From 1ba455485519001f23f9ea8c5b7e02b334f6d019 Mon Sep 17 00:00:00 2001
From: LemonBoy <thatlemon@gmail.com>
Date: Wed, 29 Jan 2020 00:08:01 +0100
Subject: [PATCH] Correct dl_iterate_phdr address

The base should be zero so that p_vaddr + dlpi_addr = p_vaddr
---
 lib/std/os.zig       |  2 +-
 lib/std/os/linux.zig | 57 --------------------------------------------
 lib/std/os/test.zig  |  3 ++-
 3 files changed, 3 insertions(+), 59 deletions(-)

diff --git a/lib/std/os.zig b/lib/std/os.zig
index c39891c6b0..f881d74835 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -2697,7 +2697,7 @@ pub fn dl_iterate_phdr(
     // the whole ELF image
     if (it.end()) {
         var info = dl_phdr_info{
-            .dlpi_addr = elf_base,
+            .dlpi_addr = 0,
             .dlpi_name = "/proc/self/exe",
             .dlpi_phdr = phdrs.ptr,
             .dlpi_phnum = ehdr.e_phnum,
diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index fcc1e62489..5c25b4369c 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -1041,63 +1041,6 @@ pub fn uname(uts: *utsname) usize {
     return syscall1(SYS_uname, @ptrToInt(uts));
 }
 
-// XXX: This should be weak
-extern const __ehdr_start: elf.Ehdr;
-
-pub fn dl_iterate_phdr(comptime T: type, callback: extern fn (info: *dl_phdr_info, size: usize, data: ?*T) i32, data: ?*T) isize {
-    if (builtin.link_libc) {
-        return std.c.dl_iterate_phdr(@ptrCast(std.c.dl_iterate_phdr_callback, callback), @ptrCast(?*c_void, data));
-    }
-
-    const elf_base = @ptrToInt(&__ehdr_start);
-    const n_phdr = __ehdr_start.e_phnum;
-    const phdrs = (@intToPtr([*]elf.Phdr, elf_base + __ehdr_start.e_phoff))[0..n_phdr];
-
-    var it = dl.linkmap_iterator(phdrs) catch return 0;
-
-    // The executable has no dynamic link segment, create a single entry for
-    // the whole ELF image
-    if (it.end()) {
-        var info = dl_phdr_info{
-            .dlpi_addr = elf_base,
-            .dlpi_name = "/proc/self/exe",
-            .dlpi_phdr = @intToPtr([*]elf.Phdr, elf_base + __ehdr_start.e_phoff),
-            .dlpi_phnum = __ehdr_start.e_phnum,
-        };
-
-        return callback(&info, @sizeOf(dl_phdr_info), data);
-    }
-
-    // Last return value from the callback function
-    var last_r: isize = 0;
-    while (it.next()) |entry| {
-        var dlpi_phdr: usize = undefined;
-        var dlpi_phnum: u16 = undefined;
-
-        if (entry.l_addr != 0) {
-            const elf_header = @intToPtr(*elf.Ehdr, entry.l_addr);
-            dlpi_phdr = entry.l_addr + elf_header.e_phoff;
-            dlpi_phnum = elf_header.e_phnum;
-        } else {
-            // This is the running ELF image
-            dlpi_phdr = elf_base + __ehdr_start.e_phoff;
-            dlpi_phnum = __ehdr_start.e_phnum;
-        }
-
-        var info = dl_phdr_info{
-            .dlpi_addr = entry.l_addr,
-            .dlpi_name = entry.l_name,
-            .dlpi_phdr = @intToPtr([*]elf.Phdr, dlpi_phdr),
-            .dlpi_phnum = dlpi_phnum,
-        };
-
-        last_r = callback(&info, @sizeOf(dl_phdr_info), data);
-        if (last_r != 0) break;
-    }
-
-    return last_r;
-}
-
 pub fn io_uring_setup(entries: u32, p: *io_uring_params) usize {
     return syscall2(SYS_io_uring_setup, entries, @ptrToInt(p));
 }
diff --git a/lib/std/os/test.zig b/lib/std/os/test.zig
index 1e51dd6f82..f71e80c7d7 100644
--- a/lib/std/os/test.zig
+++ b/lib/std/os/test.zig
@@ -186,8 +186,9 @@ fn iter_fn(info: *dl_phdr_info, size: usize, data: ?*usize) callconv(.C) i32 {
 
         if (phdr.p_type != elf.PT_LOAD) continue;
 
+        const reloc_addr = info.dlpi_addr + phdr.p_vaddr;
         // Find the ELF header
-        const elf_header = @intToPtr(*elf.Ehdr, phdr.p_vaddr - phdr.p_offset);
+        const elf_header = @intToPtr(*elf.Ehdr, reloc_addr - phdr.p_offset);
         // Validate the magic
         if (!mem.eql(u8, elf_header.e_ident[0..4], "\x7fELF")) return -1;
         // Consistency check