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/* SPDX-License-Identifier: LGPL-2.1+ */
/* Copyright (C) 2022 Kent Overstreet */
#ifndef _LINUX_PRINTBUF_H
#define _LINUX_PRINTBUF_H
#include <linux/kernel.h>
#include <linux/string.h>
/*
* Printbufs: String buffer for outputting (printing) to, for vsnprintf
*/
struct printbuf {
char *buf;
unsigned size;
unsigned pos;
};
/*
* Returns size remaining of output buffer:
*/
static inline unsigned printbuf_remaining_size(struct printbuf *out)
{
return out->pos < out->size ? out->size - out->pos : 0;
}
/*
* Returns number of characters we can print to the output buffer - i.e.
* excluding the terminating nul:
*/
static inline unsigned printbuf_remaining(struct printbuf *out)
{
return out->pos < out->size ? out->size - out->pos - 1 : 0;
}
static inline unsigned printbuf_written(struct printbuf *out)
{
return min(out->pos, out->size);
}
/*
* Returns true if output was truncated:
*/
static inline bool printbuf_overflowed(struct printbuf *out)
{
return out->pos >= out->size;
}
static inline void printbuf_nul_terminate(struct printbuf *out)
{
if (out->pos < out->size)
out->buf[out->pos] = 0;
else if (out->size)
out->buf[out->size - 1] = 0;
}
static inline void __prt_chars(struct printbuf *out, char c, unsigned n)
{
memset(out->buf + out->pos,
c,
min(n, printbuf_remaining(out)));
out->pos += n;
}
static inline void prt_chars(struct printbuf *out, char c, unsigned n)
{
__prt_chars(out, c, n);
printbuf_nul_terminate(out);
}
static inline void __prt_char(struct printbuf *out, char c)
{
if (printbuf_remaining(out))
out->buf[out->pos] = c;
out->pos++;
}
static inline void prt_char(struct printbuf *out, char c)
{
__prt_char(out, c);
printbuf_nul_terminate(out);
}
static inline void prt_bytes(struct printbuf *out, const void *b, unsigned n)
{
memcpy(out->buf + out->pos,
b,
min(n, printbuf_remaining(out)));
out->pos += n;
printbuf_nul_terminate(out);
}
static inline void prt_str(struct printbuf *out, const char *str)
{
prt_bytes(out, str, strlen(str));
}
static inline void prt_hex_byte(struct printbuf *out, u8 byte)
{
__prt_char(out, hex_asc_hi(byte));
__prt_char(out, hex_asc_lo(byte));
printbuf_nul_terminate(out);
}
static inline void prt_hex_byte_upper(struct printbuf *out, u8 byte)
{
__prt_char(out, hex_asc_upper_hi(byte));
__prt_char(out, hex_asc_upper_lo(byte));
printbuf_nul_terminate(out);
}
#define PRINTBUF_EXTERN(_buf, _size) \
((struct printbuf) { \
.buf = _buf, \
.size = _size, \
})
#endif /* _LINUX_PRINTBUF_H */
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