[RFC 1/3] eal: add a helper for reading string from sysfs

[Tiwei Bie <tiwei.bie@intel.com>]

This patch adds a helper for reading string from sysfs.

Signed-off-by: Cunming Liang <cunming.liang@intel.com>
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 lib/librte_eal/common/eal_filesystem.h |  7 +++++++
 lib/librte_eal/freebsd/eal/eal.c       | 22 ++++++++++++++++++++++
 lib/librte_eal/linux/eal/eal.c         | 22 ++++++++++++++++++++++
 lib/librte_eal/rte_eal_version.map     |  1 +
 4 files changed, 52 insertions(+)

diff --git a/lib/librte_eal/common/eal_filesystem.h b/lib/librte_eal/common/eal_filesystem.h
index 89a3added..2c823b27d 100644
--- a/lib/librte_eal/common/eal_filesystem.h
+++ b/lib/librte_eal/common/eal_filesystem.h
@@ -116,4 +116,11 @@ eal_get_hugefile_lock_path(char *buffer, size_t buflen, int f_id)
  * Used to read information from files on /sys */
 int eal_parse_sysfs_value(const char *filename, unsigned long *val);
 
+/**
+ * Function to read a line from a file on the filesystem.
+ * Used to read information from files on /sys
+ */
+int __rte_experimental
+rte_eal_parse_sysfs_str(const char *filename, char *buf, unsigned long sz);
+
 #endif /* EAL_FILESYSTEM_H */
diff --git a/lib/librte_eal/freebsd/eal/eal.c b/lib/librte_eal/freebsd/eal/eal.c
index 4e86b10b1..816cb9b91 100644
--- a/lib/librte_eal/freebsd/eal/eal.c
+++ b/lib/librte_eal/freebsd/eal/eal.c
@@ -208,6 +208,28 @@ eal_parse_sysfs_value(const char *filename, unsigned long *val)
 	return 0;
 }
 
+int
+rte_eal_parse_sysfs_str(const char *filename, char *buf, unsigned long sz)
+{
+	FILE *f;
+
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): cannot open sysfs file %s\n",
+			__func__, filename);
+		return -1;
+	}
+
+	if (fgets(buf, sz, f) == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): cannot read sysfs file %s\n",
+			__func__, filename);
+		fclose(f);
+		return -1;
+	}
+
+	fclose(f);
+	return 0;
+}
 
 /* create memory configuration in shared/mmap memory. Take out
  * a write lock on the memsegs, so we can auto-detect primary/secondary.
diff --git a/lib/librte_eal/linux/eal/eal.c b/lib/librte_eal/linux/eal/eal.c
index 13f401684..865cb19d7 100644
--- a/lib/librte_eal/linux/eal/eal.c
+++ b/lib/librte_eal/linux/eal/eal.c
@@ -293,6 +293,28 @@ eal_parse_sysfs_value(const char *filename, unsigned long *val)
 	return 0;
 }
 
+int
+rte_eal_parse_sysfs_str(const char *filename, char *buf, unsigned long sz)
+{
+	FILE *f;
+
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): cannot open sysfs file %s\n",
+			__func__, filename);
+		return -1;
+	}
+
+	if (fgets(buf, sz, f) == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): cannot read sysfs file %s\n",
+			__func__, filename);
+		fclose(f);
+		return -1;
+	}
+
+	fclose(f);
+	return 0;
+}
 
 /* create memory configuration in shared/mmap memory. Take out
  * a write lock on the memsegs, so we can auto-detect primary/secondary.
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index d6e375135..d16258ffc 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -298,6 +298,7 @@ EXPERIMENTAL {
 	rte_devargs_remove;
 	rte_devargs_type_count;
 	rte_eal_cleanup;
+	rte_eal_parse_sysfs_str;
 	rte_extmem_attach;
 	rte_extmem_detach;
 	rte_extmem_register;
-- 
2.17.1