- add chrt applet.

   text    data     bss     dec     hex filename
    769       0       0     769     301 miscutils/chrt.o
and could use some further shrinkage

6 files changed, 150 insertions, 0 deletions

diff --git a/include/applets.h b/include/applets.h
index d1bf0f36b..214e63aa2 100644
--- a/include/applets.h
+++ b/include/applets.h
@@ -74,6 +74,7 @@ USE_CHMOD(APPLET(chmod, _BB_DIR_BIN, _BB_SUID_NEVER))
 USE_CHOWN(APPLET(chown, _BB_DIR_BIN, _BB_SUID_NEVER))
 USE_CHPST(APPLET(chpst, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 USE_CHROOT(APPLET(chroot, _BB_DIR_USR_SBIN, _BB_SUID_NEVER))
+USE_CHRT(APPLET(chrt, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 USE_CHVT(APPLET(chvt, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 USE_CKSUM(APPLET(cksum, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
 USE_CLEAR(APPLET(clear, _BB_DIR_USR_BIN, _BB_SUID_NEVER))
diff --git a/include/usage.h b/include/usage.h
index d8faa4f12..4d1ecb8f5 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -382,6 +382,22 @@
 #define bbsh_full_usage \
        "The bbsh shell (command interpreter)"
 
+#define chrt_trivial_usage \
+        "[OPTION]... [prio] [pid | command [arg]...]"
+#define chrt_full_usage \
+        "manipulate real-time attributes of a process" \
+        "\n\nOptions:\n" \
+        "       -p      operate on pid\n" \
+        "       -r      set scheduling policy to SCHED_RR\n" \
+        "       -f      set scheduling policy to SCHED_FIFO\n" \
+        "       -o      set scheduling policy to SCHED_OTHER\n" \
+        "       -m      show min and max priorities"
+
+#define chrt_example_usage \
+        "$ chrt -r 4 sleep 900 ; x=$!\n" \
+        "$ chrt -f -p 3 $x\n" \
+        "You need CAP_SYS_NICE privileges to set scheduling attributes of a process"
+
 #define cp_trivial_usage \
        "[OPTION]... SOURCE DEST"
 #define cp_full_usage \
diff --git a/miscutils/Config.in b/miscutils/Config.in
index 5afeb2a7e..a1ed24368 100644
--- a/miscutils/Config.in
+++ b/miscutils/Config.in
@@ -19,6 +19,13 @@ config BBCONFIG
           The bbconfig applet will print the config file with which
           busybox was built.
 
+config CHRT
+        bool "chrt"
+        default n
+        help
+          manipulate real-time attributes of a process.
+          This requires sched_{g,s}etparam support in your libc.
+
 config CROND
         bool "crond"
         default n
diff --git a/miscutils/Kbuild b/miscutils/Kbuild
index fe147d884..455113764 100644
--- a/miscutils/Kbuild
+++ b/miscutils/Kbuild
@@ -7,6 +7,7 @@
 lib-y:=
 lib-$(CONFIG_ADJTIMEX)    += adjtimex.o
 lib-$(CONFIG_BBCONFIG)    += bbconfig.o
+lib-$(CONFIG_CHRT)        += chrt.o
 lib-$(CONFIG_CROND)       += crond.o
 lib-$(CONFIG_CRONTAB)     += crontab.o
 lib-$(CONFIG_DC)          += dc.o
diff --git a/miscutils/chrt.c b/miscutils/chrt.c
new file mode 100644
index 000000000..75d77d536
--- /dev/null
+++ b/miscutils/chrt.c
@@ -0,0 +1,124 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * chrt - manipulate real-time attributes of a process
+ * Copyright (c) 2006-2007 Bernhard Fischer
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "busybox.h"
+#include <unistd.h>
+#include <sched.h>
+#include <getopt.h> /* optind */
+#ifndef _POSIX_PRIORITY_SCHEDULING
+#warning your system may be foobared
+#endif
+static const struct {
+        const int policy;
+        const char const name[12];
+} policies[] = {
+        {SCHED_OTHER, "SCHED_OTHER"},
+        {SCHED_FIFO, "SCHED_FIFO"},
+        {SCHED_RR, "SCHED_RR"}
+};
+
+static void show_min_max(int pol) {
+        const char *fmt = "%s min/max priority\t: %d/%d\n\0%s not supported?\n";
+        int max, min;
+        max = sched_get_priority_max(pol);
+        min = sched_get_priority_min(pol);
+        if (max >= 0 && min >= 0)
+                printf(fmt, policies[pol].name, min, max);
+        else {
+                fmt += 29;
+                printf(fmt, policies[pol].name);
+        }
+}
+
+#define OPT_m (1<<0)
+#define OPT_p (1<<1)
+#define OPT_r (1<<2)
+#define OPT_f (1<<3)
+#define OPT_o (1<<4)
+
+int chrt_main(int argc, char** argv);
+int chrt_main(int argc, char** argv)
+{
+        pid_t pid = 0;
+        unsigned opt;
+        struct sched_param sp;
+        char *p_opt = NULL, *priority = NULL;
+        const char *state = "current\0new";
+        int prio = 0, policy = SCHED_RR;
+
+        opt_complementary = "r--fo:f--ro:r--fo"; /* only one policy accepted */
+        opt = getopt32(argc, argv, "+mp:rfo", &p_opt);
+        if (opt & OPT_r)
+                policy = SCHED_RR;
+        if (opt & OPT_f)
+                policy = SCHED_FIFO;
+        if (opt & OPT_o)
+                policy = SCHED_OTHER;
+
+        if (opt & OPT_m) { /* print min/max */
+                show_min_max(SCHED_FIFO);
+                show_min_max(SCHED_RR);
+                show_min_max(SCHED_OTHER);
+                fflush_stdout_and_exit(EXIT_SUCCESS);
+        }
+        if (opt & OPT_p) {
+                if (argc == optind+1) { /* -p <priority> <pid> */
+                        priority = p_opt;
+                        p_opt = argv[optind];
+                }
+                argv += optind; /* me -p <arg> */
+                pid = xatoul_range(p_opt, 1, ULONG_MAX); /* -p <pid> */
+        } else {
+                argv += optind; /* me -p <arg> */
+                priority = *argv;
+        }
+        if (priority) {
+                /* from the manpage of sched_getscheduler:
+                   [...] sched_priority can have a value
+                   in the range 0 to 99.
+                   [...] SCHED_OTHER or SCHED_BATCH  must  be  assigned
+                   the  static  priority  0. [...] SCHED_FIFO  or
+                   SCHED_RR can have a static priority in the range 1 to 99.
+                 */
+                prio = xstrtol_range(priority, 0, policy == SCHED_OTHER
+                                                                                                         ? 0 : 1, 99);
+        }
+
+        if (opt & OPT_p) {
+                int pol = 0;
+print_rt_info:
+                pol = sched_getscheduler(pid);
+                if (pol < 0)
+                        bb_perror_msg_and_die("failed to %cet pid %d's policy", 'g', pid);
+                printf("pid %d's %s scheduling policy: %s\n",
+                                pid, state, policies[pol].name);
+                if (sched_getparam(pid, &sp))
+                        bb_perror_msg_and_die("failed to get pid %d's attributes", pid);
+                printf("pid %d's %s scheduling priority: %d\n",
+                                pid, state, sp.sched_priority);
+                if (!*argv) /* no new prio given or we did print already, done. */
+                        return EXIT_SUCCESS;
+        }
+
+        sp.sched_priority = prio;
+        if (sched_setscheduler(pid, policy, &sp) < 0)
+                bb_perror_msg_and_die("failed to %cet pid %d's policy", 's', pid);
+        if (opt & OPT_p) {
+                state += 8;
+                ++argv;
+                goto print_rt_info;
+        }
+        ++argv;
+        BB_EXECVP(*argv, argv);
+        bb_perror_msg_and_die("%s", *argv);
+}
+#undef OPT_p
+#undef OPT_r
+#undef OPT_f
+#undef OPT_o
+#undef OPT_m
diff --git a/scripts/defconfig b/scripts/defconfig
index a3e59c8aa..178db1d74 100644
--- a/scripts/defconfig
+++ b/scripts/defconfig
@@ -454,6 +454,7 @@ CONFIG_FEATURE_MOUNT_LOOP=y
 #
 CONFIG_ADJTIMEX=y
 # CONFIG_BBCONFIG is not set
+CONFIG_CHRT=y
 CONFIG_CROND=y
 # CONFIG_DEBUG_CROND_OPTION is not set
 CONFIG_FEATURE_CROND_CALL_SENDMAIL=y