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/* vi: set sw=4 ts=4: */
/*
* renice implementation for busybox
*
* Copyright (C) 2005 Manuel Novoa III <mjn3@codepoet.org>
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
/* Notes:
* Setting an absolute priority was obsoleted in SUSv2 and removed
* in SUSv3. However, the common linux version of renice does
* absolute and not relative. So we'll continue supporting absolute,
* although the stdout logging has been removed since both SUSv2 and
* SUSv3 specify that stdout isn't used.
*
* This version is lenient in that it doesn't require any IDs. The
* options -p, -g, and -u are treated as mode switches for the
* following IDs (if any). Multiple switches are allowed.
*/
#include "busybox.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#include <sys/resource.h>
#if (PRIO_PROCESS < CHAR_MIN) || (PRIO_PROCESS > CHAR_MAX)
#error Assumption violated : PRIO_PROCESS value
#endif
#if (PRIO_PGRP < CHAR_MIN) || (PRIO_PGRP > CHAR_MAX)
#error Assumption violated : PRIO_PGRP value
#endif
#if (PRIO_USER < CHAR_MIN) || (PRIO_USER > CHAR_MAX)
#error Assumption violated : PRIO_USER value
#endif
static inline int int_add_no_wrap(int a, int b)
{
int s = a + b;
if (b < 0) {
if (s > a) s = INT_MIN;
} else {
if (s < a) s = INT_MAX;
}
return s;
}
int renice_main(int argc, char **argv)
{
static const char Xetpriority_msg[] = "%d : %cetpriority";
int retval = EXIT_SUCCESS;
int which = PRIO_PROCESS; /* Default 'which' value. */
int use_relative = 0;
int adjustment, new_priority;
id_t who;
++argv;
/* Check if we are using a relative adjustment. */
if (argv[0] && (argv[0][0] == '-') && (argv[0][1] == 'n') && !argv[0][2]) {
use_relative = 1;
++argv;
}
if (!*argv) { /* No args? Then show usage. */
bb_show_usage();
}
/* Get the priority adjustment (absolute or relative). */
adjustment = bb_xgetlarg(*argv, 10, INT_MIN, INT_MAX);
while (*++argv) {
/* Check for a mode switch. */
if ((argv[0][0] == '-') && argv[0][1] && !argv[0][2]) {
static const char opts[]
= { 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER };
const char *p;
if ((p = strchr(opts, argv[0][1]))) {
which = p[4];
continue;
}
}
/* Process an ID arg. */
if (which == PRIO_USER) {
struct passwd *p;
if (!(p = getpwnam(*argv))) {
bb_error_msg("unknown user: %s", *argv);
goto HAD_ERROR;
}
who = p->pw_uid;
} else {
char *e;
errno = 0;
who = strtoul(*argv, &e, 10);
if (*e || (*argv == e) || errno) {
bb_error_msg("bad value: %s", *argv);
goto HAD_ERROR;
}
}
/* Get priority to use, and set it. */
if (use_relative) {
int old_priority;
errno = 0; /* Needed for getpriority error detection. */
old_priority = getpriority(which, who);
if (errno) {
bb_perror_msg(Xetpriority_msg, who, 'g');
goto HAD_ERROR;
}
new_priority = int_add_no_wrap(old_priority, adjustment);
} else {
new_priority = adjustment;
}
if (setpriority(which, who, new_priority) == 0) {
continue;
}
bb_perror_msg(Xetpriority_msg, who, 's');
HAD_ERROR:
retval = EXIT_FAILURE;
}
/* No need to check for errors outputing to stderr since, if it
* was used, the HAD_ERROR label was reached and retval was set. */
return retval;
}
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