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nixpkgs/pkgs/tools/misc/execline/execlineb-wrapper.c
Profpatsch fc62890f2d execlineb: change execlineb wrapper to C script
Instead of using execlineb to define the execlineb wrapper, we replace
it by a little C wrapper.

This is mainly done because on non-Linux systems (i.e. mainly macOS),
it is impossible for a shebang interpreter to be itself a shebang
script.
It is, however, perfectly fine to have a chain that goes
shebang -> ELF -> shebang -> ELF -> …

Co-Authored-By: Laurent Bercot <ska-skaware@skarnet.org>
2019-10-19 15:49:39 +02:00

44 lines
1.2 KiB
C

#include <stdlib.h>
#include <string.h>
#include <skalibs/stralloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/strerr2.h>
#include <skalibs/env.h>
#define dienomem() strerr_diefu1sys(111, "stralloc_catb")
// macros from outside
/* const char* EXECLINEB_PATH; */
/* const char* EXECLINE_BIN_PATH; */
int main(int argc, char const* argv[], char const *const *envp)
{
PROG = "execlineb-wrapper";
char const* path = getenv("PATH");
stralloc path_modif = STRALLOC_ZERO;
// modify PATH if unset or EXECLINEB_BIN_PATH is not yet there
if ( !path || ! strstr(path, EXECLINE_BIN_PATH())) {
// prepend our execline path
if ( ! stralloc_cats(&path_modif, "PATH=")
|| ! stralloc_cats(&path_modif, EXECLINE_BIN_PATH()) ) dienomem();
// old path was not empty
if ( path && path[0] ) {
if ( ! stralloc_catb(&path_modif, ":", 1)
|| ! stralloc_cats(&path_modif, path) ) dienomem();
}
// append final \0
if ( ! stralloc_0(&path_modif) ) dienomem();
}
// exec into execlineb and append path_modif to the environment
xpathexec_r_name(
EXECLINEB_PATH(),
argv,
envp, env_len(envp),
path_modif.s, path_modif.len
);
}