libreboot-utils: more flexible string usage

i previously used error status and set return values
indirectly. i still do that, but where possible, i
also now return the real value.

this is because these string functions can no longer
return with error status; on error, they all abort.
this forces the program maintainer to keep their code
reliable, and removes the need to check the error status
after using syscalls, because these libc wrappers mitigate
that and make use of libc for you, including errors.

this is part of a general effort to promote safe use
of the C programming language, especially in libreboot!

Signed-off-by: Leah Rowe <leah@libreboot.org>

1 files changed, 3 insertions, 12 deletions

diff --git a/util/libreboot-utils/lib/command.c b/util/libreboot-utils/lib/command.c
index a1e46e5f..3ee75628 100644
--- a/util/libreboot-utils/lib/command.c
+++ b/util/libreboot-utils/lib/command.c
@@ -57,10 +57,7 @@ sanitize_command_index(size_t c)
 		err_exit(EINVAL, "cmd index %lu: empty str",
 		    (size_t)c);
 
-	if (slen(cmd->str, MAX_CMD_LEN +1, &rval) < 0)
-		err_exit(errno, "Could not get command length");
-
-	if (rval > MAX_CMD_LEN) {
+	if (slen(cmd->str, MAX_CMD_LEN +1, &rval) > MAX_CMD_LEN) {
 		err_exit(EINVAL, "cmd index %lu: str too long: %s",
 		    (size_t)c, cmd->str);
 	}
@@ -109,10 +106,7 @@ set_cmd(int argc, char *argv[])
 
 		cmd = x->cmd[c].str;
 
-		if (scmp(argv[2], cmd, MAX_CMD_LEN, &rval) < 0)
-			err_exit(EINVAL,
-			    "could not compare command strings");
-		if (rval != 0)
+		if (scmp(argv[2], cmd, MAX_CMD_LEN, &rval))
 			continue; /* not the right command */
 
 		/* valid command found */
@@ -239,10 +233,7 @@ parse_mac_string(void)
 
 	size_t rval;
 
-	if (slen(x->mac.str, 18, &rval) < 0)
-		err_exit(EINVAL, "Could not determine MAC length");
-
-	if (rval != 17)
+	if (slen(x->mac.str, 18, &rval) != 17)
 		err_exit(EINVAL, "MAC address is the wrong length");
 
 	memset(mac->mac_buf, 0, sizeof(mac->mac_buf));