Hi all.
I'm trying to use the execv  function in std.process, but when the program links, it gives me an  undefined reference to `execvpe' message.
This is using the latest dmd on a linux system.

In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
>
>Hi all.
>I'm trying to use the execv  function in std.process, but when the program
>links, it gives me an  undefined reference to `execvpe' message.
>This is using the latest dmd on a linux system.
>
>
I get that too. I don't know why: the prototype for execvpe is in std.c.process (which std.process imports)... I even tried re-compiling the library, but it still failed.

kinghajj wrote:
> In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> 
>>Hi all.
>>I'm trying to use the execv  function in std.process, but when the program links, it gives me an  undefined reference to `execvpe' message.
>>This is using the latest dmd on a linux system.
>>
>>
> 
> I get that too. I don't know why: the prototype for execvpe is in std.c.process
> (which std.process imports)... I even tried re-compiling the library, but it
> still failed.

Phobos uses execvpe(), but it isn't implemented by glibc, at least on my system.  execvpe() is just like execve(), except that it searches through your $PATH to find the executable.  So I added this function to my program, which seemed to make it work.  Feel free to fix the code if you find any bugs:



// HACK HACK HACK
// phobos uses execvpe(), which is not implemented in glibc.  This
// implementation provides what is missing.



/* execvpe() - execve() with PATH search */
import std.c.process;
import std.c.stdlib;
import std.string;
extern (C) int execvpe(char *file_arg, char **argv, char **envp) {
  int ret;



  char[] file = file_arg[0..strlen(file_arg)];
  char[] path;
  char[] next;



  char *temp = getenv("PATH");



  path = temp[0..strlen(temp)];



  while(path.length > 0) {
    temp = strchr(path, ':');



    if(temp == null)
      next.length = 0;
    else {
      next = path[temp-cast(char*)path+1..length];
      path = path[0..temp-cast(char*)path];
    }



    // If the exectuable is found, then this never returns.
    // But if the executable is not found, then this returns
    // some nonzero value.
    ret = execve(path~"/"~file, argv, envp);



    path = next;
  }



  return ret;
}

It's my fault. I didn't do the due diligence for ensuring that the APIs were available on Linux.

It's been noted, and is on the list for a fix. (Which might be to remove it!)

Alternatively, we might do a custom search, as has been suggested by Russ. (I'm just looking at that now.)

"kinghajj" <kinghajj_member@pathlink.com> wrote in message news:cg358e$2hh6$1@digitaldaemon.com...
> In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> >
> >Hi all.
> >I'm trying to use the execv  function in std.process, but when the program
> >links, it gives me an  undefined reference to `execvpe' message.
> >This is using the latest dmd on a linux system.
> >
> >
> I get that too. I don't know why: the prototype for execvpe is in std.c.process (which std.process imports)... I even tried re-compiling the library, but it still failed.
>
>

Russ, I'll take this as a basis for a permanent fix, if that's ok with you? (I've some ideas for making it a bit neater, and we would only implement the D version, but essentially it's a sound idea.)

"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg4udj$b0j$1@digitaldaemon.com...
> kinghajj wrote:
> > In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> >
> >>Hi all.
> >>I'm trying to use the execv  function in std.process, but when the program
> >>links, it gives me an  undefined reference to `execvpe' message.
> >>This is using the latest dmd on a linux system.
> >>
> >>
> >
> > I get that too. I don't know why: the prototype for execvpe is in std.c.process (which std.process imports)... I even tried re-compiling the library, but it still failed.
>
> Phobos uses execvpe(), but it isn't implemented by glibc, at least on my
> system.  execvpe() is just like execve(), except that it searches
> through your $PATH to find the executable.  So I added this function to
> my program, which seemed to make it work.  Feel free to fix the code if
> you find any bugs:
>
>
>
> // HACK HACK HACK
> // phobos uses execvpe(), which is not implemented in glibc.  This
> // implementation provides what is missing.
>
>
>
> /* execvpe() - execve() with PATH search */
> import std.c.process;
> import std.c.stdlib;
> import std.string;
> extern (C) int execvpe(char *file_arg, char **argv, char **envp) {
>    int ret;
>
>
>
>    char[] file = file_arg[0..strlen(file_arg)];
>    char[] path;
>    char[] next;
>
>
>
>    char *temp = getenv("PATH");
>
>
>
>    path = temp[0..strlen(temp)];
>
>
>
>    while(path.length > 0) {
>      temp = strchr(path, ':');
>
>
>
>      if(temp == null)
>        next.length = 0;
>      else {
>        next = path[temp-cast(char*)path+1..length];
>        path = path[0..temp-cast(char*)path];
>      }
>
>
>
>      // If the exectuable is found, then this never returns.
>      // But if the executable is not found, then this returns
>      // some nonzero value.
>      ret = execve(path~"/"~file, argv, envp);
>
>
>
>      path = next;
>    }
>
>
>
>    return ret;
> }
>

I don't mind, but I can't guarantee it isn't buggy.  In particular, I think that I should have added    ~\0    on the execve() call.  Right?

Matthew wrote:
> Russ, I'll take this as a basis for a permanent fix, if that's ok with you? (I've some ideas for making it a bit neater,
> and we would only implement the D version, but essentially it's a sound idea.)
> 
> "Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg4udj$b0j$1@digitaldaemon.com...
> 
>>kinghajj wrote:
>>
>>>In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
>>>
>>>
>>>>Hi all.
>>>>I'm trying to use the execv  function in std.process, but when the program
>>>>links, it gives me an  undefined reference to `execvpe' message.
>>>>This is using the latest dmd on a linux system.
>>>>
>>>>
>>>
>>>I get that too. I don't know why: the prototype for execvpe is in std.c.process
>>>(which std.process imports)... I even tried re-compiling the library, but it
>>>still failed.
>>
>>Phobos uses execvpe(), but it isn't implemented by glibc, at least on my
>>system.  execvpe() is just like execve(), except that it searches
>>through your $PATH to find the executable.  So I added this function to
>>my program, which seemed to make it work.  Feel free to fix the code if
>>you find any bugs:
>>
>>
>>
>>// HACK HACK HACK
>>// phobos uses execvpe(), which is not implemented in glibc.  This
>>// implementation provides what is missing.
>>
>>
>>
>>/* execvpe() - execve() with PATH search */
>>import std.c.process;
>>import std.c.stdlib;
>>import std.string;
>>extern (C) int execvpe(char *file_arg, char **argv, char **envp) {
>>   int ret;
>>
>>
>>
>>   char[] file = file_arg[0..strlen(file_arg)];
>>   char[] path;
>>   char[] next;
>>
>>
>>
>>   char *temp = getenv("PATH");
>>
>>
>>
>>   path = temp[0..strlen(temp)];
>>
>>
>>
>>   while(path.length > 0) {
>>     temp = strchr(path, ':');
>>
>>
>>
>>     if(temp == null)
>>       next.length = 0;
>>     else {
>>       next = path[temp-cast(char*)path+1..length];
>>       path = path[0..temp-cast(char*)path];
>>     }
>>
>>
>>
>>     // If the exectuable is found, then this never returns.
>>     // But if the executable is not found, then this returns
>>     // some nonzero value.
>>     ret = execve(path~"/"~file, argv, envp);
>>
>>
>>
>>     path = next;
>>   }
>>
>>
>>
>>   return ret;
>>}

No worries, mate. I just meant I'd steal the idea. I'm a pathological rewriter. ;)

Are you, or is anyone else, up for testing this on Linux? (I'm yet to set up D on my linux box, and I am woefully short on time. Of course, this probably means I shouldn't write any more multi-platform code before I do ...<G>)

"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg62sj$uof$1@digitaldaemon.com...
> I don't mind, but I can't guarantee it isn't buggy.  In particular, I think that I should have added    ~\0    on the execve() call.  Right?
>
> Matthew wrote:
> > Russ, I'll take this as a basis for a permanent fix, if that's ok with you? (I've some ideas for making it a bit
neater,
> > and we would only implement the D version, but essentially it's a sound idea.)
> >
> > "Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg4udj$b0j$1@digitaldaemon.com...
> >
> >>kinghajj wrote:
> >>
> >>>In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> >>>
> >>>
> >>>>Hi all.
> >>>>I'm trying to use the execv  function in std.process, but when the program
> >>>>links, it gives me an  undefined reference to `execvpe' message.
> >>>>This is using the latest dmd on a linux system.
> >>>>
> >>>>
> >>>
> >>>I get that too. I don't know why: the prototype for execvpe is in std.c.process (which std.process imports)... I even tried re-compiling the library, but it still failed.
> >>
> >>Phobos uses execvpe(), but it isn't implemented by glibc, at least on my
> >>system.  execvpe() is just like execve(), except that it searches
> >>through your $PATH to find the executable.  So I added this function to
> >>my program, which seemed to make it work.  Feel free to fix the code if
> >>you find any bugs:
> >>
> >>
> >>
> >>// HACK HACK HACK
> >>// phobos uses execvpe(), which is not implemented in glibc.  This
> >>// implementation provides what is missing.
> >>
> >>
> >>
> >>/* execvpe() - execve() with PATH search */
> >>import std.c.process;
> >>import std.c.stdlib;
> >>import std.string;
> >>extern (C) int execvpe(char *file_arg, char **argv, char **envp) {
> >>   int ret;
> >>
> >>
> >>
> >>   char[] file = file_arg[0..strlen(file_arg)];
> >>   char[] path;
> >>   char[] next;
> >>
> >>
> >>
> >>   char *temp = getenv("PATH");
> >>
> >>
> >>
> >>   path = temp[0..strlen(temp)];
> >>
> >>
> >>
> >>   while(path.length > 0) {
> >>     temp = strchr(path, ':');
> >>
> >>
> >>
> >>     if(temp == null)
> >>       next.length = 0;
> >>     else {
> >>       next = path[temp-cast(char*)path+1..length];
> >>       path = path[0..temp-cast(char*)path];
> >>     }
> >>
> >>
> >>
> >>     // If the exectuable is found, then this never returns.
> >>     // But if the executable is not found, then this returns
> >>     // some nonzero value.
> >>     ret = execve(path~"/"~file, argv, envp);
> >>
> >>
> >>
> >>     path = next;
> >>   }
> >>
> >>
> >>
> >>   return ret;
> >>}
>

I'm posting the link to an alpha on the bugs ng shortly. If you can do a test, and report back to the bugs ng, that'd be great!

"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg62sj$uof$1@digitaldaemon.com...
> I don't mind, but I can't guarantee it isn't buggy.  In particular, I think that I should have added    ~\0    on the execve() call.  Right?
>
> Matthew wrote:
> > Russ, I'll take this as a basis for a permanent fix, if that's ok with you? (I've some ideas for making it a bit
neater,
> > and we would only implement the D version, but essentially it's a sound idea.)
> >
> > "Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg4udj$b0j$1@digitaldaemon.com...
> >
> >>kinghajj wrote:
> >>
> >>>In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> >>>
> >>>
> >>>>Hi all.
> >>>>I'm trying to use the execv  function in std.process, but when the program
> >>>>links, it gives me an  undefined reference to `execvpe' message.
> >>>>This is using the latest dmd on a linux system.
> >>>>
> >>>>
> >>>
> >>>I get that too. I don't know why: the prototype for execvpe is in std.c.process (which std.process imports)... I even tried re-compiling the library, but it still failed.
> >>
> >>Phobos uses execvpe(), but it isn't implemented by glibc, at least on my
> >>system.  execvpe() is just like execve(), except that it searches
> >>through your $PATH to find the executable.  So I added this function to
> >>my program, which seemed to make it work.  Feel free to fix the code if
> >>you find any bugs:
> >>
> >>
> >>
> >>// HACK HACK HACK
> >>// phobos uses execvpe(), which is not implemented in glibc.  This
> >>// implementation provides what is missing.
> >>
> >>
> >>
> >>/* execvpe() - execve() with PATH search */
> >>import std.c.process;
> >>import std.c.stdlib;
> >>import std.string;
> >>extern (C) int execvpe(char *file_arg, char **argv, char **envp) {
> >>   int ret;
> >>
> >>
> >>
> >>   char[] file = file_arg[0..strlen(file_arg)];
> >>   char[] path;
> >>   char[] next;
> >>
> >>
> >>
> >>   char *temp = getenv("PATH");
> >>
> >>
> >>
> >>   path = temp[0..strlen(temp)];
> >>
> >>
> >>
> >>   while(path.length > 0) {
> >>     temp = strchr(path, ':');
> >>
> >>
> >>
> >>     if(temp == null)
> >>       next.length = 0;
> >>     else {
> >>       next = path[temp-cast(char*)path+1..length];
> >>       path = path[0..temp-cast(char*)path];
> >>     }
> >>
> >>
> >>
> >>     // If the exectuable is found, then this never returns.
> >>     // But if the executable is not found, then this returns
> >>     // some nonzero value.
> >>     ret = execve(path~"/"~file, argv, envp);
> >>
> >>
> >>
> >>     path = next;
> >>   }
> >>
> >>
> >>
> >>   return ret;
> >>}
>

Matthew wrote:

> No worries, mate. I just meant I'd steal the idea. I'm a pathological rewriter. ;)
> 
> Are you, or is anyone else, up for testing this on Linux? (I'm yet to set up D on my linux box, and I am woefully short on time. Of
> course, this probably means I shouldn't write any more multi-platform code before I do ...<G>)
>
> "Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg62sj$uof$1@digitaldaemon.com...
> 
>>I don't mind, but I can't guarantee it isn't buggy.  In particular, I
>>think that I should have added    ~\0    on the execve() call.  Right?
>>
>>Matthew wrote:
>>
>>> Russ, I'll take this as a basis for a permanent fix, if that's
>>> ok  with you? (I've some ideas for making it a bit
>>> neater, and we would only implement the D version, but
>>> essentially it's a  sound idea.)
>>>
>>>"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote:
>>>>kinghajj wrote:
>>>>>In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
>>>>>> I'm trying to use the execv function in std.process, but when the program links, it gives me an undefined
>>>>>> reference to `execvpe' message. This is using the latest
>>>>>> dmd on a linux system.
>>>>>
>>>>> I get that too. I don't know why: the prototype for execvpe
>>>>>  is in std.c.process (which std.process imports)... I even
>>>>> tried re-compiling the library, but it still failed.
>>>>
>>>> Phobos uses execvpe(), but it isn't implemented by glibc, at least on my system. execvpe() is just like execve(), except
>>>> that it searches through your $PATH to find the executable.
>>>> So I added this function to my program, which seemed to make
>>>> it work. Feel free to fix the code if you find any bugs:
>>>>
>>>>  // HACK HACK HACK
>>>> // phobos uses execvpe(), which is not implemented in glibc.
>>>> // This implementation provides what is missing.
>>>>
>>>>/* execvpe() - execve() with PATH search */


Wouldn't it be easier to do it as 'execvp() setting the environment'?

In C (sorry, I'm still more fluent in that):

extern char **environ;

int execvp(char *file_arg, char **argv, char **envp)
{
    char **old_env = environ;
    environ = envp;
    execvp(file_arg, argv);
    // Oops - must have failed!
    environ = old_env;
    return(-1);
}

FYI: environ is the one variable defined by POSIX with no standard header.

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler@earthlink.net, jleffler@us.ibm.com
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/

"Jonathan Leffler" <jleffler@earthlink.net> wrote in message news:cg6e21$146m$1@digitaldaemon.com...
> Matthew wrote:
>
> > No worries, mate. I just meant I'd steal the idea. I'm a pathological rewriter. ;)
> >
> > Are you, or is anyone else, up for testing this on Linux? (I'm yet to set up D on my linux box, and I am woefully short on time. Of course, this probably means I shouldn't write any more multi-platform code before I do ...<G>)
> >
> > "Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote in message news:cg62sj$uof$1@digitaldaemon.com...
> >
> >>I don't mind, but I can't guarantee it isn't buggy.  In particular, I think that I should have added    ~\0    on the execve() call.  Right?
> >>
> >>Matthew wrote:
> >>
> >>> Russ, I'll take this as a basis for a permanent fix, if that's
> >>> ok  with you? (I've some ideas for making it a bit
> >>> neater, and we would only implement the D version, but
> >>> essentially it's a  sound idea.)
> >>>
> >>>"Russ Lewis" <spamhole-2001-07-16@deming-os.org> wrote:
> >>>>kinghajj wrote:
> >>>>>In article <Pine.LNX.4.61.0408191703500.3453@debian>, Ameer Armaly says...
> >>>>>> I'm trying to use the execv function in std.process, but
> >>>>>> when the program links, it gives me an undefined
> >>>>>> reference to `execvpe' message. This is using the latest
> >>>>>> dmd on a linux system.
> >>>>>
> >>>>> I get that too. I don't know why: the prototype for execvpe
> >>>>>  is in std.c.process (which std.process imports)... I even
> >>>>> tried re-compiling the library, but it still failed.
> >>>>
> >>>> Phobos uses execvpe(), but it isn't implemented by glibc, at
> >>>> least on my system. execvpe() is just like execve(), except
> >>>> that it searches through your $PATH to find the executable.
> >>>> So I added this function to my program, which seemed to make
> >>>> it work. Feel free to fix the code if you find any bugs:
> >>>>
> >>>>  // HACK HACK HACK
> >>>> // phobos uses execvpe(), which is not implemented in glibc.
> >>>> // This implementation provides what is missing.
> >>>>
> >>>>/* execvpe() - execve() with PATH search */
>
>
> Wouldn't it be easier to do it as 'execvp() setting the environment'?
>
> In C (sorry, I'm still more fluent in that):
>
> extern char **environ;
>
> int execvp(char *file_arg, char **argv, char **envp)
> {
>      char **old_env = environ;
>      environ = envp;
>      execvp(file_arg, argv);
>      // Oops - must have failed!
>      environ = old_env;
>      return(-1);
> }
>
> FYI: environ is the one variable defined by POSIX with no standard header.

Indeed. But I don't think D supports that. (Of course, I could have provided execvpe() in C, but that'd have been more
hassle.) Nonetheless, it's worth keeping mind. Thanks