c - 为什么 GDB 无法识别我的 C 程序的语言？

Question

我正在使用书中的一个示例，其中作者编写了一个简短的、有缺陷的 C 程序来演示使用 GDB 进行调试。

#include <stdio.h>

int main (void)
{
    const int data[5] = {1, 2, 3, 4, 5};
    int i, sum;

    for (i = 0; i >= 0; ++i)
        sum += data[i];

    printf ("sum = %i\n", sum);

    return 0;
}

使用gcc -g program.c编译后，他运行gdb ./a.out并从gdb内部调用run。当它遇到程序中的缺陷时，他调用，

(gdb) print data
$1 = {1, 2, 3, 4, 5}

当我尝试同样的方法时，我得到了，

(gdb) print data
$1 = 0x100000f80
Current language:  auto; currently minimal

我做了一些挖掘，听起来好像我只看到内存地址与下面有关“当前语言”的消息相关。

我像这样编译并运行了上面的C程序，

❯ gcc -g program.c
❯ gdb ./a.out
Reading symbols for shared libraries .. done
(gdb) run
Starting program: /Users/ivan/Development/books/c/programming-in-c/a.out

GDB 然后输出一堆关于不支持的“间接”引用的行，

Reading symbols for shared libraries +..............bfd_mach_o_scan_read_symtab_symbol: symbol "_bzero" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memccpy" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memchr" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memcmp" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memcpy" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memmove" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_memset" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_strchr" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_strcmp" is unsupported 'indirect' reference: setting to undefined
bfd_mach_o_scan_read_symtab_symbol: symbol "_strncmp" is unsupported 'indirect' reference: setting to undefined

...随后是有关无法找到目标文件的警告(所有这些看起来都与 ssl/tls 相关):

...warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Objects/coretls.build/coretls.build/Objects-normal/x86_64/system_coretls_vers.o" - no debug information available for "system_coretls_vers.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_ciphersuites.a(tls_ciphersuites.o)" - no debug information available for "tls_ciphersuites.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslSession.o)" - no debug information available for "sslSession.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslCipherSpecs.o)" - no debug information available for "sslCipherSpecs.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslDigests.o)" - no debug information available for "sslDigests.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslCrypto.o)" - no debug information available for "sslCrypto.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslChangeCipher.o)" - no debug information available for "sslChangeCipher.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslCert.o)" - no debug information available for "sslCert.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslKeyExchange.o)" - no debug information available for "sslKeyExchange.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslAlertMessage.o)" - no debug information available for "sslAlertMessage.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslHandshake.o)" - no debug information available for "sslHandshake.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslHandshakeFinish.o)" - no debug information available for "sslHandshakeFinish.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(tls1Callouts.o)" - no debug information available for "tls1Callouts.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(sslHandshakeHello.o)" - no debug information available for "sslHandshakeHello.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(tls_handshake.o)" - no debug information available for "tls_handshake.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_handshake.a(ssl3Callouts.o)" - no debug information available for "ssl3Callouts.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(tls1RecordCallouts.o)" - no debug information available for "tls1RecordCallouts.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(ssl3RecordCallouts.o)" - no debug information available for "ssl3RecordCallouts.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(tls_record.o)" - no debug information available for "tls_record.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(sslRc4Cipher.o)" - no debug information available for "sslRc4Cipher.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(sslMemory.o)" - no debug information available for "sslMemory.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(sslUtils.o)" - no debug information available for "sslUtils.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(symCipherParams.o)" - no debug information available for "symCipherParams.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(sslNullCipher.o)" - no debug information available for "sslNullCipher.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(symCipher.o)" - no debug information available for "symCipher.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(tls_digest.o)" - no debug information available for "tls_digest.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(tls_hashhmac.o)" - no debug information available for "tls_hashhmac.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_record.a(tls_hmac.o)" - no debug information available for "tls_hmac.c".
warning: Could not find object file "/BinaryCache/coreTLS/coreTLS-35.40.1~1/Symbols/BuiltProducts/libcoretls_stream_parser.a(tls_stream_parser.o)" - no debug information available for "tls_stream_parser.c".
....................... done

...最后它停在程序的预期(有缺陷)行:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x0000000100006000
0x0000000100000f1e in main () at prog.18.4.c:9
9                       sum += data[i];

我使用的是 OS X Yosemite，具有以下版本的 gcc 和 gdb:

❯ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin14.5.0
Thread model: posix

❯ gdb --version
GNU gdb 6.3.50-20050815 (Apple version gdb-1824) (Wed Feb  6 22:51:23 UTC 2013)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin".

我需要做什么才能让 GDB 将其识别为 C 程序？

Answer 1

您必须使用 -g 选项编译和链接程序，以包含调试信息，例如函数和变量名称、源语言和位置...