I just proposed in
https://postgr.es/m/0191204143715.GA17312@alvherre.pgsql the addition of
strndup() to our src/port.
I think this should be pretty uncontroversial, but wanted to give a
heads-up outside that thread. I attach the patch here for completeness.
--
Álvaro Herrera http://www.twitter.com/alvherre
>From 9a92076e53a6664ec61c5f475310c5d6edb91d90 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Date: Wed, 4 Dec 2019 11:02:34 -0300
Subject: [PATCH v3 1/3] Add strndup / pg_strndup
The former is now a POSIX function. We already had pnstrdup, but it was
not offered to frontend code.
---
configure | 23 +++++++++++++++++++++++
configure.in | 3 ++-
src/common/fe_memutils.c | 26 ++++++++++++++++++++++++++
src/include/common/fe_memutils.h | 2 ++
src/include/pg_config.h.in | 7 +++++++
src/include/pg_config.h.win32 | 7 +++++++
src/include/port.h | 4 ++++
src/port/strndup.c | 32 ++++++++++++++++++++++++++++++++
8 files changed, 103 insertions(+), 1 deletion(-)
create mode 100644 src/port/strndup.c
diff --git a/configure b/configure
index 1d88983b34..fd8c759473 100755
--- a/configure
+++ b/configure
@@ -15482,6 +15482,16 @@ fi
cat >>confdefs.h <<_ACEOF
#define HAVE_DECL_STRLCPY $ac_have_decl
_ACEOF
+ac_fn_c_check_decl "$LINENO" "strndup" "ac_cv_have_decl_strndup" "$ac_includes_default"
+if test "x$ac_cv_have_decl_strndup" = xyes; then :
+ ac_have_decl=1
+else
+ ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRNDUP $ac_have_decl
+_ACEOF
ac_fn_c_check_decl "$LINENO" "strnlen" "ac_cv_have_decl_strnlen" "$ac_includes_default"
if test "x$ac_cv_have_decl_strnlen" = xyes; then :
ac_have_decl=1
@@ -15815,6 +15825,19 @@ esac
fi
+ac_fn_c_check_func "$LINENO" "strndup" "ac_cv_func_strndup"
+if test "x$ac_cv_func_strndup" = xyes; then :
+ $as_echo "#define HAVE_STRNDUP 1" >>confdefs.h
+
+else
+ case " $LIBOBJS " in
+ *" strndup.$ac_objext "* ) ;;
+ *) LIBOBJS="$LIBOBJS strndup.$ac_objext"
+ ;;
+esac
+
+fi
+
ac_fn_c_check_func "$LINENO" "strnlen" "ac_cv_func_strnlen"
if test "x$ac_cv_func_strnlen" = xyes; then :
$as_echo "#define HAVE_STRNLEN 1" >>confdefs.h
diff --git a/configure.in b/configure.in
index a2cb20b5e3..11f66d19c3 100644
--- a/configure.in
+++ b/configure.in
@@ -1679,7 +1679,7 @@ AC_CHECK_DECLS(posix_fadvise, [], [], [#include <fcntl.h>])
]) # fi
AC_CHECK_DECLS(fdatasync, [], [], [#include <unistd.h>])
-AC_CHECK_DECLS([strlcat, strlcpy, strnlen])
+AC_CHECK_DECLS([strlcat, strlcpy, strndup, strnlen])
# This is probably only present on macOS, but may as well check always
AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include <fcntl.h>])
@@ -1738,6 +1738,7 @@ AC_REPLACE_FUNCS(m4_normalize([
srandom
strlcat
strlcpy
+ strndup
strnlen
strtof
]))
diff --git a/src/common/fe_memutils.c b/src/common/fe_memutils.c
index ce99b4f4da..896e5d46ca 100644
--- a/src/common/fe_memutils.c
+++ b/src/common/fe_memutils.c
@@ -101,6 +101,26 @@ pg_strdup(const char *in)
return tmp;
}
+char *
+pg_strndup(const char *in, size_t size)
+{
+ char *tmp;
+
+ if (!in)
+ {
+ fprintf(stderr,
+ _("cannot duplicate null pointer (internal error)\n"));
+ exit(EXIT_FAILURE);
+ }
+ tmp = strndup(in, size);
+ if (!tmp)
+ {
+ fprintf(stderr, _("out of memory\n"));
+ exit(EXIT_FAILURE);
+ }
+ return tmp;
+}
+
void
pg_free(void *ptr)
{
@@ -142,6 +162,12 @@ pstrdup(const char *in)
return pg_strdup(in);
}
+char *
+pnstrdup(const char *in, Size size)
+{
+ return pg_strndup(in, size);
+}
+
void *
repalloc(void *pointer, Size size)
{
diff --git a/src/include/common/fe_memutils.h b/src/include/common/fe_memutils.h
index a1e5940d31..c8797ffe38 100644
--- a/src/include/common/fe_memutils.h
+++ b/src/include/common/fe_memutils.h
@@ -23,6 +23,7 @@
* (except pg_malloc_extended with MCXT_ALLOC_NO_OOM)
*/
extern char *pg_strdup(const char *in);
+extern char *pg_strndup(const char *in, size_t size);
extern void *pg_malloc(size_t size);
extern void *pg_malloc0(size_t size);
extern void *pg_malloc_extended(size_t size, int flags);
@@ -31,6 +32,7 @@ extern void pg_free(void *pointer);
/* Equivalent functions, deliberately named the same as backend functions */
extern char *pstrdup(const char *in);
+extern char *pnstrdup(const char *in, Size size);
extern void *palloc(Size size);
extern void *palloc0(Size size);
extern void *palloc_extended(Size size, int flags);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index c208dcdfc7..1db3f1b1e8 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -170,6 +170,10 @@
don't. */
#undef HAVE_DECL_STRLCPY
+/* Define to 1 if you have the declaration of `strndup', and to 0 if you
+ don't. */
+#undef HAVE_DECL_STRNDUP
+
/* Define to 1 if you have the declaration of `strnlen', and to 0 if you
don't. */
#undef HAVE_DECL_STRNLEN
@@ -545,6 +549,9 @@
/* Define to 1 if you have the `strlcpy' function. */
#undef HAVE_STRLCPY
+/* Define to 1 if you have the `strndup' function. */
+#undef HAVE_STRNDUP
+
/* Define to 1 if you have the `strnlen' function. */
#undef HAVE_STRNLEN
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 6c98ef4916..2ff2c3d4a8 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -129,6 +129,10 @@
don't. */
#define HAVE_DECL_RTLD_NOW 0
+/* Define to 1 if you have the declaration of `strndup', and to 0 if you
+ don't. */
+#undef HAVE_DECL_STRNDUP
+
/* Define to 1 if you have the declaration of `strnlen', and to 0 if you
don't. */
#define HAVE_DECL_STRNLEN 1
@@ -297,6 +301,9 @@
/* Define to 1 if you have the <pam/pam_appl.h> header file. */
/* #undef HAVE_PAM_PAM_APPL_H */
+/* Define to 1 if you have the `strndup' function. */
+#undef HAVE_STRNDUP
+
/* Define to 1 if you have the `strnlen' function. */
#define HAVE_STRNLEN 1
diff --git a/src/include/port.h b/src/include/port.h
index 10dcb5f0a6..e5d4486eb2 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -430,6 +430,10 @@ extern size_t strlcat(char *dst, const char *src, size_t siz);
extern size_t strlcpy(char *dst, const char *src, size_t siz);
#endif
+#if !HAVE_DECL_STRNDUP
+extern char *strndup(char *src, size_t siz);
+#endif
+
#if !HAVE_DECL_STRNLEN
extern size_t strnlen(const char *str, size_t maxlen);
#endif
diff --git a/src/port/strndup.c b/src/port/strndup.c
new file mode 100644
index 0000000000..eba41a0498
--- /dev/null
+++ b/src/port/strndup.c
@@ -0,0 +1,32 @@
+/*
+ * strndup.c
+ * Fallback implementation of strndup().
+ *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/port/strndup.c
+ */
+
+#include "c.h"
+
+/*
+ * Implementation of posix' strndup for systems where it's not available.
+ */
+char *
+strndup(const char *str, size_t siz)
+{
+ char *dst;
+ int len;
+
+ len = strnlen(str, siz);
+ dst = malloc(len + 1);
+ if (dst == NULL)
+ return NULL;
+
+ memcpy(dst, str, len);
+ dst[len + 1] = '\0';
+
+ return dst;
+}
--
2.20.1
