src/lxc/parse.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #define _GNU_SOURCE
  25 #include <stdio.h>
  26 #undef _GNU_SOURCE
  27 #include <dirent.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <sys/mman.h>
  32
  33 #include "parse.h"
  34 #include "config.h"
  35 #include "utils.h"
  36 #include "log.h"
  37
  38 lxc_log_define(parse, lxc);
  39
  40 void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
  41                   off_t offset)
  42 {
  43         void *tmp = NULL, *overlap = NULL;
  44
  45         /* We establish an anonymous mapping that is one byte larger than the
  46          * underlying file. The pages handed to us are zero filled. */
  47         tmp = mmap(addr, length + 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  48         if (tmp == MAP_FAILED)
  49                 return tmp;
  50
  51         /* Now we establish a fixed-address mapping starting at the address we
  52          * received from our anonymous mapping and replace all bytes excluding
  53          * the additional \0-byte with the file. This allows us to use normal
  54          * string-handling functions. */
  55         overlap = mmap(tmp, length, prot, MAP_FIXED | flags, fd, offset);
  56         if (overlap == MAP_FAILED)
  57                 munmap(tmp, length + 1);
  58
  59         return overlap;
  60 }
  61
  62 int lxc_strmunmap(void *addr, size_t length)
  63 {
  64         return munmap(addr, length + 1);
  65 }
  66
  67 int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback,
  68                                 void *data)
  69 {
  70         int fd;
  71         char *buf, *line;
  72         struct stat st;
  73         int ret = 0;
  74
  75         fd = open(file, O_RDONLY | O_CLOEXEC);
  76         if (fd < 0)
  77                 return -1;
  78
  79         ret = fstat(fd, &st);
  80         if (ret < 0) {
  81                 close(fd);
  82                 return -1;
  83         }
  84
  85         if (st.st_size == 0) {
  86                 close(fd);
  87                 return 0;
  88         }
  89
  90         buf = lxc_strmmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  91         if (buf == MAP_FAILED) {
  92                 close(fd);
  93                 return -1;
  94         }
  95
  96         lxc_iterate_parts(line, buf, "\n\0") {
  97                 ret = callback(line, data);
  98                 if (ret) {
  99                         /* Callback rv > 0 means stop here callback rv < 0 means
 100                          * error.
 101                          */
 102                         if (ret < 0)
 103                                 ERROR("Failed to parse config: %s", line);
 104                         break;
 105                 }
 106         }
 107
 108         lxc_strmunmap(buf, st.st_size);
 109         close(fd);
 110         return ret;
 111 }
 112
 113 int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 114 {
 115         FILE *f;
 116         int err = 0;
 117         char *line = NULL;
 118         size_t len = 0;
 119
 120         f = fopen(file, "r");
 121         if (!f) {
 122                 SYSERROR("failed to open %s", file);
 123                 return -1;
 124         }
 125
 126         while (getline(&line, &len, f) != -1) {
 127                 err = callback(line, data);
 128                 if (err) {
 129                         /* Callback rv > 0 means stop here callback rv < 0 means
 130                          * error.
 131                          */
 132                         if (err < 0)
 133                                 ERROR("Failed to parse config: %s", line);
 134                         break;
 135                 }
 136         }
 137
 138         free(line);
 139         fclose(f);
 140         return err;
 141 }