| // descriptors.cc -- manage file descriptors for gold |
| |
| // Copyright (C) 2008-2024 Free Software Foundation, Inc. |
| // Written by Ian Lance Taylor <iant@google.com>. |
| |
| // This file is part of gold. |
| |
| // This program is free software; you can redistribute it and/or modify |
| // it under the terms of the GNU General Public License as published by |
| // the Free Software Foundation; either version 3 of the License, or |
| // (at your option) any later version. |
| |
| // This program is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License |
| // along with this program; if not, write to the Free Software |
| // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| // MA 02110-1301, USA. |
| |
| #include "gold.h" |
| |
| #include <cerrno> |
| #include <cstdio> |
| #include <cstring> |
| #include <fcntl.h> |
| #include <string> |
| #include <unistd.h> |
| |
| #include "debug.h" |
| #include "parameters.h" |
| #include "options.h" |
| #include "gold-threads.h" |
| #include "descriptors.h" |
| #include "binary-io.h" |
| |
| // O_CLOEXEC is only available on newer systems. |
| #ifndef O_CLOEXEC |
| #define O_CLOEXEC 0 |
| #endif |
| |
| // Very old systems may not define FD_CLOEXEC. |
| #ifndef FD_CLOEXEC |
| #define FD_CLOEXEC 1 |
| #endif |
| |
| static inline void |
| set_close_on_exec(int fd ATTRIBUTE_UNUSED) |
| { |
| // Mingw does not define F_SETFD. |
| #ifdef F_SETFD |
| fcntl(fd, F_SETFD, FD_CLOEXEC); |
| #endif |
| } |
| |
| namespace gold |
| { |
| |
| // Class Descriptors. |
| |
| // The default for limit_ is meant to simply be large. It gets |
| // adjusted downward if we run out of file descriptors. |
| |
| Descriptors::Descriptors() |
| : lock_(NULL), initialize_lock_(&this->lock_), open_descriptors_(), |
| stack_top_(-1), current_(0), limit_(8192 - 16) |
| { |
| this->open_descriptors_.reserve(128); |
| } |
| |
| // Open a file. |
| |
| int |
| Descriptors::open(int descriptor, const char* name, int flags, int mode) |
| { |
| // We don't initialize this until we are called, because we can't |
| // initialize a Lock until we have parsed the options to find out |
| // whether we are running with threads. We can be called before |
| // options are valid when reading a linker script. |
| bool lock_initialized = this->initialize_lock_.initialize(); |
| |
| gold_assert(lock_initialized || descriptor < 0); |
| |
| if (is_debugging_enabled(DEBUG_FILES)) |
| this->limit_ = 8; |
| |
| if (descriptor >= 0) |
| { |
| Hold_lock hl(*this->lock_); |
| |
| gold_assert(static_cast<size_t>(descriptor) |
| < this->open_descriptors_.size()); |
| Open_descriptor* pod = &this->open_descriptors_[descriptor]; |
| if (pod->name == name |
| || (pod->name != NULL && strcmp(pod->name, name) == 0)) |
| { |
| gold_assert(!pod->inuse); |
| pod->inuse = true; |
| if (descriptor == this->stack_top_) |
| { |
| this->stack_top_ = pod->stack_next; |
| pod->stack_next = -1; |
| pod->is_on_stack = false; |
| } |
| gold_debug(DEBUG_FILES, "Reused existing descriptor %d for \"%s\"", |
| descriptor, name); |
| return descriptor; |
| } |
| } |
| |
| while (true) |
| { |
| // We always want to set the close-on-exec flag; we don't |
| // require callers to pass it. |
| flags |= O_CLOEXEC; |
| |
| // Always open the file as a binary file. |
| flags |= O_BINARY; |
| |
| int new_descriptor = ::open(name, flags, mode); |
| if (new_descriptor < 0 |
| && errno != ENFILE |
| && errno != EMFILE) |
| { |
| if (descriptor >= 0 && errno == ENOENT) |
| { |
| { |
| Hold_lock hl(*this->lock_); |
| |
| gold_error(_("file %s was removed during the link"), name); |
| } |
| |
| errno = ENOENT; |
| } |
| |
| gold_debug(DEBUG_FILES, "Opened new descriptor %d for \"%s\"", |
| new_descriptor, name); |
| return new_descriptor; |
| } |
| |
| if (new_descriptor >= 0) |
| { |
| // If we have any plugins, we really do need to set the |
| // close-on-exec flag, even if O_CLOEXEC is not defined. |
| // FIXME: In some cases O_CLOEXEC may be defined in the |
| // header file but not supported by the kernel. |
| // Unfortunately there doesn't seem to be any obvious way to |
| // detect that, as unknown flags passed to open are ignored. |
| if (O_CLOEXEC == 0 |
| && parameters->options_valid() |
| && parameters->options().has_plugins()) |
| set_close_on_exec(new_descriptor); |
| |
| { |
| Hold_optional_lock hl(this->lock_); |
| |
| if (static_cast<size_t>(new_descriptor) |
| >= this->open_descriptors_.size()) |
| this->open_descriptors_.resize(new_descriptor + 64); |
| |
| Open_descriptor* pod = &this->open_descriptors_[new_descriptor]; |
| pod->name = name; |
| pod->stack_next = -1; |
| pod->inuse = true; |
| pod->is_write = (flags & O_ACCMODE) != O_RDONLY; |
| pod->is_on_stack = false; |
| |
| ++this->current_; |
| if (this->current_ >= this->limit_) |
| this->close_some_descriptor(); |
| |
| gold_debug(DEBUG_FILES, "Opened new descriptor %d for \"%s\"", |
| new_descriptor, name); |
| return new_descriptor; |
| } |
| } |
| |
| // We ran out of file descriptors. |
| { |
| Hold_optional_lock hl(this->lock_); |
| |
| this->limit_ = this->current_ - 16; |
| if (this->limit_ < 8) |
| this->limit_ = 8; |
| if (!this->close_some_descriptor()) |
| gold_fatal(_("out of file descriptors and couldn't close any")); |
| } |
| } |
| } |
| |
| // Release a descriptor. |
| |
| void |
| Descriptors::release(int descriptor, bool permanent) |
| { |
| Hold_optional_lock hl(this->lock_); |
| |
| gold_assert(descriptor >= 0 |
| && (static_cast<size_t>(descriptor) |
| < this->open_descriptors_.size())); |
| Open_descriptor* pod = &this->open_descriptors_[descriptor]; |
| |
| if (permanent |
| || (this->current_ > this->limit_ && !pod->is_write)) |
| { |
| if (::close(descriptor) < 0) |
| gold_warning(_("while closing %s: %s"), pod->name, strerror(errno)); |
| pod->name = NULL; |
| --this->current_; |
| } |
| else |
| { |
| pod->inuse = false; |
| if (!pod->is_write && !pod->is_on_stack) |
| { |
| pod->stack_next = this->stack_top_; |
| this->stack_top_ = descriptor; |
| pod->is_on_stack = true; |
| } |
| } |
| |
| gold_debug(DEBUG_FILES, "Released descriptor %d for \"%s\"", |
| descriptor, pod->name); |
| } |
| |
| // Close some descriptor. The lock is held when this is called. We |
| // close the descriptor on the top of the free stack. Note that this |
| // is the opposite of an LRU algorithm--we close the most recently |
| // used descriptor. That is because the linker tends to cycle through |
| // all the files; after we release a file, we are unlikely to need it |
| // again until we have looked at all the other files. Return true if |
| // we closed a descriptor. |
| |
| bool |
| Descriptors::close_some_descriptor() |
| { |
| int last = -1; |
| int i = this->stack_top_; |
| while (i >= 0) |
| { |
| gold_assert(static_cast<size_t>(i) < this->open_descriptors_.size()); |
| Open_descriptor* pod = &this->open_descriptors_[i]; |
| if (!pod->inuse && !pod->is_write) |
| { |
| if (::close(i) < 0) |
| gold_warning(_("while closing %s: %s"), pod->name, strerror(errno)); |
| --this->current_; |
| gold_debug(DEBUG_FILES, "Closed descriptor %d for \"%s\"", |
| i, pod->name); |
| pod->name = NULL; |
| if (last < 0) |
| this->stack_top_ = pod->stack_next; |
| else |
| this->open_descriptors_[last].stack_next = pod->stack_next; |
| pod->stack_next = -1; |
| pod->is_on_stack = false; |
| return true; |
| } |
| last = i; |
| i = pod->stack_next; |
| } |
| |
| // We couldn't find any descriptors to close. This is weird but not |
| // necessarily an error. |
| return false; |
| } |
| |
| // Close all the descriptors open for reading. |
| |
| void |
| Descriptors::close_all() |
| { |
| Hold_optional_lock hl(this->lock_); |
| |
| for (size_t i = 0; i < this->open_descriptors_.size(); i++) |
| { |
| Open_descriptor* pod = &this->open_descriptors_[i]; |
| if (pod->name != NULL && !pod->inuse && !pod->is_write) |
| { |
| if (::close(i) < 0) |
| gold_warning(_("while closing %s: %s"), pod->name, strerror(errno)); |
| gold_debug(DEBUG_FILES, "Closed descriptor %d for \"%s\" (close_all)", |
| static_cast<int>(i), pod->name); |
| pod->name = NULL; |
| pod->stack_next = -1; |
| pod->is_on_stack = false; |
| } |
| } |
| this->stack_top_ = -1; |
| } |
| |
| // The single global variable which manages descriptors. |
| |
| Descriptors descriptors; |
| |
| } // End namespace gold. |