[libcamera-devel] [PATCH v2 1/2] libcamera: ipa_module: Share code to find section header of ELF header

[Laurent Pinchart]

Hi Umang,

Thank you for the patch.

On Fri, Jun 05, 2020 at 03:09:15PM +0000, Umang Jain wrote:
> Refactor the code to find section into a common helper function.
> This commit introduces no functional changes.
> 
> Signed-off-by: Umang Jain <email at uajain.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  src/libcamera/ipa_module.cpp | 29 ++++++++++++++++-------------
>  1 file changed, 16 insertions(+), 13 deletions(-)
> 
> diff --git a/src/libcamera/ipa_module.cpp b/src/libcamera/ipa_module.cpp
> index 045c8fc..f54dd8b 100644
> --- a/src/libcamera/ipa_module.cpp
> +++ b/src/libcamera/ipa_module.cpp
> @@ -88,6 +88,15 @@ int elfVerifyIdent(Span<uint8_t> elf)
>  	return 0;
>  }
>  
> +ElfW(Shdr) *elfSection(Span<uint8_t> elf, ElfW(Ehdr) *eHdr, unsigned int idx)
> +{
> +	if (idx >= eHdr->e_shnum)
> +		return nullptr;
> +
> +	off_t offset = eHdr->e_shoff + idx * eHdr->e_shentsize;
> +	return elfPointer<ElfW(Shdr)>(elf, offset);
> +}
> +
>  /**
>   * \brief Retrieve address and size of a symbol from an mmap'ed ELF file
>   * \param[in] elf Address and size of mmap'ed ELF file
> @@ -102,8 +111,7 @@ Span<uint8_t> elfLoadSymbol(Span<uint8_t> elf, const char *symbol)
>  	if (!eHdr)
>  		return {};
>  
> -	off_t offset = eHdr->e_shoff + eHdr->e_shentsize * eHdr->e_shstrndx;
> -	ElfW(Shdr) *sHdr = elfPointer<ElfW(Shdr)>(elf, offset);
> +	ElfW(Shdr) *sHdr = elfSection(elf, eHdr, eHdr->e_shstrndx);
>  	if (!sHdr)
>  		return {};
>  	off_t shnameoff = sHdr->sh_offset;
> @@ -111,12 +119,11 @@ Span<uint8_t> elfLoadSymbol(Span<uint8_t> elf, const char *symbol)
>  	/* Locate .dynsym section header. */
>  	ElfW(Shdr) *dynsym = nullptr;
>  	for (unsigned int i = 0; i < eHdr->e_shnum; i++) {
> -		offset = eHdr->e_shoff + eHdr->e_shentsize * i;
> -		sHdr = elfPointer<ElfW(Shdr)>(elf, offset);
> +		sHdr = elfSection(elf, eHdr, i);
>  		if (!sHdr)
>  			return {};
>  
> -		offset = shnameoff + sHdr->sh_name;
> +		off_t offset = shnameoff + sHdr->sh_name;
>  		char *name = elfPointer<char[8]>(elf, offset);
>  		if (!name)
>  			return {};
> @@ -132,8 +139,7 @@ Span<uint8_t> elfLoadSymbol(Span<uint8_t> elf, const char *symbol)
>  		return {};
>  	}
>  
> -	offset = eHdr->e_shoff + eHdr->e_shentsize * dynsym->sh_link;
> -	sHdr = elfPointer<ElfW(Shdr)>(elf, offset);
> +	sHdr = elfSection(elf, eHdr, dynsym->sh_link);
>  	if (!sHdr)
>  		return {};
>  	off_t dynsym_nameoff = sHdr->sh_offset;
> @@ -142,7 +148,7 @@ Span<uint8_t> elfLoadSymbol(Span<uint8_t> elf, const char *symbol)
>  	ElfW(Sym) *targetSymbol = nullptr;
>  	unsigned int dynsym_num = dynsym->sh_size / dynsym->sh_entsize;
>  	for (unsigned int i = 0; i < dynsym_num; i++) {
> -		offset = dynsym->sh_offset + dynsym->sh_entsize * i;
> +		off_t offset = dynsym->sh_offset + dynsym->sh_entsize * i;
>  		ElfW(Sym) *sym = elfPointer<ElfW(Sym)>(elf, offset);
>  		if (!sym)
>  			return {};
> @@ -165,13 +171,10 @@ Span<uint8_t> elfLoadSymbol(Span<uint8_t> elf, const char *symbol)
>  	}
>  
>  	/* Locate and return data of symbol. */
> -	if (targetSymbol->st_shndx >= eHdr->e_shnum)
> -		return {};
> -	offset = eHdr->e_shoff + targetSymbol->st_shndx * eHdr->e_shentsize;
> -	sHdr = elfPointer<ElfW(Shdr)>(elf, offset);
> +	sHdr = elfSection(elf, eHdr, targetSymbol->st_shndx);
>  	if (!sHdr)
>  		return {};
> -	offset = sHdr->sh_offset + (targetSymbol->st_value - sHdr->sh_addr);
> +	off_t offset = sHdr->sh_offset + (targetSymbol->st_value - sHdr->sh_addr);
>  	uint8_t *data = elfPointer<uint8_t>(elf, offset, targetSymbol->st_size);
>  	if (!data)
>  		return {};

-- 
Regards,

Laurent Pinchart