src/common/logging.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2009 Pierre-Marc Fournier
   5  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  */
   7
   8 #ifndef _UST_COMMON_LOGGING_H
   9 #define _UST_COMMON_LOGGING_H
  10
  11 #include <string.h>
  12 #include <sys/types.h>
  13 #include <errno.h>
  14 #include <stdarg.h>
  15 #include <stdbool.h>
  16 #include <stdio.h>
  17
  18 #include <lttng/ust-utils.h>
  19 #include <urcu/compiler.h>
  20 #include <urcu/system.h>
  21
  22 #include "common/patient.h"
  23 #include "common/compat/tid.h"
  24 #include "common/safe-snprintf.h"
  25
  26 enum lttng_ust_log_level {
  27         LTTNG_UST_LOG_LEVEL_UNKNOWN = 0,
  28         LTTNG_UST_LOG_LEVEL_SILENT,
  29         LTTNG_UST_LOG_LEVEL_DEBUG,
  30 };
  31
  32 extern int lttng_ust_log_level                  /* enum lttng_ust_log_level */
  33         __attribute__((visibility("hidden")));
  34
  35 /*
  36  * Initialize the global log level from the "LTTNG_UST_DEBUG" environment
  37  * variable.
  38  *
  39  * This could end up being called concurrently by multiple threads but doesn't
  40  * require a mutex since the input is invariant across threads and the result
  41  * will be the same.
  42  *
  43  * Return the current log level to save the caller a second read of the global
  44  * log level.
  45  */
  46 int lttng_ust_logging_init(void)
  47         __attribute__((visibility("hidden")));
  48
  49 #ifdef LTTNG_UST_DEBUG
  50 static inline
  51 bool lttng_ust_logging_debug_enabled(void)
  52 {
  53         return true;
  54 }
  55 #else /* #ifdef LTTNG_UST_DEBUG */
  56 static inline
  57 bool lttng_ust_logging_debug_enabled(void)
  58 {
  59         int current_log_level;
  60
  61         current_log_level = CMM_LOAD_SHARED(lttng_ust_log_level);
  62
  63         /* If the global log level is unknown, lazy-initialize it. */
  64         if (caa_unlikely(current_log_level == LTTNG_UST_LOG_LEVEL_UNKNOWN))
  65                 current_log_level = lttng_ust_logging_init();
  66
  67         return current_log_level == LTTNG_UST_LOG_LEVEL_DEBUG;
  68 }
  69 #endif /* #ifdef LTTNG_UST_DEBUG */
  70
  71 /*
  72  * The default component for error messages.
  73  */
  74 #ifndef UST_COMPONENT
  75 #define UST_COMPONENT libust
  76 #endif
  77
  78 #define LTTNG_UST_LOG_MAX_LEN   512
  79
  80 /*
  81  * We sometimes print in the tracing path, and tracing can occur in
  82  * signal handlers, so we must use a print method which is signal safe.
  83  */
  84 /* Can't use dynamic allocation. Limit ourselves to LTTNG_UST_LOG_MAX_LEN chars. */
  85 /* Add end of string in case of buffer overflow. */
  86 #define sigsafe_print_err(fmt, args...)                                 \
  87 do {                                                                    \
  88         if (lttng_ust_logging_debug_enabled()) {                        \
  89                 char ____buf[LTTNG_UST_LOG_MAX_LEN];                    \
  90                 int ____saved_errno;                                    \
  91                                                                         \
  92                 ____saved_errno = errno;        /* signal-safety */     \
  93                 ust_safe_snprintf(____buf, sizeof(____buf), fmt, ## args); \
  94                 ____buf[sizeof(____buf) - 1] = 0;                       \
  95                 ust_patient_write(STDERR_FILENO, ____buf, strlen(____buf)); \
  96                 errno = ____saved_errno;        /* signal-safety */     \
  97                 fflush(stderr);                                         \
  98         }                                                               \
  99 } while (0)
 100
 101 #define LTTNG_UST_STR_COMPONENT lttng_ust_stringify(UST_COMPONENT)
 102
 103 #define ERRMSG(fmt, args...)                    \
 104         do {                                    \
 105                 sigsafe_print_err(LTTNG_UST_STR_COMPONENT "[%ld/%ld]: " fmt " (in %s() at " __FILE__ ":" lttng_ust_stringify(__LINE__) ")\n", \
 106                 (long) getpid(),                \
 107                 (long) lttng_gettid(),          \
 108                 ## args, __func__);             \
 109         } while(0)
 110
 111
 112 #define DBG(fmt, args...)       ERRMSG(fmt, ## args)
 113 #define DBG_raw(fmt, args...)   sigsafe_print_err(fmt, ## args)
 114 #define WARN(fmt, args...)      ERRMSG("Warning: " fmt, ## args)
 115 #define ERR(fmt, args...)       ERRMSG("Error: " fmt, ## args)
 116 #define BUG(fmt, args...)       ERRMSG("BUG: " fmt, ## args)
 117
 118 #if !defined(__GLIBC__) || ((_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !defined(_GNU_SOURCE))
 119 /*
 120  * Version using XSI strerror_r.
 121  */
 122 #define PERROR(call, args...)                                           \
 123         do {                                                            \
 124                 if (lttng_ust_logging_debug_enabled()) {                \
 125                         char perror_buf[200] = "Error in strerror_r()"; \
 126                         strerror_r(errno, perror_buf,                   \
 127                                         sizeof(perror_buf));            \
 128                         ERRMSG("Error: " call ": %s", ## args,          \
 129                                         perror_buf);                    \
 130                 }                                                       \
 131         } while(0)
 132 #else
 133 /*
 134  * Version using GNU strerror_r, for linux with appropriate defines.
 135  */
 136 #define PERROR(call, args...)                                           \
 137         do {                                                            \
 138                 if (lttng_ust_logging_debug_enabled()) {                \
 139                         char *perror_buf;                               \
 140                         char perror_tmp[200];                           \
 141                         perror_buf = strerror_r(errno, perror_tmp,      \
 142                                         sizeof(perror_tmp));            \
 143                         ERRMSG("Error: " call ": %s", ## args,          \
 144                                         perror_buf);                    \
 145                 }                                                       \
 146         } while(0)
 147 #endif
 148
 149 #define BUG_ON(condition)                                       \
 150         do {                                                    \
 151                 if (caa_unlikely(condition))                    \
 152                         ERR("condition not respected (BUG) on line %s:%d", __FILE__, __LINE__); \
 153         } while(0)
 154 #define WARN_ON(condition)                                      \
 155         do {                                                    \
 156                 if (caa_unlikely(condition))                    \
 157                         WARN("condition not respected on line %s:%d", __FILE__, __LINE__); \
 158         } while(0)
 159 #define WARN_ON_ONCE(condition) WARN_ON(condition)
 160
 161 #endif /* _UST_COMMON_LOGGING_H */