lib/gis: Add portable G_strlcpy function (#4101)

This commit introduces a new G_strlcpy function in lib/gis, inspired by
G_asprintf. G_strlcpy provides a safer alternative to strcpy and strncpy,
with consistent behavior across different systems.

Key points:
- Implements strlcpy functionality, available natively on BSD systems
- Portable implementation for non-BSD systems (excluding Linux with libbsd)
- Based on FreeBSD's implementation:
  https://github.com/freebsd/freebsd-src/blob/98dd639c94f716858ae29958f484729b1d2fd387/sys/libkern/strlcpy.c#L28
- Designed to replace unsafe uses of strcpy and strncpy throughout the project

The function is implemented to use the native strlcpy where available,
falling back to our portable version on systems without it. This ensures
optimal performance on BSD systems while maintaining compatibility across
different platforms.

By providing G_strlcpy, we aim to improve the overall safety and
consistency of string operations in our codebase.

configure

@@ -766,6 +766,7 @@ ICONVLIB
 DLLIB
 MATHLIB
 HAVE_ASPRINTF
+HAVE_STRLCPY
 DBMIEXTRALIB
 USE_X11
 XTLIB
@@ -8311,6 +8312,12 @@ then :
 
 fi
 
+ac_fn_c_check_func "$LINENO" "strlcpy" "ac_cv_func_strlcpy"
+if test "x$ac_cv_func_strlcpy" = xyes
+then :
+  printf "%s\n" "#define HAVE_STRLCPY 1" >>confdefs.h
+
+fi
 
 
 # Test if mathlib needs -lm flag or is included with libc

configure.ac

@@ -595,6 +595,11 @@ AC_SUBST(DBMIEXTRALIB)
 AC_CHECK_FUNCS(asprintf)
 AC_SUBST(HAVE_ASPRINTF)
 
+# Test if strlcpy exists
+# This is a function part of *BSD libc (optionally available on Linux via libbsd)
+AC_CHECK_FUNCS(strlcpy)
+AC_SUBST(HAVE_STRLCPY)
+
 # Test if mathlib needs -lm flag or is included with libc
 AC_CHECK_FUNC(atan, MATHLIB=, [
 AC_CHECK_LIB(m, atan, MATHLIB=-lm, [

include/grass/config.h.in

@@ -14,6 +14,9 @@
 /* Define to 1 if you have the `asprintf' function. */
 #undef HAVE_ASPRINTF
 
+/* Define to 1 if you have the `strlcpy' function. */
+#undef HAVE_STRLCPY
+
 /* Define to 1 if you have the <bzlib.h> header file. */
 #undef HAVE_BZLIB_H
 

include/grass/defs/gis.h

@@ -152,6 +152,9 @@ int G_vfaprintf(FILE *, const char *, va_list);
 int G_vsaprintf(char *, const char *, va_list);
 int G_vsnaprintf(char *, size_t, const char *, va_list);
 
+/* strlcpy.c */
+size_t G_strlcpy(char *, const char *, size_t);
+
 /* basename.c */
 char *G_basename(char *, const char *);
 size_t G_get_num_decimals(const char *);

lib/gis/strlcpy.c

@@ -0,0 +1,76 @@
+/*!
+ * \file lib/gis/strlcpy.c
+ *
+ * \brief GIS Library - GRASS implementation of strlcpy().
+ *
+ * Loïc Bartoletti - 2024-07-25
+ *
+ * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and 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 <stddef.h>
+
+/**
+ * \brief Safe string copy function.
+ *
+ * Copy string src to buffer dst of size dsize. At most dsize-1
+ * characters will be copied. Always NUL terminates (unless dsize == 0).
+ * This function is a safer alternative to strncpy.
+ *
+ * \param[out] dst Pointer to the destination buffer.
+ * \param[in] src Pointer to the source string. Must be a NUL-terminated C
+ *                string.
+ * \param[in] dsize The size of the destination buffer.
+ *
+ * \return The total length of the string src (not including the terminating
+ *         NUL character). If the return value is >= dsize, truncation occurred.
+ *
+ * \note If truncation occurred, the return value is the length of the string
+ *       that would have been created if enough space had been available.
+ *
+ * \warning This function does not pad the destination buffer with NUL bytes
+ *          if the source string is shorter than dsize-1 bytes, unlike strncpy.
+ *
+ * \warning The src string must be a valid NUL-terminated C string. Passing an
+ *          unterminated string may result in buffer overrun.
+ */
+
+size_t G_strlcpy(char *restrict dst, const char *restrict src, size_t dsize)
+{
+#ifdef HAVE_STRLCPY
+    return strlcpy(dst, src, dsize);
+#else
+    const char *osrc = src;
+    size_t nleft = dsize;
+
+    /* Copy as many bytes as will fit. */
+    if (nleft != 0) {
+        while (--nleft != 0) {
+            if ((*dst++ = *src++) == '\0')
+                break;
+        }
+    }
+
+    /* Not enough room in dst, add NUL and traverse rest of src. */
+    if (nleft == 0) {
+        if (dsize != 0)
+            *dst = '\0'; /* NUL-terminate dst */
+        while (*src++)
+            ;
+    }
+
+    return (src - osrc - 1); /* count does not include NUL */
+#endif
+}