XAttrSet.m

//
//  XAttrSet.m
//  Backup
//
//  Created by Stefan Reitshamer on 4/27/09.
//  Copyright 2009 PhotoMinds LLC. All rights reserved.
//

#include <sys/stat.h>
#include <sys/xattr.h>
#import "XAttrSet.h"
#import "StringIO.h"
#import "DataIO.h"
#import "IntegerIO.h"
#import "Blob.h"
#import "DataInputStream.h"
#import "SetNSError.h"
#import "NSErrorCodes.h"
#import "Streams.h"
#import "NSError_extra.h"
#import "BufferedInputStream.h"
#import "NSData-Gzip.h"

#define HEADER_LENGTH (12)

@interface XAttrSet (internal)
- (BOOL)loadFromPath:(NSString *)thePath error:(NSError **)error;
- (BOOL)loadFromInputStream:(BufferedInputStream *)is error:(NSError **)error;
@end

@implementation XAttrSet
- (id)initWithPath:(NSString *)thePath error:(NSError **)error {
    if (self = [super init]) {
        xattrs = [[NSMutableDictionary alloc] init];
        NSError *myError = nil;
        if (![self loadFromPath:thePath error:&myError]) {
            if ([myError isErrorWithDomain:@"UnixErrorDomain" code:EPERM]) {
                HSLogDebug(@"%@ doesn't support extended attributes; skipping", thePath);
            } else {
                if (error != NULL) {
                    *error = myError;
                }
                [self release];
                return nil;
            }
        }
        path = [thePath retain];
    }
    return self;
}
- (id)initWithBufferedInputStream:(BufferedInputStream *)is error:(NSError **)error {
    if (self = [super init]) {
        xattrs = [[NSMutableDictionary alloc] init];
        if (![self loadFromInputStream:is error:error]) {
            [self release];
            self = nil;
        }
    }
    return self;
}
- (void)dealloc {
    [xattrs release];
    [path release];
    [super dealloc];
}
- (NSData *)toData {
    NSMutableData *mutableData = [[[NSMutableData alloc] init] autorelease];
    [mutableData appendBytes:"XAttrSetV002" length:HEADER_LENGTH];
    uint64_t count = (uint64_t)[xattrs count];
    [IntegerIO writeUInt64:count to:mutableData];
    for (NSString *name in [xattrs allKeys]) {
        [StringIO write:name to:mutableData];
        [DataIO write:[xattrs objectForKey:name] to:mutableData];
    }
    return mutableData;
}
- (NSUInteger)count {
    return [xattrs count];
}
- (unsigned long long)dataLength {
    unsigned long long total = 0;
    for (NSString *key in [xattrs allKeys]) {
        NSData *value = [xattrs objectForKey:key];
        total += [value length];
    }
    return total;
}
- (NSArray *)names {
    return [xattrs allKeys];
}
- (BOOL)applyToFile:(NSString *)thePath error:(NSError **)error {
    XAttrSet *current = [[[XAttrSet alloc] initWithPath:thePath error:error] autorelease];
    if (!current) {
        return NO;
    }
    const char *pathChars = [thePath fileSystemRepresentation];
    for (NSString *name in [current names]) {
        if (removexattr(pathChars, [name UTF8String], XATTR_NOFOLLOW) == -1) {
            int errnum = errno;
            HSLogError(@"removexattr(%@, %@) error %d: %s", thePath, name, errnum, strerror(errnum));
            SETNSERROR(@"UnixErrorDomain", errnum, @"failed to remove extended attribute %@ from %@: %s", name, thePath, strerror(errnum));
            return NO;
        }
    }
    for (NSString *key in [xattrs allKeys]) {
        NSData *value = [xattrs objectForKey:key];
        if (setxattr(pathChars, 
                     [key UTF8String],
                     [value bytes],
                     [value length],
                     0,
                     XATTR_NOFOLLOW) == -1) {
            int errnum = errno;
            HSLogError(@"setxattr(%@, %@) error %d: %s", thePath, key, errnum, strerror(errnum));
            SETNSERROR(@"UnixErrorDomain", errnum, @"failed to set extended attribute %@ on %@: %s", key, thePath, strerror(errnum));
            return NO;
        }
    }
    return YES;
}
@end

@implementation XAttrSet (internal)
- (BOOL)loadFromPath:(NSString *)thePath error:(NSError **)error {
    struct stat st;
    if (lstat([thePath fileSystemRepresentation], &st) == -1) {
        int errnum = errno;
        HSLogError(@"lstat(%@) error %d: %s", thePath, errnum, strerror(errnum));
        SETNSERROR(@"UnixErrorDomain", errnum, @"%@: %s", thePath, strerror(errnum));
        return NO;
    }
    if (S_ISREG(st.st_mode) || S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode)) {
        const char *cpath = [thePath fileSystemRepresentation];
        ssize_t xattrsize = listxattr(cpath, NULL, 0, XATTR_NOFOLLOW);
        if (xattrsize == -1) {
            int errnum = errno;
            HSLogError(@"listxattr(%@) error %d: %s", thePath, errnum, strerror(errnum));
            SETNSERROR(@"UnixErrorDomain", errnum, @"failed to list extended attributes of %@: %s", thePath, strerror(errnum));
            return NO;
        } 
        if (xattrsize > 0) {
            char *xattrbuf = (char *)malloc(xattrsize);
            xattrsize = listxattr(cpath, xattrbuf, xattrsize, XATTR_NOFOLLOW);
            if (xattrsize == -1) {
                int errnum = errno;
                HSLogError(@"listxattr(%@) error %d: %s", thePath, errnum, strerror(errnum));
                SETNSERROR(@"UnixErrorDomain", errnum, @"failed to list extended attributes of %@: %s", thePath, strerror(errnum));
                free(xattrbuf);
                return NO;
            }
            for (char *name = xattrbuf; name < (xattrbuf + xattrsize); name += strlen(name) + 1) {
                NSString *theName = [NSString stringWithUTF8String:name];
                ssize_t valuesize = getxattr(cpath, name, NULL, 0, 0, XATTR_NOFOLLOW);
                NSData *xattrData = nil;
                if (valuesize == -1) {
                    int errnum = errno;
                    HSLogError(@"getxattr(%s, %s) error %d: %s", cpath, name, errnum, strerror(errnum));
                    SETNSERROR(@"UnixErrorDomain", errnum, @"failed to read extended attribute %s of %@: %s", name, thePath, strerror(errnum));
                    free(xattrbuf);
                    return NO;
                }
                if (valuesize > 0) {
                    void *value = malloc(valuesize);
                    if (getxattr(cpath, name, value, valuesize, 0, XATTR_NOFOLLOW) == -1) {
                        int errnum = errno;
                        HSLogError(@"getxattr(%s, %s) error %d: %s", cpath, name, errnum, strerror(errnum));
                        SETNSERROR(@"UnixErrorDomain", errnum, @"failed to read extended attribute %s of %@: %s", name, thePath, strerror(errnum));
                        free(value);
                        free(xattrbuf);
                        return NO;
                    }
                    xattrData = [NSData dataWithBytes:value length:valuesize];
                    free(value);
                } else {
                    xattrData = [NSData data];
                }
                [xattrs setObject:xattrData forKey:theName];
            }
            free(xattrbuf);
        }
    }
    return YES;
}
- (BOOL)loadFromInputStream:(BufferedInputStream *)is error:(NSError **)error {
    BOOL ret = NO;
    unsigned char *buf = (unsigned char *)malloc(HEADER_LENGTH);
    if (![is readExactly:HEADER_LENGTH into:buf error:error]) {
        goto load_error;
    }
    if (strncmp((const char *)buf, "XAttrSetV002", HEADER_LENGTH)) {
        SETNSERROR(@"XAttrSetErrorDomain", ERROR_INVALID_OBJECT_VERSION, @"invalid XAttrSet header");
        goto load_error;
    }
    uint64_t count;
    if (![IntegerIO readUInt64:&count from:is error:error]) {
        goto load_error;
    }
    for (uint64_t i = 0; i < count; i++) {
        NSString *name;
        if (![StringIO read:&name from:is error:error]) {
            goto load_error;
        }
        NSData *value;
        if (![DataIO read:&value from:is error:error]) {
            goto load_error;
        }
        [xattrs setObject:value forKey:name];
    }
    ret = YES;
load_error:
    free(buf);
    return ret;
}
@end