eal: support strlcpy function

The strncpy function is error prone for doing "safe" string copies, so
we generally try to use "snprintf" instead in the code. The function
"strlcpy" is a better alternative, since it better conveys the
intention of the programmer, and doesn't suffer from the non-null
terminating behaviour of it's n'ed brethern.

The downside of this function is that it is not available by default
on linux, though standard in the BSD's. It is available on most
distros by installing "libbsd" package.

This patch therefore provides the following in rte_string_fns.h to ensure
that strlcpy is available there:
* for BSD, include string.h as normal
* if RTE_USE_LIBBSD is set, include <bsd/string.h>
* if not set, fallback to snprintf for strlcpy

Using make build system, the RTE_USE_LIBBSD is a hard-coded value to "n",
but when using meson, it's automatically set based on what is available
on the platform.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>

5 files changed, 50 insertions, 0 deletions

diff --git a/config/common_base b/config/common_base
index 348228b299..c09c7cf88e 100644
--- a/config/common_base
+++ b/config/common_base
@@ -76,6 +76,7 @@ CONFIG_RTE_EAL_VFIO=n
 CONFIG_RTE_MAX_VFIO_GROUPS=64
 CONFIG_RTE_MALLOC_DEBUG=n
 CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES=n
+CONFIG_RTE_USE_LIBBSD=n
 
 #
 # Recognize/ignore the AVX/AVX512 CPU flags for performance/power testing.
diff --git a/config/meson.build b/config/meson.build
index f8c67578df..77af5d897d 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -38,6 +38,13 @@ if numa_dep.found() and cc.has_header('numaif.h')
 	dpdk_extra_ldflags += '-lnuma'
 endif
 
+# check for strlcpy
+if host_machine.system() == 'linux' and cc.find_library('bsd', required: false).found()
+	dpdk_conf.set('RTE_USE_LIBBSD', 1)
+	add_project_link_arguments('-lbsd', language: 'c')
+	dpdk_extra_ldflags += '-lbsd'
+endif
+
 # add -include rte_config to cflags
 add_project_arguments('-include', 'rte_config.h', language: 'c')
 
diff --git a/devtools/cocci/strlcpy.cocci b/devtools/cocci/strlcpy.cocci
new file mode 100644
index 0000000000..335e271282
--- /dev/null
+++ b/devtools/cocci/strlcpy.cocci
@@ -0,0 +1,8 @@
+@use_strlcpy@
+identifier src, dst;
+expression size;
+@@
+(
+- snprintf(dst, size, "%s", src)
++ strlcpy(dst, src, size)
+)
diff --git a/lib/librte_eal/common/include/rte_string_fns.h b/lib/librte_eal/common/include/rte_string_fns.h
index e97047a47d..fcbb42e004 100644
--- a/lib/librte_eal/common/include/rte_string_fns.h
+++ b/lib/librte_eal/common/include/rte_string_fns.h
@@ -15,6 +15,8 @@
 extern "C" {
 #endif
 
+#include <stdio.h>
+
 /**
  * Takes string "string" parameter and splits it at character "delim"
  * up to maxtokens-1 times - to give "maxtokens" resulting tokens. Like
@@ -45,6 +47,35 @@ int
 rte_strsplit(char *string, int stringlen,
              char **tokens, int maxtokens, char delim);
 
+/**
+ * @internal
+ * DPDK-specific version of strlcpy for systems without
+ * libc or libbsd copies of the function
+ */
+static inline size_t
+rte_strlcpy(char *dst, const char *src, size_t size)
+{
+	return snprintf(dst, size, "%s", src);
+}
+
+/* pull in a strlcpy function */
+#ifdef RTE_EXEC_ENV_BSDAPP
+#include <string.h>
+#ifndef __BSD_VISIBLE /* non-standard functions are hidden */
+#define strlcpy(dst, src, size) rte_strlcpy(dst, src, size)
+#endif
+
+
+#else /* non-BSD platforms */
+#ifdef RTE_USE_LIBBSD
+#include <bsd/string.h>
+
+#else /* no BSD header files, create own */
+#define strlcpy(dst, src, size) rte_strlcpy(dst, src, size)
+
+#endif /* RTE_USE_LIBBSD */
+#endif /* BSDAPP */
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/mk/rte.app.mk b/mk/rte.app.mk
index a9b4b0502f..228dc19a75 100644
--- a/mk/rte.app.mk
+++ b/mk/rte.app.mk
@@ -255,6 +255,9 @@ _LDLIBS-$(CONFIG_RTE_LIBRTE_EAL)            += -lrt
 ifeq ($(CONFIG_RTE_EXEC_ENV_LINUXAPP)$(CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES),yy)
 _LDLIBS-$(CONFIG_RTE_LIBRTE_EAL)            += -lnuma
 endif
+ifeq ($(CONFIG_RTE_EXEC_ENV_LINUXAPP)$(CONFIG_RTE_USE_LIBBSD),yy)
+_LDLIBS-$(CONFIG_RTE_LIBRTE_EAL)            += -lbsd
+endif
 _LDLIBS-$(CONFIG_RTE_LIBRTE_SCHED)          += -lm
 _LDLIBS-$(CONFIG_RTE_LIBRTE_SCHED)          += -lrt
 _LDLIBS-$(CONFIG_RTE_LIBRTE_MEMBER)         += -lm