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/* $OpenBSD: cmd_exec.c,v 1.13 2023/09/04 11:35:11 espie Exp $ */
/*
* Copyright (c) 2001 Marc Espie.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OPENBSD
* PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "defines.h"
#include "cmd_exec.h"
#include "buf.h"
#include "memory.h"
#include "pathnames.h"
#include "job.h"
#include "str.h"
/* The following array is used to make a fast determination of which
* characters are interpreted specially by the shell. If a command
* contains any of these characters, it is executed by the shell, not
* directly by us. */
static char meta[256];
void
CmdExec_Init(void)
{
char *p;
for (p = "#=|^(){};&<>*?[]:$`\\\n~"; *p != '\0'; p++)
meta[(unsigned char) *p] = 1;
/* The null character serves as a sentinel in the string. */
meta[0] = 1;
}
static char **
recheck_command_for_shell(char **av)
{
char *runsh[] = {
"!", "alias", "cd", "eval", "exit", "read", "set", "ulimit",
"unalias", "unset", "wait", "umask", NULL
};
char **p;
/* optimization: if exec cmd, we avoid the intermediate shell */
if (strcmp(av[0], "exec") == 0)
av++;
if (!av[0])
return NULL;
for (p = runsh; *p; p++)
if (strcmp(av[0], *p) == 0)
return NULL;
return av;
}
void
run_command(const char *cmd, bool errCheck)
{
const char *p;
char *shargv[4];
char **todo;
shargv[0] = _PATH_BSHELL;
shargv[1] = errCheck ? "-ec" : "-c";
shargv[2] = (char *)cmd;
shargv[3] = NULL;
todo = shargv;
/* Search for meta characters in the command. If there are no meta
* characters, there's no need to execute a shell to execute the
* command. */
for (p = cmd; !meta[(unsigned char)*p]; p++)
continue;
if (*p == '\0') {
char *bp;
char **av;
int argc;
/* No meta-characters, so probably no need to exec a shell.
* Break the command into words to form an argument vector
* we can execute. */
av = brk_string(cmd, &argc, &bp);
av = recheck_command_for_shell(av);
if (av != NULL)
todo = av;
}
execvp(todo[0], todo);
if (errno == ENOENT)
fprintf(stderr, "%s: not found\n", todo[0]);
else
perror(todo[0]);
_exit(1);
}
char *
Cmd_Exec(const char *cmd, char **err)
{
int fds[2]; /* Pipe streams */
pid_t cpid; /* Child PID */
char *result; /* Result */
int status; /* Command exit status */
BUFFER buf; /* Buffer to store the result. */
char *cp; /* Pointer into result. */
ssize_t cc; /* Characters read from pipe. */
size_t length; /* Total length of result. */
*err = NULL;
/* Open a pipe for retrieving shell's output. */
if (pipe(fds) == -1) {
*err = "Couldn't create pipe for \"%s\"";
goto bad;
}
/* Fork */
switch (cpid = fork()) {
case 0:
reset_signal_mask();
/* Close input side of pipe */
(void)close(fds[0]);
/* Duplicate the output stream to the shell's output, then
* shut the extra thing down. Note we don't fetch the error
* stream: user can use redirection to grab it as this goes
* through /bin/sh.
*/
if (fds[1] != 1) {
(void)dup2(fds[1], 1);
(void)close(fds[1]);
}
run_command(cmd, false);
/*NOTREACHED*/
case -1:
*err = "Couldn't exec \"%s\"";
goto bad;
default:
/* No need for the writing half. */
(void)close(fds[1]);
Buf_Init(&buf, MAKE_BSIZE);
do {
char grab[BUFSIZ];
cc = read(fds[0], grab, sizeof(grab));
if (cc > 0)
Buf_AddChars(&buf, cc, grab);
} while (cc > 0 || (cc == -1 && errno == EINTR));
/* Close the input side of the pipe. */
(void)close(fds[0]);
/* Wait for the child to exit. */
while (waitpid(cpid, &status, 0) == -1 && errno == EINTR)
continue;
if (cc == -1)
*err = "Couldn't read shell's output for \"%s\"";
if (status)
*err = "\"%s\" returned non-zero status";
length = Buf_Size(&buf);
result = Buf_Retrieve(&buf);
/* The result is null terminated, Convert newlines to spaces. */
cp = result + length - 1;
if (cp >= result && *cp == '\n')
/* A final newline is just stripped. */
*cp-- = '\0';
while (cp >= result) {
if (*cp == '\n')
*cp = ' ';
cp--;
}
break;
}
return result;
bad:
return estrdup("");
}
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