beenull/ladybird
1
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2024-11-22 23:50:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6
ladybird/Kernel/Syscalls/write.cpp

121 lines
3.5 KiB
C++
Raw Normal View History

Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
Everything: Move to SPDX license identifiers in all files. SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
2021-04-22 08:24:48 +00:00
* SPDX-License-Identifier: BSD-2-Clause
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
*/
#include <AK/NumericLimits.h>
Meta: Split debug defines into multiple headers. The following script was used to make these changes: #!/bin/bash set -e tmp=$(mktemp -d) echo "tmp=$tmp" find Kernel \( -name '*.cpp' -o -name '*.h' \) | sort > $tmp/Kernel.files find . \( -path ./Toolchain -prune -o -path ./Build -prune -o -path ./Kernel -prune \) -o \( -name '*.cpp' -o -name '*.h' \) -print | sort > $tmp/EverythingExceptKernel.files cat $tmp/Kernel.files | xargs grep -Eho '[A-Z0-9_]+_DEBUG' | sort | uniq > $tmp/Kernel.macros cat $tmp/EverythingExceptKernel.files | xargs grep -Eho '[A-Z0-9_]+_DEBUG' | sort | uniq > $tmp/EverythingExceptKernel.macros comm -23 $tmp/Kernel.macros $tmp/EverythingExceptKernel.macros > $tmp/Kernel.unique comm -1 $tmp/Kernel.macros $tmp/EverythingExceptKernel.macros > $tmp/EverythingExceptKernel.unique cat $tmp/Kernel.unique | awk '{ print "#cmakedefine01 "$1 }' > $tmp/Kernel.header cat $tmp/EverythingExceptKernel.unique | awk '{ print "#cmakedefine01 "$1 }' > $tmp/EverythingExceptKernel.header for macro in $(cat $tmp/Kernel.unique) do cat $tmp/Kernel.files | xargs grep -l $macro >> $tmp/Kernel.new-includes ||: done cat $tmp/Kernel.new-includes | sort > $tmp/Kernel.new-includes.sorted for macro in $(cat $tmp/EverythingExceptKernel.unique) do cat $tmp/Kernel.files | xargs grep -l $macro >> $tmp/Kernel.old-includes ||: done cat $tmp/Kernel.old-includes | sort > $tmp/Kernel.old-includes.sorted comm -23 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.new comm -13 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.old comm -12 $tmp/Kernel.new-includes.sorted $tmp/Kernel.old-includes.sorted > $tmp/Kernel.includes.mixed for file in $(cat $tmp/Kernel.includes.new) do sed -i -E 's/#include <AK\/Debug\.h>/#include <Kernel\/Debug\.h>/' $file done for file in $(cat $tmp/Kernel.includes.mixed) do echo "mixed include in $file, requires manual editing." done
2021-01-25 15:07:10 +00:00
#include <Kernel/Debug.h>
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
namespace Kernel {
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
KResultOr<ssize_t> Process::sys$writev(int fd, Userspace<const struct iovec*> iov, int iov_count)
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
{
REQUIRE_PROMISE(stdio);
if (iov_count < 0)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EINVAL;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
Kernel: Refuse excessively long iovec list If a program attempts to write from more than a million different locations, there is likely shenaniganery afoot! Refuse to write to prevent kmem exhaustion. Found by fuzz-syscalls. Can be reproduced by running this in the Shell: $ syscall writev 1 [ 0 ] 0x08000000
2021-02-11 19:38:39 +00:00
// Arbitrary pain threshold.
if (iov_count > (int)MiB)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EFAULT;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
u64 total_length = 0;
Vector<iovec, 32> vecs;
Kernel: Harden sys$readv / sys$writev Vector usage against OOM.
2021-04-29 08:20:24 +00:00
if (!vecs.try_resize(iov_count))
return ENOMEM;
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
if (!copy_n_from_user(vecs.data(), iov, iov_count))
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EFAULT;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
for (auto& vec : vecs) {
total_length += vec.iov_len;
if (total_length > NumericLimits<i32>::max())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EINVAL;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
auto description = file_description(fd);
if (!description)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EBADF;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
if (!description->is_writable())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EBADF;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
int nwritten = 0;
for (auto& vec : vecs) {
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
auto buffer = UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len);
if (!buffer.has_value())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EFAULT;
auto result = do_write(*description, buffer.value(), vec.iov_len);
if (result.is_error()) {
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
if (nwritten == 0)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return result.error();
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
return nwritten;
}
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
nwritten += result.value();
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
return nwritten;
}
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
KResultOr<ssize_t> Process::do_write(FileDescription& description, const UserOrKernelBuffer& data, size_t data_size)
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
{
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
ssize_t total_nwritten = 0;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
Kernel: Support write() after setting O_APPEND on a non-seekable file Previously, Process::do_write would error if the O_APPEND flag was set on a non-seekable file. Other systems (such as Linux) seem to be OK with doing this, so we now do not attempt to seek to the end the file if it's not seekable.
2021-03-29 12:27:38 +00:00
if (description.should_append() && description.file().is_seekable()) {
Kernel: Make FileDescription::seek() return KResultOr<off_t> This exposed a bunch of places where errors were not propagated, so this patch is forced to deal with them as well.
2021-03-19 09:43:58 +00:00
auto seek_result = description.seek(0, SEEK_END);
if (seek_result.is_error())
return seek_result.error();
}
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
while ((size_t)total_nwritten < data_size) {
Kernel: Fix subtle race condition in sys$write implementation There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
2021-05-18 11:49:34 +00:00
while (!description.can_write()) {
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
if (!description.is_blocking()) {
Kernel: Fix subtle race condition in sys$write implementation There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
2021-05-18 11:49:34 +00:00
if (total_nwritten > 0)
return total_nwritten;
else
return EAGAIN;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Move block condition evaluation out of the Scheduler This makes the Scheduler a lot leaner by not having to evaluate block conditions every time it is invoked. Instead evaluate them as the states change, and unblock threads at that point. This also implements some more waitid/waitpid/wait features and behavior. For example, WUNTRACED and WNOWAIT are now supported. And wait will now not return EINTR when SIGCHLD is delivered at the same time.
2020-11-29 23:05:27 +00:00
auto unblock_flags = Thread::FileBlocker::BlockFlags::None;
AK: Simplify constructors and conversions from nullptr_t Problem: - Many constructors are defined as `{}` rather than using the ` = default` compiler-provided constructor. - Some types provide an implicit conversion operator from `nullptr_t` instead of requiring the caller to default construct. This violates the C++ Core Guidelines suggestion to declare single-argument constructors explicit (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit). Solution: - Change default constructors to use the compiler-provided default constructor. - Remove implicit conversion operators from `nullptr_t` and change usage to enforce type consistency without conversion.
2021-01-10 23:29:28 +00:00
if (Thread::current()->block<Thread::WriteBlocker>({}, description, unblock_flags).was_interrupted()) {
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
if (total_nwritten == 0)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EINTR;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Move block condition evaluation out of the Scheduler This makes the Scheduler a lot leaner by not having to evaluate block conditions every time it is invoked. Instead evaluate them as the states change, and unblock threads at that point. This also implements some more waitid/waitpid/wait features and behavior. For example, WUNTRACED and WNOWAIT are now supported. And wait will now not return EINTR when SIGCHLD is delivered at the same time.
2020-11-29 23:05:27 +00:00
// TODO: handle exceptions in unblock_flags
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
auto nwritten_or_error = description.write(data.offset(total_nwritten), data_size - total_nwritten);
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
if (nwritten_or_error.is_error()) {
Kernel: Fix subtle race condition in sys$write implementation There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
2021-05-18 11:49:34 +00:00
if (total_nwritten > 0)
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
return total_nwritten;
Kernel: Fix subtle race condition in sys$write implementation There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
2021-05-18 11:49:34 +00:00
if (nwritten_or_error.error() == EAGAIN)
continue;
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
return nwritten_or_error.error();
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Fix subtle race condition in sys$write implementation There is a slight race condition in our implementation of write(). We call File::can_write() before attempting to write to it (blocking if it returns false). If it returns true, we assume that we can write to the file, and our code assumes that File::write() cannot possibly fail by being blocked. There is, however, the rare case where another process writes to the file and prevents further writes in between the call to Files::can_write() and File::write() in the first process. This would result in the first process calling File::write() when it cannot be written to. We fix this by adding a mechanism for File::can_write() to signal that it was blocked, making it the responsibilty of File::write() to check whether it can write and then finally making sys$write() check if the write failed due to it being blocked.
2021-05-18 11:49:34 +00:00
VERIFY(nwritten_or_error.value() > 0);
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
total_nwritten += nwritten_or_error.value();
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Make File::write() and File::read() return KResultOr<size_t> Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-08-04 16:02:23 +00:00
return total_nwritten;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
Kernel: Use Userspace<T> in sys$write()
2021-03-01 13:35:06 +00:00
KResultOr<ssize_t> Process::sys$write(int fd, Userspace<const u8*> data, ssize_t size)
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
{
REQUIRE_PROMISE(stdio);
if (size < 0)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EINVAL;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
if (size == 0)
return 0;
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
Kernel: Fix build with IO_DEBUG
2021-03-01 15:07:50 +00:00
dbgln_if(IO_DEBUG, "sys$write({}, {}, {})", fd, data.ptr(), size);
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
auto description = file_description(fd);
if (!description)
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EBADF;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
if (!description->is_writable())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EBADF;
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
Kernel: Use Userspace<T> in sys$write()
2021-03-01 13:35:06 +00:00
auto buffer = UserOrKernelBuffer::for_user_buffer(data, static_cast<size_t>(size));
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
if (!buffer.has_value())
Kernel: Make all syscall functions return KResultOr<T> This makes it a lot easier to return errors since we no longer have to worry about negating EFOO errors and can just return them flat.
2021-03-01 12:49:16 +00:00
return EFAULT;
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
return do_write(*description, buffer.value(), size);
Kernel: Move syscall implementations out of Process.cpp This is something I've been meaning to do for a long time, and here we finally go. This patch moves all sys$foo functions out of Process.cpp and into files in Kernel/Syscalls/. It's not exactly one syscall per file (although it could be, but I got a bit tired of the repetitive work here..) This makes hacking on individual syscalls a lot less painful since you don't have to rebuild nearly as much code every time. I'm also hopeful that this makes it easier to understand individual syscalls. :^)
2020-07-30 21:38:15 +00:00
}
}
Reference in a new issue Copy permalink