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cmXCOFF: Add support for editing binary inside an archive

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AIX stores XCOFF `.so` binaries inside `.a` archives.

Issue: #26033
This commit is contained in:
Aditya Vidyadhar Kamath
2024-07-01 03:30:31 -05:00
committed by Brad King
parent 4ecb654ec2
commit 98013ad1ca
1 changed files with 152 additions and 11 deletions
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163
Source/cmXCOFF.cxx
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@@ -16,10 +16,19 @@
# define __XCOFF32__
# define __XCOFF64__
# include <xcoff.h>
# define __AR_BIG__
# include <ar.h>
#else
# error "This source may be compiled only on AIX."
#endif
// Function to align a number num with align_num bytes.
size_t align(size_t num, int align_num)
{
align_num = 1 << (align_num);
return (((num + align_num - 1) / align_num) * align_num);
}
class cmXCOFFInternal
{
public:
@@ -79,6 +88,12 @@ struct XCOFF64
};
const unsigned char xcoff64_magic[] = { 0x01, 0xF7 };
enum class IsArchive
{
No,
Yes,
};
template <typename XCOFF>
class Impl : public cmXCOFFInternal
{
@@ -93,6 +108,20 @@ class Impl : public cmXCOFFInternal
std::streamoff LoaderImportFileTablePos = 0;
std::vector<char> LoaderImportFileTable;
bool Read(fl_hdr& x)
{
// FIXME: Add byte swapping if needed.
return static_cast<bool>(
this->Stream->read(reinterpret_cast<char*>(&x), sizeof(x)));
}
bool Read(ar_hdr& x)
{
// FIXME: Add byte swapping if needed.
return static_cast<bool>(
this->Stream->read(reinterpret_cast<char*>(&x), sizeof(x)));
}
bool Read(typename XCOFF::filehdr& x)
{
// FIXME: Add byte swapping if needed.
@@ -130,18 +159,40 @@ class Impl : public cmXCOFFInternal
public:
Impl(cmXCOFF* external, std::unique_ptr<std::iostream> fin,
cmXCOFF::Mode mode);
cmXCOFF::Mode mode, IsArchive IsBigArchive, int nextEvenBytePos);
cm::optional<cm::string_view> GetLibPath() override;
bool SetLibPath(cm::string_view libPath) override;
bool RemoveLibPath() override;
// Needed for SetLibPath () to move in a archive while write.
IsArchive is_big_archive;
int nextEvenByte;
int bytes_to_align;
};
template <typename XCOFF>
Impl<XCOFF>::Impl(cmXCOFF* external, std::unique_ptr<std::iostream> fin,
cmXCOFF::Mode mode)
cmXCOFF::Mode mode, IsArchive IsBigArchive,
int nextEvenBytePos)
: cmXCOFFInternal(external, std::move(fin), mode)
{
this->is_big_archive = IsBigArchive;
this->nextEvenByte = nextEvenBytePos;
if (this->is_big_archive == IsArchive::Yes) {
fl_hdr header;
this->Stream->read(reinterpret_cast<char*>(&header), sizeof(fl_hdr));
long long fstmoff = std::atoll(header.fl_fstmoff);
this->Stream->seekg(fstmoff, std::ios::beg);
ar_hdr arHeader;
this->Stream->read(reinterpret_cast<char*>(&arHeader), sizeof(ar_hdr));
// Move the pointer to next even byte after reading headers.
this->Stream->seekg(this->nextEvenByte, std::ios::cur);
}
if (!this->Read(this->FileHeader)) {
this->SetErrorMessage("Failed to read XCOFF file header.");
return;
@@ -158,6 +209,7 @@ Impl<XCOFF>::Impl(cmXCOFF* external, std::unique_ptr<std::iostream> fin,
this->SetErrorMessage("XCOFF loader section missing.");
return;
}
this->bytes_to_align = this->AuxHeader.o_algndata;
if (!this->Stream->seekg((this->AuxHeader.o_snloader - 1) *
sizeof(typename XCOFF::scnhdr),
std::ios::cur)) {
@@ -172,17 +224,33 @@ Impl<XCOFF>::Impl(cmXCOFF* external, std::unique_ptr<std::iostream> fin,
this->SetErrorMessage("XCOFF loader section header missing STYP_LOADER.");
return;
}
if (!this->Stream->seekg(this->LoaderSectionHeader.s_scnptr,
std::ios::beg)) {
if (is_big_archive == IsArchive::Yes) {
size_t header_len = this->nextEvenByte + sizeof(fl_hdr) + sizeof(ar_hdr);
size_t scnptrFromArchiveStart = this->LoaderSectionHeader.s_scnptr +
align(header_len, this->bytes_to_align);
if (!this->Stream->seekg(scnptrFromArchiveStart, std::ios::beg)) {
this->SetErrorMessage("Failed to seek to XCOFF loader header.");
return;
}
} else if (!this->Stream->seekg(this->LoaderSectionHeader.s_scnptr,
std::ios::beg)) {
this->SetErrorMessage("Failed to seek to XCOFF loader header.");
return;
}
if (!this->Read(this->LoaderHeader)) {
this->SetErrorMessage("Failed to read XCOFF loader header.");
return;
}
this->LoaderImportFileTablePos =
this->LoaderSectionHeader.s_scnptr + this->LoaderHeader.l_impoff;
if (is_big_archive == IsArchive::Yes) {
size_t header_len = sizeof(fl_hdr) + sizeof(ar_hdr) + this->nextEvenByte;
size_t scnptrFromArchiveStartPlusOff = this->LoaderSectionHeader.s_scnptr +
this->LoaderHeader.l_impoff + align(header_len, this->bytes_to_align);
this->LoaderImportFileTablePos = scnptrFromArchiveStartPlusOff;
} else {
this->LoaderImportFileTablePos =
this->LoaderSectionHeader.s_scnptr + this->LoaderHeader.l_impoff;
}
if (!this->Stream->seekg(this->LoaderImportFileTablePos)) {
this->SetErrorMessage(
"Failed to seek to XCOFF loader import file id table.");
@@ -251,9 +319,18 @@ bool Impl<XCOFF>::SetLibPath(cm::string_view libPath)
this->LoaderImportFileTable = std::move(ift);
}
if (!this->Stream->seekp(this->LoaderSectionHeader.s_scnptr +
offsetof(typename XCOFF::ldhdr, l_istlen),
std::ios::beg)) {
size_t scnptr;
if (this->is_big_archive == IsArchive::Yes) {
size_t header_len = sizeof(fl_hdr) + sizeof(ar_hdr) + this->nextEvenByte;
scnptr = this->LoaderSectionHeader.s_scnptr +
offsetof(typename XCOFF::ldhdr, l_istlen) +
align(header_len, this->bytes_to_align);
} else {
scnptr = this->LoaderSectionHeader.s_scnptr +
offsetof(typename XCOFF::ldhdr, l_istlen);
}
if (!this->Stream->seekp(scnptr, std::ios::beg)) {
this->SetErrorMessage(
"Failed to seek to XCOFF loader header import file id table length.");
return false;
@@ -285,6 +362,30 @@ bool Impl<XCOFF>::RemoveLibPath()
}
}
IsArchive check_if_big_archive(const char* fname)
{
int len = std::strlen(fname);
if (len < 2) {
return IsArchive::No;
}
if (std::strcmp(fname + len - 2, ".a") == 0) {
return IsArchive::Yes;
} else {
return IsArchive::No;
}
}
size_t getLastWordLen(const std::string& path)
{
std::size_t lastSlashPos = path.find_last_of("/\\");
if (lastSlashPos == std::string::npos) {
return path.length();
}
return (path.length() - lastSlashPos - 1);
}
//============================================================================
// External class implementation.
@@ -305,6 +406,44 @@ cmXCOFF::cmXCOFF(const char* fname, Mode mode)
// Read the XCOFF magic number.
unsigned char magic[2];
// To hold the length of the shared object name in the path.
int nextEvenByte = 0;
// Read archive name length.
int archive_name_length = 0;
// If a big archive, we will read the archive file headers first.
// Then move to the next even byte to get the magic number.
if (check_if_big_archive(fname) == IsArchive::Yes) {
fl_hdr header;
f->read(reinterpret_cast<char*>(&header), sizeof(fl_hdr));
if (std::strncmp(header.fl_magic, AIAMAGBIG, SAIAMAG) != 0) {
this->ErrorMessage = "Not a valid archive file or wrong format";
return;
}
long long fstmoff = std::atoll(header.fl_fstmoff);
f->seekg(fstmoff, std::ios::beg);
ar_hdr arHeader;
f->read(reinterpret_cast<char*>(&arHeader), sizeof(ar_hdr));
// We will sometimes get /opt/freeware/lib/libshared.a. So extract
// the last part only.
// Example: libshared.a [We need to length of "libshared.a" characters].
archive_name_length = static_cast<int>(getLastWordLen(std::string(fname)));
// Move to the next even byte.
if (archive_name_length % 2 == 0) {
nextEvenByte = archive_name_length + 2;
} else {
nextEvenByte = archive_name_length + 1;
}
f->seekg(nextEvenByte, std::ios::cur);
}
if (!f->read(reinterpret_cast<char*>(magic), sizeof(magic))) {
this->ErrorMessage = "Error reading XCOFF magic number.";
return;
@@ -316,9 +455,11 @@ cmXCOFF::cmXCOFF(const char* fname, Mode mode)
// Check the XCOFF type.
if (magic[0] == xcoff32_magic[0] && magic[1] == xcoff32_magic[1]) {
this->Internal = cm::make_unique<Impl<XCOFF32>>(this, std::move(f), mode);
this->Internal = cm::make_unique<Impl<XCOFF32>>(
this, std::move(f), mode, check_if_big_archive(fname), nextEvenByte);
} else if (magic[0] == xcoff64_magic[0] && magic[1] == xcoff64_magic[1]) {
this->Internal = cm::make_unique<Impl<XCOFF64>>(this, std::move(f), mode);
this->Internal = cm::make_unique<Impl<XCOFF64>>(
this, std::move(f), mode, check_if_big_archive(fname), nextEvenByte);
} else {
this->ErrorMessage = "File is not a XCOFF32 or XCOFF64 binary.";
}