pkgs/development/skaware-packages/execline/execlineb-wrapper.c

   1 /*
   2  * A wrapper around execlineb, which provides all execline
   3  * tools on execlineb’s PATH.
   4  * It is implemented as a C program, because on non-Linux,
   5  * nested shebang lines are not supported.
   6  */
   7
   8 #include <stdlib.h>
   9 #include <string.h>
  10
  11 #include <skalibs/stralloc.h>
  12 #include <skalibs/djbunix.h>
  13 #include <skalibs/strerr2.h>
  14 #include <skalibs/env.h>
  15 #include <skalibs/exec.h>
  16
  17 #define dienomem() strerr_diefu1sys(111, "stralloc_catb")
  18
  19 // macros from outside
  20 /* const char* EXECLINEB_PATH; */
  21 /* const char* EXECLINE_BIN_PATH; */
  22
  23 int main(int argc, char const* argv[], char const *const *envp)
  24 {
  25   PROG = "execlineb-wrapper";
  26
  27   char const* path = getenv("PATH");
  28   stralloc path_modif = STRALLOC_ZERO;
  29
  30   // modify PATH if unset or EXECLINEB_BIN_PATH is not yet there
  31   if ( !path || ! strstr(path, EXECLINE_BIN_PATH())) {
  32     // prepend our execline path
  33     if ( ! stralloc_cats(&path_modif, "PATH=")
  34          || ! stralloc_cats(&path_modif, EXECLINE_BIN_PATH()) ) dienomem();
  35     // old path was not empty
  36     if ( path && path[0] ) {
  37       if ( ! stralloc_catb(&path_modif, ":", 1)
  38            || ! stralloc_cats(&path_modif, path) ) dienomem();
  39     }
  40     // append final \0
  41     if ( ! stralloc_0(&path_modif) ) dienomem();
  42   }
  43
  44   // exec into execlineb and append path_modif to the environment
  45   xmexec_aem(
  46     EXECLINEB_PATH(),
  47     argv,
  48     envp,
  49     path_modif.s, path_modif.len
  50   );
  51 }