execshell/execshell.c at master · sysvinit/execshell · GitHub

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/* see LICENSE file for license details */

#include<sys/types.h>
#include<sys/wait.h>

#include<err.h>
#include<errno.h>
#include<signal.h>
#include<spawn.h>
#include<stdlib.h>
#include<unistd.h>

#include<skalibs/env.h>
#include<skalibs/stralloc.h>
#include<execline/execline.h>

#defineUTF8

#include"linenoise/linenoise.h"
#ifdefUTF8
#include"linenoise/encodings/utf8.h"
#endif

#defineEXECSHELL_FLAGVAR "EXECSHELL_RUNNING"
#defineEXECSHELL_EXIT 112
#defineEXECSHELL_BUILTIN "self"

staticvoid*xmalloc(size_tsz) {
void*ret;

ret=malloc(sz);
if (ret==NULL) {
err(1, "could not malloc");
 }

returnret;
}

staticvoidsignal_setup() {
for (inti=1; i<NSIG; i++) {
if (i!=SIGKILL&&i!=SIGSTOP&&i!=SIGSEGV) {
signal(i, (i==SIGCHLD ? SIG_DFL : SIG_IGN));
 }
 }
}

staticvoidsignal_unsetup() {
for (inti=1; i<NSIG; i++) {
if (i!=SIGKILL&&i!=SIGSTOP&&i!=SIGSEGV) {
signal(i, SIG_DFL);
 }
 }
}

intmain(intargc, char*argv[]) {
intret, wstatus, estatus;
pid_tpid, pret;
char*buffer, **pargs, **eargs;
strallocsa=STRALLOC_ZERO;

 (void) argc;

if (getenv(EXECSHELL_FLAGVAR) ==NULL) {
/* parent process */
signal_setup();

while ((pid=fork()) >0) {
if (waitpid(pid, &wstatus, 0) ==-1) {
err(1, "parent could not wait on command runner");
 }

if (WIFEXITED(wstatus)) {
/* normal exit */
estatus=WEXITSTATUS(wstatus);

if (estatus==0||estatus==EXECSHELL_EXIT) {
/* clean exit or internal error */
exit(estatus);
 }
 } else {
/* it didn't exit normally, so something must be up */
errx(1, "command runner process died with signal");
 }
 }

if (pid==-1) {
err(1, "parent process could not fork");
 }
 } else {
if (unsetenv(EXECSHELL_FLAGVAR) ==-1) {
warn("could not unset flag environment variable");
 }
 }

/* child process */
 (void) linenoiseHistorySetMaxLen(500);

#ifdefUTF8
/* set up unicode terminal handling bits */
linenoiseSetEncodingFunctions(linenoiseUtf8PrevCharLen,
linenoiseUtf8NextCharLen,
linenoiseUtf8ReadCode);
#endif

while (1) {
errno=0;
buffer=linenoise("> ");

if (buffer==NULL) {
if (errno==EAGAIN) {
continue;
 } elseif (errno!=0) {
err(EXECSHELL_EXIT, "could not read input");
 } else {
break;
 }
 }

 (void) linenoiseHistoryAdd(buffer);
ret=el_parse_from_string(&sa, buffer);

switch (ret) {
case-4:
warnx("unmatched }");
 goto mainloop_out;
case-3:
warnx("unmatched {");
 goto mainloop_out;
case-2:
warnx("syntax error");
 goto mainloop_out;
case-1:
warnx("unable to parse input");
 goto mainloop_out;
case0:
 goto mainloop_out;
 }

pargs= (char**) xmalloc(sizeof(char*) * (ret+2));
if (!env_make((constchar**) pargs, ret, sa.s, sa.len)) {
err(1, "could not env_make");
 }
pargs[ret] =0;

if (strcmp(pargs[0], EXECSHELL_BUILTIN) ==0) {
pargs[ret] =argv[0];
pargs[ret+1] =0;

eargs=pargs+1;
pid=0;

if (setenv(EXECSHELL_FLAGVAR, "1", 1) ==-1) {
err(1, "could not set flag environment variable");
 }
 } else {
eargs=pargs;
signal_setup();
pid=fork();
 }

if (pid==-1) {
err(1, "could not fork");
 } elseif (pid==0) {
signal_unsetup();

 (void) execvp(eargs[0], eargs);
err(1, "could not execvp: %s", eargs[0]);
 }

pret=waitpid(pid, NULL, 0);
if (pret==-1) {
warn("could not waitpid");
 }
signal_unsetup();

free(pargs);

mainloop_out:
stralloc_free(&sa);
free(buffer);
 }

return0;
}