[PATCH 1/4] add function to read single line files
Sascha Hauer
s.hauer at pengutronix.de
Mon Sep 30 05:43:05 EDT 2013
Often small files are used to store the value od a variable. This
adds a function to easily read such a variable.
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
include/libbb.h | 2 ++
lib/libbb.c | 42 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/include/libbb.h b/include/libbb.h
index 47b2e08..2fe710c 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -35,4 +35,6 @@ char *simple_itoa(unsigned int i);
int write_full(int fd, void *buf, size_t size);
int read_full(int fd, void *buf, size_t size);
+char *read_file_line(const char *fmt, ...);
+
#endif /* __LIBBB_H */
diff --git a/lib/libbb.c b/lib/libbb.c
index e0d7481..6a083f9 100644
--- a/lib/libbb.c
+++ b/lib/libbb.c
@@ -176,3 +176,45 @@ int read_full(int fd, void *buf, size_t size)
return insize;
}
EXPORT_SYMBOL(read_full);
+
+/*
+ * read_file_line - read a line from a file
+ *
+ * Used to compose a filename from a printf format and to read a line from this
+ * file. All leading and trailing whitespaces (including line endings) are
+ * removed. The returned buffer must be freed with free(). This function is
+ * supposed for reading variable like content into a buffer, so files > 1024
+ * bytes are ignored.
+ */
+char *read_file_line(const char *fmt, ...)
+{
+ va_list args;
+ char *filename;
+ char *buf, *line = NULL;
+ int size, ret;
+ struct stat s;
+
+ va_start(args, fmt);
+ filename = vasprintf(fmt, args);
+ va_end(args);
+
+ ret = stat(filename, &s);
+ if (ret)
+ goto out;
+
+ if (s.st_size > 1024)
+ goto out;
+
+ buf = read_file(filename, &size);
+ if (!buf)
+ goto out;
+
+ line = strim(buf);
+
+ line = xstrdup(line);
+ free(buf);
+out:
+ free(filename);
+ return line;
+}
+EXPORT_SYMBOL_GPL(read_file_line);
--
1.8.4.rc3
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