Merge branch 'add-hostname' into 'current'

Add hostname(1) implementation

See merge request adelie/shimmy!1

4 files changed, 330 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 26b890c..4e355cb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,18 +1,24 @@
 .POSIX:
 
-all: getconf/getconf localedef/localedef
+all: getconf/getconf hostname/hostname localedef/localedef
 
 getconf/getconf:
 	cd getconf && $(MAKE)
 
+hostname/hostname:
+	cd hostname && $(MAKE)
+
 localedef/localedef:
 	cd localedef && ${MAKE}
 
 clean:
 	cd getconf && $(MAKE) clean
+	cd hostname && $(MAKE) clean
+	cd localedef && $(MAKE) clean
 
 install:
 	mkdir -p $(DESTDIR)/usr/bin
 	mkdir -p $(DESTDIR)/usr/share/man/man1
 	cd getconf && $(MAKE) install
+	cd hostname && $(MAKE) install
 	cd localedef && $(MAKE) install
diff --git a/hostname/Makefile b/hostname/Makefile
new file mode 100644
index 0000000..bb4dc1b
--- /dev/null
+++ b/hostname/Makefile
@@ -0,0 +1,16 @@
+.POSIX:
+
+VERSTR=0.7
+
+CFLAGS=-D _POSIX_C_SOURCE=200809L -D _XOPEN_SOURCE=700 -D SHIMMY_VERSION=\"$(VERSTR)\"
+
+hostname: hostname.c
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
+
+clean:
+	-rm hostname
+
+install: hostname
+	cp hostname $(DESTDIR)/usr/bin/hostname
+	cp hostname.1 $(DESTDIR)/usr/share/man/man1/hostname.1
+
diff --git a/hostname/hostname.1 b/hostname/hostname.1
new file mode 100644
index 0000000..94e12eb
--- /dev/null
+++ b/hostname/hostname.1
@@ -0,0 +1,36 @@
+.Dd April 22, 2022
+.Dt GETCONF 1 "Base Commands Manual"
+.Os "Adélie Linux"
+.Sh NAME
+.Nm hostname
+.Nd get or set node name
+.Sh SYNOPSIS
+.Nm
+.Nm
+.Op Fl F Ar filename
+.Ar name
+.Sh DESCRIPTION
+In the first form, the
+.Nm
+utility prints the current node name on the running system.
+.Pp
+In the second form, the
+.Nm
+utility sets the currenet node name to the value specified.
+.Sh OPTIONS
+.Sh DIAGNOSTICS
+.Ex -std
+.Sh SEE ALSO
+.Xr gethostname 3 ,
+.Xr getaddrinfo 3 ,
+.Xr getnameinfo 3 .
+.Sh STANDARDS
+The eventual goal for the
+.Nm
+utility is full conformance to LSB 5.0.
+.Sh AUTHORS
+.An A. Wilcox
+.Aq awilfox@adelielinux.org
+.Sh BUGS
+Documentation is incomplete.  NIS/YP domain name support is not available
+in this release.  Long options accepted by net-tools are not accepted.
diff --git a/hostname/hostname.c b/hostname/hostname.c
new file mode 100644
index 0000000..7dcef71
--- /dev/null
+++ b/hostname/hostname.c
@@ -0,0 +1,271 @@
+/*
+ * hostname - get or set the node name of the current workstation.
+ * Copyright (c) 2022 A. Wilcox.  All rights reserved.
+ * Licensed under the NCSA open source license.
+ * See LICENSE file included with this source for more information.
+ */
+
+
+#include <arpa/inet.h>	/* inet_ntop */
+#include <errno.h>	/* errno */
+#include <stdbool.h>	/* bool type and true/false */
+#include <stdio.h>	/* stderr, stdout, fprintf, fflush */
+#include <stdlib.h>	/* EXIT_FAILURE, EXIT_SUCCESS */
+#include <string.h>	/* strchr */
+#include <unistd.h>	/* getopt, sysconf */
+
+/* gai and friends */
+#include <sys/socket.h>
+#include <netdb.h>
+
+/* open, read, close */
+#include <sys/stat.h>
+#include <fcntl.h>
+
+int sethostname(const char *value,
+#ifdef __linux__
+	size_t
+#else
+	int
+#endif
+	namelen);
+
+int do_print_nodename(bool verbose, bool domain, bool fqdn, bool address, bool shorten)
+{
+	long hostname = sysconf(_SC_HOST_NAME_MAX);
+	char buf[hostname];
+	struct addrinfo *info;
+
+	if(verbose)
+	{
+		fprintf(stderr, "gethostname()=...");
+		fflush(stderr);
+	}
+	if(gethostname(buf, sizeof buf) != 0)
+	{
+		if(verbose) fprintf(stderr, "{error}\n");
+		perror("gethostname");
+		return EXIT_FAILURE;
+	}
+
+	if(verbose) fprintf(stderr, "\"%s\"\n", buf);
+
+	if(domain || fqdn || address)
+	{
+		struct addrinfo hints = {0};
+		char addr_buf[INET6_ADDRSTRLEN];
+	
+		if(verbose)
+		{
+			fprintf(stderr, "getaddrinfo(\"%s\")=...", buf);
+			fflush(stderr);
+		}
+
+		hints.ai_family = AF_UNSPEC;
+		hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
+
+		if(getaddrinfo(buf, NULL, &hints, &info) != 0)
+		{
+			if(verbose) fprintf(stderr, "{error}\n");
+			perror("getaddrinfo");
+			return EXIT_FAILURE;
+		}
+
+		if(info == NULL || info->ai_canonname == NULL)
+		{
+			if(verbose) fprintf(stderr, "{no information}\n");
+			fprintf(stderr, "No information available\n");
+			return EXIT_FAILURE;
+		}
+
+		if(getnameinfo(info->ai_addr, info->ai_addrlen, addr_buf, sizeof addr_buf,
+				NULL, 0, NI_NUMERICHOST) != 0 && address)
+		{
+			if(verbose) fprintf(stderr, "{getnameinfo returned error}\n");
+			perror("getnameinfo");
+			return EXIT_FAILURE;
+		}
+
+		if(verbose) fprintf(stderr, "resolved: %s at %s\n", info->ai_canonname, addr_buf);
+
+		if(domain)
+		{
+			char *domain = strchr(info->ai_canonname, '.');
+			if(domain == NULL)
+			{
+				fprintf(stdout, "(none)\n");
+				return EXIT_SUCCESS;
+			}
+			fprintf(stdout, "%s\n", domain + 1);
+			return EXIT_SUCCESS;
+		}
+
+		if(fqdn)
+		{
+			fprintf(stdout, "%s\n", info->ai_canonname);
+			return EXIT_SUCCESS;
+		}
+
+		if(address)
+		{
+			fprintf(stdout, "%s\n", addr_buf);
+			return EXIT_SUCCESS;
+		}
+	}
+
+	if(shorten)
+	{
+		char *domain = strchr(buf, '.');
+		if(domain != NULL) *domain = '\0';
+	}
+
+	fprintf(stdout, "%s\n", buf);
+	return EXIT_SUCCESS;
+}
+
+int do_set_nodename(bool file, const char *value)
+{
+	size_t len;
+
+	if(file)
+	{
+		/* This is insane.  There is no validation whatsoever.
+		 * However, strace on net-tools hostname(1) shows this to be
+		 * the exact algorithm used, so... */
+		char buf[1025];
+		int fildes = open(value, O_RDONLY);
+		ssize_t result = 0;
+
+		if(fildes == -1)
+		{
+			perror("open");
+			return EXIT_FAILURE;
+		}
+
+		while(true)
+		{
+			char *curr = buf;
+			memset(buf, 0, sizeof buf);
+			result = read(fildes, buf, sizeof buf - 1);
+			switch(result)
+			{
+			case -1:
+				perror("read");
+				close(fildes);
+				return EXIT_FAILURE;
+			case 0:
+				close(fildes);
+				return EXIT_SUCCESS;
+			}
+			do
+			{
+				len = strnlen(curr, result);
+				char *pos = strchr(curr, '\n');
+				if(pos)
+				{
+					len = pos - curr;
+				}
+				if(len == 0 || *curr == '#') continue;
+				while(len > 63)
+				{
+					sethostname(curr, 63);
+					len -= 63;
+					curr += 63;
+				}
+				sethostname(curr, len);
+			} while((curr = strchr(curr, '\n')) && curr++);
+		}
+	}
+
+	len = strlen(value);
+	sethostname(value, len);
+	return EXIT_SUCCESS;
+}
+
+void usage()
+{
+	fprintf(stderr, "usage:\n");
+	fprintf(stderr, "hostname {hostname|-F filename}\n");
+	fprintf(stderr, "hostname [-v] [-d|-f|-s]\n");
+	fprintf(stderr, "\n\tRetrieve or set node name.\n");
+}
+
+int main(int argc, char *argv[])
+{
+	/* Whether to use a file or argument */
+	bool is_file = false;
+	/* Enable verbose output */
+	bool verbose = false;
+	/* Intentionally shorten name to first part */
+	bool shorten = false;
+	/* Show DNS domain name only (if available) */
+	bool domain = false;
+	/* Go out of our way to show FQDN */
+	bool fqdn = false;
+	/* Print the IP address associated with this node */
+	bool address = false;
+	/* An error occurred during argument parsing */
+	bool arg_error = false;
+	/* The current argument being parsed */
+	int arg;
+
+	while((arg = getopt(argc, argv, ":FVvdfish")) != -1)
+	{
+		switch(arg)
+		{
+		case 'v':
+			verbose = true;
+			break;
+		case 'd':
+			domain = true;
+			break;
+		case 'F':
+			is_file = true;
+			break;
+		case 'f':
+			fqdn = true;
+			break;
+		case 'i':
+			address = true;
+			break;
+		case 's':
+			shorten = true;
+			break;
+		case 'h':
+			usage();
+			return EXIT_SUCCESS;
+		case 'V':
+			fprintf(stdout, "Shimmy " SHIMMY_VERSION "\n");
+			return EXIT_SUCCESS;
+		case ':':
+			fprintf(stderr, "required argument to '-%c' missing\n",
+				optopt);
+			arg_error = true;
+			break;
+		case '?':
+		default:
+			fprintf(stderr, "unrecognised option: '-%c'\n", optopt);
+			arg_error = true;
+			break;
+		}
+	}
+
+	switch(argc - optind)
+	{
+	case 0:
+		if(is_file || arg_error)
+		{
+			arg_error = true;
+			break;
+		}
+		return do_print_nodename(verbose, domain, fqdn, address, shorten);
+	case 1:
+		return do_set_nodename(is_file, argv[optind++]);
+	default:
+		/* just show usage. */
+		break;
+	}
+
+	usage();
+	return EXIT_FAILURE;
+}