[dpdk-dev] [PATCH 1/2] add support for strlcpy function

Bruce Richardson bruce.richardson at intel.com
Mon Mar 12 12:32:59 CET 2018


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 at intel.com>

----
RFC->v1:
* split patch into 2, to separate out snprintf replacement
* added missing include in mlx drivers
* adding linking support against libbsd when feature is enabled
* make strlcpy an inline function rather than macro
* fix support on BSD where strict posix compliance is requested and
  therefore strlcpy is not available.
---
 config/common_base                             |  1 +
 config/meson.build                             |  7 +++++++
 devtools/cocci/strlcpy.cocci                   |  8 +++++++
 lib/librte_eal/common/include/rte_string_fns.h | 29 ++++++++++++++++++++++++++
 mk/rte.app.mk                                  |  3 +++
 5 files changed, 48 insertions(+)
 create mode 100644 devtools/cocci/strlcpy.cocci

diff --git a/config/common_base b/config/common_base
index ad03cf433..20d4cbcf2 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 f8c67578d..77af5d897 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 000000000..335e27128
--- /dev/null
+++ b/devtools/cocci/strlcpy.cocci
@@ -0,0 +1,8 @@
+ at 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 e97047a47..f1f5b17b8 100644
--- a/lib/librte_eal/common/include/rte_string_fns.h
+++ b/lib/librte_eal/common/include/rte_string_fns.h
@@ -45,6 +45,35 @@ 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 3eb41d176..39511da93 100644
--- a/mk/rte.app.mk
+++ b/mk/rte.app.mk
@@ -248,6 +248,9 @@ _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
-- 
2.14.3



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