/*
	 * Copyright 2015-2026 the Pacemaker project contributors
	 *
	 * The version control history for this file may have further details.
	 *
	 * This source code is licensed under the GNU Lesser General Public License
	 * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
	 */
	
	#include <crm_internal.h>
	
	#include <stdbool.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <dirent.h>
	#include <ctype.h>
	
	#include <glib.h>		// g_str_has_prefix()
	
	#if HAVE_LINUX_PROCFS
	/*!
	 * \internal
	 * \brief Return name of /proc file containing the CIB daemon's load statistics
	 *
	 * \return Newly allocated memory with file name on success, NULL otherwise
	 *
	 * \note It is the caller's responsibility to free the return value.
	 *       This will return NULL if the daemon is being run via valgrind.
	 *       This should be called only on Linux systems.
	 */
	static char *
	find_cib_loadfile(const char *server)
	{
	    pid_t pid = pcmk__procfs_pid_of(server);
	
	    if (pid == 0) {
	        return NULL;
	    }
	    return pcmk__assert_asprintf("/proc/%lld/stat", (long long) pid);
	}
	
	/*!
	 * \internal
	 * \brief Get process ID and name associated with a /proc directory entry
	 *
	 * \param[in]  entry    Directory entry (must be result of readdir() on /proc)
	 * \param[out] name     If not NULL, a char[16] to hold the process name
	 * \param[out] pid      If not NULL, will be set to process ID of entry
	 *
	 * \return Standard Pacemaker return code
	 * \note This should be called only on Linux systems, as not all systems that
	 *       support /proc store process names and IDs in the same way. The kernel
	 *       limits the process name to the first 15 characters (plus terminator).
	 *       It would be nice if there were a public kernel API constant for that
	 *       limit, but there isn't.
	 */
	static int
	pcmk__procfs_process_info(const struct dirent *entry, char *name, pid_t *pid)
	{
	    int fd, local_pid;
	    FILE *file;
	    struct stat statbuf;
	    char procpath[128] = { 0 };
	
	    /* We're only interested in entries whose name is a PID,
	     * so skip anything non-numeric or that is too long.
	     *
	     * 114 = 128 - strlen("/proc/") - strlen("/status") - 1
	     */
	    local_pid = atoi(entry->d_name);
	    if ((local_pid <= 0) || (strlen(entry->d_name) > 114)) {
	        return -1;
	    }
	    if (pid) {
	        *pid = (pid_t) local_pid;
	    }
	
	    /* Get this entry's file information */
	    strcpy(procpath, "/proc/");
	    strcat(procpath, entry->d_name);
	    fd = open(procpath, O_RDONLY);
	    if (fd < 0 ) {
	        return -1;
	    }
	    if (fstat(fd, &statbuf) < 0) {
	        close(fd);
	        return -1;
	    }
	    close(fd);
	
	    /* We're only interested in subdirectories */
	    if (!S_ISDIR(statbuf.st_mode)) {
	        return -1;
	    }
	
	    /* Read the first entry ("Name:") from the process's status file.
	     * We could handle the valgrind case if we parsed the cmdline file
	     * instead, but that's more of a pain than it's worth.
	     */
	    if (name != NULL) {
	        strcat(procpath, "/status");
	        file = fopen(procpath, "r");
	        if (!file) {
	            return -1;
	        }
	        if (fscanf(file, "Name:\t%15[^\n]", name) != 1) {
	            fclose(file);
	            return -1;
	        }
	        name[15] = 0;
	        fclose(file);
	    }
	
	    return 0;
	}
	#endif // HAVE_LINUX_PROCFS
	
	/*!
	 * \internal
	 * \brief Return process ID of a named process
	 *
	 * \param[in] name  Process name (as used in /proc/.../status)
	 *
	 * \return Process ID of named process if running, 0 otherwise
	 *
	 * \note This will return 0 if the process is being run via valgrind.
	 *       This should be called only on Linux systems.
	 */
	pid_t
	pcmk__procfs_pid_of(const char *name)
	{
	#if HAVE_LINUX_PROCFS
	    DIR *dp;
	    struct dirent *entry;
	    pid_t pid = 0;
	    char entry_name[64] = { 0 };
	
	    dp = opendir("/proc");
	    if (dp == NULL) {
	        pcmk__notice("Can not read /proc directory to track existing "
	                     "components");
	        return 0;
	    }
	
	    while ((entry = readdir(dp)) != NULL) {
	        if ((pcmk__procfs_process_info(entry, entry_name, &pid) == pcmk_rc_ok)
	            && pcmk__str_eq(entry_name, name, pcmk__str_casei)
	            && (pcmk__pid_active(pid, NULL) == pcmk_rc_ok)) {
	
	            pcmk__info("Found %s active as process %lld", name,
	                       (long long) pid);
	            break;
	        }
	        pid = 0;
	    }
	    closedir(dp);
	    return pid;
	#else
	    return 0;
	#endif // HAVE_LINUX_PROCFS
	}
	
	/*!
	 * \internal
	 * \brief Calculate number of logical CPU cores from procfs
	 *
	 * \return Number of cores (or 1 if unable to determine)
	 */
	unsigned int
	pcmk__procfs_num_cores(void)
	{
	#if HAVE_LINUX_PROCFS
	    int cores = 0;
	    FILE *stream = NULL;
	
	    /* Parse /proc/stat instead of /proc/cpuinfo because it's smaller */
	    stream = fopen("/proc/stat", "r");
	    if (stream == NULL) {
	        pcmk__info("Could not open /proc/stat: %s", strerror(errno));
	
	    } else {
	        char buffer[2048];
	
	        while (fgets(buffer, sizeof(buffer), stream)) {
	            if (g_str_has_prefix(buffer, "cpu") && isdigit(buffer[3])) {
	                ++cores;
	            }
	        }
	        fclose(stream);
	    }
	    return cores? cores : 1;
	#else
	    return 1;
	#endif // HAVE_LINUX_PROCFS
	}
	
	/*!
	 * \internal
	 * \brief Get the executable path corresponding to a process ID
	 *
	 * \param[in]  pid   Process ID to check
	 * \param[out] path  Where to store executable path (can be \c NULL)
	 *
	 * \return Standard Pacemaker error code (as possible errno values from
	 *         readlink())
	 */
	int
	pcmk__procfs_pid2path(pid_t pid, char **path)
	{
	#if HAVE_LINUX_PROCFS
	    char *procfs_path = NULL;
	    ssize_t link_rc;
	
	    /* The readlink(2) man page recommends calling lstat() to get the required
	     * buffer size, and then dynamically allocate the buffer. However,
	     * st_size == 0 for symlinks under /proc. So we use PATH_MAX.
	     */
	    char real_path[PATH_MAX] = { '\0', };
	
	    pcmk__assert((path == NULL) || (*path == NULL));
	
	    procfs_path = pcmk__assert_asprintf("/proc/%lld/exe", (long long) pid);
	
	    link_rc = readlink(procfs_path, real_path, sizeof(real_path));
	    free(procfs_path);
	
	    if (link_rc < 0) {
	        return errno;
	    } else if (link_rc >= sizeof(real_path)) {
	        return ENAMETOOLONG;
	    }
	
	    if (path != NULL) {
	        /* Make Coverity happy; we already zero-initialized real_path, and we
	         * returned ENAMETOOLONG if it's no longer null-terminated
	         */
	        real_path[link_rc] = '\0';
	
	        *path = pcmk__str_copy(real_path);
	    }
	    return pcmk_rc_ok;
	#else
	    return EOPNOTSUPP;
	#endif // HAVE_LINUX_PROCFS
	}
	
	/*!
	 * \internal
	 * \brief Check whether process ID information is available from procfs
	 *
	 * \return true if process ID information is available, otherwise false
	 */
	bool
	pcmk__procfs_has_pids(void)
	{
	#if HAVE_LINUX_PROCFS
	    static bool have_pids = false;
	    static bool checked = false;
	
	    if (!checked) {
	        have_pids = pcmk__procfs_pid2path(getpid(), NULL) == pcmk_rc_ok;
	        checked = true;
	    }
	    return have_pids;
	#else
	    return false;
	#endif // HAVE_LINUX_PROCFS
	}
	
	/*!
	 * \internal
	 * \brief Return an open handle on the directory containing links to open file
	 *        descriptors, or NULL on error
	 */
	DIR *
	pcmk__procfs_fd_dir(void)
	{
	    DIR *dir = NULL;
	
	    /* /proc/self/fd (on Linux) or /dev/fd (on most OSes) contains symlinks to
	     * all open files for the current process, named as the file descriptor.
	     * Use this if available, because it's more efficient than a shotgun
	     * approach to closing descriptors.
	     */
	#if HAVE_LINUX_PROCFS
	    dir = opendir("/proc/self/fd");
	#endif // HAVE_LINUX_PROCFS
	
	    return dir;
	}
	
	/*!
	 * \internal
	 * \brief Trigger a sysrq command if supported on current platform
	 *
	 * \param[in] t  Sysrq command to trigger
	 */
	void
	pcmk__sysrq_trigger(char t)
	{
	#if HAVE_LINUX_PROCFS
	    // Root can always write here, regardless of kernel.sysrq value
	    FILE *procf = fopen("/proc/sysrq-trigger", "a");
	
	    if (procf == NULL) {
	        pcmk__warn("Could not open sysrq-trigger: %s", strerror(errno));
	    } else {
	        fprintf(procf, "%c\n", t);
	        fclose(procf);
	    }
	#endif // HAVE_LINUX_PROCFS
	}
	
	bool
	pcmk__throttle_cib_load(const char *server, float *load)
	{
	/* /proc/[pid]/stat
	 *
	 * Status information about the process.  This is used by ps(1).  It is defined
	 * in /usr/src/linux/fs/proc/array.c.
	 *
	 * The fields, in order, with their proper scanf(3) format specifiers, are:
	 *
	 * pid %d      (1)  The process ID.
	 * comm %s     (2)  The filename of the executable, in parentheses.  This is
	 *                  visible whether or not the executable is swapped out.
	 * state %c    (3)  One character from the string "RSDZTW" where R is running,
	 *                  S is sleeping in an interruptible wait, D is waiting in
	 *                  uninterruptible disk sleep, Z is zombie, T is traced or
	 *                  stopped (on a signal), and W is paging.
	 * ppid %d     (4)  The PID of the parent.
	 * pgrp %d     (5)  The process group ID of the process.
	 * session %d  (6)  The session ID of the process.
	 * tty_nr %d   (7)  The controlling terminal of the process.  (The minor device
	 *                  number is contained in the combination of bits 31 to 20 and
	 *                  7 to 0; the major device number is in bits 15 to 8.)
	 * tpgid %d    (8)  The ID of the foreground process group of the controlling
	 *                  terminal of the process.
	 * flags %u    (9)  The kernel flags word of the process.  For bit meanings, see
	 *                  the PF_* defines in the Linux kernel source file include/linux/sched.h.
	 *                  Details depend on the kernel version.
	 * minflt %lu  (10) The number of minor faults the process has made which have
	 *                  not required loading a memory page from disk.
	 * cminflt %lu (11) The number of minor faults that the process's waited-for
	 *                  children have made.
	 * majflt %lu  (12) The number of major faults the process has made which have
	 *                  required loading a memory page from disk.
	 * cmajflt %lu (13) The number of major faults that the process's waited-for
	 *                  children have made.
	 * utime %lu   (14) Amount of time that this process has been scheduled in user
	 *                  mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)).
	 *                  This includes guest time, guest_time (time spent running a
	 *                  virtual CPU, see below), so that applications that are not
	 *                  aware of the guest time field do not lose that time from
	 *                  their calculations.
	 * stime %lu   (15) Amount of time that this process has been scheduled in
	 *                  kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)).
	 */
	
	#if HAVE_LINUX_PROCFS
	    static char *loadfile = NULL;
	    static time_t last_call = 0;
	    static long ticks_per_s = 0;
	    static unsigned long last_utime, last_stime;
	
	    char buffer[64*1024];
	    FILE *stream = NULL;
	    time_t now = time(NULL);
	

	    if (load == NULL) {
	        return false;
	    } else {
	        *load = 0.0;
	    }
	

	    if (loadfile == NULL) {
	        last_call = 0;
	        last_utime = 0;
	        last_stime = 0;
	
	        loadfile = find_cib_loadfile(server);

	        if (loadfile == NULL) {
	            pcmk__warn("Couldn't find CIB load file");
	            return false;
	        }
	
	        ticks_per_s = sysconf(_SC_CLK_TCK);

	        pcmk__trace("Found %s", loadfile);
	    }
	
	    stream = fopen(loadfile, "r");

	    if (stream == NULL) {
	        int rc = errno;
	
	        pcmk__warn("Couldn't read %s: %s (%d)", loadfile, pcmk_rc_str(rc), rc);

	        g_clear_pointer(&loadfile, free);
	        return false;
	    }
	
	    if (fgets(buffer, sizeof(buffer), stream) != NULL) {
	        char *comm = pcmk__assert_alloc(256, sizeof(char));
	        char state = 0;
	        int rc = 0, pid = 0, ppid = 0, pgrp = 0, session = 0, tty_nr = 0, tpgid = 0;
	        unsigned long flags = 0, minflt = 0, cminflt = 0, majflt = 0, cmajflt = 0, utime = 0, stime = 0;
	
	        rc = sscanf(buffer, "%d %[^ ] %c %d %d %d %d %d %lu %lu %lu %lu %lu %lu %lu",
	                    &pid, comm, &state, &ppid, &pgrp, &session, &tty_nr, &tpgid,
	                    &flags, &minflt, &cminflt, &majflt, &cmajflt, &utime, &stime);
	        free(comm);
	
	        if (rc != 15) {
	            pcmk__err("Only %d of 15 fields found in %s", rc, loadfile);
	            fclose(stream);
	            return false;
	
	        } else if ((last_call > 0) && (last_call < now) && (last_utime <= utime) &&
	                   (last_stime <= stime)) {
	            time_t elapsed = now - last_call;
	            unsigned long delta_utime = utime - last_utime;
	            unsigned long delta_stime = stime - last_stime;
	
	            *load = delta_utime + delta_stime; /* Cast to a float before division */
	            *load /= ticks_per_s;
	            *load /= elapsed;
	            pcmk__debug("cib load: %f (%lu ticks in %llds)", *load,
	                        (delta_utime + delta_stime), (long long) elapsed);
	
	        } else {
	            pcmk__debug("Init %lu + %lu ticks at %lld (%lu tps)", utime, stime,
	                        (long long) now, ticks_per_s);
	        }
	
	        last_call = now;
	        last_utime = utime;
	        last_stime = stime;
	
	        fclose(stream);
	        return true;
	    }
	
	    fclose(stream);
	#endif // HAVE_LINUX_PROCFS
	    return false;
	}
	
	bool
	pcmk__throttle_load_avg(float *load)
	{
	#if HAVE_LINUX_PROCFS
	    char buffer[256];
	    FILE *stream = NULL;
	    const char *loadfile = "/proc/loadavg";
	
	    if (load == NULL) {
	        return false;
	    }
	
	    stream = fopen(loadfile, "r");
	    if (stream == NULL) {
	        int rc = errno;
	        pcmk__warn("Couldn't read %s: %s (%d)", loadfile, pcmk_rc_str(rc), rc);
	        return false;
	    }
	
	    if (fgets(buffer, sizeof(buffer), stream) != NULL) {
	        /* Grab the 1-minute average, ignore the rest */
	        *load = strtof(buffer, NULL);
	        fclose(stream);
	        return true;
	    }
	
	    fclose(stream);
	#endif // HAVE_LINUX_PROCFS
	    return false;
	}