src/nobug_ringbuffer.c

   1 /*
   2  This file is part of the NoBug debugging library.
   3
   4  Copyright (C) 2007, 2008, Christian Thaeter <chth@gmx.net>
   5
   6  This program is free software; you can redistribute it and/or modify
   7  it under the terms of the GNU General Public License as published by
   8  the Free Software Foundation; either version 2 of the License, or
   9  (at your option) any later version.
  10
  11  This program is distributed in the hope that it will be useful,
  12  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  GNU General Public License for more details.
  15
  16  You should have received a copy of the GNU General Public License
  17  along with this program; if not, contact Christian Thaeter <ct@pipapo.org>.
  18 */
  19 #include <fcntl.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <stdlib.h>
  23
  24 #include <sys/mman.h>
  25
  26 #define NOBUG_LIBNOBUG_C
  27 #include "nobug.h"
  28
  29 #define NOBUG_RINGBUFFER_MAX_MSG 4094
  30
  31 struct nobug_ringbuffer*
  32 nobug_ringbuffer_init (struct nobug_ringbuffer* self, size_t size, const char * name, int flags)
  33 {
  34   size_t pagesz = sysconf (_SC_PAGESIZE);
  35
  36   size = (size + pagesz-1) & ~(pagesz-1);
  37   self->maxmsg = (NOBUG_RINGBUFFER_MAX_MSG+2 + pagesz-1) & ~(pagesz-1);
  38
  39   self->name[255] = '\0';
  40   if (!name)
  41     {
  42       strcpy(self->name, "/tmp/nobug_ringbufferXXXXXX");
  43     }
  44   else
  45     {
  46       strncpy(self->name, name, 255);
  47     }
  48
  49   int fd = mkstemp(self->name);
  50
  51   int oflags = O_RDWR|O_CREAT;
  52   if (!(flags & NOBUG_RINGBUFFER_APPEND))
  53     oflags |= O_TRUNC;
  54
  55   if (fd == -1 && errno == EINVAL)
  56     fd = open(self->name, oflags, 0600);
  57
  58   if (fd == -1)
  59     {
  60       /* still error, exit here */
  61       fprintf(stderr, "nobug_ringbuffer: Failed to open nobug_ringbuffer %s: %s\n", self->name, strerror(errno));
  62       exit (EXIT_FAILURE);
  63     }
  64
  65   if (!name || flags & NOBUG_RINGBUFFER_TEMP)
  66     unlink (self->name);
  67
  68   if (!name || !(flags & NOBUG_RINGBUFFER_KEEP))
  69     {
  70       /* just in case we need the name later, store the first character at the end */
  71       self->name[255] = self->name[0];
  72       self->name[0] = 0;
  73     }
  74
  75   if (ftruncate(fd, size))
  76     {
  77       fprintf(stderr, "nobug_ringbuffer: Failed to truncate ringbuffer to %zd: %s\n",
  78               size, strerror(errno));
  79       exit (EXIT_FAILURE);
  80     }
  81   self->size = size;
  82
  83   /* get contigous address range */
  84   char * start = mmap (0, size+2*self->maxmsg, PROT_NONE, MAP_SHARED|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0);
  85   if (!start)
  86     {
  87       fprintf(stderr, "nobug_ringbuffer: Failed to reserve %zd bytes of address space: %s\n",
  88               size+2*self->maxmsg, strerror(errno));
  89       exit (EXIT_FAILURE);
  90     }
  91
  92   /* map the backing file */
  93   self->start = mmap (start+self->maxmsg, size, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, fd, 0);
  94   if (!self->start)
  95     {
  96       fprintf(stderr, "nobug_ringbuffer: Failed to mmap backing file, %s\n", strerror(errno));
  97       exit (EXIT_FAILURE);
  98     }
  99   /* map beginning after the end */
 100   if (!mmap (start+self->maxmsg+size, self->maxmsg, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, fd, 0))
 101     {
 102       fprintf(stderr, "nobug_ringbuffer: Failed to mmap trailing guard page, %s\n", strerror(errno));
 103       exit (EXIT_FAILURE);
 104     }
 105   /* map end before beginning */
 106   if (!mmap (start, self->maxmsg, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, fd, size-self->maxmsg))
 107     {
 108       fprintf(stderr, "nobug_ringbuffer: Failed to mmap leading guard page, %s\n", strerror(errno));
 109       exit (EXIT_FAILURE);
 110     }
 111
 112   close (fd);
 113
 114   if (flags & NOBUG_RINGBUFFER_APPEND)
 115     {
 116       start = memchr (self->start, ~0, size);
 117       if (!start)
 118         /* new file, can't append */
 119         goto init;
 120       self->pos = start-1;
 121       if (self->pos < self->start)
 122         self->pos += size;
 123     }
 124   else
 125     {
 126     init:
 127       /* set pos to the end of the file, then new writes will start at the beginning */
 128       self->pos = self->start+size-1;
 129       /* ~0 is used as marker for the turnaround point */
 130       self->pos[1] = ~0;
 131     }
 132   return self;
 133 }
 134
 135
 136 struct nobug_ringbuffer*
 137 nobug_ringbuffer_new (size_t size, const char * name, int flags)
 138 {
 139   struct nobug_ringbuffer* self = malloc (sizeof (struct nobug_ringbuffer));
 140   if (!self)
 141     return NULL;
 142   return nobug_ringbuffer_init (self, size, name, flags);
 143 }
 144
 145
 146 struct nobug_ringbuffer*
 147 nobug_ringbuffer_destroy (struct nobug_ringbuffer* self)
 148 {
 149   if (self->name[0])
 150     unlink(self->name);
 151   munmap(self->start-self->maxmsg, self->size + 2 * self->maxmsg);
 152   return self;
 153 }
 154
 155
 156 void
 157 nobug_ringbuffer_delete (struct nobug_ringbuffer* self)
 158 {
 159   free (nobug_ringbuffer_destroy (self));
 160 }
 161
 162
 163 int
 164 nobug_ringbuffer_vprintf (struct nobug_ringbuffer* self, const char* fmt, va_list ap)
 165 {
 166   int written = vsnprintf (self->pos + 1, self->maxmsg-2, fmt, ap);
 167   self->pos += (written + 1);
 168
 169   if (self->pos > self->start+self->size)
 170     self->pos -= self->size;
 171
 172   self->pos[1] = ~0;
 173
 174   return written;
 175 }
 176
 177
 178 int
 179 nobug_ringbuffer_printf (struct nobug_ringbuffer* self, const char* fmt, ...)
 180 {
 181   va_list ap;
 182   va_start (ap, fmt);
 183   int written = nobug_ringbuffer_vprintf (self, fmt, ap);
 184   va_end(ap);
 185   return written;
 186 }
 187
 188
 189 char*
 190 nobug_ringbuffer_prev (struct nobug_ringbuffer* self, char* pos)
 191 {
 192   if (!pos)
 193     pos = self->pos;
 194   else
 195     --pos;
 196
 197   while(!*--pos);
 198   while(*--pos);
 199   if (pos < self->start)
 200     pos += self->size;
 201
 202   if (pos[1] == ~0)
 203     return NULL;
 204
 205   return pos+1;
 206 }
 207
 208 char*
 209 nobug_ringbuffer_next (struct nobug_ringbuffer* self, char* pos)
 210 {
 211   if (!pos)
 212     pos = self->pos+1;
 213
 214   while (*++pos);
 215   while (!*++pos);
 216   if (pos > self->start+self->size)
 217     pos -= self->size;
 218
 219   if (*pos == ~0)
 220     return NULL;
 221
 222   return pos;
 223 }
 224
 225 int
 226 nobug_ringbuffer_save (struct nobug_ringbuffer* self, FILE* out)
 227 {
 228   int ret = 0;
 229   int cnt;
 230   char* next;
 231
 232   for (next = nobug_ringbuffer_next (self, NULL); next; next = nobug_ringbuffer_next(self, next))
 233     {
 234       cnt = fprintf (out,"%s\n", next);
 235       if (cnt < 0)
 236         return -ret-1;
 237       else
 238         ret += cnt;
 239     }
 240   return ret;
 241 }
 242
 243 int
 244 nobug_ringbuffer_load (struct nobug_ringbuffer* self, FILE* in)
 245 {
 246   int ret = 0;
 247   char buf[NOBUG_RINGBUFFER_MAX_MSG];
 248
 249   while (fgets(buf, self->maxmsg, in))
 250     {
 251       size_t l = strlen(buf);
 252       if (buf[l-1] == '\n')
 253         buf[l-1] = '\0';
 254       ret += nobug_ringbuffer_printf (self, "%s", buf);
 255     }
 256   return ret;
 257 }
 258
 259 char*
 260 nobug_ringbuffer_pos (struct nobug_ringbuffer* self)
 261 {
 262   return self->pos+1;
 263 }
 264
 265 void
 266 nobug_ringbuffer_pop (struct nobug_ringbuffer* self)
 267 {
 268   self->pos[0] = '\n';  /* clear the \0 */
 269   self->pos[1] = ' ';   /* clear the ~0 */
 270
 271   self->pos = strrchr(self->pos, 0);
 272   if (self->pos < self->start)
 273     self->pos += self->size;
 274
 275   self->pos[1] = ~0;
 276 }