coreutils

nice: Add POSIX nice

Diffstat

4 files changed, 155 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 217d169..673c463 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,6 +18,7 @@ ADD_EXECUTABLE(false    ${CMAKE_SOURCE_DIR}/src/false.c)
 ADD_EXECUTABLE(link     ${CMAKE_SOURCE_DIR}/src/link.c)
 ADD_EXECUTABLE(logname  ${CMAKE_SOURCE_DIR}/src/logname.c)
 ADD_EXECUTABLE(mkdir    ${CMAKE_SOURCE_DIR}/src/mkdir.c)
+ADD_EXECUTABLE(nice     ${CMAKE_SOURCE_DIR}/src/nice.c)
 ADD_EXECUTABLE(pwd      ${CMAKE_SOURCE_DIR}/src/pwd.c)
 ADD_EXECUTABLE(rmdir    ${CMAKE_SOURCE_DIR}/src/rmdir.c)
 ADD_EXECUTABLE(sleep    ${CMAKE_SOURCE_DIR}/src/sleep.c)
diff --git a/README.md b/README.md
index a29971b..03d2bcb 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ UNIX-like systems.
 | link             | Create a link to a file                  | POSIX    |
 | logname          | Return the user's login name             | POSIX    |
 | mkdir            | Make directories                         | POSIX    |
+| nice             | Execute with an altered nice value       | POSIX    |
 | pwd              | Print working directory                  | POSIX    |
 | rmdir            | Remove directories                       | POSIX    |
 | sleep            | Suspend execution for an interval        | POSIX    |
diff --git a/man/nice.1 b/man/nice.1
new file mode 100644
index 0000000..17ac50c
--- /dev/null
+++ b/man/nice.1
@@ -0,0 +1,49 @@
+.TH NICE 1 2020-06-27 "OMKOV coreutils" "General Commands Manual"
+.SH NAME
+nice \(em execute with an altered nice value
+.SH SYNOPSYS
+\fBnice\fR [-n \fIincrement\fR] [\fIcommand\fR [\fIargument\fR...]]
+.SH DESCRIPTION
+Execute \fIcommand\fR with the specified nice \fIincrement\fR value. If no
+\fIincrement\fR is given, it will default to 10. If no \fIcommand\fR is given,
+the current nice value will be output.
+.SH OPTIONS
+The following options are supported:
+.TP
+.B -n \fIincrement\fR
+Nice increment value.
+.TP
+.B --help
+Display help message.
+.TP
+.B --version
+Display version message.
+.SH OPERANDS
+The following operands are supported:
+.TP
+.I command
+A command to execute with the altered nice value.
+.TP
+.I argument
+An argument to pass to \fIcommand\fR.
+.SH EXIT STATUS
+Upon successful completion, the exit status of nice shall be the exit status of
+\fIcommand\fR. Otherwise, the following exit values will be returned:
+.TP
+1-125
+An error occurred.
+.TP
+\ \ 126
+\fIcommand\fR was found but could not be invoked.
+.TP
+\ \ 127
+\fIcommand\fR was not found.
+.SH STANDARDS
+The \fInice\fR utility is compliant with the IEEE Std 1003.2-1992 ("POSIX.2")
+specification.
+.SH COPYRIGHT
+.nf
+Copyright (C) 2020, Jakob Wakeling
+All rights reserved.
+OMKOV Permissive Licence (https://www.omkov.net/OLPE)
+.fi
diff --git a/src/nice.c b/src/nice.c
new file mode 100644
index 0000000..f5b98d4
--- /dev/null
+++ b/src/nice.c
@@ -0,0 +1,104 @@
+// nice.c, version 1.0.0
+// OMKOV coreutils implementation of POSIX nice
+// Copyright (C) 2020, Jakob Wakeling
+// All rights reserved.
+
+/*
+OMKOV Permissive Licence, version 1.0
+
+Copyright (C) 2020, Jakob Wakeling
+All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal with
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimers.
+* Redistributions in binary form must reproduce the above copyright notice, this
+  list of conditions and the following disclaimers in the documentation and/or
+  other materials provided with the distribution.
+* Neither the names of the copyright holders, nor the names of its contributors
+  may be used to endorse or promote products derived from this Software without
+  specific prior written permission.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT
+HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.
+*/
+
+#include "error.h"
+#include "optget.h"
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+static int n = 10;
+
+static inline void help(void);
+static inline void version(void);
+
+int main(int argc, char *argv[]) {
+	lop_t lops[] = {
+		{ "help",    ARG_NUL, 256 },
+		{ "version", ARG_NUL, 257 },
+		{ NULL, 0, 0 }
+	};
+	
+	opt_t opt = OPTGET_INIT; opt.str = "n:"; opt.lops = lops; int o;
+	while ((o = optget(&opt, argv, 0)) != -1) switch (o) {
+	case 'n': {
+		register int d; register char *p = opt.arg; bool neg = false;
+		if (*p == '-') { neg = true; ++p; } else if (*p == '+') { ++p; }
+		for (n = 0; *p >= '0' && *p <= '9'; ++p) {
+			d = (int)*p - '0';
+			if (n > (INT_MAX - d) / 10) { break; }
+			n = n * 10 + d;
+		}
+		
+		if (*p) { error(1, "%s: %s: invalid nice value", argv[0], opt.arg); }
+		if (neg) { n = -n; } break;
+	}
+	case 256: { help(); return 0; }
+	case 257: { version(); return 0; }
+	default: { return 1; }
+	}
+	
+	if (argc == 1) { printf("%d\n", nice(0)); return 0; }
+	else if (opt.ind == argc) { error(1, "%s: missing operand\n", argv[0]); }
+	
+	errno = 0; nice(n); if (errno) { warn("%s: %s", argv[0], serrno); }
+	execvp(argv[opt.ind], &argv[opt.ind]);
+	
+	warn("%s: %s: %s", argv[0], argv[opt.ind], serrno);
+	return errno = ENOENT ? 127 : 126;
+}
+
+static inline void help(void) {
+	puts("nice - execute with an altered nice value\n");
+	puts("usage: nice [-n increment] [command [argument...]]\n");
+	puts("options:");
+	puts("  -n increment  Nice increment value");
+	puts("  --help        Display help information");
+	puts("  --version     Display version information");
+	return;
+}
+
+static inline void version() {
+	puts("OMKOV coreutils nice, version 1.0.0");
+	puts("Copyright (C) 2020, Jakob Wakeling");
+	puts("All rights reserved.");
+	puts("OMKOV Permissive Licence (https://www.omkov.net/OLPE)");
+	return;
+}