On 4/20/21 1:43 PM, Mark Wielaard wrote:
> Hi Martin,
>
> On Mon, 2021-04-19 at 15:18 +0200, Martin Liška wrote:
>> I made similar changes to binutils some time ago and I would like to
>> come up with the same function for elfutils. Note that current
>> construct
>> is quite error prone, I found for instance these 2 bad usages:
>>
>> diff --git a/libdwfl/relocate.c b/libdwfl/relocate.c
>> index 88b5211d..b6de3510 100644
>> --- a/libdwfl/relocate.c
>> +++ b/libdwfl/relocate.c
>> @@ -518,7 +518,7 @@ relocate_section (Dwfl_Module *mod, Elf
>> *relocated, const GElf_Ehdr *ehdr,
>> Nothing to do here. */
>> return DWFL_E_NOERROR;
>>
>> - if (strncmp (tname, ".zdebug", strlen ("zdebug")) == 0)
>> + if (strncmp (tname, ".zdebug", strlen (".zdebug")) == 0)
>> elf_compress_gnu (tscn, 0, 0);
>>
>>if ((tshdr->sh_flags & SHF_COMPRESSED) != 0)
>> @@ -539,7 +539,7 @@ relocate_section (Dwfl_Module *mod, Elf
>> *relocated, const GElf_Ehdr *ehdr,
>>if (sname == NULL)
>> return DWFL_E_LIBELF;
>>
>> - if (strncmp (sname, ".zdebug", strlen ("zdebug")) == 0)
>> + if (strncmp (sname, ".zdebug", strlen (".zdebug")) == 0)
>> elf_compress_gnu (scn, 0, 0);
>>
>>if ((shdr->sh_flags & SHF_COMPRESSED) != 0)
>
> Urgh. Thanks for finding this!
>
>> I'm not convinced about function declaration in system.h. Is it a
>> proper location?
>
> Yes, I think it is.
>
>> And the function is not used in debuginfod/debuginfod-client.c and
>> debuginfod/debuginfod.cxx.
>> I would need another decl for these, am I right?
>
> I think they both can simply include system.h (might want to double
> check the -I search path in debuginfod/Makefile.am) because system.h
> should be stand-alone, you don't need to link to anything else.
All right, there was a different problem I had:
In file included from ../lib/system.h:39,
from debuginfod.cxx:40:
../lib/system.h: In function ‘ssize_t write_retry(int, const void*, size_t)’:
../lib/system.h:135:56: error: pointer of type ‘void *’ used in arithmetic
[-Werror=pointer-arith]
135 | ssize_t ret = TEMP_FAILURE_RETRY (write (fd, buf + recvd, len -
recvd));
|^~~
I fixed that in the attached patch.
>
> Maybe for debuginfod.cxx there is a better C++ way for strings. But if
> it uses C strings, then it could also simply include system.h.
Apparently, it's not using strncmp with a string objects.
Is the patch ready to be installed?
Thanks,
Martin
>
> Thanks,
>
> Mark
>
>From 4be9bec67e52ee6f011197951bb8810713be3eae Mon Sep 17 00:00:00 2001
From: Martin Liska
Date: Mon, 19 Apr 2021 14:33:36 +0200
Subject: [PATCH] Come up with startswith function.
backends/ChangeLog:
* aarch64_symbol.c (aarch64_data_marker_symbol): Use startswith.
* arm_symbol.c (arm_data_marker_symbol): Likewise.
debuginfod/ChangeLog:
* debuginfod-client.c (debuginfod_query_server): Use startswith.
(debuginfod_add_http_header): Likewise.
* debuginfod.cxx: Likewise.
lib/ChangeLog:
* system.h (startswith): New function.
(pwrite_retry): Cast to char *.
(write_retry): Likewise.
(pread_retry): Likewise.
libasm/ChangeLog:
* libasmP.h (asm_emit_symbol_p): Use startswith.
libdw/ChangeLog:
* dwarf_begin_elf.c (check_section): Use startswith.
libdwfl/ChangeLog:
* dwfl_frame.c (dwfl_attach_state): Use startswith.
* dwfl_module_getdwarf.c (find_symtab): Likewise.
* linux-kernel-modules.c: Likewise.
* linux-pid-attach.c (linux_proc_pid_is_stopped): Likewise.
(dwfl_linux_proc_attach): Likewise.
* relocate.c (resolve_symbol): Likewise.
(relocate_section): Likewise.
libebl/ChangeLog:
* eblobjnotetypename.c (ebl_object_note_type_name): Use startswith.
* eblopenbackend.c (default_debugscn_p): Likewise.
src/ChangeLog:
* elfclassify.c (run_classify): Use startswith.
* elfcompress.c (process_file): Likewise.
* nm.c (show_symbols_sysv): Likewise.
* readelf.c (print_debug): Likewise.
(handle_notes_data): Likewise.
(dump_data_section): Likewise.
(print_string_section): Likewise.
* strip.c (remove_debug_relocations): Likewise.
tests/ChangeLog:
* dwelf_elf_e_machine_string.c (main): Use startswith.
* dwelfgnucompressed.c (main): Likewise.
* elfgetchdr.c (main): Likewise.
* elfputzdata.c (main): Likewise.
* vdsosyms.c (module_callback): Likewise.
---
backends/aarch64_symbol.c | 4 +++-
backends/arm_symbol.c | 4 +++-
debuginfod/debuginfod-client.c | 4 ++--
debuginfod/debuginfod.cxx | 9 +
lib/system.h | 15 ---
libasm/libasmP.h | 2 +-
libdw/dwarf_begin_elf.c| 4 +++-
libdwfl/dwfl_frame.c | 4 +++-
libdwfl/dwfl_module_getdwarf.c | 4 ++--
libdwfl/linux-kernel-modules.c | 4 ++--
libdwfl/linux-pid-attach.c | 6 --
libdwfl/relocate.c | 8 +---
libebl/eblobjnotetypename.c| 5 +++--
libebl/e
