This patch changes the unlink operation of the ram fs to defer the
destruction of a file until it is no longer referenced by any VFS handle.
When unlinked, the file no longer appears in the directory. But it can
still be opened and accessed.
With this change, a parent process of a Unix-like subsystem becomes able
to pass the content of an unlinked file to a forked child process. This
mechanism is required when using the 'exec' command in Tcl scripts.
Another use case is the 'tmpfile()' function.
Fixes#3577
The 'file_size' type denotes the size of files on disk in bytes. On
32-bit architectures it is larger than the size_t, which refers to
in-memory object sizes.
Whereas the use of 'file_size' is appropriate for ftruncate and seek, it
is not a suitable type for the parameters of read/write operations
because those operations refer to in-memory buffers.
This patch replaces the use of 'file_size' by size_t. However, since it
affects all sites where the read/write interface is uses, it takes the
opportunity to replace the C-style (pointer, size) arguments by
'Byte_range_ptr' and 'Const_byte_range_ptr'.
Issue #4706
The old 'Io_response_handler::io_progress_response' interface has been
replaced by the 'Vfs::Env::User::wakeup_vfs_user' (issue #4697). The
remaining 'read_ready_response' method is now hosted in the
appropriately named 'Read_ready_response_handler'.
Issue #4706
This commit supplements the various I/O signal handlers of the VFS
plugins with calls of the new 'Vfs::Env::User::wakeup_vfs_user'
interface, which will subsequently replace the old 'Io_progress_handler'
(issue #4697).
Issue #4706
By adding a 'write_ready' interface following the lines of the existing
'read_ready', VFS plugins become able to propagate the (de-)saturation
of I/O buffers to the VFS user. This information is important when using
a non-blocking file descriptor for writing into a TCP socket. Once the
application observes EAGAIN, it expects a subsequent 'select' call to
return as soon as new I/O buffer space becomes available.
Before this patch, the select call would always return under this
condition, causing an unnecessarily busy write loop.
Issue #4697
This patch removes the 'Insufficient_buffer' exception by returning the
WRITE_ERR_WOULD_BLOCK result value instead. It also eliminates the
superfluous WRITE_ERR_AGAIN and WRITE_ERR_INTERRUPT codes.
Issue #4697
...and tighten constness in adjacent code parts.
The VFS-internal synchronization via mutexes is no longer needed because
the access to the VFS is serialized by the VFS client, i.e., the libc.
Issue #4697
This patch facilitates the batching of I/O operations in the VFS library
by replacing the implicit wakeup of remote peer (via the traditional
packet-stream interface like 'submit_packet') by explicit wakeup
signalling.
The wakeup signalling is triggered not before the VFS user settles down.
E.g., for libc-based applications, this is the case if the libc goes
idle, waiting for external I/O.
In the case of a busy writer to a non-blocking file descriptor or socket
(e.g., lighttpd), the remote peers are woken up once a write operation
yields an out-count of 0.
The deferring of wakeup signals is accommodated by the new 'Remote_io'
mechanism (vfs/remote_io.h) that is designated to be used by all VFS
plugins that interact with asynchronous Genode services for I/O.
Issue #4697
This patch splits the querying of the number of directory entries from
the directory's 'status' information. Subsuming the number of directory
entries as part of the status makes 'stat' calls too costly for some
file systems that need to read a directory for determining the number of
entries. So when stat'ing the entries of one directory that contains sub
directories, all entries of each sub directory are visited.
Thanks to Cedric Degea for pointing out this performance bottleneck!
With this change, the 'status' function returns a 'Status::size' value
of 0 when called for a directory handle.
Fixes#4603
The calculations of packet_size and packet_count in the block_io() did
not consider rounding errors. This resulted in diverging values over
several bisecting operations (/= 2) and wrongly-size packet allocations
as well as memcpy operations.
Related to #2263 (comments about partial block accesses and
_block_io()).
Fixes#4471
XML allows attribute values like <node attr="\"/>. The XML parser
wrongly reflects this case as 'Invalid_syntax'. This behavior stems from
the implicit use of the 'end_of_quote' function, which considers the
sequence of '\"' as a quoted '"' rather than the end of a quoted string.
The patch solves this problem by making the 'end_of_quote' part of
the tokenizer's scanner policy.
The patch removes the 'end_of_quote' function from 'util/string.h'
because it is not universal, and to avoid the ambiguity with
'SCANNER_POLICY::end_of_quote'.
Fixes#4431
The Single_file_system now forwards the
`File_io_service::notify_read_ready` method to the
handle as it already did for most of the other methods.
genodelabs/genode#4394
Clang likes to complain when lambdas capture parameters without
actually using them. This patch fixes a couple of such problems in VFS
related os module code.
Issue #4421
The VFS block plugin used to depend on the blocking semantics of the
packet stream's 'get_acked_packet'. This patch replaces this dependency
by the use of 'wait_and_dispatch_one_io_signal'. However, in order to
implement this change, the custom instance of a 'Signal_receiver' had to
be removed as well.
To keep this patch as little invasive as possible, it does not touch the
direct use of the block session's packet stream, which should better be
replaced by the 'Block::Connection::Job' API.
Issue #4390
This comes up when building the code with clang 13. It happens due to
recently enabled Wconversion warning, which in case of clang also
enables implicit-int-conversion warning. The warning reads:
fs_file_system.h:937:44: error: higher order bits are zeroes after
implicit conversion [-Werror,-Wimplicit-int-conversion]
::File_system::Watch_handle fs_handle { -1U };
~~~~~~~~~ ^~~
This can be fixed by properly specifying fs_handle value to be of
unsigned long type.
Issue #4354
According to clang there are two symbols which File_system can refer to:
1. namespace File_system from ram_fs/chunk.h.
2. Vfs::File_system class from vfs/file_system.h.
Make it clear we refer to the File_system namespace in this case.
Issue #3984
Instead of using the old 'ioctl' Vfs::File_io_services API implement
the I/O control functionality in a buch of files. This is similar to
the terminal-VFS plugin.
Fixes#3889.
When the 'raw' attribute is set to 'yes' the terminal VFS plugin will
ignore control characters. This in necessary for terminal connections
that transport data that contain such characters as part of message.
Fixes#3860.
Setting the 'size' attribute will restrict a reader to consume
0s up to the specified amount per VFS handle. The attribute is
parsed as 'Number_of_bytes', which will limit the amount to the
maximum of the addressable memory on the platform.
This addition comes in handy when needing to provide a synthetic
empty file with a fixed size.
Issue #3781.
- Since Genode::strncpy is not 100% compatible with the POSIX
strncpy function, better use a distinct name.
- Remove bogus return value from the function, easing the potential
enforcement of mandatory return-value checks later.
Fixes#3752
The update modification timestamp is implemented as one-shot where
the caller is expected to try again if the first attempt failed (see
current libc implementation). So the message is misleading as further
attempts might succeed.
Issue #3713.
The tar vfs plugin returns an inode value of zero and a type directory
for null records, which wrongly triggers the file-system loop detection
of the find utility. This patch returns the node pointer as inode value
instead, which is a unique value.
Fixes#3695
