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/* ISC license. */
#include <unistd.h>
#include <sys/resource.h>
#include <skalibs/types.h>
#include <skalibs/strerr2.h>
#include <skalibs/env.h>
#include <skalibs/djbunix.h>
#define USAGE "fdreserve n prog..."
#define MAXFDS 1024
unsigned int doit (char *modif, unsigned int i, int fd)
{
unsigned int pos = 2 ;
modif[0] = 'F' ; modif[1] = 'D' ;
pos += uint_fmt(modif + pos, i) ;
modif[pos++] = '=' ;
pos += uint_fmt(modif + pos, (unsigned int)fd) ;
modif[pos++] = 0 ;
return pos ;
}
int main (int argc, char const *const *argv, char const *const *envp)
{
unsigned int n ;
PROG = "fdreserve" ;
if ((argc < 3) || !uint0_scan(argv[1], &n))
strerr_dieusage(100, USAGE) ;
{
struct rlimit lim ;
if (getrlimit(RLIMIT_NOFILE, &lim) < 0) strerr_diefu1sys(111, "getrlimit") ;
if (n > lim.rlim_cur) strerr_dief1x(100, "too many requested fds") ;
}
{
char modif[12 * n] ; /* enough for n times "FDaaaa=bbbb\0" */
unsigned int j = 0 ;
{
int fd[n >> 1][2] ;
unsigned int i = 0 ;
for (; i < (n>>1) ; i++)
if (pipe(fd[i]) < 0)
strerr_diefu1sys(111, "reserve fds") ;
if (n & 1)
{
int lastfd = open_read("/dev/null") ;
if (lastfd < 0)
strerr_diefu1sys(111, "reserve last fd") ;
fd_close(lastfd) ;
j += doit(modif + j, n-1, lastfd) ;
}
for (i = 0 ; i < (n>>1) ; i++)
{
fd_close(fd[i][0]) ;
fd_close(fd[i][1]) ;
j += doit(modif + j, i<<1, fd[i][0]) ;
j += doit(modif + j, (i<<1)|1, fd[i][1]) ;
}
}
xpathexec_r(argv+2, envp, env_len(envp), modif, j) ;
}
}
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