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, 13 insertions, 22 deletions

diff --git a/util/libreboot-utils/lib/mkhtemp.c b/util/libreboot-utils/lib/mkhtemp.c
index 2ef26d67..0560da47 100644
--- a/util/libreboot-utils/lib/mkhtemp.c
+++ b/util/libreboot-utils/lib/mkhtemp.c
@@ -120,8 +120,6 @@ new_tmp_common(int *fd, char **path, int type,
 	if (tmpdir == NULL)
 		goto err;
 
-	if (slen(tmpdir, maxlen, &dirlen) < 0)
-		goto err;
 	if (*tmpdir == '\0')
 		goto err;
 	if (*tmpdir != '/')
@@ -132,15 +130,12 @@ new_tmp_common(int *fd, char **path, int type,
 	else
 		templatestr = "tmp.XXXXXXXXXX";
 
-	if (slen(templatestr, maxlen, &templatestr_len) < 0)
-		goto err;
-
 	/* may as well calculate in advance */
-	destlen = dirlen + 1 + templatestr_len;
+	destlen = slen(tmpdir, maxlen, &dirlen) + 1
+	    + slen(templatestr, maxlen, &templatestr_len);
 	/* full path: */
-	if (scatn(3, (const char *[]) { tmpdir, "/", templatestr },
-	    maxlen, &dest) < 0)
-		goto err;
+	dest = scatn(3, (const char *[]) { tmpdir, "/", templatestr },
+	    maxlen, &dest);
 
 	fname = dest + dirlen + 1;
 
@@ -312,12 +307,10 @@ same_dir(const char *a, const char *b)
 
 	/* optimisation: if both dirs
 	   are the same, we don't need
-	   to check anything. sehr schnell:
+	   to check anything. sehr schnell!
 	 */
-	if (scmp(a, b, maxlen, &rval_scmp) < 0)
-		goto err_same_dir;
 	/* bonus: scmp checks null for us */
-	if (rval_scmp == 0)
+	if (!scmp(a, b, maxlen, &rval_scmp))
 		goto success_same_dir;
 
 	fd_a = fs_open(a, O_RDONLY | O_DIRECTORY | O_NOFOLLOW);
@@ -550,19 +543,17 @@ mkhtemp(int *fd,
 	if (if_err(fd == NULL || template == NULL || fname == NULL ||
 	          st_dir_initial == NULL, EFAULT) ||
 	    if_err(*fd >= 0, EEXIST) ||
-	    if_err(dirfd < 0, EBADF)
-	      ||
-	    if_err_sys(slen(template, max_len, &template_len) < 0) ||
-	    if_err(template_len >= max_len, EMSGSIZE)
-	      ||
-	    if_err_sys(slen(fname, max_len, &fname_len) < 0) ||
-	    if_err(fname == NULL, EINVAL) ||
-	    if_err(strrchr(fname, '/') != NULL, EINVAL))
+	    if_err(dirfd < 0, EBADF))
 		return -1;
 
-	for (end = template + template_len; /* count X */
+	/* count X */
+	for (end = template + slen(template, max_len, &template_len);
 	    end > template && *--end == 'X'; xc++);
 
+	fname_len = slen(fname, max_len, &fname_len);
+	if (if_err(strrchr(fname, '/') != NULL, EINVAL))
+		return -1;
+
 	if (if_err(xc < 3 || xc > template_len, EINVAL) ||
 	    if_err(fname_len > template_len, EOVERFLOW))
 		return -1;