skeud

commit: a5b101daf714dfeb3cddc9ea973f6199c69d0924
parent e016382605f6cdc93afc3bd63d8df6a53225b80c
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Sun, 28 Sep 2025 14:04:48 +0200

Improve error messages

Diffstat:
M
common.c
30
+++++++++++++++++++++++-------
M
common.h
1
+
M
login.c
29
++++++++++++++++-------------
M
su.c
10
+++++-----

4 files changed, 45 insertions(+), 25 deletions(-)
diff --git a/common.c b/common.c
@@ -16,6 +16,22 @@
 #undef MIN
 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
 
+// doesn't exits to make sure cleanup is done
+int
+skeud_err(const char *errmsg, int err)
+{
+	fputs(argv0, stderr);
+	fputs(": error: ", stderr);
+	fputs(errmsg, stderr);
+	if(err != 0)
+	{
+		fputs(": ", stderr);
+		fputs(strerror(err), stderr);
+	}
+	fputs("\n", stderr);
+	return fflush(stderr);
+}
+
 // Needs to be constant-time
 bool
 hash_match(const char *a, size_t alen, const char *b, size_t blen)
@@ -42,7 +58,7 @@ skeud_crypt_check(const char *hash, const char *password)
 	char *chk_hash = crypt(password, hash);
 	if(chk_hash == NULL)
 	{
-		fprintf(stderr, "%s: error: Failed hashing password: %s\n", argv0, strerror(errno));
+		skeud_err("Failed hashing password", errno);
 		return false;
 	}
 
@@ -65,19 +81,19 @@ skeud_getpass(char **password)
 	FILE *tty = fopen("/dev/tty", "rb+");
 	if(tty == NULL)
 	{
-		perror("skeud_getpass: error: open(\"/dev/tty\")");
+		skeud_err("Failed opening '/dev/tty'", errno);
 		return got;
 	}
 	int tty_fd = fileno(tty);
 	if(tty_fd < 0)
 	{
-		perror("skeud_getpass: error: fileno(tty)");
+		skeud_err("Failed getting fd from '/dev/tty' stream", errno);
 		goto getpass_end;
 	}
 
 	if(tcgetattr(tty_fd, &t) < 0)
 	{
-		perror("skeud_getpass: error: tcgetattr");
+		skeud_err("Failed getting terminal attributes", errno);
 		goto getpass_end;
 	}
 
@@ -86,7 +102,7 @@ skeud_getpass(char **password)
 	t.c_lflag &= ~ECHO;
 	if(tcsetattr(tty_fd, TCSANOW, &t) < 0)
 	{
-		perror("skeud_getpass: error: tcsetattr(~ECHO)");
+		skeud_err("Failed disabling terminal echo", errno);
 		goto getpass_end;
 	}
 
@@ -94,7 +110,7 @@ skeud_getpass(char **password)
 	got   = getline(password, &len, tty);
 	if(got < 0)
 	{
-		if(errno != 0) perror("skeud_getpass: error: getline");
+		if(errno != 0) skeud_err("Failed reading line", errno);
 		goto getpass_clean;
 	}
 	fputs("\n", tty);
@@ -106,7 +122,7 @@ getpass_clean:
 	t.c_lflag ^= ECHO;
 	if(tcsetattr(tty_fd, TCSANOW, &t) < 0)
 	{
-		perror("skeud_getpass: error: tcsetattr(ECHO)");
+		skeud_err("Failed re-enabling terminal echo", errno);
 		explicit_bzero(password, got);
 		got = -1;
 		goto getpass_end;
diff --git a/common.h b/common.h
@@ -8,6 +8,7 @@ extern const char *argv0;
 
 #define strlen0(str) str ? strlen(str) : 0
 
+int skeud_err(const char *errmsg, int err);
 bool hash_match(const char *a, size_t alen, const char *b, size_t blen);
 bool skeud_crypt_check(const char *hash, const char *password);
 ssize_t skeud_getpass(char **password);
diff --git a/login.c b/login.c
@@ -47,17 +47,17 @@ process_pwent(struct passwd *pwent)
 	/* considers that STDIN_FILENO is close enough to the current tty */
 	if(fchown(STDIN_FILENO, pwent->pw_uid, tty_gid) < 0)
 	{
-		perror("login: error: fchown");
+		perror("login: error: Failed setting TTY owner:group");
 		return 1;
 	}
 	if(fchmod(STDIN_FILENO, TTY_PERMS))
 	{
-		perror("login: error: fchmod");
+		perror("login: error: Failed setting TTY permissions");
 		return 1;
 	}
 	if(setgid(pwent->pw_gid) < 0)
 	{
-		perror("login: error: setgid");
+		perror("login: error: Failed setting group-id");
 		return 1;
 	}
 	if(initgroups(pwent->pw_name, pwent->pw_gid) < 0)
@@ -67,7 +67,7 @@ process_pwent(struct passwd *pwent)
 	}
 	if(setuid(pwent->pw_uid) < 0)
 	{
-		perror("login: error: setuid");
+		perror("login: error: Failed setting user-id");
 		return 1;
 	}
 
@@ -77,7 +77,10 @@ process_pwent(struct passwd *pwent)
 
 		if(chdir(pwent->pw_dir) != 0)
 		{
-			fprintf(stderr, "login: warning: Failed to change current directory to: %s\n", pwent->pw_dir);
+			fprintf(stderr,
+			        "login: warning: Failed to change current directory to '%s': %s\n",
+			        pwent->pw_dir,
+			        strerror(errno));
 		}
 	}
 
@@ -96,7 +99,7 @@ main(int argc, char *argv[])
 
 	if(getuid() != 0)
 	{
-		fprintf(stderr, "login: error: Not super-user\n");
+		fputs("login: error: Not super-user\n", stderr);
 		return 1;
 	}
 
@@ -119,7 +122,7 @@ main(int argc, char *argv[])
 			fprintf(stderr, "login: error: Unrecognized option: '-%c'\n", optopt);
 			return 1;
 		default:
-			fprintf(stderr, "login: error: Unknown getopt state, aborting\n");
+			fputs("login: error: Unknown getopt state, aborting\n", stderr);
 			abort();
 		}
 	}
@@ -158,7 +161,7 @@ main(int argc, char *argv[])
 		ssize_t got = getline(&username_buf, &len, stdin);
 		if(got < 0)
 		{
-			if(errno != 0) perror("login: error: getline");
+			if(errno != 0) skeud_err("Failed reading line", errno);
 			free(username_buf);
 			return 1;
 		}
@@ -175,7 +178,7 @@ main(int argc, char *argv[])
 	pwent = getpwnam(username);
 	if(errno != 0)
 	{
-		perror("login: warning: getpwnam");
+		perror("login: warning: Failed getting passwd entry");
 	}
 
 	if(!opt_f)
@@ -192,7 +195,7 @@ main(int argc, char *argv[])
 		struct spwd *swent = getspnam(username);
 		if(errno != 0)
 		{
-			perror("login: getspnam");
+			perror("login: warning: Failed getting shadow passwd entry");
 		}
 		else
 		{
@@ -225,7 +228,7 @@ main(int argc, char *argv[])
 		{
 			free(username_buf);
 			sleep(2);
-			fprintf(stderr, "login: error: Invalid username or password\n");
+			fputs("login: error: Invalid username or password\n", stderr);
 			return 1;
 		}
 	}
@@ -278,12 +281,12 @@ main(int argc, char *argv[])
 	{
 		if(errno == ENOENT)
 		{
-			perror("login: error: execve");
+			perror("login: error: Failed executing shell");
 			return 127;
 		}
 		else
 		{
-			perror("login: error: execve");
+			perror("login: error: Failed executing shell");
 			return 126;
 		}
 	}
diff --git a/su.c b/su.c
@@ -39,7 +39,7 @@ main(int argc, char *argv[])
 
 	if(geteuid() != 0)
 	{
-		fprintf(stderr, "su: error: Not effectively super-user. Missing setuid?\n");
+		fputs("su: error: Not effectively super-user. Missing setuid?\n", stderr);
 		return 1;
 	}
 
@@ -57,7 +57,7 @@ main(int argc, char *argv[])
 		case 's': // shell
 			if(getuid() != 0)
 			{
-				fprintf(stderr, "su: error: Only the super-user can override the target shell\n");
+				fputs("su: error: Only the super-user can override the target shell\n", stderr);
 				return 1;
 			}
 
@@ -66,7 +66,7 @@ main(int argc, char *argv[])
 		case 'p': // preserve environment
 			if(getuid() != 0)
 			{
-				fprintf(stderr, "su: error: Only the super-user can preserve the environment\n");
+				fputs("su: error: Only the super-user can preserve the environment\n", stderr);
 				return 1;
 			}
 
@@ -79,7 +79,7 @@ main(int argc, char *argv[])
 			fprintf(stderr, "su: error: Unrecognized option: '-%c'\n", optopt);
 			return 1;
 		default:
-			fprintf(stderr, "su: error: Unknown getopt state, aborting\n");
+			fputs("su: error: Unknown getopt state, aborting\n", stderr);
 			abort();
 		}
 	}
@@ -113,7 +113,7 @@ main(int argc, char *argv[])
 	{
 		if(errno != 0)
 		{
-			perror("su: error: getpwnam");
+			perror("su: error: Failed getting passwd entry");
 		}
 		else
 		{