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/*
** 1998-09-18 - Maintain an instance of the 'file' external command as a child process, and
** feed it typing requests when necessary. We will only start 'file' ONCE per
** entire gentoo session (typically), thus amortizing its startup costs over
** a very (?) long time. The aim of all this is hopefully to make typing using
** the file rules cheaper.
** 2002-01-03 - It's a while later, the file command on your system might now have the -n
** option which causes it to flush its output, and enables this module to do
** it's thing in the way intended. Used by cmd_info.c.
*/
#include "gentoo.h"
#include <fcntl.h>
#include <ctype.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include "dialog.h"
#include "children.h"
#include "file.h"
/* ----------------------------------------------------------------------------------------- */
static struct {
gint file_in; /* Writing end of pipe connected to command's stdin. */
gint file_out; /* Reading end of pipe connected to command's stdout. */
} file_info = { -1, -1 };
/* ----------------------------------------------------------------------------------------- */
static void start_file(MainInfo *min, const gchar *cmd)
{
pid_t child;
gint fd_in[2], fd_out[2];
if(pipe(fd_in) != 0)
return;
if(pipe(fd_out) != 0)
{
close(fd_in[STDIN_FILENO]);
close(fd_in[STDOUT_FILENO]);
return;
}
child = fork();
if(child == 0) /* Now in child? */
{
guint bits = 0U;
if(close(STDIN_FILENO) == 0)
{
if(dup(fd_in[STDIN_FILENO]) == STDIN_FILENO)
bits |= (close(fd_in[STDOUT_FILENO]) == 0);
}
if(close(STDOUT_FILENO) == 0)
{
if(dup(fd_out[STDOUT_FILENO]) == STDOUT_FILENO)
bits |= (close(fd_out[STDIN_FILENO]) == 0) << 1;
}
if(bits == 3U)
execlp(cmd, cmd, "-n", "-f", "-", NULL);
fprintf(stderr, "FILE: execlp() of '%s' failed (code %d)\n", cmd, errno);
exit(EXIT_FAILURE);
}
else if(child > 0) /* In parent? */
{
chd_register(cmd, child, CGF_RUNINBG, FALSE);
file_info.file_in = fd_in[STDOUT_FILENO];
file_info.file_out = fd_out[STDIN_FILENO];
if(close(fd_in[STDIN_FILENO]) == 0)
{
if(close(fd_out[STDOUT_FILENO]) == 0)
{
if(fcntl(file_info.file_out, F_SETFL, O_NONBLOCK) == 0)
return;
}
}
}
close(fd_in[STDIN_FILENO]);
close(fd_in[STDOUT_FILENO]);
close(fd_out[STDIN_FILENO]);
close(fd_out[STDOUT_FILENO]);
dlg_dialog_async_new_error("Couldn't fork() to run\nthe 'file' command!");
}
/* ----------------------------------------------------------------------------------------- */
/* 1998-09-18 - Run 'file' on the supplied file name, and return a pointer to its result line.
** The returned string will be the result of 'file', minus the header and the
** trailing newline. The returned string is static, and only valid up until the
** next call to this function. If the execution fails, NULL is returned.
*/
const gchar * fle_file(MainInfo *min, const gchar *name)
{
if(file_info.file_in < 0)
start_file(min, "file");
if(file_info.file_in > 0) /* File command running? */
{
static gchar resp[PATH_MAX + 256];
gchar line[PATH_MAX + 32];
gint len, got;
fd_set fds_read;
struct timeval to;
len = g_snprintf(line, sizeof line, "%s\n", name);
if(write(file_info.file_in, line, len) != len)
{
perror("Write to pipe");
return NULL;
}
FD_ZERO(&fds_read);
FD_SET(file_info.file_out, &fds_read);
to.tv_sec = 1U;
to.tv_usec = 0U;
if((select(file_info.file_out + 1, &fds_read, NULL, NULL, &to)) > 0)
{
if(FD_ISSET(file_info.file_out, &fds_read))
{
errno = 0;
if((got = read(file_info.file_out, resp, sizeof resp - 1)) > 0)
{
const gchar *cp;
resp[got - 1] = '\0';
if((cp = strchr(resp, ':')) != NULL)
{
cp++;
while(*cp && isspace((guchar) *cp))
cp++;
return cp;
}
}
if(errno && errno != EAGAIN)
perror("Read from pipe");
}
}
else
perror("select");
}
return NULL;
}
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