Don't require environment variable to start with "pass:" prefix + some code clean-up.

frontend/src/main.c

@@ -25,22 +25,25 @@
 #include <signal.h>
 #include <assert.h>
 
-/* Const */
+// ==========================================================================
+// Constants
+// ==========================================================================
+
 #define BUFFER_SIZE 4096U
 
-/* Op-mode */
+#define MODE_HELP 0
-#define SLUNK_MODE_HELP 0
+#define MODE_VERS 1
-#define SLUNK_MODE_VERS 1
+#define MODE_ENCR 2
-#define SLUNK_MODE_ENCR 2
+#define MODE_DECR 3
-#define SLUNK_MODE_DECR 3
+#define MODE_PASS 4
-#define SLUNK_MODE_PASS 4
+#define MODE_TEST 5
-#define SLUNK_MODE_TEST 5
 
+#define PW_FROM_ENV (!(argc > 4))
+
+static const CHR* const ENV_PASSWRD = T("SLUNK_PASSPHRASE");
 static const CHR* const PREFIX_PASS = T("pass:");
 static const CHR* const PREFIX_FILE = T("file:");
 
-static const CHR* const ENV_PASSWD_NAME = T("SLUNK_PASSPHRASE");
-
 static const char PASSWD_SYMBOLS[] =
 {
 	'!', '#', '$', '%', '&', '(', ')', '*', '+', ',', '-', '.', '/', '0', '1',
@@ -51,42 +54,44 @@ static const char PASSWD_SYMBOLS[] =
 	'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~'
 };
 
+static const size_t RCMD_PWDLEN_LENGTH = 12U;
+static const size_t DFLT_PWDLEN_LENGTH = 20U;
+
 static const uint64_t MAGIC_NUMBER = 0x243F6A8885A308D3ull;
 
 // ==========================================================================
 // Auxiliary functions
 // ==========================================================================
 
-static int parse_mode(const CHR* const command)
+static int parse_slunk_mode(const CHR* const command)
 {
 	if ((!STRICMP(command, T("-h"))) || (!STRICMP(command, T("/?"))) || (!STRICMP(command, T("--help"))))
 	{
-		return SLUNK_MODE_HELP;
+		return MODE_HELP;
 	}
 	else if ((!STRICMP(command, T("-v"))) || (!STRICMP(command, T("--version"))))
 	{
-		return SLUNK_MODE_VERS;
+		return MODE_VERS;
 	}
 	else if ((!STRICMP(command, T("-e"))) || (!STRICMP(command, T("--encrypt"))))
 	{
-		return SLUNK_MODE_ENCR;
+		return MODE_ENCR;
 	}
 	else if ((!STRICMP(command, T("-d"))) || (!STRICMP(command, T("--decrypt"))))
 	{
-		return SLUNK_MODE_DECR;
+		return MODE_DECR;
 	}
 	else if ((!STRICMP(command, T("-p"))) || (!STRICMP(command, T("--make-pw"))))
 	{
-		return SLUNK_MODE_PASS;
+		return MODE_PASS;
 	}
 	else if ((!STRICMP(command, T("-t"))) || (!STRICMP(command, T("--self-test"))))
 	{
-		return SLUNK_MODE_TEST;
+		return MODE_TEST;
 	}
 	else
 	{
-		FPRINTF(stderr, T("Error: The specified command \"%") T(PRISTR) T("\" is unknown!\n\n"), command);
+		return -1; /*invalid command*/
-		exit(EXIT_FAILURE);
 	}
 }
 
@@ -100,22 +105,29 @@ static void print_manpage(const CHR *const program)
 	FPRINTF(stderr, T("  %") T(PRISTR) T(" --encrypt [pass:<pass>|file:<file>] <input.txt> <output.enc>\n"), program);
 	FPRINTF(stderr, T("  %") T(PRISTR) T(" --decrypt [pass:<pass>|file:<file>] <input.enc> <output.txt>\n"), program);
 	FPRINTF(stderr, T("  %") T(PRISTR) T(" --make-pw [<length>]\n\n"), program);
-	FPRINTF(stderr, T("Optionally, reads passphrase from the %") T(PRISTR) T(" environment variable.\n\n"), ENV_PASSWD_NAME);
+	FPRINTF(stderr, T("Optionally, reads passphrase from the %") T(PRISTR) T(" environment variable.\n\n"), ENV_PASSWRD);
 }
 
-static char *duplicate_string(const CHR *const passphrase)
+static char *copy_passphrase(const CHR *const passphrase)
 {
+	if ((!passphrase) || (!passphrase[0U]))
+	{
+		FPUTS(T("Error: The passphrase input string must not be empty!\n\n"), stderr);
+		return NULL;
+	}
+
 	char *const buffer = CHR_to_utf8(passphrase);
 	if (!buffer)
 	{
 		FPUTS(T("Error: Failed to allocate the string buffer!\n\n"), stderr);
 	}
+
 	return buffer;
 }
 
-static char *read_passphrase(const CHR* const file_name)
+static char *read_passphrase(const CHR *const file_name)
 {
-	if (file_name && (!file_name[0U]))
+	if ((!file_name) || (!file_name[0U]))
 	{
 		FPUTS(T("Error: The passphrase input file name must not be empty!\n\n"), stderr);
 		return NULL;
@@ -133,7 +145,7 @@ static char *read_passphrase(const CHR* const file_name)
 	FILE *const file_in = use_stdin ? stdin : FOPEN(file_name, T("rb"));
 	if (!file_in)
 	{
-		FPRINTF(stderr, T("Error: Failed to open file \"%") T(PRISTR) T("\" for reading!\n\n"), file_name);
+		FPRINTF(stderr, T("Error: Failed to open input file \"%") T(PRISTR) T("\" for reading!\n\n"), file_name);
 		free(buffer);
 		return NULL;
 	}
@@ -225,20 +237,20 @@ clean_up:
 	return result;
 }
 
-static int open_files(FILE **const file_in, FILE **const file_out, const CHR* const input_path, const CHR* const output_path)
+static int open_files(FILE **const file_in, FILE **const file_out, const CHR *const input_path, const CHR *const output_path)
 {
-	*file_in = FOPEN(input_path, T("rb"));
+	if (!(*file_in = FOPEN(input_path, T("rb"))))
-	if (!(*file_in))
 	{
-		FPRINTF(stderr, T("Error: Failed to open file \"%") T(PRISTR) T("\" for reading!\n\n"), input_path);
+		FPRINTF(stderr, T("Error: Failed to open input file \"%") T(PRISTR) T("\" for reading!\n\n"), input_path);
+		*file_out = NULL;
 		return EXIT_FAILURE;
 	}
 
-	*file_out = FOPEN(output_path, T("wb"));
+	if (!(*file_out = FOPEN(output_path, T("wb"))))
-	if (!(*file_out))
 	{
-		FPRINTF(stderr, T("Error: Failed to open file \"%") T(PRISTR) T("\" for writing!\n\n"), output_path);
+		FPRINTF(stderr, T("Error: Failed to open output file \"%") T(PRISTR) T("\" for writing!\n\n"), output_path);
 		fclose(*file_in);
+		*file_in = NULL;
 		return EXIT_FAILURE;
 	}
 
@@ -763,20 +775,26 @@ int MAIN(const int argc, CHR *const argv[])
 		goto clean_up;
 	}
 
-	const int mode = parse_mode(argv[1U]);
+	const int slunk_mode = parse_slunk_mode(argv[1U]);
-	switch (mode)
+	switch (slunk_mode)
 	{
-	case SLUNK_MODE_HELP:
+	case MODE_HELP:
 		print_manpage(get_file_name(argv[0U]));
-	case SLUNK_MODE_VERS:
+	case MODE_VERS:
 		result = EXIT_SUCCESS;
 		goto clean_up;
-	case SLUNK_MODE_PASS:
+	case MODE_ENCR:
-		result = generate_passphrase((argc > 2) ? STRTOUL(argv[2U]) : 24U);
+	case MODE_DECR:
+		break; /*fallthrough*/
+	case MODE_PASS:
+		result = generate_passphrase((argc > 2) ? STRTOUL(argv[2U]) : DFLT_PWDLEN_LENGTH);
 		goto clean_up;
-	case SLUNK_MODE_TEST:
+	case MODE_TEST:
 		result = run_self_test();
 		goto clean_up;
+	default:
+		FPRINTF(stderr, T("Error: The specified command \"%") T(PRISTR) T("\" is unknown!\n\n"), argv[1U]);
+		goto clean_up;
 	}
 
 	if (argc < 4)
@@ -785,8 +803,8 @@ int MAIN(const int argc, CHR *const argv[])
 		goto clean_up;
 	}
 
-	const CHR *const passphrase = (argc > 4) ? argv[2U] : GETENV(ENV_PASSWD_NAME);
+	const CHR *const passphrase = PW_FROM_ENV ? GETENV(ENV_PASSWRD) : argv[2U];
-	const CHR *const input_file = argv[(argc > 4) ? 3U : 2U], *const output_file = argv[(argc > 4) ? 4U : 3U];
+	const CHR *const input_file = argv[PW_FROM_ENV ? 2U : 3U], *const output_file = argv[PW_FROM_ENV ? 3U : 4U];
 
 	if ((!passphrase) || (!passphrase[0U]))
 	{
@@ -794,11 +812,14 @@ int MAIN(const int argc, CHR *const argv[])
 		goto clean_up;
 	}
 
-	if (STRICMP(passphrase, T("-")) && (!STARTS_WITH(passphrase, PREFIX_PASS)) && (!STARTS_WITH(passphrase, PREFIX_FILE)))
+	if ((!PW_FROM_ENV) && STRICMP(passphrase, T("-")))
+	{
+		if ((!STARTS_WITH(passphrase, PREFIX_PASS)) && (!STARTS_WITH(passphrase, PREFIX_FILE)))
 		{
 			FPRINTF(stderr, T("Error: The passphrase must start with a '%") T(PRISTR) T("' or '%") T(PRISTR) T("' prefix!\n\n"), PREFIX_PASS, PREFIX_FILE);
 			goto clean_up;
 		}
+	}
 
 	if ((!input_file[0U]) || (!output_file[0U]))
 	{
@@ -810,9 +831,9 @@ int MAIN(const int argc, CHR *const argv[])
 	/* Initialize passphrase                                 */
 	/* ----------------------------------------------------- */
 
-	passphrase_buffer = STARTS_WITH(passphrase, PREFIX_PASS) ? duplicate_string(passphrase + STRLEN(PREFIX_PASS)) :
+	if (!(passphrase_buffer = PW_FROM_ENV ? copy_passphrase(passphrase) :
-			(STARTS_WITH(passphrase, PREFIX_FILE) ? read_passphrase(passphrase + STRLEN(PREFIX_FILE)) : read_passphrase(NULL));
+			(STARTS_WITH(passphrase, PREFIX_PASS) ? copy_passphrase(passphrase + STRLEN(PREFIX_PASS)) :
-	if (!passphrase_buffer)
+			(STARTS_WITH(passphrase, PREFIX_FILE) ? read_passphrase(passphrase + STRLEN(PREFIX_FILE)) : read_passphrase(T("-"))))))
 	{
 		goto clean_up;
 	}
@@ -822,18 +843,18 @@ int MAIN(const int argc, CHR *const argv[])
 	const size_t passphrase_len = strlen(passphrase_buffer);
 	if (passphrase_len < SLUNKCRYPT_PWDLEN_MIN)
 	{
-		FPRINTF(stderr, T("Error: Passphrase must be at least %") T(PRIu64) T(" characters in length!\n\n"), (uint64_t)SLUNKCRYPT_PWDLEN_MIN);
+		FPRINTF(stderr, T("Error: Passphrase must be at least %u characters in length!\n\n"), (unsigned)SLUNKCRYPT_PWDLEN_MIN);
 		goto clean_up;
 	}
 	else if (passphrase_len > SLUNKCRYPT_PWDLEN_MAX)
 	{
-		FPRINTF(stderr, T("Error: Passphrase must be at most %") T(PRIu64) T(" characters in length!\n\n"), (uint64_t)SLUNKCRYPT_PWDLEN_MAX);
+		FPRINTF(stderr, T("Error: Passphrase must be at most %u characters in length!\n\n"),  (unsigned)SLUNKCRYPT_PWDLEN_MAX);
 		goto clean_up;
 	}
 
-	if (passphrase_len < 12U)
+	if (passphrase_len < RCMD_PWDLEN_LENGTH)
 	{
-		FPUTS(T("Warning: Using a *short* passphrase; a length of 12 characters or more is recommended!\n\n"), stderr);
+		FPRINTF(stderr, T("Warning: Using a *short* passphrase; a length of %u characters or more is recommended!\n\n"), (unsigned)RCMD_PWDLEN_LENGTH);
 	}
 	else if (weak_passphrase(passphrase_buffer))
 	{
@@ -846,12 +867,12 @@ int MAIN(const int argc, CHR *const argv[])
 
 	const clock_t clk_start = clock();
 
-	switch (mode)
+	switch (slunk_mode)
 	{
-	case SLUNK_MODE_ENCR:
+	case MODE_ENCR:
 		result = encrypt(passphrase_buffer, input_file, output_file);
 		break;
-	case SLUNK_MODE_DECR:
+	case MODE_DECR:
 		result = decrypt(passphrase_buffer, input_file, output_file);
 		break;
 	default: