Add service command that dumps the command lines of a service file

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

servicecmd/Makemodule.am

@@ -1,7 +1,8 @@
 SRVHEADERS = servicecmd/servicecmd.h
 
 service_SOURCES = servicecmd/servicecmd.c servicecmd/help.c servicecmd/list.c
-service_SOURCES += servicecmd/enable.c servicecmd/disable.c $(SRVHEADERS)
+service_SOURCES += servicecmd/enable.c servicecmd/disable.c
+service_SOURCES += servicecmd/dumpscript.c $(SRVHEADERS)
 service_CPPFLAGS = $(AM_CPPFLAGS)
 service_CFLAGS = $(AM_CFLAGS)
 service_LDFLAGS = $(AM_LDFLAGS)

servicecmd/dumpscript.c

@@ -0,0 +1,182 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "servicecmd.h"
+#include "service.h"
+
+static service_t *try_load(const char *directory, const char *filename)
+{
+	int dirfd, type;
+	struct stat sb;
+	service_t *svc;
+
+	dirfd = open(directory, O_RDONLY | O_DIRECTORY);
+
+	if (dirfd < 0) {
+		perror(directory);
+		return NULL;
+	}
+
+	if (fstatat(dirfd, filename, &sb, AT_SYMLINK_NOFOLLOW)) {
+		fprintf(stderr, "stat %s/%s: %s\n",
+			directory, filename, strerror(errno));
+		close(dirfd);
+		return NULL;
+	}
+
+	type = (sb.st_mode & S_IFMT);
+
+	if (type != S_IFREG && type != S_IFLNK)
+		return NULL;
+
+	svc = rdsvc(dirfd, filename);
+	close(dirfd);
+	return svc;
+}
+
+enum {
+	NEED_QUOTES = 0x01,
+	NEED_ESCAPE = 0x02,
+};
+
+static int check_str(const char *str)
+{
+	int ret = 0;
+
+	while (*str != '\0') {
+		if (isspace(*str))
+			ret |= NEED_QUOTES;
+
+		if (!isascii(*str) || !isprint(*str))
+			ret |= NEED_ESCAPE | NEED_QUOTES;
+
+		if (*str == '\\' || *str == '"' || *str == '\n')
+			ret |= NEED_ESCAPE | NEED_QUOTES;
+
+		++str;
+	}
+
+	return ret;
+}
+
+static void print_str(const char *str)
+{
+	int flags = check_str(str);
+
+	if (flags & NEED_QUOTES)
+		fputc('"', stdout);
+
+	if (flags & NEED_ESCAPE) {
+		while (*str != '\0') {
+			switch (*str) {
+			case '\a': fputs("\\a", stdout); break;
+			case '\b': fputs("\\b", stdout); break;
+			case '\f': fputs("\\f", stdout); break;
+			case '\r': fputs("\\r", stdout); break;
+			case '\t': fputs("\\t", stdout); break;
+			case '\n': fputs("\\n", stdout); break;
+			case '\\':
+			case '"':
+				fprintf(stdout, "\\%c", *str);
+				break;
+			default:
+				if (!isascii(*str) || !isprint(*str)) {
+					fprintf(stdout, "\\x%02X", *str);
+				} else {
+					fputc(*str, stdout);
+				}
+				break;
+			}
+			++str;
+		}
+	} else {
+		fputs(str, stdout);
+	}
+
+	if (flags & NEED_QUOTES)
+		fputc('"', stdout);
+}
+
+static int cmd_dumpscript(int argc, char **argv)
+{
+	char *filename, *ptr;
+	service_t *svc;
+	size_t len;
+	exec_t *e;
+	int i;
+
+	if (check_arguments(argv[0], argc, 2, 3))
+		return EXIT_FAILURE;
+
+	for (len = 1, i = 1; i < argc; ++i)
+		len += strlen(argv[i]) + 1;
+
+	filename = alloca(len);
+	filename[0] = '\0';
+
+	for (i = 1; i < argc; ++i) {
+		if (i > 1)
+			strcat(filename, "@");
+		strcat(filename, argv[i]);
+	}
+
+	svc = try_load(SVCDIR, filename);
+
+	if (svc == NULL) {
+		fprintf(stderr, "Could not load service '%s'\n", filename);
+		return EXIT_FAILURE;
+	}
+
+	fprintf(stdout, "#\n# commands executed for serice '%s'\n#\n",
+		filename);
+
+	for (e = svc->exec; e != NULL; e = e->next) {
+		ptr = e->args;
+
+		for (i = 0; i < e->argc; ++i) {
+			if (i)
+				fputc(' ', stdout);
+
+			print_str(ptr);
+			ptr += strlen(ptr) + 1;
+		}
+		
+		putchar('\n');
+	}
+
+	delsvc(svc);
+	return EXIT_SUCCESS;
+}
+
+static command_t dumpscript = {
+	.cmd = "dumpscript",
+	.usage = "<name> [arguments]",
+	.s_desc = "print commands executed for a service",
+	.l_desc = "This parses a service file from " SVCDIR " and "
+		  "produces a pseudo-shell-script containing the "
+		  "exact commands after argument expansion that init "
+		  "runs when starting the service.",
+	.run_cmd = cmd_dumpscript,
+};
+
+REGISTER_COMMAND(dumpscript)