From 8e8998e778408cd42194225ae6fd3c581ac4be5c Mon Sep 17 00:00:00 2001
From: Trent Huber <trentmhuber@gmail.com>
Date: Thu, 20 Nov 2025 00:31:33 -0500
Subject: [PATCH] Fix undefined behavior, more cleaning

---
 src/builtins/alias.c   |  9 ++++-----
 src/builtins/build.c   |  3 +--
 src/builtins/builtin.c |  1 -
 src/builtins/builtin.h |  5 +++++
 src/builtins/cd.c      |  4 ++--
 src/builtins/fg.c      |  5 +----
 src/builtins/fg.h      |  1 -
 src/builtins/list.h    |  6 ------
 src/builtins/pwd.c     |  7 +++----
 src/input.c            |  6 +++---
 src/parse.c            | 10 +++++-----
 src/signals.c          | 20 ++++++++++----------
 src/utils.c            | 30 ++++++++++++++----------------
 tools/install.c        |  5 ++---
 tools/uninstall.c      |  2 +-
 15 files changed, 51 insertions(+), 63 deletions(-)
 delete mode 100644 src/builtins/list.h

diff --git a/src/builtins/alias.c b/src/builtins/alias.c
index 1f4a21b..42105a8 100644
--- a/src/builtins/alias.c
+++ b/src/builtins/alias.c
@@ -38,12 +38,11 @@ char **parsealias(char *value) {
 
 	if (!value) return NULL;
 
+	c = (struct context){.b = c.buffer, .alias = 1};
 	strcpy(c.buffer, value);
-	l = strlen(value);
-	c.buffer[l + 1] = '\0';
-	c.buffer[l] = ';';
-	c.b = c.buffer;
-	c.alias = 1;
+	l = strlen(c.buffer);
+	c.buffer[l++] = ';';
+	c.buffer[l] = '\0';
 
 	if (!parse(&c)) return NULL;
 
diff --git a/src/builtins/build.c b/src/builtins/build.c
index a115a39..30ad344 100644
--- a/src/builtins/build.c
+++ b/src/builtins/build.c
@@ -21,8 +21,7 @@ int main(void) {
 	if (!(dir = opendir("./")))
 		err(EXIT_FAILURE, "Unable to open current directory");
 
-	dprintf(listfd, "#include <stddef.h>\n\n#include \"builtin.h\"\n"
-	        "#include \"list.h\"\n\n");
+	dprintf(listfd, "#include <stddef.h>\n\n#include \"builtin.h\"\n\n");
 
 	src = srcs;
 	errno = 0;
diff --git a/src/builtins/builtin.c b/src/builtins/builtin.c
index cf2d914..1e005bf 100644
--- a/src/builtins/builtin.c
+++ b/src/builtins/builtin.c
@@ -3,7 +3,6 @@
 #include <string.h>
 
 #include "builtin.h"
-#include "list.h"
 #include "utils.h"
 
 int (*getbuiltin(char *name))(char **args, size_t numargs) {
diff --git a/src/builtins/builtin.h b/src/builtins/builtin.h
index 768ba7e..0aeaf3a 100644
--- a/src/builtins/builtin.h
+++ b/src/builtins/builtin.h
@@ -1,2 +1,7 @@
+extern struct builtin {
+	char *name;
+	int (*func)(char **args, size_t numargs);
+} builtins[];
+
 int (*getbuiltin(char *name))(char **args, size_t numargs);
 int usage(char *program, char *options);
diff --git a/src/builtins/cd.c b/src/builtins/cd.c
index 12451af..acd9c4f 100644
--- a/src/builtins/cd.c
+++ b/src/builtins/cd.c
@@ -20,8 +20,8 @@ int cd(char **args, size_t numargs) {
 			return EXIT_FAILURE;
 		}
 		l = strlen(buffer);
-		buffer[l + 1] = '\0';
-		buffer[l] = '/';
+		buffer[l++] = '/';
+		buffer[l] = '\0';
 		break;
 	default:
 		return usage(args[0], "[directory]");
diff --git a/src/builtins/fg.c b/src/builtins/fg.c
index 0812bee..5b94fc8 100644
--- a/src/builtins/fg.c
+++ b/src/builtins/fg.c
@@ -96,6 +96,7 @@ int runfg(pid_t id) {
 			exit(EXIT_SUCCESS);
 		}
 		if (sigint) sigint = 0;
+		if (sigwinch) sigwinch = 0;
 	}
 	setsig(SIGCHLD, &defaultaction);
 	fgjob.done = errno = 0;
@@ -123,10 +124,6 @@ int runfg(pid_t id) {
 	return 1;
 }
 
-void deinitfg(void) {
-	setconfig(&canonical);
-}
-
 int fg(char **args, size_t numargs) {
 	struct bgjob job;
 	long l;
diff --git a/src/builtins/fg.h b/src/builtins/fg.h
index f1dab38..1308bcc 100644
--- a/src/builtins/fg.h
+++ b/src/builtins/fg.h
@@ -3,4 +3,3 @@ extern struct termios canonical;
 int setconfig(struct termios *mode);
 void initfg(void);
 int runfg(pid_t id);
-void deinitfg(void);
diff --git a/src/builtins/list.h b/src/builtins/list.h
deleted file mode 100644
index 0c4a403..0000000
--- a/src/builtins/list.h
+++ /dev/null
@@ -1,6 +0,0 @@
-struct builtin {
-	char *name;
-	int (*func)(char **args, size_t numargs);
-};
-
-extern struct builtin builtins[];
diff --git a/src/builtins/pwd.c b/src/builtins/pwd.c
index c6a6a28..6c5b9db 100644
--- a/src/builtins/pwd.c
+++ b/src/builtins/pwd.c
@@ -18,10 +18,9 @@ int pwd(char **args, size_t numargs) {
 			note("Unable to get current working directory");
 			return EXIT_FAILURE;
 		}
-		l = strlen(buffer);
-		if (buffer[l - 1] != '/') {
-			buffer[l] = '/';
-			buffer[l + 1] = '\0';
+		if (buffer[(l = strlen(buffer)) - 1] != '/') {
+			buffer[l++] = '/';
+			buffer[l] = '\0';
 		}
 		if (setenv("PWD", buffer, 1) == -1) {
 			note("Unable to set $PWD$");
diff --git a/src/input.c b/src/input.c
index fbf60b4..e6b363d 100644
--- a/src/input.c
+++ b/src/input.c
@@ -32,15 +32,15 @@ int stringinput(struct context *c) {
 	end = c->string;
 	while (*end && *end != '\n') ++end;
 	l = end - c->string;
-	while (*end == '\n') ++end; /* `scriptinput()' uses `stringinput()' */
+	while (*end == '\n') ++end;
 	if (l > MAXCHARS) {
 		note("Line too long, exceeds %d character limit", MAXCHARS);
 		return 0;
 	}
 
 	strncpy(c->buffer, c->string, l);
-	c->buffer[l] = ';';
-	c->buffer[l + 1] = '\0';
+	c->buffer[l++] = ';';
+	c->buffer[l] = '\0';
 	c->string = end;
 
 	return 1;
diff --git a/src/parse.c b/src/parse.c
index b090409..3ed02ca 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -129,16 +129,16 @@ int parse(struct context *c) {
 	case '\\':
 		if (!quote) break;
 		switch (*(c->b + 1)) {
+		default:
+			memmove(c->b, c->b + 1, end-- - c->b);
+			--c->b;
+			*(c->b + 1) = *c->b;
 		case '$':
 		case '~':
 		case '"':
 		case '\\':
-			break;
-		default:
-			memmove(c->b, c->b + 1, end-- - c->b--);
-			*(c->b + 1) = *c->b;
+			memmove(c->b, c->b + 1, end-- - c->b);
 		}
-		memmove(c->b, c->b + 1, end-- - c->b);
 		break;
 	case '*':
 	case '?':
diff --git a/src/signals.c b/src/signals.c
index 4d65872..3f4318d 100644
--- a/src/signals.c
+++ b/src/signals.c
@@ -5,7 +5,7 @@
 
 #include "utils.h"
 
-int sigwinch, sigquit, sigint;
+int sigquit, sigint, sigwinch;
 sigset_t shellsigmask, childsigmask;
 struct sigaction defaultaction;
 
@@ -14,12 +14,6 @@ void setsig(int sig, struct sigaction *act) {
 		fatal("Unable to install %s handler", strsignal(sig));
 }
 
-static void sigwinchhandler(int sig) {
-	(void)sig;
-
-	sigwinch = 1;
-}
-
 static void sigquithandler(int sig) {
 	(void)sig;
 
@@ -32,6 +26,12 @@ static void siginthandler(int sig) {
 	sigint = 1;
 }
 
+static void sigwinchhandler(int sig) {
+	(void)sig;
+
+	sigwinch = 1;
+}
+
 void initsignals(void) {
 	struct sigaction action;
 
@@ -46,9 +46,6 @@ void initsignals(void) {
 	setsig(SIGTTOU, &defaultaction);
 	setsig(SIGTTIN, &defaultaction);
 
-	action = (struct sigaction){.sa_handler = sigwinchhandler};
-	setsig(SIGWINCH, &action);
-
 	action = (struct sigaction){.sa_handler = sigquithandler};
 	setsig(SIGHUP, &action);
 	setsig(SIGQUIT, &action);
@@ -56,4 +53,7 @@ void initsignals(void) {
 
 	action = (struct sigaction){.sa_handler = siginthandler};
 	setsig(SIGINT, &action);
+
+	action = (struct sigaction){.sa_handler = sigwinchhandler};
+	setsig(SIGWINCH, &action);
 }
diff --git a/src/utils.c b/src/utils.c
index f7de714..a59c0b7 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -57,19 +57,18 @@ void init(void) {
 		note("Unable to update $SHLVL$ environment variable");
 
 	if (!(home = getenv("HOME"))) fatal("Unable to find home directory");
-	l = strlen(home);
-	if (home[l - 1] != '/') {
+	if (home[(l = strlen(home)) - 1] != '/') {
 		strcpy(buffer, home);
-		buffer[l] = '/';
-		buffer[l + 1] = '\0';
+		buffer[l++] = '/';
+		buffer[l] = '\0';
 		if (setenv("HOME", buffer, 1) == -1 || !(home = getenv("HOME")))
 			note("Unable to append trailing slash to $HOME$");
 	}
 
 	if (!getcwd(buffer, PATH_MAX)) fatal("Unable to find current directory");
 	l = strlen(buffer);
-	buffer[l] = '/';
-	buffer[l + 1] = '\0';
+	buffer[l++] = '/';
+	buffer[l] = '\0';
 	if (setenv("PWD", buffer, 1) == -1)
 		note("Unable to append trailing slash to $PWD$");
 
@@ -90,8 +89,7 @@ char *catpath(char *dir, char *filename, char *buffer) {
 	size_t l;
 	int slash;
 
-	l = strlen(dir);
-	slash = dir[l - 1] == '/';
+	slash = dir[(l = strlen(dir)) - 1] == '/';
 	if (l + slash + strlen(filename) + 1 > PATH_MAX) {
 		note("Path name `%s%s%s' too long", dir, slash ? "/" : "", filename);
 		return NULL;
@@ -105,7 +103,7 @@ char *catpath(char *dir, char *filename, char *buffer) {
 }
 
 char *quoted(char *token) {
-	char *p, *q, quote;
+	char *p, *end, quote;
 	enum {
 		NONE,
 		DOUBLE,
@@ -119,8 +117,8 @@ char *quoted(char *token) {
 	degree = NONE;
 	for (p = token; *p; ++p) switch(*p) {
 	case '[':
-		for (q = p; *q; ++q) if (*q == ']') break;
-		if (!*q) continue;
+		for (end = p; *end; ++end) if (*end == ']') break;
+		if (!*end) continue;
 	case '>':
 	case '<':
 	case '*':
@@ -146,18 +144,18 @@ char *quoted(char *token) {
 	p = buffer;
 	*p++ = quote;
 	strcpy(p, token);
-	for (q = p; *q; ++q);
+	for (end = p; *end; ++end);
 	if (degree != SINGLE) for (; *p; ++p) switch (*p)
 	case '$':
 	case '~':
 	case '"':
 		if (degree == ESCAPEDOUBLE) {
 		case '\\':
-			memmove(p + 1, p, ++q - p);
+			memmove(p + 1, p, ++end - p);
 			*p++ = '\\';
 		}
-	*q++ = quote;
-	*q++ = '\0';
+	*end++ = quote;
+	*end = '\0';
 
 	return buffer;
 }
@@ -165,5 +163,5 @@ char *quoted(char *token) {
 void deinit(void) {
 	deinithistory();
 	deinitbg();
-	deinitfg();
+	setconfig(&canonical);
 }
diff --git a/tools/install.c b/tools/install.c
index 883514c..6ceb77f 100644
--- a/tools/install.c
+++ b/tools/install.c
@@ -23,13 +23,12 @@ int main(int argc, char **argv) {
 
 	strcat(path, "bin/");
 	if ((cpid = fork()) == -1) err(EXIT_FAILURE, "Unable to fork");
-	else if (cpid == 0)
-		run("/bin/mkdir", LIST("mkdir", "-p", path), "create", path);
+	if (!cpid) run("/bin/mkdir", LIST("mkdir", "-p", path), "create", path);
 	await(cpid, "create", path);
 
 	strcat(path, "thus");
 	if ((cpid = fork()) == -1) err(EXIT_FAILURE, "Unable to fork");
-	else if (cpid == 0)
+	if (!cpid)
 		run("/bin/cp", LIST("cp", "-f", "bin/thus", path), "copy", "bin/thus");
 	await(cpid, "copy", "bin/thus");
 
diff --git a/tools/uninstall.c b/tools/uninstall.c
index cca930f..a8b190f 100644
--- a/tools/uninstall.c
+++ b/tools/uninstall.c
@@ -12,7 +12,7 @@ int main(int argc, char **argv) {
 	if (argc != 1) err(EXIT_FAILURE, "usage: %s\n", argv[0]);
 
 	if ((cpid = fork()) == -1) err(EXIT_FAILURE, "Unable to fork");
-	else if (cpid == 0)
+	if (!cpid)
 		run("/bin/rm", LIST("rm", STR(PATH), "uninstall"), "remove", STR(PATH));
 	await(cpid, "remove", STR(PATH));
 
-- 
2.51.0