renice.c 3.8 KB

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  1. /* vi: set sw=4 ts=4: */
  2. /*
  3. * renice implementation for busybox
  4. *
  5. * Copyright (C) 2005 Manuel Novoa III <mjn3@codepoet.org>
  6. *
  7. * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  8. */
  9. /* Notes:
  10. * Setting an absolute priority was obsoleted in SUSv2 and removed
  11. * in SUSv3. However, the common linux version of renice does
  12. * absolute and not relative. So we'll continue supporting absolute,
  13. * although the stdout logging has been removed since both SUSv2 and
  14. * SUSv3 specify that stdout isn't used.
  15. *
  16. * This version is lenient in that it doesn't require any IDs. The
  17. * options -p, -g, and -u are treated as mode switches for the
  18. * following IDs (if any). Multiple switches are allowed.
  19. */
  20. //config:config RENICE
  21. //config: bool "renice (4.2 kb)"
  22. //config: default y
  23. //config: help
  24. //config: Renice alters the scheduling priority of one or more running
  25. //config: processes.
  26. //applet:IF_RENICE(APPLET_NOEXEC(renice, renice, BB_DIR_USR_BIN, BB_SUID_DROP, renice))
  27. //kbuild:lib-$(CONFIG_RENICE) += renice.o
  28. //usage:#define renice_trivial_usage
  29. //usage: "[-n] PRIORITY [[-p | -g | -u] ID...]..."
  30. //usage:#define renice_full_usage "\n\n"
  31. //usage: "Change scheduling priority of a running process\n"
  32. //usage: "\n -n Add PRIORITY to current nice value"
  33. //usage: "\n Without -n, nice value is set to PRIORITY"
  34. //usage: "\n -p Process ids (default)"
  35. //usage: "\n -g Process group ids"
  36. //usage: "\n -u Process user names"
  37. #include "libbb.h"
  38. int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  39. int renice_main(int argc UNUSED_PARAM, char **argv)
  40. {
  41. static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
  42. int retval = EXIT_SUCCESS;
  43. int which = PRIO_PROCESS; /* Default 'which' value. */
  44. int use_relative = 0;
  45. int adjustment, new_priority;
  46. unsigned who;
  47. char *arg;
  48. /* Yes, they are not #defines in glibc 2.4! #if won't work */
  49. BUILD_BUG_ON(PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX);
  50. BUILD_BUG_ON(PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX);
  51. BUILD_BUG_ON(PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX);
  52. arg = *++argv;
  53. /* Check if we are using a relative adjustment. */
  54. if (arg && arg[0] == '-' && arg[1] == 'n') {
  55. use_relative = 1;
  56. if (!arg[2])
  57. arg = *++argv;
  58. else
  59. arg += 2;
  60. }
  61. if (!arg) { /* No args? Then show usage. */
  62. bb_show_usage();
  63. }
  64. /* Get the priority adjustment (absolute or relative). */
  65. adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
  66. while ((arg = *++argv) != NULL) {
  67. /* Check for a mode switch. */
  68. if (arg[0] == '-' && arg[1]) {
  69. static const char opts[] ALIGN1 = {
  70. 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
  71. };
  72. const char *p = strchr(opts, arg[1]);
  73. if (p) {
  74. which = p[4];
  75. if (!arg[2])
  76. continue;
  77. arg += 2;
  78. }
  79. }
  80. /* Process an ID arg. */
  81. if (which == PRIO_USER) {
  82. struct passwd *p;
  83. /* NB: use of getpwnam makes it risky to be NOFORK, switch to getpwnam_r? */
  84. p = getpwnam(arg);
  85. if (!p) {
  86. bb_error_msg("unknown user %s", arg);
  87. goto HAD_ERROR;
  88. }
  89. who = p->pw_uid;
  90. } else {
  91. who = bb_strtou(arg, NULL, 10);
  92. if (errno) {
  93. bb_error_msg("invalid number '%s'", arg);
  94. goto HAD_ERROR;
  95. }
  96. }
  97. /* Get priority to use, and set it. */
  98. if (use_relative) {
  99. int old_priority;
  100. errno = 0; /* Needed for getpriority error detection. */
  101. old_priority = getpriority(which, who);
  102. if (errno) {
  103. bb_perror_msg(Xetpriority_msg, 'g');
  104. goto HAD_ERROR;
  105. }
  106. new_priority = old_priority + adjustment;
  107. } else {
  108. new_priority = adjustment;
  109. }
  110. if (setpriority(which, who, new_priority) == 0) {
  111. continue;
  112. }
  113. bb_perror_msg(Xetpriority_msg, 's');
  114. HAD_ERROR:
  115. retval = EXIT_FAILURE;
  116. }
  117. /* No need to check for errors outputting to stderr since, if it
  118. * was used, the HAD_ERROR label was reached and retval was set. */
  119. return retval;
  120. }