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Message-ID: <5cd6a28148eab3fff4af4ef2197ed0788f141f52.1764107117.git.alx@kernel.org>
Date: Tue, 25 Nov 2025 22:49:29 +0100
From: Alejandro Colomar <alx@...nel.org>
To: musl@...ts.openwall.com
Cc: Alejandro Colomar <alx@...nel.org>
Subject: [PATCH v2 1/1] include/string.h: Implement QChar wrappers
standardized in C23
I used compound literals instead of casts because they're less
dangerous. They only allow conversions that would be legal implicitly.
The register storage-class specifier is used because compound literals
are lvalues. register makes sure one can't take the address of them.
That is, it rejects:
&strchr(s, c);
Signed-off-by: Alejandro Colomar <alx@...nel.org>
---
include/string.h | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/include/string.h b/include/string.h
index 83e2b946..c492698a 100644
--- a/include/string.h
+++ b/include/string.h
@@ -24,6 +24,16 @@ extern "C" {
#include <bits/alltypes.h>
+#define __QCharof(s) typeof \
+( \
+ _Generic(s, \
+ const char *: (const char){}, \
+ const void *: (const char){}, \
+ char *: (char){}, \
+ void *: (char){} \
+ ) \
+)
+
void *memcpy (void *__restrict, const void *__restrict, size_t);
void *memmove (void *, const void *, size_t);
void *memset (void *, int, size_t);
@@ -55,6 +65,13 @@ size_t strlen (const char *);
char *strerror (int);
+#if __STDC_VERSION__ >= 202311L
+# define strchr(s, ...) ((register __QCharof(s) *){ strchr(s, __VA_ARGS__)})
+# define strrchr(s, ...) ((register __QCharof(s) *){strrchr(s, __VA_ARGS__)})
+# define strpbrk(s, ...) ((register __QCharof(s) *){strpbrk(s, __VA_ARGS__)})
+# define strstr(s, ...) ((register __QCharof(s) *){ strstr(s, __VA_ARGS__)})
+#endif
+
#if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
#include <strings.h>
#endif
@@ -95,6 +112,10 @@ char *strchrnul(const char *, int);
char *strcasestr(const char *, const char *);
void *memrchr(const void *, int, size_t);
void *mempcpy(void *, const void *, size_t);
+# if __STDC_VERSION__ >= 202311L
+# define strchrnul(s, ...) ((register __QCharof(s) *){ strchrnul(s, __VA_ARGS__)})
+# define strcasestr(s, ...) ((register __QCharof(s) *){strcasestr(s, __VA_ARGS__)})
+# endif
#endif
#ifdef __cplusplus
--
2.51.0
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