From: Karel Zak <kzak@redhat.com>
Date: Fri, 22 Jul 2011 09:15:28 +0000 (+0200)
Subject: ionice: improve command line interpretation
X-Git-Tag: v2.20-rc1~49
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fcc2b2da4ca5efcc82d31b11cdb9b16f90cd31c3;p=thirdparty%2Futil-linux.git

ionice: improve command line interpretation

 ionice                       : print the current I/O prio.
 ionice COMMAND               : exec command with default (best-effort) class
 ionice -p PID [...]          : return info about the PID(s)
 ionice -c CLASS COMMAND      : exec command with the class
 ionice -c CLASS -p PID [...] : modify PID(s) class

This should be backwardly compatible and also compatible with nice(1)
from coreutils.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/schedutils/ionice.1 b/schedutils/ionice.1
index 1a01b3b870..4f9cd5041e 100644
--- a/schedutils/ionice.1
+++ b/schedutils/ionice.1
@@ -25,6 +25,11 @@ This program sets or gets the io scheduling class and priority for a program.
 If no arguments or just \fB\-p\fR is given, \fBionice\fR will query the current
 io scheduling class and priority for that process.
 
+If no class is given than
+.I COMMAND
+will be executed with "best effort" scheduling class. The default
+priority argument is 4.
+
 As of this writing, a process can be in one of three scheduling classes:
 .IP "\fBIdle\fP"
 A program running with idle io priority will only get disk time when no other
diff --git a/schedutils/ionice.c b/schedutils/ionice.c
index 7c6897f08b..f1db216ef1 100644
--- a/schedutils/ionice.c
+++ b/schedutils/ionice.c
@@ -151,11 +151,6 @@ int main(int argc, char **argv)
 			usage(stderr);
 		}
 
-	if (!set && !pid && optind == argc)
-		errx(EXIT_FAILURE, _("PID or COMMAND not specified"));
-	if (!set && !pid)
-		errx(EXIT_FAILURE, _("scheduling for the COMMAND not specified"));
-
 	switch (ioclass) {
 		case IOPRIO_CLASS_NONE:
 			if (set & 1)
@@ -174,28 +169,42 @@ int main(int argc, char **argv)
 			errx(EXIT_FAILURE, _("bad prio class %d"), ioclass);
 	}
 
-	if (!set) {
+	if (!set && !pid && optind == argc)
+		/*
+		 * ionice without options, print the current ioprio
+		 */
+		ioprio_print(0);
+
+	else if (!set && pid) {
+		/*
+		 * ionice -p PID [PID ...]
+		 */
 		ioprio_print(pid);
 
 		for(; argv[optind]; ++optind) {
 			pid = strtol_or_err(argv[optind], _("failed to parse pid"));
 			ioprio_print(pid);
 		}
-	} else {
-		if (pid) {
-			ioprio_setpid(pid, ioclass, data);
+	} else if (set && pid) {
+		/*
+		 * ionice -c CLASS -p PID [PID ...]
+		 */
+		ioprio_setpid(pid, ioclass, data);
 
-			for(; argv[optind]; ++optind) {
-				pid = strtol_or_err(argv[optind], _("failed to parse pid"));
-				ioprio_setpid(pid, ioclass, data);
-			}
-		} else if (argv[optind]) {
-			ioprio_setpid(0, ioclass, data);
-			execvp(argv[optind], &argv[optind]);
-			/* execvp should never return */
-			err(EXIT_FAILURE, _("executing %s failed"), argv[optind]);
+		for(; argv[optind]; ++optind) {
+			pid = strtol_or_err(argv[optind], _("failed to parse pid"));
+			ioprio_setpid(pid, ioclass, data);
 		}
-	}
+	} else if (argv[optind]) {
+		/*
+		 * ionice [-c CLASS] COMMAND
+		 */
+		ioprio_setpid(0, ioclass, data);
+		execvp(argv[optind], &argv[optind]);
+		err(EXIT_FAILURE, _("executing %s failed"), argv[optind]);
+	} else
+		usage(stderr);
+
 
 	return EXIT_SUCCESS;
 }