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 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <dirent.h>
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/mman.h>
  33
  34 #include "config.h"
  35 #include "log.h"
  36 #include "parse.h"
  37 #include "utils.h"
  38
  39 lxc_log_define(parse, lxc);
  40
  41 void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
  42                   off_t offset)
  43 {
  44         void *tmp = NULL, *overlap = NULL;
  45
  46         /* We establish an anonymous mapping that is one byte larger than the
  47          * underlying file. The pages handed to us are zero filled. */
  48         tmp = mmap(addr, length + 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  49         if (tmp == MAP_FAILED)
  50                 return tmp;
  51
  52         /* Now we establish a fixed-address mapping starting at the address we
  53          * received from our anonymous mapping and replace all bytes excluding
  54          * the additional \0-byte with the file. This allows us to use normal
  55          * string-handling functions. */
  56         overlap = mmap(tmp, length, prot, MAP_FIXED | flags, fd, offset);
  57         if (overlap == MAP_FAILED)
  58                 munmap(tmp, length + 1);
  59
  60         return overlap;
  61 }
  62
  63 int lxc_strmunmap(void *addr, size_t length)
  64 {
  65         return munmap(addr, length + 1);
  66 }
  67
  68 int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback,
  69                                 void *data)
  70 {
  71         int fd;
  72         char *buf, *line;
  73         struct stat st;
  74         int ret = 0;
  75
  76         fd = open(file, O_RDONLY | O_CLOEXEC);
  77         if (fd < 0)
  78                 return -1;
  79
  80         ret = fstat(fd, &st);
  81         if (ret < 0) {
  82                 close(fd);
  83                 return -1;
  84         }
  85
  86         if (st.st_size == 0) {
  87                 close(fd);
  88                 return 0;
  89         }
  90
  91         buf = lxc_strmmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  92         if (buf == MAP_FAILED) {
  93                 close(fd);
  94                 return -1;
  95         }
  96
  97         lxc_iterate_parts(line, buf, "\n\0") {
  98                 ret = callback(line, data);
  99                 if (ret) {
 100                         /* Callback rv > 0 means stop here callback rv < 0 means
 101                          * error.
 102                          */
 103                         if (ret < 0)
 104                                 ERROR("Failed to parse config: %s", line);
 105                         break;
 106                 }
 107         }
 108
 109         lxc_strmunmap(buf, st.st_size);
 110         close(fd);
 111         return ret;
 112 }
 113
 114 int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 115 {
 116         FILE *f;
 117         int err = 0;
 118         char *line = NULL;
 119         size_t len = 0;
 120
 121         f = fopen(file, "r");
 122         if (!f) {
 123                 SYSERROR("failed to open %s", file);
 124                 return -1;
 125         }
 126
 127         while (getline(&line, &len, f) != -1) {
 128                 err = callback(line, data);
 129                 if (err) {
 130                         /* Callback rv > 0 means stop here callback rv < 0 means
 131                          * error.
 132                          */
 133                         if (err < 0)
 134                                 ERROR("Failed to parse config: %s", line);
 135                         break;
 136                 }
 137         }
 138
 139         free(line);
 140         fclose(f);
 141         return err;
 142 }