after

commit e9d14c1f997bea3068913cf242c50108b8cd3e36
Author: e-zk <58356365+e-zk@users.noreply.github.com>
Date:   Mon,  7 Dec 2020 15:51:24 +1000

initial commit

Diffstat:
A
README
 | 
27
+++++++++++++++++++++++++++
A
after.c
 | 
143
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
mkfile
 | 
10
++++++++++

3 files changed, 180 insertions(+), 0 deletions(-)
diff --git a/README b/README
@@ -0,0 +1,27 @@
+after
+=====
+
+After the specified process dies, echo a string. (OpenBSD only).
+
+Usage
+-----
+
+	after [-h] [-v] [-p pid | -n process_name] -e string
+
+The process to watch is specified `-p pid' or `-n process_name'.
+After this process dies the string specified by `-e string' will be printed
+to standard output.
+
+Examples
+--------
+
+The following are some examples to illustrate how after can be useful (or not).
+
+Notify yourself when your build is done:
+
+	$ after -p 2027 -e "build is done!"
+
+Put your machine to sleep after your updates are complete:
+
+	$ after -n pkg_add -e "doas zzz" | sh
+
diff --git a/after.c b/after.c
@@ -0,0 +1,143 @@
+#include <sys/param.h>	/* MAXCOMLEN NODEV */
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/proc.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <kvm.h>
+#include <locale.h>
+#include <nlist.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+
+static void
+usage(void)
+{
+	printf("usage: after [-h] [-v] [-p pid | -n process_name] -e string\n");
+}
+
+int
+pid_is_in(int pid, struct kinfo_proc **kinfo, int entries)
+{
+	int i;
+	for (i = 0; i < entries; i++) {
+		if (kinfo[i]->p_pid == pid)
+			return 0;
+	}
+	return -1;
+}
+
+int
+pname_is_in(char *pname, struct kinfo_proc **kinfo, int entries)
+{
+	int i;
+	for (i = 0; i < entries; i++) {
+		if (strcmp(kinfo[i]->p_comm, pname) == 0)
+			return 0;
+	}
+	return -1;
+}
+
+struct kinfo_proc **
+get_proc_list(kvm_t *kd, int *entries) {
+	int i;
+	struct kinfo_proc *kp, **kinfo;
+
+	// get proc list
+	kp = kvm_getprocs(kd, KERN_PROC_ALL, 0, sizeof(*kp), entries);
+	if (kp == NULL)
+		errx(1, "%s", kvm_geterr(kd));
+
+	// this may not be necessary since we are not sorting our array at any point
+	if ((kinfo = reallocarray(NULL, *entries, sizeof(*kinfo))) == NULL)
+		err(1, "failed to allocate memory for proc pointers");
+	for (i = 0; i < *entries; i++)
+		kinfo[i] = &kp[i];
+
+	return kinfo;
+}
+
+int 
+main(int argc, char *argv[])
+{
+	int i, ch, entries, verbose = 0, pid = 0;
+	char *prog_name = argv[0], *pname = NULL, *cmd = NULL;
+	char errbuf[_POSIX2_LINE_MAX];
+
+	struct kinfo_proc **kinfo;
+	kvm_t *kd;
+
+	// argument parsing...
+	while((ch = getopt(argc, argv, "hn:p:ve:")) != -1)
+		switch(ch) {
+		case 'n':
+			pname = optarg;
+			break;
+		case 'p':
+			sscanf(optarg, "%d", &pid);
+			break;
+		case 'e':
+			cmd = optarg;
+			break;
+		case 'v':
+			verbose = 1;
+			break;
+		case 'h':
+			usage();
+			return 0;
+		default:
+			usage();
+			exit(1);
+		}
+	argc -= optind;
+	argv += optind;
+
+	// show usage if neither a pid nor a pname are given
+	if (!(pname != NULL || pid != 0)) {
+		usage();
+		exit(1);
+	}
+
+
+	// initialise virtual memory access
+	kd = kvm_openfiles(NULL, NULL, NULL, KVM_NO_FILES, errbuf);
+	if (kd == NULL)
+		errx(1, "%s", errbuf);
+
+	// get initial process list
+	kinfo = get_proc_list(kd, &entries);
+
+	// if a process name is given
+	if (pname != NULL) {
+		while(pname_is_in(pname, kinfo, entries) == 0) {
+			kinfo = get_proc_list(kd, &entries);
+			if (verbose == 1)
+				fprintf(stderr, "%s: waiting...\n", prog_name);
+			sleep(1);
+		}
+	}
+	else {
+		while(pid_is_in(pid, kinfo, entries) == 0) {
+			kinfo = get_proc_list(kd, &entries);
+			if (verbose == 1)
+				fprintf(stderr, "%s: waiting...\n", prog_name);
+			sleep(1);
+		}
+	}
+
+	if (verbose == 1)
+		fprintf(stderr, "%s: process not in process list.\n", prog_name);
+
+	printf("%s\n", cmd);
+
+	return 0;
+}
diff --git a/mkfile b/mkfile
@@ -0,0 +1,10 @@
+PREFIX=/usr/local
+CFLAGS=
+LDFLAGS=-lkvm
+CC=cc
+
+after: after.c
+	$CC $LDFLAGS $CFLAGS -o after after.c
+
+clean:V:
+	rm after