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[lldb][Mach-O] Handle shared cache binaries correctly #117832

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Merged
merged 3 commits into from
Nov 28, 2024
Merged

[lldb][Mach-O] Handle shared cache binaries correctly #117832

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00a429c
[lldb][Mach-O] Handle shared cache binaries correctly
jasonmolenda Nov 27, 2024
5761360
Define a local version of symtab_command w/ larger offsets
jasonmolenda Nov 27, 2024
8e7dd93
Add comment with symtab_command decl to clarify reads
jasonmolenda Nov 27, 2024
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18 changes: 13 additions & 5 deletions lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2235,11 +2235,11 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
LLDB_LOG(log, "Parsing symbol table for {0}", file_name);
Progress progress("Parsing symbol table", file_name);

llvm::MachO::symtab_command symtab_load_command = {0, 0, 0, 0, 0, 0};
llvm::MachO::linkedit_data_command function_starts_load_command = {0, 0, 0, 0};
llvm::MachO::linkedit_data_command exports_trie_load_command = {0, 0, 0, 0};
llvm::MachO::dyld_info_command dyld_info = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
llvm::MachO::dysymtab_command dysymtab = m_dysymtab;
SymtabCommandLargeOffsets symtab_load_command;
// The data element of type bool indicates that this entry is thumb
// code.
typedef AddressDataArray<lldb::addr_t, bool, 100> FunctionStarts;
Expand Down Expand Up @@ -2276,12 +2276,20 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
// Watch for the symbol table load command
switch (lc.cmd) {
case LC_SYMTAB:
// struct symtab_command {
// uint32_t cmd; /* LC_SYMTAB */
// uint32_t cmdsize; /* sizeof(struct symtab_command) */
// uint32_t symoff; /* symbol table offset */
// uint32_t nsyms; /* number of symbol table entries */
// uint32_t stroff; /* string table offset */
// uint32_t strsize; /* string table size in bytes */
// };
symtab_load_command.cmd = lc.cmd;
symtab_load_command.cmdsize = lc.cmdsize;
// Read in the rest of the symtab load command
if (m_data.GetU32(&offset, &symtab_load_command.symoff, 4) ==
nullptr) // fill in symoff, nsyms, stroff, strsize fields
return;
symtab_load_command.symoff = m_data.GetU32(&offset);
symtab_load_command.nsyms = m_data.GetU32(&offset);
symtab_load_command.stroff = m_data.GetU32(&offset);
symtab_load_command.strsize = m_data.GetU32(&offset);
break;

case LC_DYLD_INFO:
Expand Down
13 changes: 13 additions & 0 deletions lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.h
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,19 @@ class ObjectFileMachO : public lldb_private::ObjectFile {
bool IsValid() { return all_image_infos.size() > 0; }
};

// The LC_SYMTAB's symtab_command structure uses 32-bit file offsets
// for two fields, but ObjectFileMachO needs to calculate the offsets
// in virtual address layout from the start of the TEXT segment, and
// that span may be larger than 4GB.
struct SymtabCommandLargeOffsets {
uint32_t cmd = 0; /* LC_SYMTAB */
uint32_t cmdsize = 0; /* sizeof(struct symtab_command) */
lldb::offset_t symoff = 0; /* symbol table offset */
uint32_t nsyms = 0; /* number of symbol table entries */
lldb::offset_t stroff = 0; /* string table offset */
uint32_t strsize = 0; /* string table size in bytes */
};

/// Get the list of binary images that were present in the process
/// when the corefile was produced.
/// \return
Expand Down