[skonfig.c] Implement option parser

3 files changed, 245 insertions, 10 deletions

diff --git a/Makefile.am b/Makefile.am
index 2a9c70c..b53241a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-AM_CFLAGS = -std=c99 -D_FORTIFY_SOURCE=2 -D_POSIX_C_SOURCE=1
+AM_CFLAGS = -std=c99 -D_FORTIFY_SOURCE=2 -D_POSIX_C_SOURCE=200112L
 AM_CFLAGS += -Wall
 
 if DEBUG
diff --git a/configure.ac b/configure.ac
index 0d29814..a0b8fdd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,18 +11,27 @@ AC_CONFIG_FILES([Makefile])
 AM_INIT_AUTOMAKE([subdir-objects])
 
 # Checks for programs.
-AC_PROG_CC
-
 AC_LANG([C])
 
+AC_PROG_CC
+# autoconf 2.70 obsoletes AC_PROG_CC_C99 and includes it in AC_PROG_CC
+m4_version_prereq([2.70],[],[AC_PROG_CC_C99])
+
 # Checks for libraries.
 
 # Checks for header files.
-AC_CHECK_HEADERS([stdio.h])
+AC_HEADER_STDC
+AC_HEADER_STDBOOL
+AC_CHECK_HEADERS([sys/stat.h])
+AC_HEADER_STAT
 
 # Checks for typedefs, structures, and compiler characteristics.
+AC_C_CONST
+AC_C_RESTRICT
+AC_TYPE_UINT8_T
 
 # Checks for library functions.
+AC_CHECK_FUNCS_ONCE([getenv getpwuid stat strncpy strncat])
 
 # Add debug support
 AC_ARG_ENABLE(
diff --git a/src/skonfig.c b/src/skonfig.c
index 09e2a40..b5ab37b 100644
--- a/src/skonfig.c
+++ b/src/skonfig.c
@@ -1,16 +1,242 @@
+#include "../config.h"
+
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <pwd.h>
+#include <sys/stat.h>
 
-#ifdef HAVE_CONFIG_H
-#include "../config.h"
-#else
-#error no config.h
+#if HAVE_STDBOOL_H
+#include <stdbool.h>
 #endif
+#if HAVE_STDINT_H
+#include <stdint.h>
+#endif
+
+struct sk_options {
+	const char *conf_root;
+	bool dry_run;
+	const char *init_manifest;
+	unsigned int jobs;
+	uint8_t verbosity;
+	const char *target_host;
+};
+
+static const char *EXECNAME = PACKAGE;  /* default */
+
+/* utils */
+
+#define arraylen(a) (sizeof(a)/sizeof(*a))
+
+static bool is_dir(const char * restrict pathname) {
+	/**
+	 * Check if a given pathname is a directory.
+	 *
+	 * @returns true if the given pathname exists and is a directory, false
+	 * otherwise.
+	 */
+#ifdef STAT_MACROS_BROKEN
+#error stat() macros are broken on this system. Cannot compile is_dir().
+#endif
+	struct stat s;
+	return (0 == stat(pathname, &s) && S_ISDIR(s.st_mode));
+}
+
+static const char *myhome() {
+	/**
+	 * Returns a pointer to a string containing the current user’s home
+	 * directory.
+	 * The returned pointer points to a static location (don’t free() it) and
+	 * may be changed on future invocations.
+	 *
+	 * This function makes sure that the returned string is null-terminated and
+	 * truncates the result to fit within PATH_MAX if necessary.
+	 *
+	 * @returns home dir
+	 */
+	static char home[PATH_MAX+1];
+
+	home[0] = '\0';
+	if (!getenv("HOME")) {
+		(void)strncpy(home, getenv("HOME"), PATH_MAX);
+	} else {  /* HOME unset or empty */
+		(void)strncpy(home, getpwuid(getuid())->pw_dir, PATH_MAX);
+	}
+	home[PATH_MAX] = '\0';
+
+	return (const char *)&home;
+}
+
+
+/* help */
+
+void sk_print_usage(FILE *outstream) {
+	fprintf(
+		outstream,
+		"usage: %s [-h] [-n] [-v] [-V] [-j JOBS] [-i MANIFEST] target_host\n",
+		EXECNAME);
+}
+
+void sk_print_version(FILE *outstream) {
+	fprintf(outstream, "%s %s\n", PACKAGE, VERSION);
+}
+
+void sk_print_help(FILE *outstream) {
+	/* usage */
+	sk_print_usage(outstream);
+	fprintf(outstream, "\n");
 
-#include "config.h"
+	/* version */
+	sk_print_version(outstream);
+	fprintf(outstream, "\n");
+
+	/* positional arguments */
+	fprintf(
+		outstream,
+		"positional arguments:\n"
+		"  target_host    host to configure\n"
+		"\n");
+
+	/* optional arguments */
+	fprintf(
+		outstream,
+		"optional arguments:\n"
+		"  -i             path to the manifest to be used or '-' to read from stdin\n"
+		"  -j             number of jobs to execute objects in parallel\n"
+		"  -h             show this help and exit\n"
+		"  -n             dry run: do not execute generated code\n"
+		"  -v             increase verbosity (repeat for more verbosity)\n"
+		"  -V             output version information and exit\n"
+		"\n");
+}
+
+
+/* argument parsing */
+
+static int sk_get_global_opts(
+	int argc, char *argv[], struct sk_options *options) {
+	/**
+	 * Parse skonfig options.
+	 * Will update the `options` struct.
+	 *
+	 * Options defined to print some information and exit the program will
+	 * already do so in this function, in which case the function will never
+	 * return.
+	 *
+	 * @returns true if no errors occurred during parsing, false otherwise.
+	 */
+
+	extern char *optarg;
+	extern int opterr, optind, optopt;
+	opterr = 0;
+
+	int c;
+	unsigned int posind = 1, errors = 0;
+	bool eoo = false;  /* end of options */
+
+	while (optind < argc) {
+		while (!eoo && (c = getopt(argc, argv, ":i:j:hnvV")) != -1) {
+			switch (c) {
+			case 'i':
+				options->init_manifest = optarg;
+				break;
+			case 'j': {
+				unsigned int j;
+				if ('-' == optarg[0] || 1 > (j = atoi(optarg))) {
+					fprintf(stderr, "-j must be at least 1. Assuming -j 1.\n");
+					j = 1;
+				}
+				options->jobs = j;
+				break;
+			}
+			case 'h':
+				sk_print_help(stdout);
+				exit(EXIT_SUCCESS);
+			case 'n':
+				options->dry_run = true;
+				break;
+			case 'v':
+				options->verbosity++;
+				break;
+			case 'V':
+				sk_print_version(stdout);
+				exit(EXIT_SUCCESS);
+			case ':':
+				fprintf(stderr, "%s: option requires an argument -- %c\n", EXECNAME, optopt);
+				errors++;
+				break;
+			case '?':
+			default:
+				fprintf(stderr, "%s: illegal option -- %c\n", EXECNAME, optopt);
+				errors++;
+				break;
+			}
+		}
+
+		if (0 == strcmp("--", argv[optind-1])) {
+			eoo = true;
+		}
+
+		/* handle positional argument */
+		switch (posind) {
+		case 1:
+			/* target host */
+			options->target_host = argv[optind];  /* XXX: strcpy() needed? */
+			break;
+		default:
+			fprintf(stderr, "%s: unrecognized positional argument: %s\n",
+			        EXECNAME, argv[optind]);
+			errors++;
+			break;
+		}
+
+		posind++; optind++;
+	};
+
+	if (errors) {
+		sk_print_usage(stderr);
+		return false;
+	}
+	return true;
+}
 
 int main(int argc, char *argv[]) {
+	EXECNAME = argv[0];
+
 #if DEBUG
 	printf("Debugging enabled.\n");
 #endif
-	return 0;
+
+	/* determine absolute path to ~/.skonfig */
+	char default_conf_root[PATH_MAX+1] = "";
+	(void)strncpy(default_conf_root, myhome(), arraylen(default_conf_root)-1);
+	strncat(default_conf_root, "/.skonfig",
+	        (arraylen(default_conf_root) - strlen(default_conf_root)));
+
+	struct sk_options options = {
+		/* defaults */
+		.conf_root = (const char *)default_conf_root,
+		.dry_run = false,
+		.init_manifest = "manifest/init",
+		.jobs = 1,
+		.verbosity = 0,
+		.target_host = NULL
+	};
+
+	sk_get_global_opts(argc, argv, &options);
+
+	/* check if conf_root exists */
+	if (!is_dir(options.conf_root)) {
+		fprintf(stderr, "Cannot find configuration directory.\n");
+		perror(options.conf_root);  /* is_dir sets errno */
+		/* TODO: Add link to Getting Started guide */
+		return EXIT_FAILURE;
+	}
+
+	printf("conf dir: %s\n", options.conf_root);
+	printf("target host: %s\n", options.target_host);
+
+	return EXIT_SUCCESS;
 }