From 000f57e11cf3272951cd3463f5d8bb82bc8e3903 Mon Sep 17 00:00:00 2001
From: pommicket <pommicket@gmail.com>
Date: Sun, 6 Nov 2022 22:11:41 -0500
Subject: read symbol type

---
 .gitignore         |  1 +
 src/elf.rs         | 12 ++++++++++++
 src/linker.rs      | 20 ++++++++++++--------
 test.c             |  8 +++++---
 tests/dylib-test.c | 12 ++++++++++++
 tests/dylib.c      |  4 ++++
 tests/dylib.h      |  8 ++++++++
 7 files changed, 54 insertions(+), 11 deletions(-)
 create mode 100644 tests/dylib-test.c
 create mode 100644 tests/dylib.c
 create mode 100644 tests/dylib.h

diff --git a/.gitignore b/.gitignore
index 52f2ae5..437eab9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 /target
 *.o
+*.so
 tags
 TAGS
 *.out
diff --git a/src/elf.rs b/src/elf.rs
index 2a51082..41ce491 100644
--- a/src/elf.rs
+++ b/src/elf.rs
@@ -373,6 +373,18 @@ impl From<u8> for SymbolType {
 	}
 }
 
+impl From<SymbolType> for u8 {
+	fn from(x: SymbolType) -> Self {
+		use SymbolType::*;
+		match x {
+			Function => STT_FUNC,
+			Object => STT_OBJECT,
+			Section => STT_SECTION,
+			Other(x) => x,
+		}
+	}
+}
+
 #[derive(Debug, Copy, Clone)]
 pub enum SymbolValue {
 	Undefined,
diff --git a/src/linker.rs b/src/linker.rs
index f8f5760..8126d19 100644
--- a/src/linker.rs
+++ b/src/linker.rs
@@ -302,6 +302,8 @@ struct Relocation {
 	/// symbol that needs to be supplied
 	sym: SymbolName,
 	r#type: elf::RelType,
+	/// type of `sym`
+	symbol_type: elf::SymbolType,
 	addend: i64,
 }
 
@@ -400,8 +402,10 @@ struct LinkerOutput {
 	relocations: Vec<(Relocation, u64)>,
 	/// contents of dynamic strtab.
 	strtab: Vec<u8>,
-	/// offsets into dynamic strtab where symbol names appear.
-	symbol_strtab_offsets: HashMap<SymbolName, u64>,
+	/// (offset into strtab, type) 
+	/// Seems like no one sets the type of undefined symbols.
+	/// Still, might as well pretend they do.
+	dynsyms: HashMap<SymbolName, (u64, elf::SymbolType)>,
 	/// array of stratb pointers to library names.
 	lib_strtab_offsets: Vec<u64>,
 }
@@ -416,7 +420,7 @@ impl LinkerOutput {
 			interp: vec![],
 			relocations: vec![],
 			lib_strtab_offsets: vec![],
-			symbol_strtab_offsets: HashMap::new(),
+			dynsyms: HashMap::new(),
 			strtab: vec![0],
 		}
 	}
@@ -450,10 +454,10 @@ impl LinkerOutput {
 	pub fn add_relocation(&mut self, symbol_names: &SymbolNames, rel: &Relocation, addr: u64) {
 		let name = rel.sym;
 
-		if self.symbol_strtab_offsets.get(&name).is_none() {
+		if self.dynsyms.get(&name).is_none() {
 			let s = symbol_names.get_str(name).unwrap();
 			let offset = self.add_string(s);
-			self.symbol_strtab_offsets.insert(name, offset);
+			self.dynsyms.insert(name, (offset, rel.symbol_type));
 		}
 		self.relocations.push((rel.clone(), addr));
 	}
@@ -559,12 +563,11 @@ impl LinkerOutput {
 			let null_symbol = [0; mem::size_of::<elf::Sym32>()];
 			out.write_all(&null_symbol)?;
 			let mut symbols: HashMap<SymbolName, u32> = HashMap::new();
-			for (i, (sym, strtab_offset)) in self.symbol_strtab_offsets.iter().enumerate() {
+			for (i, (sym, (strtab_offset, symbol_type))) in self.dynsyms.iter().enumerate() {
 				symbols.insert(*sym, (i + 1) as u32);
-				// @TODO: allow STT_OBJECT as well
 				let sym = elf::Sym32 {
 					name: *strtab_offset as u32,
-					info: elf::STB_GLOBAL << 4 | elf::STT_FUNC,
+					info: elf::STB_GLOBAL << 4 | u8::from(*symbol_type),
 					value: 0,
 					size: 0,
 					other: 0,
@@ -812,6 +815,7 @@ impl<'a> Linker<'a> {
 					r#where,
 					source_id,
 					sym,
+					symbol_type: rel.symbol.r#type,
 					r#type: rel.r#type,
 					addend: rel.addend,
 				});
diff --git a/test.c b/test.c
index ef50528..4b86a0b 100644
--- a/test.c
+++ b/test.c
@@ -1,9 +1,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int x;
-void entry() {
-	puts("Hello, world!");
+extern int errno;
+int main() {
+	errno = 0;
+	fopen("zzz","r");
+	printf("%d\n",errno);
 	//printf("hello\n");
 	exit(0);
 	    
diff --git a/tests/dylib-test.c b/tests/dylib-test.c
new file mode 100644
index 0000000..ae824b0
--- /dev/null
+++ b/tests/dylib-test.c
@@ -0,0 +1,12 @@
+#include "dylib.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+void entry(void) {
+	the_number = 7;
+	printf("%d\n",the_number);
+	bigger();
+	printf("%d\n",the_number);
+	
+	exit(0);
+}
diff --git a/tests/dylib.c b/tests/dylib.c
new file mode 100644
index 0000000..8da43a8
--- /dev/null
+++ b/tests/dylib.c
@@ -0,0 +1,4 @@
+#include "dylib.h"
+
+int the_number;
+void bigger() { the_number += 1; }
diff --git a/tests/dylib.h b/tests/dylib.h
new file mode 100644
index 0000000..3b5d369
--- /dev/null
+++ b/tests/dylib.h
@@ -0,0 +1,8 @@
+// here is a realyl great dynami library i made it myself
+#ifndef DYLIB_H_IS_REALLY_INCLUDED____
+#define DYLIB_H_IS_REALLY_INCLUDED____
+// ---------------dylib HEADER FILE ---------
+// /PLEASE INCLUDE IF YOU WANT TO USE dylib
+extern int the_number; // the number what it is
+void bigger(void); // make the number bigger by 1
+#endif // DYLIB_H_IS_REALLY_INCLUDED____
-- 
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