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/*++
/* NAME
/* exec_command 3
/* SUMMARY
/* execute command
/* SYNOPSIS
/* #include <exec_command.h>
/*
/* NORETURN exec_command(command)
/* const char *command;
/* DESCRIPTION
/* \fIexec_command\fR() replaces the current process by an instance
/* of \fIcommand\fR. This routine uses a simple heuristic to avoid
/* the overhead of running a command shell interpreter.
/* DIAGNOSTICS
/* This routine never returns. All errors are fatal.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <unistd.h>
#include <string.h>
#ifdef USE_PATHS_H
#include <paths.h>
#endif
#include <errno.h>
#include <string.h>
/* Utility library. */
#include <msg.h>
#include <argv.h>
#include <exec_command.h>
/* Application-specific. */
#define SPACE_TAB " \t"
/* exec_command - exec command */
NORETURN exec_command(const char *command)
{
ARGV *argv;
/*
* Character filter. In this particular case, we allow space and tab in
* addition to the regular character set.
*/
static char ok_chars[] = "1234567890!@%-_=+:,./\
abcdefghijklmnopqrstuvwxyz\
ABCDEFGHIJKLMNOPQRSTUVWXYZ" SPACE_TAB;
/*
* See if this command contains any shell magic characters.
*/
if (command[strspn(command, ok_chars)] == 0
&& command[strspn(command, SPACE_TAB)] != 0) {
/*
* No shell meta characters found, so we can try to avoid the overhead
* of running a shell. Just split the command on whitespace and exec
* the result directly.
*/
argv = argv_split(command, SPACE_TAB);
(void) execvp(argv->argv[0], argv->argv);
/*
* Auch. Perhaps they're using some shell built-in command.
*/
if (errno != ENOENT || strchr(argv->argv[0], '/') != 0)
msg_fatal("execvp %s: %m", argv->argv[0]);
/*
* Not really necessary, but...
*/
argv_free(argv);
}
/*
* Pass the command to a shell.
*/
(void) execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
msg_fatal("execl %s: %m", _PATH_BSHELL);
}
#ifdef TEST
/*
* Yet another proof-of-concept test program.
*/
#include <vstream.h>
#include <msg_vstream.h>
int main(int argc, char **argv)
{
msg_vstream_init(argv[0], VSTREAM_ERR);
if (argc != 2)
msg_fatal("usage: %s 'command'", argv[0]);
exec_command(argv[1]);
}
#endif
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