LibELF: Use StringBuilders instead of Strings for the interpreter path

This is required for the Kernel's usage of LibELF, since Strings do not
expose allocation failure.

4 files changed, 17 insertions, 6 deletions

diff --git a/Userland/Libraries/LibELF/DynamicLoader.cpp b/Userland/Libraries/LibELF/DynamicLoader.cpp
index d0332c2f62..d2a986f483 100644
--- a/Userland/Libraries/LibELF/DynamicLoader.cpp
+++ b/Userland/Libraries/LibELF/DynamicLoader.cpp
@@ -122,8 +122,11 @@ bool DynamicLoader::validate()
     auto* elf_header = (ElfW(Ehdr)*)m_file_data;
     if (!validate_elf_header(*elf_header, m_file_size))
         return false;
-    if (!validate_program_headers(*elf_header, m_file_size, (u8*)m_file_data, m_file_size, &m_program_interpreter))
+    StringBuilder interpreter_path_builder;
+    auto result_or_error = validate_program_headers(*elf_header, m_file_size, (u8*)m_file_data, m_file_size, &interpreter_path_builder);
+    if (result_or_error.is_error() || !result_or_error.value())
         return false;
+    m_program_interpreter = interpreter_path_builder.string_view();
     return true;
 }
 
diff --git a/Userland/Libraries/LibELF/Image.cpp b/Userland/Libraries/LibELF/Image.cpp
index d610a08291..88e66dee5d 100644
--- a/Userland/Libraries/LibELF/Image.cpp
+++ b/Userland/Libraries/LibELF/Image.cpp
@@ -126,7 +126,14 @@ bool Image::parse()
         return false;
     }
 
-    if (!validate_program_headers(header(), m_size, m_buffer, m_size, nullptr, m_verbose_logging)) {
+    auto result_or_error = validate_program_headers(header(), m_size, m_buffer, m_size, nullptr, m_verbose_logging);
+    if (result_or_error.is_error()) {
+        if (m_verbose_logging)
+            dbgln("ELF::Image::parse(): Failed validating ELF Program Headers");
+        m_valid = false;
+        return false;
+    }
+    if (!result_or_error.value()) {
         if (m_verbose_logging)
             dbgln("ELF::Image::parse(): ELF Program Headers not valid");
         m_valid = false;
diff --git a/Userland/Libraries/LibELF/Validation.cpp b/Userland/Libraries/LibELF/Validation.cpp
index 525d242286..d363dfef11 100644
--- a/Userland/Libraries/LibELF/Validation.cpp
+++ b/Userland/Libraries/LibELF/Validation.cpp
@@ -192,7 +192,7 @@ bool validate_elf_header(const ElfW(Ehdr) & elf_header, size_t file_size, bool v
     return true;
 }
 
-bool validate_program_headers(const ElfW(Ehdr) & elf_header, size_t file_size, const u8* buffer, size_t buffer_size, String* interpreter_path, bool verbose)
+ErrorOr<bool> validate_program_headers(const ElfW(Ehdr) & elf_header, size_t file_size, const u8* buffer, size_t buffer_size, StringBuilder* interpreter_path_builder, bool verbose)
 {
     Checked<size_t> total_size_of_program_headers = elf_header.e_phnum;
     total_size_of_program_headers *= elf_header.e_phentsize;
@@ -268,8 +268,8 @@ bool validate_program_headers(const ElfW(Ehdr) & elf_header, size_t file_size, c
                     dbgln("Found PT_INTERP header ({}), but p_filesz is invalid ({})", header_index, program_header.p_filesz);
                 return false;
             }
-            if (interpreter_path)
-                *interpreter_path = String((const char*)&buffer[program_header.p_offset], program_header.p_filesz - 1);
+            if (interpreter_path_builder)
+                TRY(interpreter_path_builder->try_append({ &buffer[program_header.p_offset], program_header.p_filesz - 1 }));
             break;
         case PT_LOAD:
         case PT_DYNAMIC:
diff --git a/Userland/Libraries/LibELF/Validation.h b/Userland/Libraries/LibELF/Validation.h
index 7b097abf8b..41b6b4957e 100644
--- a/Userland/Libraries/LibELF/Validation.h
+++ b/Userland/Libraries/LibELF/Validation.h
@@ -8,10 +8,11 @@
 
 #include <AK/String.h>
 #include <LibC/elf.h>
+#include <limits.h>
 
 namespace ELF {
 
 bool validate_elf_header(const ElfW(Ehdr) & elf_header, size_t file_size, bool verbose = true);
-bool validate_program_headers(const ElfW(Ehdr) & elf_header, size_t file_size, const u8* buffer, size_t buffer_size, String* interpreter_path, bool verbose = true);
+ErrorOr<bool> validate_program_headers(const ElfW(Ehdr) & elf_header, size_t file_size, const u8* buffer, size_t buffer_size, StringBuilder* interpreter_path_builder, bool verbose = true);
 
 } // end namespace ELF