hare

commit df4284d616b4107ac680852d82812da74c56da6e
parent 3a6d409e84e13fba8972da4c641e8b52b06822de
Author: Drew DeVault <sir@cmpwn.com>
Date:   Mon,  5 Apr 2021 11:54:13 -0400

unix: add nice

Diffstat:
M
rt/+linux/syscalls.ha
 | 
10
++++++++++
M
rt/+linux/types.ha
 | 
5
+++++
M
scripts/gen-stdlib
 | 
2
++
M
stdlib.mk
 | 
2
++
A
unix/nice+linux.ha
 | 
23
+++++++++++++++++++++++

5 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/rt/+linux/syscalls.ha b/rt/+linux/syscalls.ha
@@ -575,3 +575,13 @@ export fn getresgid(gid: *gid_t, egid: *gid_t, sgid: *gid_t) (void | errno) = {
 		sgid: uintptr: u64))?;
 	return;
 };
+
+export fn getpriority(which: int, who: id_t) (int | errno) = {
+	return wrap_return(syscall2(SYS_setpriority,
+		which: u64, who: u64))?: int;
+};
+
+export fn setpriority(which: int, who: id_t, prio: int) (void | errno) = {
+	wrap_return(syscall3(SYS_setpriority, which: u64, who: u64, prio: u64))?;
+	return;
+};
diff --git a/rt/+linux/types.ha b/rt/+linux/types.ha
@@ -3,6 +3,7 @@ export type dev_t = u64;
 export type ino_t = u64;
 export type nlink_t = u64;
 export type mode_t = uint;
+export type id_t = uint;
 export type uid_t = uint;
 export type gid_t = uint;
 export type time_t = i64;
@@ -551,3 +552,7 @@ export type cmsg = struct {
 	hdr: cmsghdr,
 	cmsg_data: [*]u8,
 };
+
+export def PRIO_PROCESS: int = 0;
+export def PRIO_PGRP: int = 1;
+export def PRIO_USER: int = 2;
diff --git a/scripts/gen-stdlib b/scripts/gen-stdlib
@@ -571,7 +571,9 @@ unicode() {
 }
 
 unix() {
+	# XXX: getuid and setuid are probably platform-specific too
 	gen_srcs unix \
+		nice'$(PLATFORM)'.ha \
 		getuid.ha \
 		setuid.ha
 	gen_ssa unix
diff --git a/stdlib.mk b/stdlib.mk
@@ -762,6 +762,7 @@ $(HARECACHE)/unicode/unicode.ssa: $(stdlib_unicode_srcs) $(stdlib_rt)
 
 # unix
 stdlib_unix_srcs= \
+	$(STDLIB)/unix/nice$(PLATFORM).ha \
 	$(STDLIB)/unix/getuid.ha \
 	$(STDLIB)/unix/setuid.ha
 
@@ -1569,6 +1570,7 @@ $(TESTCACHE)/unicode/unicode.ssa: $(testlib_unicode_srcs) $(testlib_rt)
 
 # unix
 testlib_unix_srcs= \
+	$(STDLIB)/unix/nice$(PLATFORM).ha \
 	$(STDLIB)/unix/getuid.ha \
 	$(STDLIB)/unix/setuid.ha
 
diff --git a/unix/nice+linux.ha b/unix/nice+linux.ha
@@ -0,0 +1,23 @@
+use errors;
+use rt;
+
+// Adds the argument to the niceness of the current process. The input should be
+// between -20 and 19 (inclusive); lower numbers represent a higher priority.
+// Generally, you must have elevated permissions to reduce your niceness, but
+// not to increase it.
+export fn nice(inc: int) (void | errors::opaque) = {
+	let prio = inc;
+	if (inc > -40 && inc <= 40) {
+		prio += rt::getpriority(rt::PRIO_PROCESS, 0) as int;
+	};
+	if (prio > 19) {
+		prio = 19;
+	};
+	if (prio < -20) {
+		prio = -20;
+	};
+	return match (rt::setpriority(rt::PRIO_PROCESS, 0, prio)) {
+		void => void,
+		err: rt::errno => errors::errno(err),
+	};
+};