about summary refs log tree commit diff
diff options
context:
space:
mode:
authorGabriel Ravier <gabravier@gmail.com>2023-01-04 16:07:19 +0100
committerRich Felker <dalias@aerifal.cx>2023-02-12 17:50:59 -0500
commit07616721f1fa6cb215ffbef23441cae80412484f (patch)
tree58c92a1039672246f43cc776bbbf5d93ad561169
parent35fdfe62a4ff471074ca53b7626ec80e83d244bd (diff)
downloadmusl-07616721f1fa6cb215ffbef23441cae80412484f.tar.gz
musl-07616721f1fa6cb215ffbef23441cae80412484f.tar.xz
musl-07616721f1fa6cb215ffbef23441cae80412484f.zip
fix return value of wcs{,n}cmp for extreme wchar_t values
As a result of using simple subtraction to implement the return values
for wcscmp and wcsncmp, integer overflow can occur (producing
undefined behavior, and in practice, a wrong comparison result). This
does not occur for meaningful character values (21-bit range) but the
functions are specified to work on arbitrary wchar_t arrays.

This patch replaces the subtraction with a little bit of code that
orders the characters correctly, returning -1 if the character from
the first string is smaller than the one from the second, 0 if they
are equal and 1 if the character from the first string is larger than
the one from the second.
-rw-r--r--src/string/wcscmp.c2
-rw-r--r--src/string/wcsncmp.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/src/string/wcscmp.c b/src/string/wcscmp.c
index 26eeee70..286ec3ea 100644
--- a/src/string/wcscmp.c
+++ b/src/string/wcscmp.c
@@ -3,5 +3,5 @@
 int wcscmp(const wchar_t *l, const wchar_t *r)
 {
 	for (; *l==*r && *l && *r; l++, r++);
-	return *l - *r;
+	return *l < *r ? -1 : *l > *r;
 }
diff --git a/src/string/wcsncmp.c b/src/string/wcsncmp.c
index 4ab32a92..2b3558bf 100644
--- a/src/string/wcsncmp.c
+++ b/src/string/wcsncmp.c
@@ -3,5 +3,5 @@
 int wcsncmp(const wchar_t *l, const wchar_t *r, size_t n)
 {
 	for (; n && *l==*r && *l && *r; n--, l++, r++);
-	return n ? *l - *r : 0;
+	return n ? (*l < *r ? -1 : *l > *r) : 0;
 }