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
  25 #include "conf.h"
  26 #include "utils.h"
  27
  28 /*
  29  *  get_session_name
  30  *
  31  *  Return allocated string with the session name found in the config
  32  *  directory.
  33  */
  34 char *get_session_name(void)
  35 {
  36         char *path, *session_name = NULL;
  37
  38         /* Get path to config file */
  39         path = config_get_default_path();
  40         if (path == NULL) {
  41                 goto error;
  42         }
  43
  44         /* Get session name from config */
  45         session_name = config_read_session_name(path);
  46         if (session_name == NULL) {
  47                 goto error;
  48         }
  49
  50         DBG2("Config file path found: %s", path);
  51         DBG("Session name found: %s", session_name);
  52         return session_name;
  53
  54 error:
  55         return NULL;
  56 }
  57
  58
  59 /*
  60  * list_cmd_options
  61  *
  62  * Prints a simple list of the options available to a command. This is intended
  63  * to be easily parsed for bash completion.
  64  */
  65 void list_cmd_options(FILE *ofp, struct poptOption *options)
  66 {
  67         int i;
  68         struct poptOption *option = NULL;
  69
  70         for (i = 0; options[i].longName != NULL; i++) {
  71                 option = &options[i];
  72
  73                 fprintf(ofp, "--%s\n", option->longName);
  74
  75                 if (isprint(option->shortName)) {
  76                         fprintf(ofp, "-%c\n", option->shortName);
  77                 }
  78         }
  79 }
  80
  81 /*
  82  * fls: returns the position of the most significant bit.
  83  * Returns 0 if no bit is set, else returns the position of the most
  84  * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
  85  */
  86 #if defined(__i386) || defined(__x86_64)
  87 static inline
  88 unsigned int fls_u32(uint32_t x)
  89 {
  90         int r;
  91
  92         asm("bsrl %1,%0\n\t"
  93             "jnz 1f\n\t"
  94             "movl $-1,%0\n\t"
  95             "1:\n\t"
  96             : "=r" (r) : "rm" (x));
  97         return r + 1;
  98 }
  99 #define HAS_FLS_U32
 100 #endif
 101
 102 #if defined(__x86_64)
 103 static inline
 104 unsigned int fls_u64(uint64_t x)
 105 {
 106         long r;
 107
 108         asm("bsrq %1,%0\n\t"
 109             "jnz 1f\n\t"
 110             "movq $-1,%0\n\t"
 111             "1:\n\t"
 112             : "=r" (r) : "rm" (x));
 113         return r + 1;
 114 }
 115 #define HAS_FLS_U64
 116 #endif
 117
 118 #ifndef HAS_FLS_U64
 119 static __attribute__((unused))
 120 unsigned int fls_u64(uint64_t x)
 121 {
 122         unsigned int r = 64;
 123
 124         if (!x)
 125                 return 0;
 126
 127         if (!(x & 0xFFFFFFFF00000000ULL)) {
 128                 x <<= 32;
 129                 r -= 32;
 130         }
 131         if (!(x & 0xFFFF000000000000ULL)) {
 132                 x <<= 16;
 133                 r -= 16;
 134         }
 135         if (!(x & 0xFF00000000000000ULL)) {
 136                 x <<= 8;
 137                 r -= 8;
 138         }
 139         if (!(x & 0xF000000000000000ULL)) {
 140                 x <<= 4;
 141                 r -= 4;
 142         }
 143         if (!(x & 0xC000000000000000ULL)) {
 144                 x <<= 2;
 145                 r -= 2;
 146         }
 147         if (!(x & 0x8000000000000000ULL)) {
 148                 x <<= 1;
 149                 r -= 1;
 150         }
 151         return r;
 152 }
 153 #endif
 154
 155 #ifndef HAS_FLS_U32
 156 static __attribute__((unused))
 157 unsigned int fls_u32(uint32_t x)
 158 {
 159         unsigned int r = 32;
 160
 161         if (!x)
 162                 return 0;
 163         if (!(x & 0xFFFF0000U)) {
 164                 x <<= 16;
 165                 r -= 16;
 166         }
 167         if (!(x & 0xFF000000U)) {
 168                 x <<= 8;
 169                 r -= 8;
 170         }
 171         if (!(x & 0xF0000000U)) {
 172                 x <<= 4;
 173                 r -= 4;
 174         }
 175         if (!(x & 0xC0000000U)) {
 176                 x <<= 2;
 177                 r -= 2;
 178         }
 179         if (!(x & 0x80000000U)) {
 180                 x <<= 1;
 181                 r -= 1;
 182         }
 183         return r;
 184 }
 185 #endif
 186
 187 static
 188 unsigned int fls_ulong(unsigned long x)
 189 {
 190 #if (CAA_BITS_PER_LONG == 32)
 191         return fls_u32(x);
 192 #else
 193         return fls_u64(x);
 194 #endif
 195 }
 196
 197 /*
 198  * Return the minimum order for which x <= (1UL << order).
 199  * Return -1 if x is 0.
 200  */
 201 int get_count_order_u32(uint32_t x)
 202 {
 203         if (!x)
 204                 return -1;
 205
 206         return fls_u32(x - 1);
 207 }
 208
 209 /*
 210  * Return the minimum order for which x <= (1UL << order).
 211  * Return -1 if x is 0.
 212  */
 213 int get_count_order_u64(uint64_t x)
 214 {
 215         if (!x)
 216                 return -1;
 217
 218         return fls_u64(x - 1);
 219 }
 220
 221 /*
 222  * Return the minimum order for which x <= (1UL << order).
 223  * Return -1 if x is 0.
 224  */
 225 int get_count_order_ulong(unsigned long x)
 226 {
 227         if (!x)
 228                 return -1;
 229
 230         return fls_ulong(x - 1);
 231 }