在没有/ proc/self/exe的情况下查找当前可执行文件的路径

Question

在我看来Linux使用/ proc/self/exe很容易.但我想知道是否有一种方便的方法可以在C/C++中使用跨平台接口查找当前应用程序的目录.我已经看到一些项目与argv [0]混在一起,但它似乎并不完全可靠.

如果你曾经不得不支持Mac OS X,它没有/ proc /,你会做什么？使用#ifdefs隔离特定于平台的代码(例如NSBundle)？或者尝试从argv [0],$ PATH等等推断出可执行文件的路径,冒着在边缘情况下发现错误的风险？

Answer 1

一些特定于OS的接口:

• Mac OS X的:_NSGetExecutablePath()(男子3使dyld)
• Linux的: readlink /proc/self/exe
• Solaris上: getexecname()
• FreeBSD的: sysctl CTL_KERN KERN_PROC KERN_PROC_PATHNAME -1
• 如果 FreeBSD 有procfs :( readlink /proc/curproc/fileFreeBSD默认没有procfs)
• NetBSD的: readlink /proc/curproc/exe
• DragonFly BSD: readlink /proc/curproc/file
• Windows:GetModuleFileName()with hModule=NULL

便携式(但不太可靠)的方法是使用argv[0].尽管可以通过调用程序将其设置为任何内容,但按照惯例,它可以设置为可执行文件的路径名或使用的名称$PATH.

某些shell(包括bash和ksh)在执行之前将环境变量" _" 设置为可执行文件的完整路径.在这种情况下,您可以使用getenv("_")它来获得它.然而,这是不可靠的,因为并非所有shell都这样做,并且它可以设置为任何内容,或者在执行程序之前不会更改它的父进程遗留下来.

Answer 2

使用/proc/self/exe不便携且不可靠.在我的Ubuntu 12.04系统上,您必须是root才能阅读/遵循符号链接.这将使Boost示例和可能whereami()发布的解决方案失败.

这篇文章很长,但讨论了实际问题,并提供了实际工作的代码以及对测试套件的验证.

The best way to find your program is to retrace the same steps the system uses. This is done by using argv[0] resolved against file system root, pwd, path environment and considering symlinks, and pathname canonicalization. This is from memory but I have done this in the past successfully and tested it in a variety of different situations. It is not guaranteed to work, but if it doesn't you probably have much bigger problems and it is more reliable overall than any of the other methods discussed. There are situations on a Unix compatible system in which proper handling of argv[0] will not get you to your program but then you are executing in a certifiably broken environment. It is also fairly portable to all Unix derived systems since around 1970 and even some non-Unix derived systems as it basically relies on libc() standard functionality and standard command line functionality. It should work on Linux (all versions), Android, Chrome OS, Minix, original Bell Labs Unix, FreeBSD, NetBSD, OpenBSD, BSD x.x, SunOS, Solaris, SYSV, HPUX, Concentrix, SCO, Darwin, AIX, OS X, Nextstep, etc. And with a little modification probably VMS, VM/CMS, DOS/Windows, ReactOS, OS/2, etc. If a program was launched directly from a GUI environment, it should have set argv[0] to an absolute path.

Understand that almost every shell on every Unix compatible operating system that has ever been released basically finds programs the same way and sets up the operating environment almost the same way (with some optional extras). And any other program that launches a program is expected to create the same environment (argv, environment strings, etc.) for that program as if it were run from a shell, with some optional extras. A program or user can setup an environment that deviates from this convention for other subordinate programs that it launches but if it does, this is a bug and the program has no reasonable expectation that the subordinate program or its subordinates will function correctly.

Possible values of argv[0] include:

• /path/to/executable — absolute path
• ../bin/executable — relative to pwd
• bin/executable — relative to pwd
• ./foo — relative to pwd
• executable — basename, find in path
• bin//executable — relative to pwd, non-canonical
• src/../bin/executable — relative to pwd, non-canonical, backtracking
• bin/./echoargc — relative to pwd, non-canonical

Values you should not see:

• ~/bin/executable — rewritten before your program runs.
• ~user/bin/executable — rewritten before your program runs
• alias — rewritten before your program runs
• $shellvariable — rewritten before your program runs
• *foo* — wildcard, rewritten before your program runs, not very useful
• ?foo? — wildcard, rewritten before your program runs, not very useful

In addition, these may contain non-canonical path names and multiple layers of symbolic links. In some cases, there may be multiple hard links to the same program. For example, /bin/ls, /bin/ps, /bin/chmod, /bin/rm, etc. may be hard links to /bin/busybox.

To find yourself, follow the steps below:

• Save pwd, PATH, and argv[0] on entry to your program (or initialization of your library) as they may change later.

• Optional: particularly for non-Unix systems, separate out but don't discard the pathname host/user/drive prefix part, if present; the part which often precedes a colon or follows an initial "//".

• If argv[0] is an absolute path, use that as a starting point. An absolute path probably starts with "/" but on some non-Unix systems it might start with "\" or a drive letter or name prefix followed by a colon.

• Else if argv[0] is a relative path (contains "/" or "\" but doesn't start with it, such as "../../bin/foo", then combine pwd+"/"+argv[0] (use present working directory from when program started, not current).

• Else if argv[0] is a plain basename (no slashes), then combine it with each entry in PATH environment variable in turn and try those and use the first one which succeeds.

• Optional: Else try the very platform specific /proc/self/exe, /proc/curproc/file (BSD), and (char *)getauxval(AT_EXECFN), and dlgetname(...) if present. You might even try these before argv[0]-based methods, if they are available and you don't encounter permission issues. In the somewhat unlikely event (when you consider all versions of all systems) that they are present and don't fail, they might be more authoritative.

• Optional: check for a path name passed in using a command line parameter.

• Optional: check for a pathname in the environment explicitly passed in by your wrapper script, if any.

• 可选:作为最后的手段尝试环境变量"_".它可能完全指向不同的程序,例如用户shell.

• 解析符号链接,可能有多个图层.存在无限循环的可能性,但如果它们存在,则程序可能不会被调用.

• Canonicalize filename by resolving substrings like "/foo/../bar/" to "/bar/". Note this may potentially change the meaning if you cross a network mount point, so canonization is not always a good thing. On a network server, ".." in symlink may be used to traverse a path to another file in the server context instead of on the client. In this case, you probably want the client context so canonicalization is ok. Also convert patterns like "/./" to "/" and "//" to "/". In shell, readlink --canonicalize will resolve multiple symlinks and canonicalize name. Chase may do similar but isn't installed. realpath() or canonicalize_file_name(), if present, may help.

If realpath() doesn't exist at compile time, you might borrow a copy from a permissively licensed library distribution, and compile it in yourself rather than reinventing the wheel. Fix the potential buffer overflow (pass in sizeof output buffer, think strncpy() vs strcpy()) if you will be using a buffer less than PATH_MAX. It may be easier just to use a renamed private copy rather than testing if it exists. Permissive license copy from android/darwin/bsd: https://android.googlesource.com/platform/bionic/+/f077784/libc/upstream-freebsd/lib/libc/stdlib/realpath.c

Be aware that multiple attempts may be successful or partially successful and they might not all point to the same executable, so consider verifying your executable; however, you may not have read permission — if you can't read it, don't treat that as a failure. Or verify something in proximity to your executable such as the "../lib/" directory you are trying to find. You may have multiple versions, packaged and locally compiled versions, local and network versions, and local and USB-drive portable versions, etc. and there is a small possibility that you might get two incompatible results from different methods of locating. And "_" may simply point to the wrong program.

A program using execve can deliberately set argv[0] to be incompatible with the actual path used to load the program and corrupt PATH, "_", pwd, etc. though there isn't generally much reason to do so; but this could have security implications if you have vulnerable code that ignores the fact that your execution environment can be changed in variety of ways including, but not limited, to this one (chroot, fuse filesystem, hard links, etc.) It is possible for shell commands to set PATH but fail to export it.

You don't necessarily need to code for non-Unix systems but it would be a good idea to be aware of some of the peculiarities so you can write the code in such a way that it isn't as hard for someone to port later. Be aware that some systems (DEC VMS, DOS, URLs, etc.) might have drive names or other prefixes which end with a colon such as "C:\", "sys$drive:[foo]bar", and "file:///foo/bar/baz". Old DEC VMS systems use "[" and "]" to enclose the directory portion of the path though this may have changed if your program is compiled in a POSIX environment. Some systems, such as VMS, may have a file version (separated by a semicolon at the end). Some systems use two consecutive slashes as in "//drive/path/to/file" or "user@host:/path/to/file" (scp command) or "file://hostname/path/to/file" (URL). In some cases (DOS, windoze), PATH might have different separator characters — ";" vs ":" and "\" vs "/" for a path separator. In csh/tsh there is "path" (delimited with spaces) and "PATH" delimited with colons but your program should receive PATH so you don't need to worry about path. DOS and some other systems can have relative paths that start with a drive prefix. C:foo.exe refers to foo.exe in the current directory on drive C, so you do need to lookup current directory on C: and use that for pwd.

An example of symlinks and wrappers on my system:

/usr/bin/google-chrome is symlink to
/etc/alternatives/google-chrome  which is symlink to
/usr/bin/google-chrome-stable which is symlink to
/opt/google/chrome/google-chrome which is a bash script which runs
/opt/google/chome/chrome

Note that user bill posted a link above to a program at HP that handles the three basic cases of argv[0]. It needs some changes, though:

• It will be necessary to rewrite all the strcat() and strcpy() to use strncat() and strncpy(). Even though the variables are declared of length PATHMAX, an input value of length PATHMAX-1 plus the length of concatenated strings is > PATHMAX and an input value of length PATHMAX would be unterminated.
• It needs to be rewritten as a library function, rather than just to print out results.
  • It fails to canonicalize names (use the realpath code I linked to above)
  • It fails to resolve symbolic links (use the realpath code)

So, if you combine both the HP code and the realpath code and fix both to be resistant to buffer overflows, then you should have something which can properly interpret argv[0].

The following illustrates actual values of argv[0] for various ways of invoking the same program on Ubuntu 12.04. And yes, the program was accidentally named echoargc instead of echoargv. This was done using a script for clean copying but doing it manually in shell gets same results (except aliases don't work in script unless you explicitly enable them).

cat ~/src/echoargc.c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
main(int argc, char **argv)
{
  printf("  argv[0]=\"%s\"\n", argv[0]);
  sleep(1);  /* in case run from desktop */
}
tcc -o ~/bin/echoargc ~/src/echoargc.c 
cd ~
/home/whitis/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
echoargc
  argv[0]="echoargc"
bin/echoargc
  argv[0]="bin/echoargc"
bin//echoargc
  argv[0]="bin//echoargc"
bin/./echoargc
  argv[0]="bin/./echoargc"
src/../bin/echoargc
  argv[0]="src/../bin/echoargc"
cd ~/bin
*echo*
  argv[0]="echoargc"
e?hoargc
  argv[0]="echoargc"
./echoargc
  argv[0]="./echoargc"
cd ~/src
../bin/echoargc
  argv[0]="../bin/echoargc"
cd ~/junk
~/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
~whitis/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
alias echoit=~/bin/echoargc
echoit
  argv[0]="/home/whitis/bin/echoargc"
echoarg=~/bin/echoargc
$echoarg
  argv[0]="/home/whitis/bin/echoargc"
ln -s ~/bin/echoargc junk1
./junk1
  argv[0]="./junk1"
ln -s /home/whitis/bin/echoargc junk2
./junk2
  argv[0]="./junk2"
ln -s junk1 junk3
./junk3
  argv[0]="./junk3"


gnome-desktop-item-edit --create-new ~/Desktop
# interactive, create desktop link, then click on it
  argv[0]="/home/whitis/bin/echoargc"
# interactive, right click on gnome application menu, pick edit menus
# add menu item for echoargc, then run it from gnome menu
 argv[0]="/home/whitis/bin/echoargc"

 cat ./testargcscript 2>&1 | sed -e 's/^/    /g'
#!/bin/bash
# echoargc is in ~/bin/echoargc
# bin is in path
shopt -s expand_aliases
set -v
cat ~/src/echoargc.c
tcc -o ~/bin/echoargc ~/src/echoargc.c 
cd ~
/home/whitis/bin/echoargc
echoargc
bin/echoargc
bin//echoargc
bin/./echoargc
src/../bin/echoargc
cd ~/bin
*echo*
e?hoargc
./echoargc
cd ~/src
../bin/echoargc
cd ~/junk
~/bin/echoargc
~whitis/bin/echoargc
alias echoit=~/bin/echoargc
echoit
echoarg=~/bin/echoargc
$echoarg
ln -s ~/bin/echoargc junk1
./junk1
ln -s /home/whitis/bin/echoargc junk2
./junk2
ln -s junk1 junk3
./junk3

These examples illustrate that the techniques described in this post should work in a wide range of circumstances and why some of the steps are necessary.

EDIT: Now, the program that prints argv[0] has been updated to actually find itself.

// Copyright 2015 by Mark Whitis.  License=MIT style
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <limits.h>
#include <assert.h>
#include <string.h>
#include <errno.h>

// "look deep into yourself, Clarice"  -- Hanibal Lector
char findyourself_save_pwd[PATH_MAX];
char findyourself_save_argv0[PATH_MAX];
char findyourself_save_path[PATH_MAX];
char findyourself_path_separator='/';
char findyourself_path_separator_as_string[2]="/";
char findyourself_path_list_separator[8]=":";  // could be ":; "
char findyourself_debug=0;

int findyourself_initialized=0;

void findyourself_init(char *argv0)
{

  getcwd(findyourself_save_pwd, sizeof(findyourself_save_pwd));

  strncpy(findyourself_save_argv0, argv0, sizeof(findyourself_save_argv0));
  findyourself_save_argv0[sizeof(findyourself_save_argv0)-1]=0;

  strncpy(findyourself_save_path, getenv("PATH"), sizeof(findyourself_save_path));
  findyourself_save_path[sizeof(findyourself_save_path)-1]=0;
  findyourself_initialized=1;
}


int find_yourself(char *result, size_t size_of_result)
{
  char newpath[PATH_MAX+256];
  char newpath2[PATH_MAX+256];

  assert(findyourself_initialized);
  result[0]=0;

  if(findyourself_save_argv0[0]==findyourself_path_separator) {
    if(findyourself_debug) printf("  absolute path\n");
     realpath(findyourself_save_argv0, newpath);
     if(findyourself_debug) printf("  newpath=\"%s\"\n", newpath);
     if(!access(newpath, F_OK)) {
        strncpy(result, newpath, size_of_result);
        result[size_of_result-1]=0;
        return(0);
     } else {
    perror("access failed 1");
      }
  } else if( strchr(findyourself_save_argv0, findyourself_path_separator )) {
    if(findyourself_debug) printf("  relative path to pwd\n");
    strncpy(newpath2, findyourself_save_pwd, sizeof(newpath2));
    newpath2[sizeof(newpath2)-1]=0;
    strncat(newpath2, findyourself_path_separator_as_string, sizeof(newpath2));
    newpath2[sizeof(newpath2)-1]=0;
    strncat(newpath2, findyourself_save_argv0, sizeof(newpath2));
    newpath2[sizeof(newpath2)-1]=0;
    realpath(newpath2, newpath);
    if(findyourself_debug) printf("  newpath=\"%s\"\n", newpath);
    if(!access(newpath, F_OK)) {
        strncpy(result, newpath, size_of_result);
        result[size_of_result-1]=0;
        return(0);
     } else {
    perror("access failed 2");
      }
  } else {
    if(findyourself_debug) printf("  searching $PATH\n");
    char *saveptr;
    char *pathitem;
    for(pathitem=strtok_r(findyourself_save_path, findyourself_path_list_separator,  &saveptr); pathitem; pathitem=strtok_r(NULL, findyourself_path_list_separator, &saveptr) ) {
       if(findyourself_debug>=2) printf("pathitem=\"%s\"\n", pathitem);
       strncpy(newpath2, pathitem, sizeof(newpath2));
       newpath2[sizeof(newpath2)-1]=0;
       strncat(newpath2, findyourself_path_separator_as_string, sizeof(newpath2));
       newpath2[sizeof(newpath2)-1]=0;
       strncat(newpath2, findyourself_save_argv0, sizeof(newpath2));
       newpath2[sizeof(newpath2)-1]=0;
       realpath(newpath2, newpath);
       if(findyourself_debug) printf("  newpath=\"%s\"\n", newpath);
      if(!access(newpath, F_OK)) {
          strncpy(result, newpath, size_of_result);
          result[size_of_result-1]=0;
          return(0);
      } 
    } // end for
    perror("access failed 3");

  } // end else
  // if we get here, we have tried all three methods on argv[0] and still haven't succeeded.   Include fallback methods here.
  return(1);
}

main(int argc, char **argv)
{
  findyourself_init(argv[0]);

  char newpath[PATH_MAX];
  printf("  argv[0]=\"%s\"\n", argv[0]);
  realpath(argv[0], newpath);
  if(strcmp(argv[0],newpath)) { printf("  realpath=\"%s\"\n", newpath); }
  find_yourself(newpath, sizeof(newpath));
  if(1 || strcmp(argv[0],newpath)) { printf("  findyourself=\"%s\"\n", newpath); }
  sleep(1);  /* in case run from desktop */
}

And here is the output which demonstrates that in every one of the previous tests it actually did find itself.

tcc -o ~/bin/echoargc ~/src/echoargc.c 
cd ~
/home/whitis/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
echoargc
  argv[0]="echoargc"
  realpath="/home/whitis/echoargc"
  findyourself="/home/whitis/bin/echoargc"
bin/echoargc
  argv[0]="bin/echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
bin//echoargc
  argv[0]="bin//echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
bin/./echoargc
  argv[0]="bin/./echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
src/../bin/echoargc
  argv[0]="src/../bin/echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
cd ~/bin
*echo*
  argv[0]="echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
e?hoargc
  argv[0]="echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
./echoargc
  argv[0]="./echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
cd ~/src
../bin/echoargc
  argv[0]="../bin/echoargc"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
cd ~/junk
~/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
~whitis/bin/echoargc
  argv[0]="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
alias echoit=~/bin/echoargc
echoit
  argv[0]="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
echoarg=~/bin/echoargc
$echoarg
  argv[0]="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
rm junk1 junk2 junk3
ln -s ~/bin/echoargc junk1
./junk1
  argv[0]="./junk1"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
ln -s /home/whitis/bin/echoargc junk2
./junk2
  argv[0]="./junk2"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"
ln -s junk1 junk3
./junk3
  argv[0]="./junk3"
  realpath="/home/whitis/bin/echoargc"
  findyourself="/home/whitis/bin/echoargc"

The two GUI launches described above also correctly find the program.

There is one potential pitfall. The access() function drops permissions if the program is setuid before testing. If there is a situation where the program can be found as an elevated user but not as a regular user, then there might be a situation where these tests would fail, although it is unlikely the program could actually be executed under those circumstances. One could use euidaccess() instead. It is possible, however, that it might find an inaccessable program earlier on path than the actual user could.

Answer 3

查看来自Gregory Pakosz(只有一个C文件)的whereami图书馆; 它允许您在各种平台上获取当前可执行文件的完整路径.目前,它可以在这里作为github的回购.

Answer 4

使这项工作跨平台可靠地工作需要使用 #ifdef 语句。

下面的代码在 Windows、Linux、MacOS、Solaris 或 FreeBSD 中查找可执行文件的路径（尽管 FreeBSD 未经测试）。它使用 Boost 1.55.0（或更高版本）来简化代码，但如果您愿意，可以很容易地将其删除。只需使用像 _MSC_VER 和 __linux 这样的定义作为操作系统和编译器的要求。

#include <string>
#include <boost/predef/os.h>

#if (BOOST_OS_WINDOWS)
#  include <stdlib.h>
#elif (BOOST_OS_SOLARIS)
#  include <stdlib.h>
#  include <limits.h>
#elif (BOOST_OS_LINUX)
#  include <unistd.h>
#  include <limits.h>
#elif (BOOST_OS_MACOS)
#  include <mach-o/dyld.h>
#elif (BOOST_OS_BSD_FREE)
#  include <sys/types.h>
#  include <sys/sysctl.h>
#endif

/*
 * Returns the full path to the currently running executable,
 * or an empty string in case of failure.
 */
std::string getExecutablePath() {
    #if (BOOST_OS_WINDOWS)
        char *exePath;
        if (_get_pgmptr(&exePath) != 0)
            exePath = "";
    #elif (BOOST_OS_SOLARIS)
        char exePath[PATH_MAX];
        if (realpath(getexecname(), exePath) == NULL)
            exePath[0] = '\0';
    #elif (BOOST_OS_LINUX)
        char exePath[PATH_MAX];
        ssize_t len = ::readlink("/proc/self/exe", exePath, sizeof(exePath));
        if (len == -1 || len == sizeof(exePath))
            len = 0;
        exePath[len] = '\0';
    #elif (BOOST_OS_MACOS)
        char exePath[PATH_MAX];
        uint32_t len = sizeof(exePath);
        if (_NSGetExecutablePath(exePath, &len) != 0) {
            exePath[0] = '\0'; // buffer too small (!)
        } else {
            // resolve symlinks, ., .. if possible
            char *canonicalPath = realpath(exePath, NULL);
            if (canonicalPath != NULL) {
                strncpy(exePath,canonicalPath,len);
                free(canonicalPath);
            }
        }
    #elif (BOOST_OS_BSD_FREE)
        char exePath[2048];
        int mib[4];  mib[0] = CTL_KERN;  mib[1] = KERN_PROC;  mib[2] = KERN_PROC_PATHNAME;  mib[3] = -1;
        size_t len = sizeof(exePath);
        if (sysctl(mib, 4, exePath, &len, NULL, 0) != 0)
            exePath[0] = '\0';
    #endif
        return std::string(exePath);
}

上述版本返回包括可执行文件名称的完整路径。如果您想要没有可执行文件名称的路径，#include boost/filesystem.hpp>请将 return 语句更改为：

return strlen(exePath)>0 ? boost::filesystem::path(exePath).remove_filename().make_preferred().string() : std::string();

Answer 5

如果你不得不支持，比如说，没有 /proc/ 的 Mac OS X，你会怎么做？使用 #ifdefs 来隔离特定于平台的代码（例如 NSBundle）？

是的，隔离特定于平台的代码 #ifdefs是完成此操作的常规方式。

另一种方法是拥有一个 clean #ifdef-less 头文件，其中包含函数声明并将实现放在特定于平台的源文件中。

例如，查看POCO（可移植组件）C++ 库如何为它们的Environment类做类似的事情。

Answer 6

在Linux上，使用或者/proc/self/exe或argv[0]使用ELF解释器传递的信息的替代方法，由glibc提供，如下所示：

#include <stdio.h>
#include <sys/auxv.h>

int main(int argc, char **argv)
{
    printf("%s\n", (char *)getauxval(AT_EXECFN));
    return(0);
}

请注意，这getauxval是一个glibc扩展，为确保功能强大，您应检查它是否不返回NULL（表明ELF解释器未提供该AT_EXECFN参数），但我认为这在Linux上实际上不是问题。

Answer 7

AFAIK，没有这样的方法。而且还存在一个歧义：如果同一个可执行文件有多个硬链接“指向”它，您希望得到什么答案？（硬链接实际上并不“指向”，它们是同一个文件，只是位于文件系统层次结构中的另一个位置。）

一旦execve()成功执行新的二进制文件，有关原始程序参数的所有信息都会丢失。