src/bin/lttng/utils.c

   1 /*
   2  * Copyright (c)  2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <stdlib.h>
  20 #include <ctype.h>
  21 #include <limits.h>
  22
  23 #include <common/error.h>
  24 #include <common/utils.h>
  25
  26 #include "conf.h"
  27 #include "utils.h"
  28
  29 /*
  30  *  get_session_name
  31  *
  32  *  Return allocated string with the session name found in the config
  33  *  directory.
  34  */
  35 char *get_session_name(void)
  36 {
  37         char *path, *session_name = NULL;
  38
  39         /* Get path to config file */
  40         path = utils_get_home_dir();
  41         if (path == NULL) {
  42                 goto error;
  43         }
  44
  45         /* Get session name from config */
  46         session_name = config_read_session_name(path);
  47         if (session_name == NULL) {
  48                 goto error;
  49         }
  50
  51         DBG2("Config file path found: %s", path);
  52         DBG("Session name found: %s", session_name);
  53         return session_name;
  54
  55 error:
  56         return NULL;
  57 }
  58
  59
  60 /*
  61  * list_cmd_options
  62  *
  63  * Prints a simple list of the options available to a command. This is intended
  64  * to be easily parsed for bash completion.
  65  */
  66 void list_cmd_options(FILE *ofp, struct poptOption *options)
  67 {
  68         int i;
  69         struct poptOption *option = NULL;
  70
  71         for (i = 0; options[i].longName != NULL; i++) {
  72                 option = &options[i];
  73
  74                 fprintf(ofp, "--%s\n", option->longName);
  75
  76                 if (isprint(option->shortName)) {
  77                         fprintf(ofp, "-%c\n", option->shortName);
  78                 }
  79         }
  80 }
  81
  82 /*
  83  * fls: returns the position of the most significant bit.
  84  * Returns 0 if no bit is set, else returns the position of the most
  85  * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
  86  */
  87 #if defined(__i386) || defined(__x86_64)
  88 static inline
  89 unsigned int fls_u32(uint32_t x)
  90 {
  91         int r;
  92
  93         asm("bsrl %1,%0\n\t"
  94             "jnz 1f\n\t"
  95             "movl $-1,%0\n\t"
  96             "1:\n\t"
  97             : "=r" (r) : "rm" (x));
  98         return r + 1;
  99 }
 100 #define HAS_FLS_U32
 101 #endif
 102
 103 #if defined(__x86_64)
 104 static inline
 105 unsigned int fls_u64(uint64_t x)
 106 {
 107         long r;
 108
 109         asm("bsrq %1,%0\n\t"
 110             "jnz 1f\n\t"
 111             "movq $-1,%0\n\t"
 112             "1:\n\t"
 113             : "=r" (r) : "rm" (x));
 114         return r + 1;
 115 }
 116 #define HAS_FLS_U64
 117 #endif
 118
 119 #ifndef HAS_FLS_U64
 120 static __attribute__((unused))
 121 unsigned int fls_u64(uint64_t x)
 122 {
 123         unsigned int r = 64;
 124
 125         if (!x)
 126                 return 0;
 127
 128         if (!(x & 0xFFFFFFFF00000000ULL)) {
 129                 x <<= 32;
 130                 r -= 32;
 131         }
 132         if (!(x & 0xFFFF000000000000ULL)) {
 133                 x <<= 16;
 134                 r -= 16;
 135         }
 136         if (!(x & 0xFF00000000000000ULL)) {
 137                 x <<= 8;
 138                 r -= 8;
 139         }
 140         if (!(x & 0xF000000000000000ULL)) {
 141                 x <<= 4;
 142                 r -= 4;
 143         }
 144         if (!(x & 0xC000000000000000ULL)) {
 145                 x <<= 2;
 146                 r -= 2;
 147         }
 148         if (!(x & 0x8000000000000000ULL)) {
 149                 x <<= 1;
 150                 r -= 1;
 151         }
 152         return r;
 153 }
 154 #endif
 155
 156 #ifndef HAS_FLS_U32
 157 static __attribute__((unused))
 158 unsigned int fls_u32(uint32_t x)
 159 {
 160         unsigned int r = 32;
 161
 162         if (!x)
 163                 return 0;
 164         if (!(x & 0xFFFF0000U)) {
 165                 x <<= 16;
 166                 r -= 16;
 167         }
 168         if (!(x & 0xFF000000U)) {
 169                 x <<= 8;
 170                 r -= 8;
 171         }
 172         if (!(x & 0xF0000000U)) {
 173                 x <<= 4;
 174                 r -= 4;
 175         }
 176         if (!(x & 0xC0000000U)) {
 177                 x <<= 2;
 178                 r -= 2;
 179         }
 180         if (!(x & 0x80000000U)) {
 181                 x <<= 1;
 182                 r -= 1;
 183         }
 184         return r;
 185 }
 186 #endif
 187
 188 static
 189 unsigned int fls_ulong(unsigned long x)
 190 {
 191 #if (CAA_BITS_PER_LONG == 32)
 192         return fls_u32(x);
 193 #else
 194         return fls_u64(x);
 195 #endif
 196 }
 197
 198 /*
 199  * Return the minimum order for which x <= (1UL << order).
 200  * Return -1 if x is 0.
 201  */
 202 int get_count_order_u32(uint32_t x)
 203 {
 204         if (!x)
 205                 return -1;
 206
 207         return fls_u32(x - 1);
 208 }
 209
 210 /*
 211  * Return the minimum order for which x <= (1UL << order).
 212  * Return -1 if x is 0.
 213  */
 214 int get_count_order_u64(uint64_t x)
 215 {
 216         if (!x)
 217                 return -1;
 218
 219         return fls_u64(x - 1);
 220 }
 221
 222 /*
 223  * Return the minimum order for which x <= (1UL << order).
 224  * Return -1 if x is 0.
 225  */
 226 int get_count_order_ulong(unsigned long x)
 227 {
 228         if (!x)
 229                 return -1;
 230
 231         return fls_ulong(x - 1);
 232 }