[thirdparty/squid.git] / src / unlinkd.cc

/*
 * Copyright (C) 1996-2025 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

/* DEBUG: section 02    Unlink Daemon */

#include "squid.h"

#if USE_UNLINKD
#include "fd.h"
#include "fde.h"
#include "fs_io.h"
#include "globals.h"
#include "SquidConfig.h"
#include "SquidIpc.h"
#include "StatCounters.h"
#include "store/Disk.h"
#include "tools.h"
#include "unlinkd.h"

#include <chrono>
#include <thread>

/* This code gets linked to Squid */

static int unlinkd_wfd = -1;
static int unlinkd_rfd = -1;

static void * hIpc;
static pid_t pid;

#define UNLINKD_QUEUE_LIMIT 20

void
unlinkdUnlink(const char *path)
{
    char buf[MAXPATHLEN];
    int l;
    int bytes_written;
    static int queuelen = 0;

    if (unlinkd_wfd < 0) {
        debug_trap("unlinkdUnlink: unlinkd_wfd < 0");
        safeunlink(path, 0);
        return;
    }

    /*
     * If the queue length is greater than our limit, then we pause
     * for a small amount of time, hoping that unlinkd has some
     * feedback for us.  Maybe it just needs a slice of the CPU's
     * time.
     */
    if (queuelen >= UNLINKD_QUEUE_LIMIT) {
#if defined(USE_EPOLL) || defined(USE_KQUEUE) || defined(USE_DEVPOLL)
        /*
         * DPW 2007-04-23
         * We can't use fd_set when using epoll() or kqueue().  In
         * these cases we block for 10 ms.
         */
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
#else
        /*
         * DPW 2007-04-23
         * When we can use select, block for up to 100 ms.
         */
        struct timeval to;
        fd_set R;
        FD_ZERO(&R);
        FD_SET(unlinkd_rfd, &R);
        to.tv_sec = 0;
        to.tv_usec = 100000;
        select(unlinkd_rfd + 1, &R, nullptr, nullptr, &to);
#endif
    }

    /*
    * If there is at least one outstanding unlink request, then
    * try to read a response.  If there's nothing to read we'll
    * get an EWOULDBLOCK or whatever.  If we get a response, then
    * decrement the queue size by the number of newlines read.
    */
    if (queuelen > 0) {
        int bytes_read;
        int i;
        char rbuf[512];
        bytes_read = read(unlinkd_rfd, rbuf, 511);

        if (bytes_read > 0) {
            rbuf[bytes_read] = '\0';

            for (i = 0; i < bytes_read; ++i)
                if ('\n' == rbuf[i])
                    --queuelen;

            assert(queuelen >= 0);
        }
    }

    l = strlen(path);
    assert(l < MAXPATHLEN);
    xstrncpy(buf, path, MAXPATHLEN);
    buf[l] = '\n';
    ++l;
    bytes_written = write(unlinkd_wfd, buf, l);

    if (bytes_written < 0) {
        int xerrno = errno;
        debugs(2, DBG_IMPORTANT, "ERROR: unlinkdUnlink: write FD " << unlinkd_wfd << " failed: " << xstrerr(xerrno));
        safeunlink(path, 0);
        return;
    } else if (bytes_written != l) {
        debugs(2, DBG_IMPORTANT, "unlinkdUnlink: FD " << unlinkd_wfd << " only wrote " << bytes_written << " of " << l << " bytes");
        safeunlink(path, 0);
        return;
    }

    ++statCounter.unlink.requests;
    /*
    * Increment this syscalls counter here, even though the syscall
    * is executed by the helper process.  We try to be consistent
    * in counting unlink operations.
    */
    ++statCounter.syscalls.disk.unlinks;
    ++queuelen;
}

void
unlinkdClose(void)
#if _SQUID_WINDOWS_
{

    if (unlinkd_wfd > -1) {
        debugs(2, DBG_IMPORTANT, "Closing unlinkd pipe on FD " << unlinkd_wfd);
        shutdown(unlinkd_wfd, SD_BOTH);
        comm_close(unlinkd_wfd);

        if (unlinkd_wfd != unlinkd_rfd)
            comm_close(unlinkd_rfd);

        unlinkd_wfd = -1;

        unlinkd_rfd = -1;
    }

    if (hIpc) {
        if (WaitForSingleObject(hIpc, 5000) != WAIT_OBJECT_0) {
            getCurrentTime();
            debugs(2, DBG_IMPORTANT, "WARNING: unlinkdClose: (unlinkd," << pid << "d) didn't exit in 5 seconds");
        }

        CloseHandle(hIpc);
    }
}
#else
{

    if (unlinkd_wfd < 0)
        return;

    debugs(2, DBG_IMPORTANT, "Closing unlinkd pipe on FD " << unlinkd_wfd);

    file_close(unlinkd_wfd);

    if (unlinkd_wfd != unlinkd_rfd)
        file_close(unlinkd_rfd);

    unlinkd_wfd = -1;

    unlinkd_rfd = -1;
}

#endif

bool
unlinkdNeeded(void)
{
    // we should start unlinkd if there are any cache_dirs using it
    for (size_t i = 0; i < Config.cacheSwap.n_configured; ++i) {
        const RefCount<SwapDir> sd = Config.cacheSwap.swapDirs[i];
        if (sd->unlinkdUseful())
            return true;
    }

    return false;
}

void
unlinkdInit(void)
{
    if (unlinkd_wfd >= 0)
        return; // unlinkd already started

    const char *args[2];
    Ip::Address localhost;

    args[0] = "(unlinkd)";
    args[1] = nullptr;
    localhost.setLocalhost();

    pid = ipcCreate(
#if USE_POLL && _SQUID_OSF_
              /* pipes and poll() don't get along on DUNIX -DW */
              IPC_STREAM,
#elif _SQUID_WINDOWS_
              /* select() will fail on a pipe */
              IPC_TCP_SOCKET,
#else
              /* We currently need to use FIFO.. see below */
              IPC_FIFO,
#endif
              Config.Program.unlinkd,
              args,
              "unlinkd",
              localhost,
              &unlinkd_rfd,
              &unlinkd_wfd,
              &hIpc);

    if (pid < 0)
        fatal("Failed to create unlinkd subprocess");

    std::this_thread::sleep_for(std::chrono::milliseconds(250));

    fd_note(unlinkd_wfd, "squid -> unlinkd");

    fd_note(unlinkd_rfd, "unlinkd -> squid");

    commUnsetFdTimeout(unlinkd_rfd);
    commUnsetFdTimeout(unlinkd_wfd);

    /*
    * unlinkd_rfd should already be non-blocking because of
    * ipcCreate.  We change unlinkd_wfd to blocking mode because
    * we never want to lose an unlink request, and we don't have
    * code to retry if we get EWOULDBLOCK.  Unfortunately, we can
    * do this only for the IPC_FIFO case.
    */
    assert(fd_table[unlinkd_rfd].flags.nonblocking);

    if (FD_PIPE == fd_table[unlinkd_wfd].type)
        commUnsetNonBlocking(unlinkd_wfd);

    debugs(2, DBG_IMPORTANT, "Unlinkd pipe opened on FD " << unlinkd_wfd);

#if _SQUID_WINDOWS_

    debugs(2, 4, "Unlinkd handle: 0x" << std::hex << hIpc << std::dec << ", PID: " << pid);

#endif

}
#endif /* USE_UNLINKD */
Commit	Line	Data
	1	/*
	2	* Copyright (C) 1996-2025 The Squid Software Foundation and contributors
	3	*
	4	* Squid software is distributed under GPLv2+ license and includes
	5	* contributions from numerous individuals and organizations.
	6	* Please see the COPYING and CONTRIBUTORS files for details.
	7	*/
	8
	9	/* DEBUG: section 02 Unlink Daemon */
	10
	11	#include "squid.h"
	12
	13	#if USE_UNLINKD
	14	#include "fd.h"
	15	#include "fde.h"
	16	#include "fs_io.h"
	17	#include "globals.h"
	18	#include "SquidConfig.h"
	19	#include "SquidIpc.h"
	20	#include "StatCounters.h"
	21	#include "store/Disk.h"
	22	#include "tools.h"
	23	#include "unlinkd.h"
	24
	25	#include <chrono>
	26	#include <thread>
	27
	28	/* This code gets linked to Squid */
	29
	30	static int unlinkd_wfd = -1;
	31	static int unlinkd_rfd = -1;
	32
	33	static void * hIpc;
	34	static pid_t pid;
	35
	36	#define UNLINKD_QUEUE_LIMIT 20
	37
	38	void
	39	unlinkdUnlink(const char *path)
	40	{
	41	char buf[MAXPATHLEN];
	42	int l;
	43	int bytes_written;
	44	static int queuelen = 0;
	45
	46	if (unlinkd_wfd < 0) {
	47	debug_trap("unlinkdUnlink: unlinkd_wfd < 0");
	48	safeunlink(path, 0);
	49	return;
	50	}
	51
	52	/*
	53	* If the queue length is greater than our limit, then we pause
	54	* for a small amount of time, hoping that unlinkd has some
	55	* feedback for us. Maybe it just needs a slice of the CPU's
	56	* time.
	57	*/
	58	if (queuelen >= UNLINKD_QUEUE_LIMIT) {
	59	#if defined(USE_EPOLL) \|\| defined(USE_KQUEUE) \|\| defined(USE_DEVPOLL)
	60	/*
	61	* DPW 2007-04-23
	62	* We can't use fd_set when using epoll() or kqueue(). In
	63	* these cases we block for 10 ms.
	64	*/
	65	std::this_thread::sleep_for(std::chrono::milliseconds(10));
	66	#else
	67	/*
	68	* DPW 2007-04-23
	69	* When we can use select, block for up to 100 ms.
	70	*/
	71	struct timeval to;
	72	fd_set R;
	73	FD_ZERO(&R);
	74	FD_SET(unlinkd_rfd, &R);
	75	to.tv_sec = 0;
	76	to.tv_usec = 100000;
	77	select(unlinkd_rfd + 1, &R, nullptr, nullptr, &to);
	78	#endif
	79	}
	80
	81	/*
	82	* If there is at least one outstanding unlink request, then
	83	* try to read a response. If there's nothing to read we'll
	84	* get an EWOULDBLOCK or whatever. If we get a response, then
	85	* decrement the queue size by the number of newlines read.
	86	*/
	87	if (queuelen > 0) {
	88	int bytes_read;
	89	int i;
	90	char rbuf[512];
	91	bytes_read = read(unlinkd_rfd, rbuf, 511);
	92
	93	if (bytes_read > 0) {
	94	rbuf[bytes_read] = '\0';
	95
	96	for (i = 0; i < bytes_read; ++i)
	97	if ('\n' == rbuf[i])
	98	--queuelen;
	99
	100	assert(queuelen >= 0);
	101	}
	102	}
	103
	104	l = strlen(path);
	105	assert(l < MAXPATHLEN);
	106	xstrncpy(buf, path, MAXPATHLEN);
	107	buf[l] = '\n';
	108	++l;
	109	bytes_written = write(unlinkd_wfd, buf, l);
	110
	111	if (bytes_written < 0) {
	112	int xerrno = errno;
	113	debugs(2, DBG_IMPORTANT, "ERROR: unlinkdUnlink: write FD " << unlinkd_wfd << " failed: " << xstrerr(xerrno));
	114	safeunlink(path, 0);
	115	return;
	116	} else if (bytes_written != l) {
	117	debugs(2, DBG_IMPORTANT, "unlinkdUnlink: FD " << unlinkd_wfd << " only wrote " << bytes_written << " of " << l << " bytes");
	118	safeunlink(path, 0);
	119	return;
	120	}
	121
	122	++statCounter.unlink.requests;
	123	/*
	124	* Increment this syscalls counter here, even though the syscall
	125	* is executed by the helper process. We try to be consistent
	126	* in counting unlink operations.
	127	*/
	128	++statCounter.syscalls.disk.unlinks;
	129	++queuelen;
	130	}
	131
	132	void
	133	unlinkdClose(void)
	134	#if _SQUID_WINDOWS_
	135	{
	136
	137	if (unlinkd_wfd > -1) {
	138	debugs(2, DBG_IMPORTANT, "Closing unlinkd pipe on FD " << unlinkd_wfd);
	139	shutdown(unlinkd_wfd, SD_BOTH);
	140	comm_close(unlinkd_wfd);
	141
	142	if (unlinkd_wfd != unlinkd_rfd)
	143	comm_close(unlinkd_rfd);
	144
	145	unlinkd_wfd = -1;
	146
	147	unlinkd_rfd = -1;
	148	}
	149
	150	if (hIpc) {
	151	if (WaitForSingleObject(hIpc, 5000) != WAIT_OBJECT_0) {
	152	getCurrentTime();
	153	debugs(2, DBG_IMPORTANT, "WARNING: unlinkdClose: (unlinkd," << pid << "d) didn't exit in 5 seconds");
	154	}
	155
	156	CloseHandle(hIpc);
	157	}
	158	}
	159	#else
	160	{
	161
	162	if (unlinkd_wfd < 0)
	163	return;
	164
	165	debugs(2, DBG_IMPORTANT, "Closing unlinkd pipe on FD " << unlinkd_wfd);
	166
	167	file_close(unlinkd_wfd);
	168
	169	if (unlinkd_wfd != unlinkd_rfd)
	170	file_close(unlinkd_rfd);
	171
	172	unlinkd_wfd = -1;
	173
	174	unlinkd_rfd = -1;
	175	}
	176
	177	#endif
	178
	179	bool
	180	unlinkdNeeded(void)
	181	{
	182	// we should start unlinkd if there are any cache_dirs using it
	183	for (size_t i = 0; i < Config.cacheSwap.n_configured; ++i) {
	184	const RefCount<SwapDir> sd = Config.cacheSwap.swapDirs[i];
	185	if (sd->unlinkdUseful())
	186	return true;
	187	}
	188
	189	return false;
	190	}
	191
	192	void
	193	unlinkdInit(void)
	194	{
	195	if (unlinkd_wfd >= 0)
	196	return; // unlinkd already started
	197
	198	const char *args[2];
	199	Ip::Address localhost;
	200
	201	args[0] = "(unlinkd)";
	202	args[1] = nullptr;
	203	localhost.setLocalhost();
	204
	205	pid = ipcCreate(
	206	#if USE_POLL && _SQUID_OSF_
	207	/* pipes and poll() don't get along on DUNIX -DW */
	208	IPC_STREAM,
	209	#elif _SQUID_WINDOWS_
	210	/* select() will fail on a pipe */
	211	IPC_TCP_SOCKET,
	212	#else
	213	/* We currently need to use FIFO.. see below */
	214	IPC_FIFO,
	215	#endif
	216	Config.Program.unlinkd,
	217	args,
	218	"unlinkd",
	219	localhost,
	220	&unlinkd_rfd,
	221	&unlinkd_wfd,
	222	&hIpc);
	223
	224	if (pid < 0)
	225	fatal("Failed to create unlinkd subprocess");
	226
	227	std::this_thread::sleep_for(std::chrono::milliseconds(250));
	228
	229	fd_note(unlinkd_wfd, "squid -> unlinkd");
	230
	231	fd_note(unlinkd_rfd, "unlinkd -> squid");
	232
	233	commUnsetFdTimeout(unlinkd_rfd);
	234	commUnsetFdTimeout(unlinkd_wfd);
	235
	236	/*
	237	* unlinkd_rfd should already be non-blocking because of
	238	* ipcCreate. We change unlinkd_wfd to blocking mode because
	239	* we never want to lose an unlink request, and we don't have
	240	* code to retry if we get EWOULDBLOCK. Unfortunately, we can
	241	* do this only for the IPC_FIFO case.
	242	*/
	243	assert(fd_table[unlinkd_rfd].flags.nonblocking);
	244
	245	if (FD_PIPE == fd_table[unlinkd_wfd].type)
	246	commUnsetNonBlocking(unlinkd_wfd);
	247
	248	debugs(2, DBG_IMPORTANT, "Unlinkd pipe opened on FD " << unlinkd_wfd);
	249
	250	#if _SQUID_WINDOWS_
	251
	252	debugs(2, 4, "Unlinkd handle: 0x" << std::hex << hIpc << std::dec << ", PID: " << pid);
	253
	254	#endif
	255
	256	}
	257	#endif /* USE_UNLINKD */
	258