
fskit_entry_unlock( parent );
fskit_safe_free( path );
*err = -ENOENT;
return NULL;
}
// now child exists.
// don't lock it, though, since we have to pass it to truncate or open
// do we have to truncate?
if( (flags & O_TRUNC) && (flags & (O_RDWR | O_WRONLY)) ) {
// run user truncate
// NOTE: do *not* lock it--it has to be unlocked for running user-given routes
rc = fskit_run_user_trunc( core, path, child, 0, NULL );
if( rc != 0 ) {
// truncate failed
fskit_entry_unlock( parent );
fskit_safe_free( path );
*err = rc;
return NULL;
}
}
if( !created ) {
// do the open
// NOTE: do *not* lock it--it has to be unlocked for running user-given routes
rc = fskit_do_open( core, path, parent, child, flags, user, group, &handle_data );
if( rc != 0 ) {
// open failed
fskit_entry_unlock( parent );
fskit_safe_free( path );
*err = rc;
return NULL;
}
}
// done with parent
fskit_entry_unlock( parent );
// still here--we can open the file now!
fskit_entry_set_atime( child, NULL );
ret = fskit_file_handle_create( core, child, path, flags, handle_data );
fskit_safe_free( path );
if( ret == NULL ) {
// only possible if we're out of memory!
*err = -ENOMEM;
}
return ret;
}