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/*BINFMTC: -DLIBDIR='"/usr/lib"' ilistcreate.c
Copy-on-write filesystem invocation.
GPL v2 or later
Copyright 2005-2009 Junichi Uekawa.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/wait.h>
#include "ilist.h"
const char* ilist_PRGNAME="cow-shell";
static const char* ilistpath="./.ilist";
/*
* remove ilist after use.
*/
static void ilist_deleter(const char* ilistfile)
{
if(fork()==0)
{
/* I am the child process */
pid_t parent_pid=getppid();
if (daemon(0,1) < 0)
{
perror("cow-shell daemon");
exit (-1);
}
while (kill(parent_pid,0) >= 0)
{
sleep(1);
}
if (unlink(ilistfile)==-1)
{
perror("cow-shell unlink .ilist");
exit(1);
}
exit(0);
}
}
/**
* Set environment variables.
*/
static void set_env_vars() {
char* buf;
// For sending down as environment variable, use a canonicalized version.
char* canonicalized_ilistpath=canonicalize_file_name(ilistpath);
setenv("COWDANCER_ILISTFILE",
canonicalized_ilistpath,1);
unsetenv("COWDANCER_IGNORE");
free(canonicalized_ilistpath);
asprintf(&buf, "%s%s%s",
getenv("LD_PRELOAD")?:"",
getenv("LD_PRELOAD")?" ":"",
getenv("COWDANCER_SO") ?: LIBDIR "/cowdancer/libcowdancer.so");
setenv("LD_PRELOAD", buf, 1);
free(buf);
}
/* give me a command-line to exec,
and I will cow-keep what's under this directory. */
int main(int ac, char** av)
{
struct stat st;
int cowdancer_reuse;
cowdancer_reuse=getenv("COWDANCER_REUSE") &&
!strcmp(getenv("COWDANCER_REUSE"),"yes") ;
if (cowdancer_reuse && !stat(ilistpath, &st))
{
/* if reuse flag is on and file already exists
do nothing */
}
else
{
if (unlink(ilistpath)==-1)
{
if (errno == ENOENT)
{
/* expected */
}
else
{
perror("cow-shell: unlink of .ilist failed");
return 1;
}
}
if(ilistcreate(ilistpath, NULL))
{
ilist_outofmemory(".ilist creation failed");
return 1;
}
}
set_env_vars();
if (!cowdancer_reuse)
{
/* if reuse flag is not on, remove the file */
ilist_deleter(ilistpath);
}
if (ac>1)
execvp(av[1], av+1);
else
{
const char* myshell=getenv("SHELL")?:"/bin/sh";
fprintf(stderr, "Invoking %s\n", myshell);
execlp(myshell,
myshell,
NULL);
perror("cow-shell: exec");
fprintf(stderr, "Falling back to /bin/sh\n");
execlp("/bin/sh",
"/bin/sh",
NULL);
}
perror("cow-shell: exec");
return 1;
}
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