Factor out a chunk of complexity into a new subroutine. This is an incremental step in adding ELF32 support to the existing ELF64 section support, for handling GPU firmware.
Signed-off-by: John Hubbard <[email protected]> --- drivers/gpu/nova-core/firmware.rs | 39 +++++++++++++++---------------- 1 file changed, 19 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/nova-core/firmware.rs b/drivers/gpu/nova-core/firmware.rs index 31a89abc5a87..5ed079a45ec2 100644 --- a/drivers/gpu/nova-core/firmware.rs +++ b/drivers/gpu/nova-core/firmware.rs @@ -267,6 +267,24 @@ unsafe impl FromBytes for Elf64Hdr {} // SAFETY: all bit patterns are valid for this type, and it doesn't use interior mutability. unsafe impl FromBytes for Elf64SHdr {} + /// Check if the section name at `strtab_offset + name_offset` equals `target`. + fn section_name_eq(elf: &[u8], strtab_offset: u64, name_offset: u32, target: &str) -> bool { + strtab_offset + // Compute the index into the ELF image. + .checked_add(u64::from(name_offset)) + .and_then(|idx| usize::try_from(idx).ok()) + // Get the start of the name. + .and_then(|name_idx| elf.get(name_idx..)) + // Stop at the first `0`. + .and_then(|s| s.get(0..=s.iter().position(|b| *b == 0)?)) + // Convert into CStr. + .and_then(|s| CStr::from_bytes_with_nul(s).ok()) + // Convert into str. + .and_then(|s| s.to_str().ok()) + // Check that the name matches. + .is_some_and(|s| s == target) + } + /// Tries to extract section with name `name` from the ELF64 image `elf`, and returns it. pub(super) fn elf64_section<'a, 'b>(elf: &'a [u8], name: &'b str) -> Option<&'a [u8]> { let hdr = &elf @@ -298,26 +316,7 @@ pub(super) fn elf64_section<'a, 'b>(elf: &'a [u8], name: &'b str) -> Option<&'a return false; }; - let Some(name_idx) = strhdr - .0 - .sh_offset - .checked_add(u64::from(hdr.0.sh_name)) - .and_then(|idx| usize::try_from(idx).ok()) - else { - return false; - }; - - // Get the start of the name. - elf.get(name_idx..) - // Stop at the first `0`. - .and_then(|nstr| nstr.get(0..=nstr.iter().position(|b| *b == 0)?)) - // Convert into CStr. This should never fail because of the line above. - .and_then(|nstr| CStr::from_bytes_with_nul(nstr).ok()) - // Convert into str. - .and_then(|c_str| c_str.to_str().ok()) - // Check that the name matches. - .map(|str| str == name) - .unwrap_or(false) + section_name_eq(elf, strhdr.0.sh_offset, hdr.0.sh_name, name) }) // Return the slice containing the section. .and_then(|sh| { -- 2.52.0
