src/basic/sysctl-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <stdio.h>
   6 #include <unistd.h>
   7
   8 #include "fd-util.h"
   9 #include "fileio.h"
  10 #include "log.h"
  11 #include "macro.h"
  12 #include "path-util.h"
  13 #include "string-util.h"
  14 #include "sysctl-util.h"
  15
  16 char *sysctl_normalize(char *s) {
  17         char *n;
  18
  19         n = strpbrk(s, "/.");
  20
  21         /* If the first separator is a slash, the path is
  22          * assumed to be normalized and slashes remain slashes
  23          * and dots remains dots. */
  24
  25         if (n && *n == '.')
  26                 /* Dots become slashes and slashes become dots. Fun. */
  27                 do {
  28                         if (*n == '.')
  29                                 *n = '/';
  30                         else
  31                                 *n = '.';
  32
  33                         n = strpbrk(n + 1, "/.");
  34                 } while (n);
  35
  36         path_simplify(s);
  37
  38         /* Kill the leading slash, but keep the first character of the string in the same place. */
  39         if (*s == '/' && *(s+1))
  40                 memmove(s, s+1, strlen(s));
  41
  42         return s;
  43 }
  44
  45 int sysctl_write(const char *property, const char *value) {
  46         char *p;
  47         _cleanup_close_ int fd = -1;
  48
  49         assert(property);
  50         assert(value);
  51
  52         log_debug("Setting '%s' to '%.*s'.", property, (int) strcspn(value, NEWLINE), value);
  53
  54         p = strjoina("/proc/sys/", property);
  55         fd = open(p, O_WRONLY|O_CLOEXEC);
  56         if (fd < 0)
  57                 return -errno;
  58
  59         if (!endswith(value, "\n"))
  60                 value = strjoina(value, "\n");
  61
  62         if (write(fd, value, strlen(value)) < 0)
  63                 return -errno;
  64
  65         return 0;
  66 }
  67
  68 int sysctl_writef(const char *property, const char *format, ...) {
  69         _cleanup_free_ char *v = NULL;
  70         va_list ap;
  71         int r;
  72
  73         va_start(ap, format);
  74         r = vasprintf(&v, format, ap);
  75         va_end(ap);
  76
  77         if (r < 0)
  78                 return -ENOMEM;
  79
  80         return sysctl_write(property, v);
  81 }
  82
  83 int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value) {
  84         const char *p;
  85
  86         assert(IN_SET(af, AF_INET, AF_INET6));
  87         assert(property);
  88         assert(value);
  89
  90         p = strjoina("/proc/sys/net/ipv", af == AF_INET ? "4" : "6",
  91                      ifname ? "/conf/" : "", strempty(ifname),
  92                      property[0] == '/' ? "" : "/", property);
  93
  94         log_debug("Setting '%s' to '%s'", p, value);
  95
  96         return write_string_file(p, value, WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_DISABLE_BUFFER);
  97 }
  98
  99 int sysctl_read(const char *property, char **ret) {
 100         char *p;
 101
 102         assert(property);
 103         assert(ret);
 104
 105         p = strjoina("/proc/sys/", property);
 106         return read_full_virtual_file(p, ret, NULL);
 107 }
 108
 109 int sysctl_read_ip_property(int af, const char *ifname, const char *property, char **ret) {
 110         _cleanup_free_ char *value = NULL;
 111         const char *p;
 112         int r;
 113
 114         assert(IN_SET(af, AF_INET, AF_INET6));
 115         assert(property);
 116
 117         p = strjoina("/proc/sys/net/ipv", af == AF_INET ? "4" : "6",
 118                      ifname ? "/conf/" : "", strempty(ifname),
 119                      property[0] == '/' ? "" : "/", property);
 120
 121         r = read_full_virtual_file(p, &value, NULL);
 122         if (r < 0)
 123                 return r;
 124
 125         truncate_nl(value);
 126         if (ret)
 127                 *ret = TAKE_PTR(value);
 128
 129         return r;
 130 }