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e98aab7ea9
`--repro` is a hidden command flag for debugging. Previously, if the flag was given, mold would create a `.repro` section in an output file with all input files as its contents. The flaw of the design is that when mold fails to create an output file, no .repro section would be created. So I changed the behavior in this commit. Now, the tar file is created as an independent file.
110 lines
2.9 KiB
C++
110 lines
2.9 KiB
C++
#include "mold.h"
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namespace mold {
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// A tar file consists of one or more Ustar header followed by data.
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// Each Ustar header represents a single file in an archive.
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//
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// tar is an old file format, and its `name` field is only 100 bytes long.
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// If `name` is longer than 100 bytes, we can emit a PAX header before a
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// Ustar header to store a long filename.
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//
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// For simplicity, we always emit a PAX header even for a short filename.
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struct UstarHeader {
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UstarHeader() {
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memset(this, 0, sizeof(*this));
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}
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void finalize() {
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memset(checksum, ' ', sizeof(checksum));
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memcpy(magic, "ustar", 5);
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memcpy(version, "00", 2);
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// Compute checksum
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int sum = 0;
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for (i64 i = 0; i < sizeof(*this); i++)
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sum += ((u8 *)this)[i];
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assert(sum < 1000000);
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sprintf(checksum, "%06o", sum);
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}
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char name[100];
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char mode[8];
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char uid[8];
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char gid[8];
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char size[12];
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char mtime[12];
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char checksum[8];
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char typeflag[1];
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char linkname[100];
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char magic[6];
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char version[2];
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char uname[32];
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char gname[32];
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char devmajor[8];
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char devminor[8];
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char prefix[155];
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char pad[12];
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};
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static std::string encode_path(std::string basedir, std::string path) {
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path = path_clean(basedir + "/" + path);
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// Construct a string which contains something like
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// "16 path=foo/bar\n" where 16 is the size of the string
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// including the size string itself.
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i64 len = std::string(" path=\n").size() + path.size();
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i64 total = std::to_string(len).size() + len;
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total = std::to_string(total).size() + len;
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return std::to_string(total) + " path=" + path + "\n";
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}
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std::unique_ptr<TarWriter>
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TarWriter::open(std::string output_path, std::string basedir) {
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FILE *out = fopen(output_path.c_str(), "w");
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if (!out)
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return nullptr;
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return std::unique_ptr<TarWriter>(new TarWriter(out, basedir));
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}
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TarWriter::~TarWriter() {
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fclose(out);
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}
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void TarWriter::append(std::string path, std::string_view data) {
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// Write PAX header
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static_assert(sizeof(UstarHeader) == BLOCK_SIZE);
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UstarHeader pax;
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std::string attr = encode_path(basedir, path);
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sprintf(pax.size, "%011zo", attr.size());
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pax.typeflag[0] = 'x';
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pax.finalize();
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fwrite(&pax, sizeof(pax), 1, out);
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// Write pathname
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fwrite(attr.data(), attr.size(), 1, out);
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fseek(out, align_to(ftell(out), BLOCK_SIZE), SEEK_SET);
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// Write Ustar header
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UstarHeader ustar;
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memcpy(ustar.mode, "0000664", 8);
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sprintf(ustar.size, "%011zo", data.size());
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ustar.finalize();
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fwrite(&ustar, sizeof(ustar), 1, out);
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// Write file contents
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fwrite(data.data(), data.size(), 1, out);
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fseek(out, align_to(ftell(out), BLOCK_SIZE), SEEK_SET);
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// A tar file must ends with two empty blocks, so write such
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// terminator and seek back.
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u8 terminator[BLOCK_SIZE * 2] = {};
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fwrite(&terminator, BLOCK_SIZE * 2, 1, out);
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fseek(out, -BLOCK_SIZE * 2, SEEK_END);
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assert(ftell(out) % BLOCK_SIZE == 0);
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}
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} // namespace mold
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