diff options
| -rw-r--r-- | include/linux/kernel.h | 6 | ||||
| -rw-r--r-- | kernel/printk.c | 52 |
2 files changed, 58 insertions, 0 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 5fdbc814c2e..c680e1e6e9a 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -172,6 +172,9 @@ asmlinkage int vprintk(const char *fmt, va_list args) __attribute__ ((format (printf, 1, 0))); asmlinkage int printk(const char * fmt, ...) __attribute__ ((format (printf, 1, 2))) __cold; +extern int log_buf_get_len(void); +extern int log_buf_read(int idx); +extern int log_buf_copy(char *dest, int idx, int len); #else static inline int vprintk(const char *s, va_list args) __attribute__ ((format (printf, 1, 0))); @@ -179,6 +182,9 @@ static inline int vprintk(const char *s, va_list args) { return 0; } static inline int printk(const char *s, ...) __attribute__ ((format (printf, 1, 2))); static inline int __cold printk(const char *s, ...) { return 0; } +static inline int log_buf_get_len(void) { return 0; } +static inline int log_buf_read(int idx) { return 0; } +static inline int log_buf_copy(char *dest, int idx, int len) { return 0; } #endif unsigned long int_sqrt(unsigned long); diff --git a/kernel/printk.c b/kernel/printk.c index b2b5c3a22a3..52493474f0a 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -220,6 +220,58 @@ static inline void boot_delay_msec(void) #endif /* + * Return the number of unread characters in the log buffer. + */ +int log_buf_get_len(void) +{ + return logged_chars; +} + +/* + * Copy a range of characters from the log buffer. + */ +int log_buf_copy(char *dest, int idx, int len) +{ + int ret, max; + bool took_lock = false; + + if (!oops_in_progress) { + spin_lock_irq(&logbuf_lock); + took_lock = true; + } + + max = log_buf_get_len(); + if (idx < 0 || idx >= max) { + ret = -1; + } else { + if (len > max) + len = max; + ret = len; + idx += (log_end - max); + while (len-- > 0) + dest[len] = LOG_BUF(idx + len); + } + + if (took_lock) + spin_unlock_irq(&logbuf_lock); + + return ret; +} + +/* + * Extract a single character from the log buffer. + */ +int log_buf_read(int idx) +{ + char ret; + + if (log_buf_copy(&ret, idx, 1) == 1) + return ret; + else + return -1; +} + +/* * Commands to do_syslog: * * 0 -- Close the log. Currently a NOP. |