Simplift and change style

Signed-off-by: Mattias Andrée <maandree@kth.se>

5 files changed, 134 insertions, 127 deletions

diff --git a/Makefile b/Makefile
index 42036ba..2cd5a07 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ all: slack
 slack: slack.o
 	$(CC) -o $@ $^ $(LDFLAGS)
 
-slack.o: slack.c
+slack.o: slack.c arg.h
 	$(CC) -c -o $@ $< $(CFLAGS) $(CPPFLAGS)
 
 install: slack
diff --git a/README b/README
index da60144..bfb5961 100644
--- a/README
+++ b/README
@@ -2,8 +2,7 @@ NAME
 	slack - Spawn processes with customised timer slack
 
 SYNOPSIS
-	slack (get | GET)
-	slack ((reset | INTERVAL) [--fatal] [--] COMMAND...)
+	slack [-f] ('get' | 'GET' | ('reset' | interval) command [argument] ...
 
 DESCRIPTION
 	Get the current timer slack value or spawn a new process
@@ -17,13 +16,13 @@ DESCRIPTION
 
 	If the verb reset is used, the process shall set the
 	timer slack value for the process to the default timer
-	slack value, and exec(3) to COMMAND.
+	slack value, and exec(3) to command.
 
-	If an INTERVAL is given, the process shall set the
-	timer slack value for the process to INTERVAL, and
-	exec(3) to COMMAND.
+	If an interval is given, the process shall set the
+	timer slack value for the process to interval, and
+	exec(3) to command.
 
-	INTERVAL must be a positive number, optionally with
+	interval must be a positive number, optionally with
 	a prefix. Recognised prefixes (and units) are:
 
 	ns, n               nanoseconds (default)
@@ -35,7 +34,7 @@ DESCRIPTION
 	on PID 1.
 
 OPTIONS
-	--fatal
+	-f
 		Fail if the timer slack value cannot be set.
 
 NOTES
diff --git a/arg.h b/arg.h
new file mode 100644
index 0000000..09a5350
--- /dev/null
+++ b/arg.h
@@ -0,0 +1,38 @@
+/*
+ * Copy me if you can.
+ * by 20h
+ */
+
+#ifndef ARG_H__
+#define ARG_H__
+
+extern char *argv0;
+
+/* use main(int argc, char *argv[]) */
+#define ARGBEGIN	for (argv0 = *argv, argv++, argc--;\
+					argv[0] && argv[0][0] && argv[0][1];\
+					argc--, argv++) {\
+				char argc_;\
+				char **argv_;\
+				int brk_;\
+				if (argv[0][0] == '-') {\
+					if (argv[0][1] == '-' && argv[0][2] == '\0') {\
+						argv++;\
+						argc--;\
+						break;\
+					}\
+					for (brk_ = 0, argv[0]++, argv_ = argv;\
+							argv[0][0] && !brk_;\
+							argv[0]++) {\
+						if (argv_ != argv)\
+							break;\
+						argc_ = argv[0][0];\
+						switch (argc_)
+
+#define ARGEND				}\
+				} else {\
+					break;\
+				}\
+			}
+
+#endif
diff --git a/slack.1 b/slack.1
index f8a0c37..92289fc 100644
--- a/slack.1
+++ b/slack.1
@@ -3,12 +3,10 @@
 slack - Spawn processes with customised timer slack
 .SH SYNOPSIS
 .B slack
-(get | GET)
-.br
-.B slack
-.RI ((reset\ |\  INTERVAL )
-[\-\-fatal] [--]
-.IR COMMAND ...)
+[-f] ('get' | 'GET' | ('reset' |
+.IR interval )
+.I command
+.RI [ argument ]\ ...)
 .SH DESCRIPTION
 If the verb 
 .B get
@@ -24,19 +22,19 @@ If the verb reset is used, the process shall set the timer slack value
 for the process to the default timer slack value, and
 .BR exec (3)
 to
-.IR COMMAND .
+.IR command .
 .PP
 If an
-.I INTERVAL
+.I interval
 is given, the process shall set the timer slack value for the process
 to
-.IR INTERVAL ,
+.IR interval ,
 and
 .BR exec (3)
 to
-.IR COMMAND .
+.IR command .
 .PP
-.I INTERVAL
+.I interval
 must be a positive number, optionally with a prefix. Recognised
 prefixes (and units) are:
 .TP
@@ -55,7 +53,7 @@ seconds
 The default timer slack value is the timer slack value on PID 1.
 .SH OPTIONS
 .TP
-.B \-\-fatal
+.B \-f
 Fail if the timer slack value cannot be set.
 .SH NOTES
 Real-time threads do not slack around.
diff --git a/slack.c b/slack.c
index 28b5171..af4cf58 100644
--- a/slack.c
+++ b/slack.c
@@ -1,119 +1,91 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/prctl.h>
+#include <errno.h>
 #include <stdio.h>
-#include <string.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
-#include <sys/prctl.h>
 
+#include "arg.h"
 
+#define NS (1L)
+#define US (1000L)
+#define MS (1000L * 1000L)
+#define S  (1000L * 1000L * 1000L)
 
-#define NS  (1L)
-#define US  (1000L)
-#define MS  (1000L * 1000L)
-#define S   (1000L * 1000L * 1000L)
+char *argv0;
 
-
-static void usage(void)
+static void
+usage(void)
 {
-  printf("USAGE: slack (get | GET | ((reset | <interval>) [--fatal] [--] <command...>))\n");
-  printf("\n");
-  printf("The <interval> must be a positive number optionally with a suffix:\n");
-  printf("  ns  n           nanoseconds (default)\n");
-  printf("  µs  µ  us  u    microseconds\n");
-  printf("  ms  m           milliseconds\n");
-  printf("  s               seconds\n");
-  printf("\n");
-  printf("If `GET' is used rather than `get', the timer slack value will be printed in\n");
-  printf("nanoseconds without suffix. `GET' and `get' prints the current timer slack\n");
-  printf("value and exits.\n");
-  printf("\n");
-  printf("`reset` reset the timer slack value to the default (the time slack value for\n");
-  printf("the init process (PID 1) has.)\n");
-  printf("\n");
-  printf("Unless `--fatal` is used, the program will run <command> even if the timer\n");
-  printf("slack could not be set.\n");
-  printf("\n");
+	fprintf(stderr, "usage: %s [-f] ('get' | 'GET' | (('reset' | interval) command [argument] ...))\n", argv0);
+	exit(1);
 }
 
-
-int main(int argc, char** argv)
+int
+main(int argc, char **argv)
 {
-  long slackvalue, r;
-  int i, j, fatal = 0;
-  char** exec_argv;
-  
-  if ((argc < 2) || !strcmp(argv[1], "--help") || !strcmp(argv[1], "help"))
-    return usage(), argc < 2 ? 1 : 0;
-  
-  if (!strcmp(argv[1], "get") || !strcmp(argv[1], "GET"))
-    {
-      const char* suffix;
-      if (r = prctl(PR_GET_TIMERSLACK), r < 0)
-	perror(*argv);
-      else
-	{
-	  if (!strcmp(argv[1], "GET"))
-	    suffix = "";
-	  else if (r %  S == 0)  suffix =  "s", r /=  S;
-	  else if (r % MS == 0)  suffix = "ms", r /= MS;
-	  else if (r % US == 0)  suffix = "µs", r /= US;
-	  else                   suffix = "ns";
-	  printf("%li%s\n", r, suffix);
+	int fatal;
+	long int slackvalue;
+	const char *suffix;
+	char *end;
+	int r;
+
+	ARGBEGIN {
+	case 'f':
+		fatal = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc)
+		usage();
+
+	if (!strcmp(*argv, "get") || !strcmp(*argv, "GET")) {
+		if (argc > 1)
+			usage();
+		r = prctl(PR_GET_TIMERSLACK);
+		if (r < 0)
+			return fprintf(stderr, "%s: prctl PR_GET_TIMERSLACK: %s\n", argv0, strerror(errno)), 1;
+		if (!strcmp(*argv, "GET")) suffix = "";
+		else if (r %  S == 0)      suffix =  "s", r /=  S;
+		else if (r % MS == 0)      suffix = "ms", r /= MS;
+		else if (r % US == 0)      suffix = "µs", r /= US;
+		else                       suffix = "ns";
+		printf("%i%s\n", r, suffix);
+		return 0;
+	}
+
+	if (argc < 2)
+		usage();
+
+	if (!strcmp(*argv, "reset")) {
+		slackvalue = 0;
+	} else {
+		slackvalue = strtol(*argv, &end, 10);
+		if (end == *argv)
+			return fprintf(stderr, "%s: no slack value specified\n", argv0), 1;
+		if      (!strcmp(end, "n") || !strcmp(end, "ns") || !strcmp(end, ""))  slackvalue *= NS;
+		else if (!strcmp(end, "µ") || !strcmp(end, "µs"))                      slackvalue *= US;
+		else if (!strcmp(end, "u") || !strcmp(end, "us"))                      slackvalue *= US;
+		else if (!strcmp(end, "m") || !strcmp(end, "ms"))                      slackvalue *= MS;
+		else if (!strcmp(end, "s"))                                            slackvalue *=  S;
+		else
+			return fprintf(stderr, "%s: unrecognised suffix for slack value\n", argv0), 1;
+		if (slackvalue <= 0)
+			return fprintf(stderr, "%s: invalid slack value: %lins\n", argv0, slackvalue), 1;
+	}
+
+	r = prctl(PR_SET_TIMERSLACK, slackvalue);
+	if (r < 0) {
+		fprintf(stderr, "%s: prctl PR_SET_TIMERSLACK %li: %s\n", argv0, slackvalue, strerror(errno));
+		if (fatal)
+			return 1;
 	}
-      return r > 0 ? 0 : 1;
-    }
-  
-  for (i = 2; i < argc; i++)
-    if (!strcmp(argv[i], "--fatal"))
-      fatal = 1;
-    else if (!strcmp(argv[i], "--"))
-      {
-	i++;
-	break;
-      }
-    else if (strstr(argv[i], "-") == argv[i])
-      return usage(), 1;
-    else
-      break;
-  
-  if (i == argc)
-    return usage(), 1;
-  
-  exec_argv = malloc((argc - i + 1) * sizeof(char*));
-  if (exec_argv == NULL)
-    return perror(*argv), 2;
-  exec_argv[argc - i] = NULL;
-  for (j = 0; i < argc; j++, i++)
-    exec_argv[j] = argv[i];
-  
-  if (!strcmp(argv[1], "reset"))
-    slackvalue = 0;
-  else
-    {
-      char* end;
-      
-      slackvalue = strtol(argv[1], &end, 10);
-      if (end == argv[1])
-	return fprintf(stderr, "No slack value specified."), free(exec_argv), 1;
-      
-      if      (!strcmp(end, "n") || !strcmp(end, "ns") || !strcmp(end, ""))  slackvalue *= NS;
-      else if (!strcmp(end, "µ") || !strcmp(end, "µs"))                      slackvalue *= US;
-      else if (!strcmp(end, "u") || !strcmp(end, "us"))                      slackvalue *= US;
-      else if (!strcmp(end, "m") || !strcmp(end, "ms"))                      slackvalue *= MS;
-      else if (!strcmp(end, "s"))                                            slackvalue *=  S;
-      else
-	return fprintf(stderr, "Unrecognised suffix for slack value."), free(exec_argv), 1;
-      
-      if (slackvalue <= 0)
-	return fprintf(stderr, "Invalid slack value: %lins", slackvalue), free(exec_argv), 1;
-    }
-  
-  if (r = prctl(PR_SET_TIMERSLACK, slackvalue), r < 0)
-    if (perror(*argv), fatal)
-      return free(exec_argv), 2;
-  
-  execvp(*exec_argv, exec_argv);
-  perror(*argv);
-  free(exec_argv);
-  return 2;
-}
 
+	argv++;
+	execvp(*argv, argv);
+	fprintf(stderr, "%s: execvp %s: %s\n", argv0, *argv, strerror(errno));
+	return 1;
+}