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(svn r13697) -Feature: Add some support for symbolic links in .tar files.

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pull/155/head
frosch 16 years ago
parent dfeb80fb9b
commit ac0ae1536f
1 changed files with 159 additions and 19 deletions
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178
src/fileio.cpp
Unescape Escape View File

@ -223,6 +223,9 @@ const char *_searchpaths[NUM_SEARCHPATHS];
TarList _tar_list;
TarFileList _tar_filelist;
typedef std::map<std::string, std::string> TarLinkList;
static TarLinkList _tar_linklist; ///< List of directory links
/**
* Check whether the given file exists
* @param filename the file to try for existance
@ -357,11 +360,31 @@ FILE *FioFOpenFile(const char *filename, const char *mode, Subdirectory subdir,
/* We can only use .tar in case of data-dir, and read-mode */
if (f == NULL && subdir == DATA_DIR && mode[0] == 'r') {
static const uint MAX_RESOLVED_LENGTH = 2 * (100 + 100 + 155) + 1; // Enough space to hold two filenames plus link. See 'TarHeader'.
char resolved_name[MAX_RESOLVED_LENGTH];
/* Filenames in tars are always forced to be lowercase */
char *lcfilename = strdup(filename);
strtolower(lcfilename);
TarFileList::iterator it = _tar_filelist.find(lcfilename);
free(lcfilename);
strcpy(resolved_name, filename);
strtolower(resolved_name);
uint resolved_len = strlen(resolved_name);
/* Resolve ONE directory link */
for (TarLinkList::iterator link = _tar_linklist.begin(); link != _tar_linklist.end(); link++) {
const std::string &src = link->first;
uint len = src.length();
if (resolved_len >= len && resolved_name[len - 1] == PATHSEPCHAR && src.compare(0, len, resolved_name, len) == 0) {
/* Apply link */
char resolved_name2[MAX_RESOLVED_LENGTH];
const std::string &dest = link->second;
strcpy(resolved_name2, &(resolved_name[len]));
strcpy(resolved_name, dest.c_str());
strcpy(&(resolved_name[dest.length()]), resolved_name2);
break; // Only resolve one level
}
}
TarFileList::iterator it = _tar_filelist.find(resolved_name);
if (it != _tar_filelist.end()) {
f = FioFOpenFileTar(&((*it).second), filesize);
}
@ -443,6 +466,22 @@ char *BuildWithFullPath(const char *dir)
return dest;
}
/**
* Simplify filenames from tars.
* Replace '/' by PATHSEPCHAR, and force 'name' to lowercase.
* @param name Filename to process.
*/
static void SimplifyFileName(char *name)
{
/* Force lowercase */
strtolower(name);
/* Tar-files always have '/' path-seperator, but we want our PATHSEPCHAR */
#if (PATHSEPCHAR != '/')
for (char *n = name; *n != '\0'; n++) if (*n == '/') *n = PATHSEPCHAR;
#endif
}
static bool TarListAddFile(const char *filename)
{
/* The TAR-header, repeated for every file */
@ -478,9 +517,13 @@ static bool TarListAddFile(const char *filename)
tar_entry->filename = strdup(filename);
_tar_list.insert(TarList::value_type(filename, tar_entry));
TarLinkList links; ///< Temporary list to collect links
TarHeader th;
char buf[sizeof(th.name) + 1], *end;
char name[sizeof(th.prefix) + 1 + sizeof(th.name) + 1];
char link[sizeof(th.linkname) + 1];
char dest[sizeof(th.prefix) + 1 + sizeof(th.name) + 1 + 1 + sizeof(th.linkname) + 1];
size_t num = 0, pos = 0;
/* Make a char of 512 empty bytes */
@ -522,24 +565,95 @@ static bool TarListAddFile(const char *filename)
buf[sizeof(th.size)] = '\0';
int skip = strtol(buf, &end, 8);
/* 0 byte sized files can be skipped (dirs, symlinks, ..) */
if (skip == 0) continue;
switch (th.typeflag) {
case '\0':
case '0': { // regular file
/* Ignore empty files */
if (skip == 0) break;
/* Store this entry in the list */
TarFileListEntry entry;
entry.tar = tar_entry;
entry.size = skip;
entry.position = pos;
/* Force lowercase */
strtolower(name);
if (strlen(name) == 0) break;
/* Tar-files always have '/' path-seperator, but we want our PATHSEPCHAR */
#if (PATHSEPCHAR != '/')
for (char *n = name; *n != '\0'; n++) if (*n == '/') *n = PATHSEPCHAR;
#endif
/* Store this entry in the list */
TarFileListEntry entry;
entry.tar = tar_entry;
entry.size = skip;
entry.position = pos;
/* Convert to lowercase and our PATHSEPCHAR */
SimplifyFileName(name);
DEBUG(misc, 6, "Found file in tar: %s (%d bytes, %d offset)", name, skip, pos);
if (_tar_filelist.insert(TarFileList::value_type(name, entry)).second) num++;
DEBUG(misc, 6, "Found file in tar: %s (%d bytes, %d offset)", name, skip, pos);
if (_tar_filelist.insert(TarFileList::value_type(name, entry)).second) num++;
break;
}
case '1': // hard links
case '2': { // symbolic links
/* Copy the destination of the link in a safe way at the end of 'linkname' */
memcpy(link, th.linkname, sizeof(th.linkname));
link[sizeof(th.linkname)] = '\0';
if (strlen(name) == 0 || strlen(link) == 0) break;
/* Convert to lowercase and our PATHSEPCHAR */
SimplifyFileName(name);
SimplifyFileName(link);
/* Only allow relative links */
if (link[0] == PATHSEPCHAR) {
DEBUG(misc, 1, "Ignoring absolute link in tar: %s -> %s", name, link);
break;
}
/* Process relative path.
* Note: The destination of links must not contain any directory-links. */
strcpy(dest, name);
char *destpos = strrchr(dest, PATHSEPCHAR);
if (destpos == NULL) destpos = dest;
*destpos = '\0';
char *pos = link;
while (*pos != '\0') {
char *next = strchr(link, PATHSEPCHAR);
if (next == NULL) next = pos + strlen(pos);
/* Skip '.' (current dir) */
if (next != pos + 1 || pos[0] != '.') {
if (next == pos + 2 && pos[0] == '.' && pos[1] == '.') {
/* level up */
if (dest[0] == '\0') {
DEBUG(misc, 1, "Ignoring link pointing outside of data directory: %s -> %s", name, link);
break;
}
/* Truncate 'dest' after last PATHSEPCHAR.
* This assumes, that the truncated part is a real directory and not a link */
destpos = strrchr(dest, PATHSEPCHAR);
if (destpos == NULL) destpos = dest;
} else {
/* Append at end of 'dest' */
if (destpos != dest) *(destpos++) = PATHSEPCHAR;
strncpy(destpos, pos, next - pos);
destpos += next - pos;
}
*destpos = '\0';
}
pos = next;
}
/* Store links in temporary list */
DEBUG(misc, 6, "Found link in tar: %s -> %s", name, dest);
links.insert(TarLinkList::value_type(name, dest));
break;
}
default:
/* Ignore other types */
break;
}
/* Skip to the next block.. */
skip = Align(skip, 512);
@ -550,6 +664,32 @@ static bool TarListAddFile(const char *filename)
DEBUG(misc, 1, "Found tar '%s' with %d new files", filename, num);
fclose(f);
/* Resolve file links and store directory links.
* We restrict usage of links to two cases:
* 1) Links to directories:
* Both the source path and the destination path must NOT contain any further links.
* When resolving files at most one directory link is resolved.
* 2) Links to files:
* The destination path must NOT contain any links.
* The source path may contain one directory link.
*/
for (TarLinkList::iterator link = links.begin(); link != links.end(); link++) {
const std::string &src = link->first;
const std::string &dest = link->second;
TarFileList::iterator dest_file = _tar_filelist.find(dest);
if (dest_file != _tar_filelist.end()) {
/* Link to file. Process the link like the destination file. */
_tar_filelist.insert(TarFileList::value_type(src, dest_file->second));
} else {
/* Destination file not found. Assume 'link to directory' */
/* Append PATHSEPCHAR to 'src' and 'dest' */
const std::string src_path = src + PATHSEPCHAR;
const std::string dst_path = (dest.length() == 0 ? "" : dest + PATHSEPCHAR);
_tar_linklist.insert(TarLinkList::value_type(src_path, dst_path));
}
}
return true;
}

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