Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 268 insertions, 0 deletions

diff --git a/src/basic/procfs-util.c b/src/basic/procfs-util.c
new file mode 100644
index 0000000..7aaf95b
--- /dev/null
+++ b/src/basic/procfs-util.c
@@ -0,0 +1,268 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+
+#include "alloc-util.h"
+#include "def.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "procfs-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+
+int procfs_tasks_get_limit(uint64_t *ret) {
+        _cleanup_free_ char *value = NULL;
+        uint64_t pid_max, threads_max;
+        int r;
+
+        assert(ret);
+
+        /* So there are two sysctl files that control the system limit of processes:
+         *
+         * 1. kernel.threads-max: this is probably the sysctl that makes more sense, as it directly puts a limit on
+         *    concurrent tasks.
+         *
+         * 2. kernel.pid_max: this limits the numeric range PIDs can take, and thus indirectly also limits the number
+         *    of concurrent threads. AFAICS it's primarily a compatibility concept: some crappy old code used a signed
+         *    16bit type for PIDs, hence the kernel provides a way to ensure the PIDs never go beyond INT16_MAX by
+         *    default.
+         *
+         * By default #2 is set to much lower values than #1, hence the limit people come into contact with first, as
+         * it's the lowest boundary they need to bump when they want higher number of processes.
+         *
+         * Also note the weird definition of #2: PIDs assigned will be kept below this value, which means the number of
+         * tasks that can be created is one lower, as PID 0 is not a valid process ID. */
+
+        r = read_one_line_file("/proc/sys/kernel/pid_max", &value);
+        if (r < 0)
+                return r;
+
+        r = safe_atou64(value, &pid_max);
+        if (r < 0)
+                return r;
+
+        value = mfree(value);
+        r = read_one_line_file("/proc/sys/kernel/threads-max", &value);
+        if (r < 0)
+                return r;
+
+        r = safe_atou64(value, &threads_max);
+        if (r < 0)
+                return r;
+
+        /* Subtract one from pid_max, since PID 0 is not a valid PID */
+        *ret = MIN(pid_max-1, threads_max);
+        return 0;
+}
+
+int procfs_tasks_set_limit(uint64_t limit) {
+        char buffer[DECIMAL_STR_MAX(uint64_t)+1];
+        _cleanup_free_ char *value = NULL;
+        uint64_t pid_max;
+        int r;
+
+        if (limit == 0) /* This makes no sense, we are userspace and hence count as tasks too, and we want to live,
+                         * hence the limit conceptually has to be above 0. Also, most likely if anyone asks for a zero
+                         * limit he/she probably means "no limit", hence let's better refuse this to avoid
+                         * confusion. */
+                return -EINVAL;
+
+        /* The Linux kernel doesn't allow this value to go below 20, hence don't allow this either, higher values than
+         * TASKS_MAX are not accepted by the pid_max sysctl. We'll treat anything this high as "unbounded" and hence
+         * set it to the maximum. */
+        limit = CLAMP(limit, 20U, TASKS_MAX);
+
+        r = read_one_line_file("/proc/sys/kernel/pid_max", &value);
+        if (r < 0)
+                return r;
+        r = safe_atou64(value, &pid_max);
+        if (r < 0)
+                return r;
+
+        /* As pid_max is about the numeric pid_t range we'll bump it if necessary, but only ever increase it, never
+         * decrease it, as threads-max is the much more relevant sysctl. */
+        if (limit > pid_max-1) {
+                sprintf(buffer, "%" PRIu64, limit+1); /* Add one, since PID 0 is not a valid PID */
+                r = write_string_file("/proc/sys/kernel/pid_max", buffer, WRITE_STRING_FILE_DISABLE_BUFFER);
+                if (r < 0)
+                        return r;
+        }
+
+        sprintf(buffer, "%" PRIu64, limit);
+        r = write_string_file("/proc/sys/kernel/threads-max", buffer, WRITE_STRING_FILE_DISABLE_BUFFER);
+        if (r < 0) {
+                uint64_t threads_max;
+
+                /* Hmm, we couldn't write this? If so, maybe it was already set properly? In that case let's not
+                 * generate an error */
+
+                value = mfree(value);
+                if (read_one_line_file("/proc/sys/kernel/threads-max", &value) < 0)
+                        return r; /* return original error */
+
+                if (safe_atou64(value, &threads_max) < 0)
+                        return r; /* return original error */
+
+                if (MIN(pid_max-1, threads_max) != limit)
+                        return r; /* return original error */
+
+                /* Yay! Value set already matches what we were trying to set, hence consider this a success. */
+        }
+
+        return 0;
+}
+
+int procfs_tasks_get_current(uint64_t *ret) {
+        _cleanup_free_ char *value = NULL;
+        const char *p, *nr;
+        size_t n;
+        int r;
+
+        assert(ret);
+
+        r = read_one_line_file("/proc/loadavg", &value);
+        if (r < 0)
+                return r;
+
+        /* Look for the second part of the fourth field, which is separated by a slash from the first part. None of the
+         * earlier fields use a slash, hence let's use this to find the right spot. */
+        p = strchr(value, '/');
+        if (!p)
+                return -EINVAL;
+
+        p++;
+        n = strspn(p, DIGITS);
+        nr = strndupa(p, n);
+
+        return safe_atou64(nr, ret);
+}
+
+static uint64_t calc_gcd64(uint64_t a, uint64_t b) {
+
+        while (b > 0) {
+                uint64_t t;
+
+                t = a % b;
+
+                a = b;
+                b = t;
+        }
+
+        return a;
+}
+
+int procfs_cpu_get_usage(nsec_t *ret) {
+        _cleanup_free_ char *first_line = NULL;
+        unsigned long user_ticks, nice_ticks, system_ticks, irq_ticks, softirq_ticks,
+                guest_ticks = 0, guest_nice_ticks = 0;
+        long ticks_per_second;
+        uint64_t sum, gcd, a, b;
+        const char *p;
+        int r;
+
+        assert(ret);
+
+        r = read_one_line_file("/proc/stat", &first_line);
+        if (r < 0)
+                return r;
+
+        p = first_word(first_line, "cpu");
+        if (!p)
+                return -EINVAL;
+
+        if (sscanf(p, "%lu %lu %lu %*u %*u %lu %lu %*u %lu %lu",
+                   &user_ticks,
+                   &nice_ticks,
+                   &system_ticks,
+                   &irq_ticks,
+                   &softirq_ticks,
+                   &guest_ticks,
+                   &guest_nice_ticks) < 5) /* we only insist on the first five fields */
+                return -EINVAL;
+
+        ticks_per_second = sysconf(_SC_CLK_TCK);
+        if (ticks_per_second  < 0)
+                return -errno;
+        assert(ticks_per_second > 0);
+
+        sum = (uint64_t) user_ticks + (uint64_t) nice_ticks + (uint64_t) system_ticks +
+                (uint64_t) irq_ticks + (uint64_t) softirq_ticks +
+                (uint64_t) guest_ticks + (uint64_t) guest_nice_ticks;
+
+        /* Let's reduce this fraction before we apply it to avoid overflows when converting this to µsec */
+        gcd = calc_gcd64(NSEC_PER_SEC, ticks_per_second);
+
+        a = (uint64_t) NSEC_PER_SEC / gcd;
+        b = (uint64_t) ticks_per_second / gcd;
+
+        *ret = DIV_ROUND_UP((nsec_t) sum * (nsec_t) a, (nsec_t) b);
+        return 0;
+}
+
+int procfs_memory_get(uint64_t *ret_total, uint64_t *ret_used) {
+        uint64_t mem_total = UINT64_MAX, mem_free = UINT64_MAX;
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        f = fopen("/proc/meminfo", "re");
+        if (!f)
+                return -errno;
+
+        for (;;) {
+                _cleanup_free_ char *line = NULL;
+                uint64_t *v;
+                char *p, *e;
+                size_t n;
+
+                r = read_line(f, LONG_LINE_MAX, &line);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return -EINVAL; /* EOF: Couldn't find one or both fields? */
+
+                p = first_word(line, "MemTotal:");
+                if (p)
+                        v = &mem_total;
+                else {
+                        p = first_word(line, "MemFree:");
+                        if (p)
+                                v = &mem_free;
+                        else
+                                continue;
+                }
+
+                /* Determine length of numeric value */
+                n = strspn(p, DIGITS);
+                if (n == 0)
+                        return -EINVAL;
+                e = p + n;
+
+                /* Ensure the line ends in " kB" */
+                n = strspn(e, WHITESPACE);
+                if (n == 0)
+                        return -EINVAL;
+                if (!streq(e + n, "kB"))
+                        return -EINVAL;
+
+                *e = 0;
+                r = safe_atou64(p, v);
+                if (r < 0)
+                        return r;
+                if (*v == UINT64_MAX)
+                        return -EINVAL;
+
+                if (mem_total != UINT64_MAX && mem_free != UINT64_MAX)
+                        break;
+        }
+
+        if (mem_free > mem_total)
+                return -EINVAL;
+
+        if (ret_total)
+                *ret_total = mem_total * 1024U;
+        if (ret_used)
+                *ret_used = (mem_total - mem_free) * 1024U;
+        return 0;
+}