Hello, it seems to me that the popen() does not work correctly in applications running on hosts without "/bin/sh" available.
The Cygwin's popen() should normally work in a way that after vfork(), the
execl("/bin/sh"...) is tried first and if it fails, the execlp("sh"...) is tried to
find "sh" on PATH. (see source in newlib/libc/posix.c/popen.c, or code lines bellow).
A problem is that the execlp() gets never called because unsuccessful execl() causes
vfork-ed child process to exit. Workaround is to use fork() instead of vfork() but
this is perhaps too expensive.
Does anybody face similar problem ?
Is there any workaround if I want/need to use the built-in popen()?
Many Thanks,
Michal
Just for clarification, this is the sequence in newlib/libc/posix.c/popen.c:
....
execl(_PATH_BSHELL, "sh", "-c", program, NULL);
#ifdef __CYGWIN__
/* On cygwin32, we may not have /bin/sh. In that
case, try to find sh on PATH. */
execlp("sh", "sh", "-c", program, NULL);
#endif
....
Attached there are two example files. The file "fails.c" shows application which fails
to spawn simple "pwd" when /bin/sh is not on path. The file "works.c" shows the
private popen2() workaround using fork().
fails.c
Description: Binary data
works.c
Description: Binary data
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