check for and use C library provided strlcpy and strlcat

The musl-libc library provides implementations of strlcpy and strlcat,
so introduce a feature check for it and only use the kvmtool
implementation if there is no library support for it.
This avoids clashes with the public definition.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Makefile

@@ -199,6 +199,11 @@ endif
 # On a given system, some libs may link statically, some may not; so, check
 # both and only build those that link!
 
+ifeq ($(call try-build,$(SOURCE_STRLCPY),$(CFLAGS),),y)
+	CFLAGS_DYNOPT	+= -DHAVE_STRLCPY
+	CFLAGS_STATOPT	+= -DHAVE_STRLCPY
+endif
+
 ifeq ($(call try-build,$(SOURCE_BFD),$(CFLAGS),-lbfd -static),y)
 	CFLAGS_STATOPT	+= -DCONFIG_HAS_BFD
 	OBJS_STATOPT	+= symbol.o

config/feature-tests.mak

@@ -196,3 +196,13 @@ int main(void)
 	return 0;
 }
 endef
+
+define SOURCE_STRLCPY
+#include <string.h>
+
+int main(void)
+{
+	strlcpy(NULL, NULL, 0);
+	return 0;
+}
+endef

include/kvm/strbuf.h

@@ -6,8 +6,10 @@
 
 int prefixcmp(const char *str, const char *prefix);
 
+#ifndef HAVE_STRLCPY
 extern size_t strlcat(char *dest, const char *src, size_t count);
 extern size_t strlcpy(char *dest, const char *src, size_t size);
+#endif
 
 /* some inline functions */
 

util/strbuf.c

@@ -13,6 +13,7 @@ int prefixcmp(const char *str, const char *prefix)
 	}
 }
 
+#ifndef HAVE_STRLCPY
 /**
  * strlcat - Append a length-limited, %NUL-terminated string to another
  * @dest: The string to be appended to
@@ -60,3 +61,4 @@ size_t strlcpy(char *dest, const char *src, size_t size)
 	}
 	return ret;
 }
+#endif