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v261
src/basic/procfs-util.c
256 строк
8 KB
Yu Watanabe
tree-wide: normalize comment style
15 дек 2025, 02:50
15 дек 2025, 02:50
9337814
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/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include <unistd.h> #include "alloc-util.h" #include "extract-word.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" #include "time-util.h" int procfs_get_pid_max(uint64_t *ret) { _cleanup_free_ char *value = NULL; int r; assert(ret); r = read_one_line_file("/proc/sys/kernel/pid_max", &value); if (r < 0) return r; return safe_atou64(value, ret); } int procfs_get_threads_max(uint64_t *ret) { _cleanup_free_ char *value = NULL; int r; assert(ret); r = read_one_line_file("/proc/sys/kernel/threads-max", &value); if (r < 0) return r; return safe_atou64(value, ret); } int procfs_tasks_set_limit(uint64_t limit) { char buffer[DECIMAL_STR_MAX(uint64_t)+1]; 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 they probably mean "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 = procfs_get_pid_max(&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) { xsprintf(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; } xsprintf(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 */ if (procfs_get_threads_max(&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_safe(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 convert_meminfo_value_to_uint64_bytes(const char *s, uint64_t *ret) { _cleanup_free_ char *w = NULL; uint64_t v; int r; assert(s); assert(ret); r = extract_first_word(&s, &w, /* separators= */ NULL, /* flags= */ 0); if (r < 0) return r; if (r == 0) return -EINVAL; /* Ensure the line ends in "kB" */ if (!streq(s, "kB")) return -EINVAL; r = safe_atou64(w, &v); if (r < 0) return r; if (v == UINT64_MAX) return -EINVAL; if (!MUL_ASSIGN_SAFE(&v, U64_KB)) return -EOVERFLOW; *ret = v; return 0; } int procfs_memory_get(uint64_t *ret_total, uint64_t *ret_used) { uint64_t mem_total = UINT64_MAX, mem_available = 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; 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, "MemAvailable:"); if (p) v = &mem_available; else continue; } r = convert_meminfo_value_to_uint64_bytes(p, v); if (r < 0) return r; if (mem_total != UINT64_MAX && mem_available != UINT64_MAX) break; } if (mem_available > mem_total) return -EINVAL; if (ret_total) *ret_total = mem_total; if (ret_used) *ret_used = mem_total - mem_available; return 0; }