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, void *data)
  69 {
  70         int fd, saved_errno;
  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                 SYSERROR("Failed to open config file \"%s\"", file);
  78                 return -1;
  79         }
  80
  81         ret = fstat(fd, &st);
  82         if (ret < 0) {
  83                 SYSERROR("Failed to stat config file \"%s\"", file);
  84                 goto on_error_fstat;
  85         }
  86
  87         ret = 0;
  88         if (st.st_size == 0)
  89                 goto on_error_fstat;
  90
  91         ret = -1;
  92         buf = lxc_strmmap(NULL, st.st_size, PROT_READ | PROT_WRITE,
  93                           MAP_PRIVATE | MAP_POPULATE, fd, 0);
  94         if (buf == MAP_FAILED) {
  95                 SYSERROR("Failed to map config file \"%s\"", file);
  96                 goto on_error;
  97         }
  98
  99         lxc_iterate_parts(line, buf, "\n\0") {
 100                 ret = callback(line, data);
 101                 if (ret) {
 102                         /* Callback rv > 0 means stop here callback rv < 0 means
 103                          * error.
 104                          */
 105                         if (ret < 0)
 106                                 ERROR("Failed to parse config file \"%s\" at "
 107                                       "line \"%s\"",
 108                                       file, line);
 109                         break;
 110                 }
 111         }
 112
 113 on_error:
 114         if (lxc_strmunmap(buf, st.st_size) < 0) {
 115                 SYSERROR("Failed to unmap config file \"%s\"", file);
 116                 if (ret == 0)
 117                         ret = -1;
 118         }
 119
 120 on_error_fstat:
 121         saved_errno = errno;
 122         close(fd);
 123         errno = saved_errno;
 124
 125         return ret;
 126 }
 127
 128 int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 129 {
 130         FILE *f;
 131         int err = 0;
 132         char *line = NULL;
 133         size_t len = 0;
 134
 135         f = fopen(file, "r");
 136         if (!f) {
 137                 SYSERROR("failed to open %s", file);
 138                 return -1;
 139         }
 140
 141         while (getline(&line, &len, f) != -1) {
 142                 err = callback(line, data);
 143                 if (err) {
 144                         /* Callback rv > 0 means stop here callback rv < 0 means
 145                          * error.
 146                          */
 147                         if (err < 0)
 148                                 ERROR("Failed to parse config: %s", line);
 149                         break;
 150                 }
 151         }
 152
 153         free(line);
 154         fclose(f);
 155         return err;
 156 }