SQUASHFS/squashfs-tools-4.4/squashfs-tools/read_file.c

   1 /*
   2  * Create a squashfs filesystem.  This is a highly compressed read only
   3  * filesystem.
   4  *
   5  * Copyright (c) 2012
   6  * Phillip Lougher <phillip@squashfs.org.uk>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2,
  11  * or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21  *
  22  * read_file.c
  23  */
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <ctype.h>
  29 #include <errno.h>
  30
  31 #include "error.h"
  32
  33 #define TRUE 1
  34 #define FALSE 0
  35 #define MAX_LINE 16384
  36
  37 /*
  38  * Read file, passing each line to parse_line() for
  39  * parsing.
  40  *
  41  * Lines can be split across multiple lines using "\".
  42  *
  43  * Blank lines and comment lines indicated by # are supported.
  44  */
  45 int read_file(char *filename, char *type, int (parse_line)(char *))
  46 {
  47         FILE *fd;
  48         char *def, *err, *line = NULL;
  49         int res, size = 0;
  50
  51         fd = fopen(filename, "r");
  52         if(fd == NULL) {
  53                 ERROR("Could not open %s device file \"%s\" because %s\n",
  54                         type, filename, strerror(errno));
  55                 return FALSE;
  56         }
  57
  58         while(1) {
  59                 int total = 0;
  60
  61                 while(1) {
  62                         int len;
  63
  64                         if(total + (MAX_LINE + 1) > size) {
  65                                 line = realloc(line, size += (MAX_LINE + 1));
  66                                 if(line == NULL)
  67                                         MEM_ERROR();
  68                         }
  69
  70                         err = fgets(line + total, MAX_LINE + 1, fd);
  71                         if(err == NULL)
  72                                 break;
  73
  74                         len = strlen(line + total);
  75                         total += len;
  76
  77                         if(len == MAX_LINE && line[total - 1] != '\n') {
  78                                 /* line too large */
  79                                 ERROR("Line too long when reading "
  80                                         "%s file \"%s\", larger than "
  81                                         "%d bytes\n", type, filename, MAX_LINE);
  82                                 goto failed;
  83                         }
  84
  85                         /*
  86                          * Remove '\n' terminator if it exists (the last line
  87                          * in the file may not be '\n' terminated)
  88                          */
  89                         if(len && line[total - 1] == '\n') {
  90                                 line[-- total] = '\0';
  91                                 len --;
  92                         }
  93
  94                         /*
  95                          * If no line continuation then jump out to
  96                          * process line.  Note, we have to be careful to
  97                          * check for "\\" (backslashed backslash) and to
  98                          * ensure we don't look at the previous line
  99                          */
 100                         if(len == 0 || line[total - 1] != '\\' || (len >= 2 &&
 101                                         strcmp(line + total - 2, "\\\\") == 0))
 102                                 break;
 103                         else
 104                                 total --;
 105                 }
 106
 107                 if(err == NULL) {
 108                         if(ferror(fd)) {
 109                                 ERROR("Reading %s file \"%s\" failed "
 110                                         "because %s\n", type, filename,
 111                                         strerror(errno));
 112                                 goto failed;
 113                         }
 114
 115                         /*
 116                          * At EOF, normally we'll be finished, but, have to
 117                          * check for special case where we had "\" line
 118                          * continuation and then hit EOF immediately afterwards
 119                          */
 120                         if(total == 0)
 121                                 break;
 122                         else
 123                                 line[total] = '\0';
 124                 }
 125
 126                 /* Skip any leading whitespace */
 127                 for(def = line; isspace(*def); def ++);
 128
 129                 /* if line is now empty after skipping characters, skip it */
 130                 if(*def == '\0')
 131                         continue;
 132
 133                 /* if comment line, skip */
 134                 if(*def == '#')
 135                         continue;
 136
 137                 res = parse_line(def);
 138                 if(res == FALSE)
 139                         goto failed;
 140         }
 141
 142         fclose(fd);
 143         free(line);
 144         return TRUE;
 145
 146 failed:
 147         fclose(fd);
 148         free(line);
 149         return FALSE;
 150 }