1 files changed, 340 insertions, 0 deletions
diff --git a/src/libnix/archive.cc b/src/libnix/archive.cc
new file mode 100644
index 000000000000..9039ad7db43e
--- /dev/null
+++ b/src/libnix/archive.cc
@@ -0,0 +1,340 @@
+#include <cerrno>
+#include <algorithm>
+#include <vector>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <fcntl.h>
+
+#include "archive.hh"
+#include "util.hh"
+
+
+static string archiveVersion1 = "nix-archive-1";
+
+
+static void writePadding(unsigned int len, DumpSink & sink)
+{
+    if (len % 8) {
+        unsigned char zero[8];
+        memset(zero, 0, sizeof(zero));
+        sink(zero, 8 - (len % 8));
+    }
+}
+
+
+static void writeInt(unsigned int n, DumpSink & sink)
+{
+    unsigned char buf[8];
+    memset(buf, 0, sizeof(buf));
+    buf[0] = n & 0xff;
+    buf[1] = (n >> 8) & 0xff;
+    buf[2] = (n >> 16) & 0xff;
+    buf[3] = (n >> 24) & 0xff;
+    sink(buf, sizeof(buf));
+}
+
+
+static void writeString(const string & s, DumpSink & sink)
+{
+    unsigned int len = s.length();
+    writeInt(len, sink);
+    sink((const unsigned char *) s.c_str(), len);
+    writePadding(len, sink);
+}
+
+
+static void dump(const string & path, DumpSink & sink);
+
+
+static void dumpEntries(const Path & path, DumpSink & sink)
+{
+    DIR * dir = opendir(path.c_str());
+    if (!dir) throw SysError("opening directory " + path);
+
+    vector<string> names;
+
+    struct dirent * dirent;
+    while (errno = 0, dirent = readdir(dir)) {
+        string name = dirent->d_name;
+        if (name == "." || name == "..") continue;
+        names.push_back(name);
+    }
+    if (errno) throw SysError("reading directory " + path);
+
+    sort(names.begin(), names.end());
+
+    for (vector<string>::iterator it = names.begin();
+         it != names.end(); it++)
+    {
+        writeString("entry", sink);
+        writeString("(", sink);
+        writeString("name", sink);
+        writeString(*it, sink);
+        writeString("node", sink);
+        dump(path + "/" + *it, sink);
+        writeString(")", sink);
+    }
+    
+    closedir(dir); /* !!! close on exception */
+}
+
+
+static void dumpContents(const Path & path, unsigned int size, 
+    DumpSink & sink)
+{
+    writeString("contents", sink);
+    writeInt(size, sink);
+
+    int fd = open(path.c_str(), O_RDONLY);
+    if (fd == -1) throw SysError(format("opening file `%1%'") % path);
+    
+    unsigned char buf[65536];
+
+    unsigned int total = 0;
+    ssize_t n;
+    while ((n = read(fd, buf, sizeof(buf)))) {
+        if (n == -1) throw SysError("reading file " + path);
+        total += n;
+        sink(buf, n);
+    }
+
+    if (total != size)
+        throw SysError("file changed while reading it: " + path);
+
+    writePadding(size, sink);
+
+    close(fd); /* !!! close on exception */
+}
+
+
+static void dump(const Path & path, DumpSink & sink)
+{
+    struct stat st;
+    if (lstat(path.c_str(), &st))
+        throw SysError(format("getting attributes of path `%1%'") % path);
+
+    writeString("(", sink);
+
+    if (S_ISREG(st.st_mode)) {
+        writeString("type", sink);
+        writeString("regular", sink);
+        if (st.st_mode & S_IXUSR) {
+            writeString("executable", sink);
+            writeString("", sink);
+        }
+        dumpContents(path, st.st_size, sink);
+    } 
+
+    else if (S_ISDIR(st.st_mode)) {
+        writeString("type", sink);
+        writeString("directory", sink);
+        dumpEntries(path, sink);
+    }
+
+    else if (S_ISLNK(st.st_mode)) {
+        writeString("type", sink);
+        writeString("symlink", sink);
+        char buf[st.st_size];
+        if (readlink(path.c_str(), buf, st.st_size) != st.st_size)
+            throw SysError("reading symbolic link " + path);
+        writeString("target", sink);
+        writeString(string(buf, st.st_size), sink);
+    }
+
+    else throw Error("unknown file type: " + path);
+
+    writeString(")", sink);
+}
+
+
+void dumpPath(const Path & 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((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 Path & path, RestoreSource & source);
+
+
+static void restoreEntry(const Path & 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 Path & 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 Path & 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 == "executable" && type == tpRegular) {
+            readString(source);
+            struct stat st;
+            if (fstat(fd, &st) == -1)
+                throw SysError("fstat");
+            if (fchmod(fd, st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
+                throw SysError("fchmod");
+        }
+
+        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 Path & path, RestoreSource & source)
+{
+    if (readString(source) != archiveVersion1)
+        throw badArchive("expected Nix archive");
+    restore(path, source);
+}
+