[Mesa-dev] [PATCH 1/2] util: Add utility build-id code.

Kristian H. Kristensen krh at bitplanet.net
Tue Feb 14 19:39:05 UTC 2017


Matt Turner <mattst88 at gmail.com> writes:

> Provides the ability to read the .note.gnu.build-id section of ELF
> binaries, which is inserted by the --build-id=... flag to ld.
> ---
>  configure.ac              |   2 +
>  src/util/Makefile.sources |   2 +
>  src/util/build_id.c       | 109 ++++++++++++++++++++++++++++++++++++++++++++++
>  src/util/build_id.h       |  56 ++++++++++++++++++++++++
>  4 files changed, 169 insertions(+)
>  create mode 100644 src/util/build_id.c
>  create mode 100644 src/util/build_id.h
>
> diff --git a/configure.ac b/configure.ac
> index f001743..99c74f0 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -768,6 +768,8 @@ LIBS="$LIBS $DLOPEN_LIBS"
>  AC_CHECK_FUNCS([dladdr])
>  LIBS="$save_LIBS"
>  
> +AC_CHECK_FUNC([dl_iterate_phdr], [DEFINES="$DEFINES -DHAVE_DL_ITERATE_PHDR"])
> +
>  case "$host_os" in
>  darwin*)
>      ;;
> diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
> index a68a5fe..4c12e5f 100644
> --- a/src/util/Makefile.sources
> +++ b/src/util/Makefile.sources
> @@ -2,6 +2,8 @@ MESA_UTIL_FILES :=	\
>  	bitscan.c \
>  	bitscan.h \
>  	bitset.h \
> +	build_id.c \
> +	build_id.h \
>  	crc32.c \
>  	crc32.h \
>  	debug.c \
> diff --git a/src/util/build_id.c b/src/util/build_id.c
> new file mode 100644
> index 0000000..a2e21b7
> --- /dev/null
> +++ b/src/util/build_id.c
> @@ -0,0 +1,109 @@
> +/*
> + * Copyright © 2016 Intel Corporation

I don't like it either, but we're in 2017 now.

Kristian

> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#ifdef HAVE_DL_ITERATE_PHDR
> +#include <link.h>
> +#include <stddef.h>
> +#include <string.h>
> +
> +#include "build_id.h"
> +
> +#define ALIGN(val, align)      (((val) + (align) - 1) & ~((align) - 1))
> +
> +struct note {
> +   ElfW(Nhdr) nhdr;
> +
> +   char name[4];
> +   uint8_t build_id[0];
> +};
> +
> +struct callback_data {
> +   const char *name;
> +   struct note *note;
> +};
> +
> +static int
> +build_id_find_nhdr_callback(struct dl_phdr_info *info, size_t size, void *data_)
> +{
> +   struct callback_data *data = data_;
> +
> +   char *ptr = strstr(info->dlpi_name, data->name);
> +   if (ptr == NULL || ptr[strlen(data->name)] != '\0')
> +      return 0;
> +
> +   for (unsigned i = 0; i < info->dlpi_phnum; i++) {
> +      if (info->dlpi_phdr[i].p_type != PT_NOTE)
> +         continue;
> +
> +      struct note *note = (void *)(info->dlpi_addr +
> +                                   info->dlpi_phdr[i].p_vaddr);
> +      ptrdiff_t len = info->dlpi_phdr[i].p_filesz;
> +
> +      while (len >= sizeof(struct note)) {
> +         if (note->nhdr.n_type == NT_GNU_BUILD_ID &&
> +            note->nhdr.n_descsz != 0 &&
> +            note->nhdr.n_namesz == 4 &&
> +            memcmp(note->name, "GNU", 4) == 0) {
> +            data->note = note;
> +            return 1;
> +         }
> +
> +         size_t offset = sizeof(ElfW(Nhdr)) +
> +                         ALIGN(note->nhdr.n_namesz, 4) +
> +                         ALIGN(note->nhdr.n_descsz, 4);
> +         note = (struct note *)((char *)note + offset);
> +         len -= offset;
> +      }
> +   }
> +
> +   return 0;
> +}
> +
> +const struct note *
> +build_id_find_nhdr(const char *name)
> +{
> +   struct callback_data data = {
> +      .name = name,
> +      .note = NULL,
> +   };
> +
> +   if (dl_iterate_phdr(build_id_find_nhdr_callback, &data)) {
> +      return data.note;
> +   } else {
> +      return NULL;
> +   }
> +}
> +
> +unsigned
> +build_id_length(const struct note *note)
> +{
> +   return note->nhdr.n_descsz;
> +}
> +
> +void
> +build_id_read(const struct note *note, unsigned char *build_id)
> +{
> +   memcpy(build_id, note->build_id, note->nhdr.n_descsz);
> +}
> +
> +#endif
> diff --git a/src/util/build_id.h b/src/util/build_id.h
> new file mode 100644
> index 0000000..0eaecf9
> --- /dev/null
> +++ b/src/util/build_id.h
> @@ -0,0 +1,56 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +struct note;
> +
> +#ifdef HAVE_DL_ITERATE_PHDR
> +
> +const struct note *
> +build_id_find_nhdr(const char *name);
> +
> +unsigned
> +build_id_length(const struct note *note);
> +
> +void
> +build_id_read(const struct note *note, unsigned char *build_id);
> +
> +#else
> +
> +static inline const struct note *
> +build_id_find_nhdr(const char *name)
> +{
> +   return NULL;
> +}
> +
> +static inline unsigned
> +build_id_length(const struct note *note)
> +{
> +   return 0;
> +}
> +
> +static inline void
> +build_id_read(const struct note *note, unsigned char *build_id)
> +{
> +}
> +
> +#endif
> -- 
> 2.10.2
>
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