OOPListParsing.m

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/*
 
OOPListParsing.m
 
Oolite
Copyright (C) 2004-2013 Giles C Williams and contributors
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
 
*/
 
 
#import "OOPListParsing.h"
#import "OOLogging.h"
#import "OOStringParsing.h"
#import "NSDataOOExtensions.h"
#include <ctype.h>
#include <string.h>
 
 
#if !OOLITE_GNUSTEP
#define NO_DYNAMIC_PLIST_DTD_CHANGE
#endif
 
 
static NSString * const kOOLogPListFoundationParseError     = @"plist.parse.failed";
static NSString * const kOOLogPListWrongType                = @"plist.wrongType";
 
 
#ifndef NO_DYNAMIC_PLIST_DTD_CHANGE
static NSData *ChangeDTDIfApplicable(NSData *data);
#endif
 
static NSData *CopyDataFromFile(NSString *path);
static id ValueIfClass(id value, Class class);
 
 
id OOPropertyListFromData(NSData *data, NSString *whereFrom)
{
    id          result = nil;
    NSString    *error = nil;
    
    if (data != nil)
    {
#ifndef NO_DYNAMIC_PLIST_DTD_CHANGE
        data = ChangeDTDIfApplicable(data);
#endif
        
        result = [NSPropertyListSerialization propertyListFromData:data mutabilityOption:NSPropertyListImmutable format:NULL errorDescription:&error];
        if (result == nil)  // Foundation parser failed
        {   
#if OOLITE_RELEASE_PLIST_ERROR_STRINGS
            [error autorelease];
#endif
            // Ensure we can say something sensible...
            if (error == nil) error = @"<no error message>";
            if (whereFrom == nil) whereFrom = @"<data in memory>";
            
            OOLog(kOOLogPListFoundationParseError, @"Failed to parse %@ as a property list.\n%@", whereFrom, error);
        }
    }
    
    return result;
}
 
 
id OOPropertyListFromFile(NSString *path)
{
    id          result = nil;
    NSData      *data = nil;
    
    if (path != nil)
    {
        // Load file, if it exists...
        data = CopyDataFromFile(path);
        if (data != nil)
        {
            // ...and parse it
            result = OOPropertyListFromData(data, path);
            [data release];
        }
        // Non-existent file is not an error.
    }
    
    return result;
}
 
 
#ifndef NO_DYNAMIC_PLIST_DTD_CHANGE
static NSData *ChangeDTDIfApplicable(NSData *data)
{
    const uint8_t       *bytes = NULL;
    uint8_t             *newBytes = NULL;
    size_t              length,
                        newLength,
                        offset = 0,
                        newOffset = 0;
    const char          xmlDeclLine[] = "<\?xml version=\"1.0\" encoding=\"UTF-8\"\?>";
    const char          *appleDTDLines[] = 
                        {
                            "<!DOCTYPE plist PUBLIC \"-//Apple Computer//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">",
                            "<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">",
                            NULL
                        };
    const char          gstepDTDLine[] = "<!DOCTYPE plist PUBLIC \"-//GNUstep//DTD plist 0.9//EN\" \"http://www.gnustep.org/plist-0_9.xml\">";
    const char          *srcDTDLine = NULL;
    size_t              srcDTDLineSize = 0;
    unsigned            i;
    
    length = [data length];
    if (length < sizeof xmlDeclLine) return data;
    
    bytes = [data bytes];
    
    // Check if it starts with an XML declaration. Bogus: there are valid XML declarations which don't match xmlDeclLine.
    if (memcmp(bytes, xmlDeclLine, sizeof xmlDeclLine - 1) != 0) return data;
    
    offset += sizeof xmlDeclLine - 1;
    while (offset < length && isspace(bytes[offset]))  ++offset;
    
    // Check if first non-blank stuff after XML declaration is any known Apple plist DTD. Also somewhat bogus.
    for (i = 0; ; i++)
    {
        srcDTDLine = appleDTDLines[i];
        if (srcDTDLine == NULL)  return data;  // No matches
        
        srcDTDLineSize = strlen(appleDTDLines[i]);
        
        if (srcDTDLineSize <= length - offset &&
            memcmp(bytes + offset, srcDTDLine, srcDTDLineSize) == 0)
        {
            // Match
            break;
        }
    }
    
    offset += srcDTDLineSize;
    
    newLength = length - offset + sizeof xmlDeclLine + sizeof gstepDTDLine - 1;
    newBytes = malloc(newLength);
    if (newBytes == NULL) return data;
    
    // Construct modified version with altered DTD line
    memcpy(newBytes, xmlDeclLine, sizeof xmlDeclLine - 1);
    newOffset = sizeof xmlDeclLine - 1;
    newBytes[newOffset++] = '\n';
    memcpy(newBytes + newOffset, gstepDTDLine, sizeof gstepDTDLine - 1);
    newOffset += sizeof gstepDTDLine - 1;
    memcpy(newBytes + newOffset, bytes + offset, length - offset);
    
    return [NSData dataWithBytes:newBytes length:newLength];
}
#endif
 
 
/*  Load data from file. Returns a retained pointer.
    -initWithContentsOfMappedFile fails quietly under OS X if there's no file,
    but GNUstep complains.
*/
static NSData *CopyDataFromFile(NSString *path)
{
    return [[NSData oo_dataWithOXZFile:path] retain];
#if 0
// without OXZ extension. Code to be deleted once everything is working
#if OOLITE_MAC_OS_X
    return [[NSData alloc] initWithContentsOfMappedFile:path];
#else
    NSFileManager   *fmgr = [NSFileManager defaultManager];
    BOOL            dir;
    
    if ([fmgr fileExistsAtPath:path isDirectory:&dir])
    {
        if (!dir)
        {
            return [[NSData alloc] initWithContentsOfMappedFile:path];
        }
        else
        {
            OOLog(kOOLogFileNotFound, @"Expected property list but found directory at %@", path);
        }
    }
    
    return nil;
#endif
#endif
}
// Wrappers which ensure that the plist contains the right type of object.
NSDictionary *OODictionaryFromData(NSData *data, NSString *whereFrom)
{
    id result = OOPropertyListFromData(data, whereFrom);
    return ValueIfClass(result, [NSDictionary class]);
}
 
 
NSDictionary *OODictionaryFromFile(NSString *path)
{
    id result = OOPropertyListFromFile(path);
    return ValueIfClass(result, [NSDictionary class]);
}
 
 
NSArray *OOArrayFromData(NSData *data, NSString *whereFrom)
{
    id result = OOPropertyListFromData(data, whereFrom);
    return ValueIfClass(result, [NSArray class]);
}
 
 
NSArray *OOArrayFromFile(NSString *path)
{
    id result = OOPropertyListFromFile(path);
    return ValueIfClass(result, [NSArray class]);
}
 
 
// Ensure that object is of desired class.
static id ValueIfClass(id value, Class class)
{
    if (value != nil && ![value isKindOfClass:class])
    {
        OOLog(kOOLogPListWrongType, @"Property list is wrong type - expected %@, got %@.", class, [value class]);
        value = nil;
    }
    return value;
}