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Pathlocks Implementation for Windows (#10586)

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Based on Volth's original port.

Co-authored-by: volth <volth@volth.com>
This commit is contained in:
Dylan Green 2024-04-22 10:08:10 -05:00 • committed by GitHub
parent e1fd0e0a8c
commit aa165301d1
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GPG key ID: B5690EEEBB952194
7 changed files with 178 additions and 62 deletions
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2
src/libstore/unix/lock.cc
View file

@ -9,8 +9,6 @@
namespace nix {
using namespace nix::unix;
#if __linux__
static std::vector<gid_t> get_group_list(const char *username, gid_t group_id)

38
src/libstore/unix/pathlocks-impl.hh
View file

@ -1,38 +0,0 @@
#pragma once
///@file
#include "file-descriptor.hh"
namespace nix::unix {
/**
* Open (possibly create) a lock file and return the file descriptor.
* -1 is returned if create is false and the lock could not be opened
* because it doesn't exist. Any other error throws an exception.
*/
AutoCloseFD openLockFile(const Path & path, bool create);
/**
* Delete an open lock file.
*/
void deleteLockFile(const Path & path, int fd);
enum LockType { ltRead, ltWrite, ltNone };
bool lockFile(int fd, LockType lockType, bool wait);
struct FdLock
{
int fd;
bool acquired = false;
FdLock(int fd, LockType lockType, bool wait, std::string_view waitMsg);
~FdLock()
{
if (acquired)
lockFile(fd, ltNone, false);
}
};
}

24
src/libstore/unix/pathlocks.cc
View file

@ -14,9 +14,7 @@
namespace nix {
using namespace nix::unix;
AutoCloseFD unix::openLockFile(const Path & path, bool create)
AutoCloseFD openLockFile(const Path & path, bool create)
{
AutoCloseFD fd;
@ -28,20 +26,20 @@ AutoCloseFD unix::openLockFile(const Path & path, bool create)
}
void unix::deleteLockFile(const Path & path, int fd)
void deleteLockFile(const Path & path, Descriptor desc)
{
/* Get rid of the lock file. Have to be careful not to introduce
races. Write a (meaningless) token to the file to indicate to
other processes waiting on this lock that the lock is stale
(deleted). */
unlink(path.c_str());
writeFull(fd, "d");
writeFull(desc, "d");
/* Note that the result of unlink() is ignored; removing the lock
file is an optimisation, not a necessity. */
}
bool unix::lockFile(int fd, LockType lockType, bool wait)
bool lockFile(Descriptor desc, LockType lockType, bool wait)
{
int type;
if (lockType == ltRead) type = LOCK_SH;
@ -50,7 +48,7 @@ bool unix::lockFile(int fd, LockType lockType, bool wait)
else abort();
if (wait) {
while (flock(fd, type) != 0) {
while (flock(desc, type) != 0) {
checkInterrupt();
if (errno != EINTR)
throw SysError("acquiring/releasing lock");
@ -58,7 +56,7 @@ bool unix::lockFile(int fd, LockType lockType, bool wait)
return false;
}
} else {
while (flock(fd, type | LOCK_NB) != 0) {
while (flock(desc, type | LOCK_NB) != 0) {
checkInterrupt();
if (errno == EWOULDBLOCK) return false;
if (errno != EINTR)
@ -149,16 +147,16 @@ void PathLocks::unlock()
}
FdLock::FdLock(int fd, LockType lockType, bool wait, std::string_view waitMsg)
: fd(fd)
FdLock::FdLock(Descriptor desc, LockType lockType, bool wait, std::string_view waitMsg)
: desc(desc)
{
if (wait) {
if (!lockFile(fd, lockType, false)) {
if (!lockFile(desc, lockType, false)) {
printInfo("%s", waitMsg);
acquired = lockFile(fd, lockType, true);
acquired = lockFile(desc, lockType, true);
}
} else
acquired = lockFile(fd, lockType, false);
acquired = lockFile(desc, lockType, false);
}