[klibc] Implement stpcpy() and stpncpy()

These functions are included in POSIX.1-2008, and current upstream
dash now uses stpncpy() without providing a fallback definition.

Also add tests for these functions.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

6 files changed, 121 insertions, 0 deletions

diff --git a/usr/include/string.h b/usr/include/string.h
index 0c8c0461555bd..86d5b6c6b289f 100644
--- a/usr/include/string.h
+++ b/usr/include/string.h
@@ -45,5 +45,7 @@ __extern size_t strspn(const char *, const char *);
 __extern char *strstr(const char *, const char *);
 __extern char *strtok(char *, const char *);
 __extern char *strtok_r(char *, const char *, char **);
+__extern char *stpcpy(char *, const char *);
+__extern char *stpncpy(char *, const char *, size_t);
 
 #endif				/* _STRING_H */
diff --git a/usr/klibc/Kbuild b/usr/klibc/Kbuild
index 19ccfbec3f535..b966e306ee1c0 100644
--- a/usr/klibc/Kbuild
+++ b/usr/klibc/Kbuild
@@ -46,6 +46,7 @@ klib-y += vsnprintf.o snprintf.o vsprintf.o sprintf.o \
 	  strstr.o strncmp.o strncpy.o strrchr.o \
 	  strxspn.o strspn.o strcspn.o strpbrk.o strsep.o strtok.o \
 	  strtok_r.o \
+	  stpcpy.o stpncpy.o \
 	  fnmatch.o \
 	  gethostname.o getdomainname.o getcwd.o \
 	  seteuid.o setegid.o \
diff --git a/usr/klibc/stpcpy.c b/usr/klibc/stpcpy.c
new file mode 100644
index 0000000000000..c5fc607dca849
--- /dev/null
+++ b/usr/klibc/stpcpy.c
@@ -0,0 +1,19 @@
+/*
+ * stpcpy.c
+ */
+
+#include <string.h>
+
+char *stpcpy(char *dst, const char *src)
+{
+	char ch;
+
+	for (;;) {
+		*dst = ch = *src++;
+		if (!ch)
+			break;
+		dst++;
+	}
+
+	return dst;
+}
diff --git a/usr/klibc/stpncpy.c b/usr/klibc/stpncpy.c
new file mode 100644
index 0000000000000..f28992ab8f5cf
--- /dev/null
+++ b/usr/klibc/stpncpy.c
@@ -0,0 +1,23 @@
+/*
+ * stpncpy.c
+ */
+
+#include <string.h>
+
+char *stpncpy(char *dst, const char *src, size_t n)
+{
+	char *end;
+	char ch;
+
+	while (n) {
+		ch = *src++;
+		if (!ch)
+			break;
+		n--;
+		*dst++ = ch;
+	}
+
+	end = dst;
+	memset(dst, 0, n);
+	return end;
+}
diff --git a/usr/klibc/tests/Kbuild b/usr/klibc/tests/Kbuild
index c7ca531f726db..50e381602e36b 100644
--- a/usr/klibc/tests/Kbuild
+++ b/usr/klibc/tests/Kbuild
@@ -42,6 +42,7 @@ sscanf.shared-y		:= sscanf.o
 stat.shared-y		:= stat.o
 statfs.shared-y		:= statfs.o
 stdio.shared-y		:= stdio.o
+stpcpy.shared-y		:= stpcpy.o
 strlcpycat.shared-y	:= strlcpycat.o
 strtoimax.shared-y	:= strtoimax.o
 strtotime.shared-y	:= strtotime.o
diff --git a/usr/klibc/tests/stpcpy.c b/usr/klibc/tests/stpcpy.c
new file mode 100644
index 0000000000000..4340f61a8e090
--- /dev/null
+++ b/usr/klibc/tests/stpcpy.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(void)
+{
+	char temp[10];
+#define clear_temp() strcpy(temp, "XXXXXXXXX")
+	char *end;
+
+	printf("stpcpy:\n");
+
+	clear_temp();
+	end = stpcpy(temp, "123");
+	printf("'%s'len:%zu strlen:%zu\n", temp, end - temp, strlen(temp));
+	if (end != temp + 3 || memcmp(temp, "123\0XXXXX", 10))
+		goto error;
+
+	clear_temp();
+	end = stpcpy(temp, "");
+	printf("'%s'len:%zu strlen:%zu\n", temp, end - temp, strlen(temp));
+	if (end != temp || memcmp(temp, "\0XXXXXXXX", 10))
+		goto error;
+
+	clear_temp();
+	end = stpcpy(temp, "1234567");
+	printf("'%s'len:%zu strlen:%zu\n", temp, end - temp, strlen(temp));
+	if (end != temp + 7 || memcmp(temp, "1234567\0X", 10))
+		goto error;
+
+	printf("\n");
+	printf("stpncpy:\n");
+
+	clear_temp();
+	end = stpncpy(temp, "123", 8);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 8));
+	if (end != temp + 3 || memcmp(temp, "123\0\0\0\0\0X", 10))
+		goto error;
+
+	clear_temp();
+	end = stpncpy(temp, "", 8);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 8));
+	if (end != temp || memcmp(temp, "\0\0\0\0\0\0\0\0X", 10))
+		goto error;
+
+	clear_temp();
+	end = stpncpy(temp, "1234567890", 8);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 8));
+	if (end != temp + 8 || memcmp(temp, "12345678X", 10))
+		goto error;
+
+	clear_temp();
+	end = stpncpy(temp, "123", 5);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 5));
+	if (end != temp + 3 || memcmp(temp, "123\0\0XXXX", 10))
+		goto error;
+
+	clear_temp();
+	end = stpncpy(temp, "123", 1);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 1));
+	if (end != temp + 1 || memcmp(temp, "1XXXXXXXX", 10))
+		goto error;
+
+	clear_temp();
+	end = stpncpy(temp, "123", 0);
+	printf("'%s'len:%zu strnlen:%zu\n", temp, end - temp, strnlen(temp, 0));
+	if (end != temp || memcmp(temp, "XXXXXXXXX", 10))
+		goto error;
+
+	exit(0);
+error:
+	printf("unexpected result\n");
+	exit(1);
+}