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| -rw-r--r-- | include/linux/printbuf.h | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/include/linux/printbuf.h b/include/linux/printbuf.h new file mode 100644 index 000000000000..1aa3331bf00b --- /dev/null +++ b/include/linux/printbuf.h @@ -0,0 +1,122 @@ +/* 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 out->size ? min(out->pos, out->size - 1) : 0; +} + +/* + * 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_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_chars(struct printbuf *out, char c, unsigned n) +{ + unsigned i, can_print = min(n, printbuf_remaining(out)); + + for (i = 0; i < can_print; i++) + out->buf[out->pos++] = c; + out->pos += n - can_print; +} + +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_bytes(struct printbuf *out, const void *b, unsigned n) +{ + unsigned i, can_print = min(n, printbuf_remaining(out)); + + for (i = 0; i < can_print; i++) + out->buf[out->pos++] = ((char *) b)[i]; + out->pos += n - can_print; + + 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 */ |