strlcpy: add strlcpy and strlcat.

Author: dlbeer

Makefile

@@ -38,6 +38,7 @@ TESTS = \
     tests/bint$(TEST) \
     tests/slist$(TEST) \
     tests/cbuf$(TEST) \
+    tests/strlcpy$(TEST) \
     tests/syserr$(TEST) \
     tests/clock$(TEST) \
     tests/thr$(TEST) \
@@ -109,6 +110,9 @@ tests/slist$(TEST): tests/test_slist.o src/slist.o
 tests/cbuf$(TEST): tests/test_cbuf.o src/cbuf.o
 	$(CC) -o $@ $^
 
+tests/strlcpy$(TEST): tests/test_strlcpy.o src/strlcpy.o
+	$(CC) -o $@ $^
+
 tests/syserr$(TEST): tests/test_syserr.o
 	$(CC) -o $@ $^
 

README

@@ -19,6 +19,7 @@ directory are:
     - slab: pooled object allocator
     - slist: intrusive singly-linked list
     - strbuf: resizable string-buffer
+    - strlcpy: strlcpy() and strlcat()
     - vector: resizable array
 
   * io: portable asynchronous IO and system utilities:

src/strlcpy.c

@@ -0,0 +1,50 @@
+/* strlcpy - safe string copy
+ * Copyright (C) 2013 Daniel Beer <[email protected]>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <string.h>
+#include "strlcpy.h"
+
+size_t strlcpy(char *dst, const char *src, size_t size)
+{
+	const size_t src_len = strlen(src);
+	const size_t max_len = size - 1;
+	const size_t len = src_len > max_len ? max_len : src_len;
+
+	if (!size)
+		return 0;
+
+	memcpy(dst, src, len);
+	dst[len] = 0;
+
+	return src_len;
+}
+
+size_t strlcat(char *dst, const char *src, size_t size)
+{
+	const size_t dst_len = strlen(dst);
+	const size_t src_len = strlen(src);
+	const size_t res_len = dst_len + src_len;
+	const size_t max_len = size - dst_len - 1;
+	const size_t copy = src_len > max_len ? max_len : src_len;
+
+	if (!size || (size - 1) < dst_len)
+		return 0;
+
+	memcpy(dst + dst_len, src, copy);
+	dst[dst_len + copy] = 0;
+
+	return res_len;
+}

src/strlcpy.h

@@ -0,0 +1,26 @@
+/* strlcpy - safe string copy
+ * Copyright (C) 2013 Daniel Beer <[email protected]>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef STRLCPY_H_
+#define STRLCPY_H_
+
+#include <stddef.h>
+
+/* As per OpenBSD man page */
+size_t strlcpy(char *dst, const char *src, size_t size);
+size_t strlcat(char *dst, const char *src, size_t size);
+
+#endif

tests/test_strlcpy.c

@@ -0,0 +1,49 @@
+/* strlcpy - safe string copy
+ * Copyright (C) 2013 Daniel Beer <[email protected]>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <string.h>
+#include <assert.h>
+#include "strlcpy.h"
+
+int main(void)
+{
+	char buf[16];
+	int i;
+
+	buf[0] = 0;
+	i = strlcpy(buf, "Foo", sizeof(buf));
+	assert(i == 3);
+
+	buf[0] = 0;
+	i = strlcpy(buf, "This is a long string", sizeof(buf));
+	assert(i >= sizeof(buf));
+	assert(!strcmp(buf, "This is a long "));
+
+	buf[0] = 0;
+	i = strlcat(buf, "This is", sizeof(buf));
+	assert(i == 7);
+	assert(!strcmp(buf, "This is"));
+
+	i = strlcat(buf, " a ", sizeof(buf));
+	assert(i == 10);
+	assert(!strcmp(buf, "This is a "));
+
+	i = strlcat(buf, "long string", sizeof(buf));
+	assert(i >= sizeof(buf));
+	assert(!strcmp(buf, "This is a long "));
+
+	return 0;
+}