src/shared/psi-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <stdio.h>
   4 #include <unistd.h>
   5
   6 #include "alloc-util.h"
   7 #include "errno-util.h"
   8 #include "extract-word.h"
   9 #include "fd-util.h"
  10 #include "fileio.h"
  11 #include "parse-util.h"
  12 #include "psi-util.h"
  13 #include "string-util.h"
  14 #include "stat-util.h"
  15 #include "strv.h"
  16
  17 int read_resource_pressure(const char *path, PressureType type, ResourcePressure *ret) {
  18         _cleanup_free_ char *line = NULL;
  19         _cleanup_fclose_ FILE *f = NULL;
  20         unsigned field_filled = 0;
  21         ResourcePressure rp = {};
  22         const char *t, *cline;
  23         char *word;
  24         int r;
  25
  26         assert(path);
  27         assert(IN_SET(type, PRESSURE_TYPE_SOME, PRESSURE_TYPE_FULL));
  28         assert(ret);
  29
  30         if (type == PRESSURE_TYPE_SOME)
  31                 t = "some";
  32         else if (type == PRESSURE_TYPE_FULL)
  33                 t = "full";
  34         else
  35                 return -EINVAL;
  36
  37         r = fopen_unlocked(path, "re", &f);
  38          if (r < 0)
  39                  return r;
  40
  41         for (;;) {
  42                 _cleanup_free_ char *l = NULL;
  43                 char *w;
  44
  45                 r = read_line(f, LONG_LINE_MAX, &l);
  46                 if (r < 0)
  47                         return r;
  48                 if (r == 0)
  49                         break;
  50
  51                 w = first_word(l, t);
  52                 if (w) {
  53                         line = TAKE_PTR(l);
  54                         cline = w;
  55                         break;
  56                 }
  57         }
  58
  59         if (!line)
  60                 return -ENODATA;
  61
  62         /* extracts either avgX=Y.Z or total=X */
  63         while ((r = extract_first_word(&cline, &word, NULL, 0)) > 0) {
  64                 _cleanup_free_ char *w = word;
  65                 const char *v;
  66
  67                 if ((v = startswith(w, "avg10="))) {
  68                         if (field_filled & (1U << 0))
  69                                 return -EINVAL;
  70
  71                         field_filled |= 1U << 0;
  72                         r = parse_loadavg_fixed_point(v, &rp.avg10);
  73                 } else if ((v = startswith(w, "avg60="))) {
  74                         if (field_filled & (1U << 1))
  75                                 return -EINVAL;
  76
  77                         field_filled |= 1U << 1;
  78                         r = parse_loadavg_fixed_point(v, &rp.avg60);
  79                 } else if ((v = startswith(w, "avg300="))) {
  80                         if (field_filled & (1U << 2))
  81                                 return -EINVAL;
  82
  83                         field_filled |= 1U << 2;
  84                         r = parse_loadavg_fixed_point(v, &rp.avg300);
  85                 } else if ((v = startswith(w, "total="))) {
  86                         if (field_filled & (1U << 3))
  87                                 return -EINVAL;
  88
  89                         field_filled |= 1U << 3;
  90                         r = safe_atou64(v, &rp.total);
  91                 } else
  92                         continue;
  93
  94                 if (r < 0)
  95                         return r;
  96         }
  97
  98         if (r < 0)
  99                 return r;
 100
 101         if (field_filled != 15U)
 102                 return -EINVAL;
 103
 104         *ret = rp;
 105         return 0;
 106 }
 107
 108 int is_pressure_supported(void) {
 109         const char *p;
 110
 111         /* The pressure files, both under /proc and in cgroups, will exist
 112          * even if the kernel has PSI support disabled; we have to read
 113          * the file to make sure it doesn't return -EOPNOTSUPP */
 114         FOREACH_STRING(p, "/proc/pressure/cpu", "/proc/pressure/io", "/proc/pressure/memory") {
 115                 int r;
 116
 117                 r = read_virtual_file(p, 0, NULL, NULL);
 118                 if (r == -ENOENT || ERRNO_IS_NOT_SUPPORTED(r))
 119                         return 0;
 120                 if (r < 0)
 121                         return r;
 122         }
 123
 124         return 1;
 125 }