add function to read single line files
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@pengutronix.de>
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@ -35,4 +35,6 @@ char *simple_itoa(unsigned int i);
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int write_full(int fd, void *buf, size_t size);
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int read_full(int fd, void *buf, size_t size);
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char *read_file_line(const char *fmt, ...);
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#endif /* __LIBBB_H */
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43
lib/libbb.c
43
lib/libbb.c
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@ -176,3 +176,46 @@ int read_full(int fd, void *buf, size_t size)
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return insize;
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}
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EXPORT_SYMBOL(read_full);
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/*
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* read_file_line - read a line from a file
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*
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* Used to compose a filename from a printf format and to read a line from this
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* file. All leading and trailing whitespaces (including line endings) are
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* removed. The returned buffer must be freed with free(). This function is
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* supposed for reading variable like content into a buffer, so files > 1024
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* bytes are ignored.
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*/
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char *read_file_line(const char *fmt, ...)
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{
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va_list args;
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char *filename;
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char *buf, *line = NULL;
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size_t size;
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int ret;
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struct stat s;
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va_start(args, fmt);
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filename = vasprintf(fmt, args);
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va_end(args);
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ret = stat(filename, &s);
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if (ret)
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goto out;
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if (s.st_size > 1024)
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goto out;
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buf = read_file(filename, &size);
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if (!buf)
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goto out;
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line = strim(buf);
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line = xstrdup(line);
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free(buf);
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out:
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free(filename);
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return line;
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}
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EXPORT_SYMBOL_GPL(read_file_line);
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