1 files changed, 108 insertions, 15 deletions

diff --git a/alias.c b/alias.c
index 23c557a..bc3e604 100644
--- a/alias.c
+++ b/alias.c
@@ -24,26 +24,52 @@
 #include <unistd.h>
 
 struct alias {
+	struct alias *next;
+	struct alias *prev;
 	char *alias;
 	char *command;
 };
 
 static struct alias *aliases = NULL;
 
-static void set_alias(const char *alias, const char *command)
+static int set_alias(const char *alias, const char *command)
 {
-	(void)alias; (void)command;
-}
+	struct alias *p = aliases;
+	for (; p != NULL; p = p->next) {
+		if (strcmp(p->alias, alias) == 0) {
+			free(p->command);
+			p->command = strdup(command);
+			return 0;
+		}
+	}
+
+	struct alias *a = calloc(1, sizeof(*a));
+	if (a == NULL) {
+		return 1;
+	}
+
+	a->alias = strdup(alias);
+	a->command = strdup(command);
 
-char * sh_get_alias(const char *alias)
-{
 	if (aliases == NULL) {
-		return NULL;
+		aliases = a;
+		return 0;
+	}
+
+	for (p = aliases; p->next != NULL; p = p->next) {
+		/* find tail */
 	}
+	p->next = a;
+	a->prev = p;
+
+	return 0;
+}
 
-	for (int i = 0; aliases[i].alias; i++) {
-		if (!strcmp(aliases[i].alias, alias)) {
-			return aliases[i].command;
+char * sh_get_alias(const char *alias)
+{
+	for (struct alias *p = aliases; p != NULL; p = p->next) {
+		if (!strcmp(p->alias, alias)) {
+			return p->command;
 		}
 	}
 
@@ -67,28 +93,95 @@ int alias_main(int argc, char *argv[])
 	}
 
 	if (argv[optind] == NULL) {
-		for (int i = 0; aliases && aliases[i].alias; i++) {
-			printf("%s=%s\n", aliases[i].alias, aliases[i].command);
+		for (struct alias *p = aliases; p != NULL; p = p->next) {
+			printf("%s=%s\n", p->alias, p->command);
 		}
 		return 0;
 	}
 
+	int ret = 0;
 	do {
 		char *a = argv[optind++];
 		char *eq = strchr(a, '=');
 		if (eq) {
 			*eq = '\0';
-			set_alias(a, eq + 1);
+			ret |= set_alias(a, eq + 1);
 		} else {
 			show_alias(a);
 		}
 	} while (optind < argc);
 
-	return 0;
+	return ret;
+}
+
+static struct alias *free_alias(struct alias *alias)
+{
+	struct alias *next = alias->next;
+	if (alias == aliases) {
+		aliases = next;
+	}
+
+	if (alias->next) {
+		alias->next->prev = alias->prev;
+	}
+
+	if (alias->prev) {
+		alias->prev->next = alias->next;
+	}
+
+	free(alias->alias);
+	free(alias->command);
+	free(alias);
+	return next;
 }
 
 int unalias_main(int argc, char **argv)
 {
-	printf("Sorry, %s isn't implemented yet.\n", argv[0]);
-	return argc;
+	int all = 0;
+
+	int c = 0;
+	while (getopt(argc, argv, "a") != -1) {
+		switch (c) {
+		case 'a':
+			all = 1;
+			break;
+
+		default:
+			return 1;
+		}
+	}
+
+	if (all) {
+		if (optind < argc) {
+			fprintf(stderr, "unalias: -a takes no arguments\n");
+			return 1;
+		}
+		for (struct alias *p = aliases; p != NULL; p = free_alias(p)) {
+			/* handled by update step */
+		}
+		return 0;
+	}
+
+	if (optind >= argc) {
+		fprintf(stderr, "unalias: missing operands\n");
+		return 1;
+	}
+
+	int ret = 0;
+	for (int i = optind; i < argc; i++) {
+		int removed = 0;
+		for (struct alias *p = aliases; p != NULL; p = p->next) {
+			if (strcmp(p->alias, argv[i]) == 0) {
+				removed = 1;
+				free_alias(p);
+				break;
+			}
+		}
+		if (!removed) {
+			fprintf(stderr, "unalias: %s not defined\n", argv[i]);
+			ret = 1;
+		}
+	}
+
+	return ret;
 }