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* A function to restore from a Nix archive.

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* addValue() can now import any dumpable FS object.
This commit is contained in:
Eelco Dolstra 2003-06-23 13:27:59 +00:00
parent 85effedca3
commit 5f5cab0ac7
6 changed files with 293 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

196
src/archive.cc
View file

@ -10,7 +10,10 @@
#include "util.hh"
static void pad(unsigned int len, DumpSink & sink)
static string archiveVersion1 = "nix-archive-1";
static void writePadding(unsigned int len, DumpSink & sink)
{
if (len % 8) {
unsigned char zero[8];
@ -37,10 +40,13 @@ static void writeString(const string & s, DumpSink & sink)
unsigned int len = s.length();
writeInt(len, sink);
sink((const unsigned char *) s.c_str(), len);
pad(len, sink);
writePadding(len, sink);
}
static void dump(const string & path, DumpSink & sink);
static void dumpEntries(const string & path, DumpSink & sink)
{
DIR * dir = opendir(path.c_str());
@ -65,8 +71,8 @@ static void dumpEntries(const string & path, DumpSink & sink)
writeString("(", sink);
writeString("name", sink);
writeString(*it, sink);
writeString("file", sink);
dumpPath(path + "/" + *it, sink);
writeString("node", sink);
dump(path + "/" + *it, sink);
writeString(")", sink);
}
@ -96,13 +102,13 @@ static void dumpContents(const string & path, unsigned int size,
if (total != size)
throw SysError("file changed while reading it: " + path);
pad(size, sink);
writePadding(size, sink);
close(fd); /* !!! close on exception */
}
void dumpPath(const string & path, DumpSink & sink)
static void dump(const string & path, DumpSink & sink)
{
struct stat st;
if (lstat(path.c_str(), &st))
@ -138,6 +144,182 @@ void dumpPath(const string & path, DumpSink & sink)
}
void restorePath(const string & path, ReadSource & source)
void dumpPath(const string & path, DumpSink & sink)
{
writeString(archiveVersion1, sink);
dump(path, sink);
}
static Error badArchive(string s)
{
return Error("bad archive: " + s);
}
static void readPadding(unsigned int len, RestoreSource & source)
{
if (len % 8) {
unsigned char zero[8];
unsigned int n = 8 - (len % 8);
source(zero, n);
for (unsigned int i = 0; i < n; i++)
if (zero[i]) throw badArchive("non-zero padding");
}
}
static unsigned int readInt(RestoreSource & source)
{
unsigned char buf[8];
source(buf, sizeof(buf));
if (buf[4] || buf[5] || buf[6] || buf[7])
throw Error("implementation cannot deal with > 32-bit integers");
return
buf[0] |
(buf[1] << 8) |
(buf[2] << 16) |
(buf[3] << 24);
}
static string readString(RestoreSource & source)
{
unsigned int len = readInt(source);
char buf[len];
source((const unsigned char *) buf, len);
readPadding(len, source);
return string(buf, len);
}
static void skipGeneric(RestoreSource & source)
{
if (readString(source) == "(") {
while (readString(source) != ")")
skipGeneric(source);
}
}
static void restore(const string & path, RestoreSource & source);
static void restoreEntry(const string & path, RestoreSource & source)
{
string s, name;
s = readString(source);
if (s != "(") throw badArchive("expected open tag");
while (1) {
s = readString(source);
if (s == ")") {
break;
} else if (s == "name") {
name = readString(source);
} else if (s == "node") {
if (s == "") throw badArchive("entry name missing");
restore(path + "/" + name, source);
} else {
throw badArchive("unknown field " + s);
skipGeneric(source);
}
}
}
static void restoreContents(int fd, const string & path, RestoreSource & source)
{
unsigned int size = readInt(source);
unsigned int left = size;
unsigned char buf[65536];
while (left) {
unsigned int n = sizeof(buf);
if (n > left) n = left;
source(buf, n);
if (write(fd, buf, n) != (ssize_t) n)
throw SysError("writing file " + path);
left -= n;
}
readPadding(size, source);
}
static void restore(const string & path, RestoreSource & source)
{
string s;
s = readString(source);
if (s != "(") throw badArchive("expected open tag");
enum { tpUnknown, tpRegular, tpDirectory, tpSymlink } type = tpUnknown;
int fd = -1; /* !!! close on exception */
while (1) {
s = readString(source);
if (s == ")") {
break;
}
else if (s == "type") {
if (type != tpUnknown)
throw badArchive("multiple type fields");
string t = readString(source);
if (t == "regular") {
type = tpRegular;
fd = open(path.c_str(), O_CREAT | O_EXCL | O_WRONLY, 0666);
if (fd == -1)
throw SysError("creating file " + path);
}
else if (t == "directory") {
type = tpDirectory;
if (mkdir(path.c_str(), 0777) == -1)
throw SysError("creating directory " + path);
}
else if (t == "symlink") {
type = tpSymlink;
}
else throw badArchive("unknown file type " + t);
}
else if (s == "contents" && type == tpRegular) {
restoreContents(fd, path, source);
}
else if (s == "entry" && type == tpDirectory) {
restoreEntry(path, source);
}
else if (s == "target" && type == tpSymlink) {
string target = readString(source);
if (symlink(target.c_str(), path.c_str()) == -1)
throw SysError("creating symlink " + path);
}
else {
throw badArchive("unknown field " + s);
skipGeneric(source);
}
}
if (fd != -1) close(fd);
}
void restorePath(const string & path, RestoreSource & source)
{
if (readString(source) != archiveVersion1)
throw badArchive("expected Nix archive");
restore(path, source);
}