6597729 RFE: Alternative ksh93 version of libc::wordexp() should use posix_spawn()

Contributed by Roland Mainz <roland.mainz@nrubsig.org>

1 files changed, 170 insertions, 107 deletions

diff --git a/usr/src/lib/libc/port/regex/wordexp.c b/usr/src/lib/libc/port/regex/wordexp.c
index 9c834b2b54..cbf9295fdb 100644
--- a/usr/src/lib/libc/port/regex/wordexp.c
+++ b/usr/src/lib/libc/port/regex/wordexp.c
@@ -40,11 +40,8 @@
  *
  * Copyright 1985, 1992 by Mortice Kern Systems Inc.  All rights reserved.
  * Modified by Roland Mainz <roland.mainz@nrubsig.org> to support ksh93.
- *
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #pragma	weak _wordexp = wordexp
 #pragma	weak _wordfree = wordfree
 
@@ -75,6 +72,12 @@
 #define	INITIAL	8		/* initial pathv allocation */
 #define	BUFSZ	256		/* allocation unit of the line buffer */
 
+/*
+ * Needs no locking if fetched only once.
+ * See getenv()/putenv()/setenv().
+ */
+extern	const char **_environ;
+
 /* Local prototypes */
 static int append(wordexp_t *, char *);
 
@@ -97,25 +100,37 @@ mystpcpy(char *s1, const char *s2)
 
 /*
  * Do word expansion.
- * We built a mini-script in |buff| which takes care of all details,
+ * We build a mini-script in |buff| which takes care of all details,
  * including stdin/stdout/stderr redirection, WRDE_NOCMD mode and
  * the word expansion itself.
  */
 int
 wordexp(const char *word, wordexp_t *wp, int flags)
 {
-	char *args[10];
+	const char *path = "/usr/bin/ksh93";
 	wordexp_t wptmp;
 	size_t si;
-	int i;
 	pid_t pid;
-	char *line, *eob, *cp;	/* word from shell */
+	char *line, *eob, *cp;		/* word from shell */
 	int rv = WRDE_ERRNO;
 	int status;
-	int pv[2];		/* pipe from shell stdout */
-	FILE *fp;		/* pipe read stream */
-	int serrno, tmpalloc;
+	int pv[2];			/* pipe from shell stdout */
+	FILE *fp;			/* pipe read stream */
+	int tmpalloc;
+	char *wd = NULL;
+	const char **env = NULL;
+	const char **envp;
+	const char *ev;
+	int n;
+	posix_spawnattr_t attr;
+	posix_spawn_file_actions_t fact;
+	int error;
 	int cancel_state;
+	size_t bufflen; /* Length of |buff| */
+	char *buff;
+	char *currbuffp; /* Current position of '\0' in |buff| */
+	char *args[10];
+	int i;
 
 	/*
 	 * Do absolute minimum necessary for the REUSE flag. Eventually
@@ -137,7 +152,7 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 	/*
 	 * Man page says:
 	 * 2. All of the calls must set WRDE_DOOFFS, or all must not
-	 * set it.
+	 *    set it.
 	 * Therefore, if it's not set, we_offs will always be reset.
 	 */
 	if ((flags & WRDE_DOOFFS) == 0)
@@ -145,14 +160,13 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 
 	/*
 	 * If we get APPEND|REUSE, how should we do?
-	 * We allocate the buffer anyway to avoid segfault.
+	 * allocating buffer anyway to avoid segfault.
 	 */
 	tmpalloc = 0;
 	if ((flags & WRDE_APPEND) == 0 || (flags & WRDE_REUSE)) {
 		wptmp.we_wordc = 0;
 		wptmp.we_wordn = wptmp.we_offs + INITIAL;
-		wptmp.we_wordv = (char **)malloc(
-		    sizeof (char *) * wptmp.we_wordn);
+		wptmp.we_wordv = malloc(sizeof (char *) * wptmp.we_wordn);
 		if (wptmp.we_wordv == NULL)
 			return (WRDE_NOSPACE);
 		wptmp.we_wordp = wptmp.we_wordv + wptmp.we_offs;
@@ -163,98 +177,139 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 
 	/*
 	 * The UNIX98 Posix conformance test suite requires
-	 * wordexp() to not be a cancellation point.
+	 * |wordexp()| to not be a cancellation point.
 	 */
 	(void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancel_state);
 
 	/*
-	 * Set up pipe from shell stdout to "fp" for us
+	 * Make sure PWD is in the environment.
 	 */
-	if (pipe(pv) < 0)
-		goto cleanup;
+	if ((envp = _environ) == NULL) {
+		/* can happen when processing a SunOS 4.x AOUT file */
+		ev = NULL;
+		n = 0;
+	} else {
+		for (n = 0; (ev = envp[n]) != NULL; n++) {
+			if (*ev == 'P' && strncmp(ev, "PWD=", 4) == 0)
+				break;
+		}
+	}
+	if (ev == NULL) {	/* PWD missing from the environment */
+		/* allocate a new environment */
+		if ((env = malloc((n + 2) * sizeof (char *))) == NULL ||
+		    (wd = malloc(PATH_MAX + 4)) == NULL)
+			goto cleanup;
+		for (i = 0; i < n; i++)
+			env[i] = envp[i];
+		(void) strcpy(wd, "PWD=");
+		if (getcwd(&wd[4], PATH_MAX) == NULL)
+			(void) strcpy(&wd[4], "/");
+		env[i] = wd;
+		env[i + 1] = NULL;
+		envp = env;
+	}
 
 	/*
-	 * Fork/exec shell
+	 * Calculate size of required buffer (which is size of the
+	 * input string (|word|) plus all string literals below;
+	 * this value MUST be adjusted each time the literals are
+	 * changed!!).
 	 */
+	bufflen = 165 + strlen(word);
+	buff = alloca(bufflen);
+	i = 0;
 
-	if ((pid = fork()) == -1) {
-		serrno = errno;
-		(void) close(pv[0]);
-		(void) close(pv[1]);
-		errno = serrno;
-		goto cleanup;
-	}
+	/* Start filling the buffer */
+	buff[0] = '\0';
+	currbuffp = buff;
 
-	if (pid == 0) {	 /* child */
+	if (flags & WRDE_UNDEF)
+		currbuffp = mystpcpy(currbuffp, "set -o nounset\n");
+	if ((flags & WRDE_SHOWERR) == 0) {
 		/*
-		 * Calculate size of required buffer (which is size of the
-		 * input string (|word|) plus all string literals below;
-		 * this value MUST be adjusted each time the literals are
-		 * changed!!!!).
+		 * The newline ('\n') is neccesary to make sure that
+		 * the redirection to /dev/null is already active in
+		 * the case the printf below contains a syntax
+		 * error...
 		 */
-		size_t bufflen = 124+strlen(word); /* Length of |buff| */
-		char *buff = alloca(bufflen);
-		char *currbuffp; /* Current position of '\0' in |buff| */
-		int i;
-		const char *path;
-
-		(void) dup2(pv[1], 1);
-		(void) close(pv[0]);
-		(void) close(pv[1]);
-
-		path = "/usr/bin/ksh93";
-		i = 0;
-
-		/* Start filling the buffer */
-		buff[0] = '\0';
-		currbuffp = buff;
-
-		if (flags & WRDE_UNDEF)
-			currbuffp = mystpcpy(currbuffp, "set -o nounset ; ");
-		if ((flags & WRDE_SHOWERR) == 0) {
-			/*
-			 * The newline ('\n') is neccesary to make sure that
-			 * the redirection to /dev/null is already active in
-			 * the case the printf below contains a syntax
-			 * error...
-			 */
-			currbuffp = mystpcpy(currbuffp, "exec 2>/dev/null\n");
-		}
-		/* Squish stdin */
-		currbuffp = mystpcpy(currbuffp, "exec 0</dev/null\n");
-
-		if (flags & WRDE_NOCMD) {
-			/*
-			 * Switch to restricted shell (rksh) mode here to
-			 * put the word expansion into a "cage" which
-			 * prevents users from executing external commands
-			 * (outside those listed by ${PATH} (which we set
-			 * explicitly to /usr/no/such/path/element/)).
-			 */
-			currbuffp = mystpcpy(currbuffp, "set -o restricted\n");
+		currbuffp = mystpcpy(currbuffp, "exec 2>/dev/null\n");
+	}
+	/* Squish stdin */
+	currbuffp = mystpcpy(currbuffp, "exec 0</dev/null\n");
 
-			(void) putenv("PATH=/usr/no/such/path/element/");
+	if (flags & WRDE_NOCMD) {
+		/*
+		 * Switch to restricted shell (rksh) mode here to
+		 * put the word expansion into a "cage" which
+		 * prevents users from executing external commands
+		 * (outside those listed by ${PATH} (which we set
+		 * explicitly to /usr/no/such/path/element/)).
+		 */
+		currbuffp = mystpcpy(currbuffp,
+		    "export PATH=/usr/no/such/path/element/ ; "
+		    "set -o restricted\n");
+	}
 
-		}
+	(void) snprintf(currbuffp, bufflen,
+	    "print -f '%%s\\000' -- %s", word);
 
-		(void) snprintf(currbuffp, bufflen,
-		    "print -f \"%%s\\000\" %s", word);
+	args[i++] = strrchr(path, '/') + 1;
+	args[i++] = "-c";
+	args[i++] = buff;
+	args[i++] = NULL;
 
-		args[i++] = strrchr(path, '/') + 1;
-		args[i++] = "-c";
-		args[i++] = buff;
-		args[i++] = NULL;
+	if ((error = posix_spawnattr_init(&attr)) != 0) {
+		errno = error;
+		goto cleanup;
+	}
+	if ((error = posix_spawn_file_actions_init(&fact)) != 0) {
+		(void) posix_spawnattr_destroy(&attr);
+		errno = error;
+		goto cleanup;
+	}
 
-		(void) execv(path, args);
-		_exit(127);
+	/*
+	 * Set up pipe from shell stdout to "fp" for us
+	 */
+	if (pipe(pv) < 0) {
+		error = errno;
+		(void) posix_spawnattr_destroy(&attr);
+		(void) posix_spawn_file_actions_destroy(&fact);
+		errno = error;
+		goto cleanup;
 	}
 
+	/*
+	 * Spawn shell
+	 */
+	error = posix_spawnattr_setflags(&attr,
+	    POSIX_SPAWN_NOSIGCHLD_NP | POSIX_SPAWN_WAITPID_NP);
+	if (error == 0)
+		error = posix_spawn_file_actions_adddup2(&fact, pv[1], 1);
+	if (error == 0 && pv[0] != 1)
+		error = posix_spawn_file_actions_addclose(&fact, pv[0]);
+	if (error == 0 && pv[1] != 1)
+		error = posix_spawn_file_actions_addclose(&fact, pv[1]);
+	if (error == 0 && !(flags & WRDE_SHOWERR))
+		error = posix_spawn_file_actions_addopen(&fact, 2,
+		    "/dev/null", O_WRONLY, 0);
+
+	if (error == 0)
+		error = posix_spawn(&pid, path, &fact, &attr,
+		    (char *const *)args, (char *const *)envp);
+	(void) posix_spawnattr_destroy(&attr);
+	(void) posix_spawn_file_actions_destroy(&fact);
 	(void) close(pv[1]);
+	if (error) {
+		(void) close(pv[0]);
+		errno = error;
+		goto cleanup;
+	}
 
 	if ((fp = fdopen(pv[0], "rF")) == NULL) {
-		serrno = errno;
+		error = errno;
 		(void) close(pv[0]);
-		errno = serrno;
+		errno = error;
 		goto wait_cleanup;
 	}
 
@@ -265,14 +320,16 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 	 */
 	cp = line = malloc(BUFSZ);
 	if (line == NULL) {
+		error = errno;
 		(void) fclose(fp);
-		rv = WRDE_NOSPACE;
+		errno = error;
 		goto wait_cleanup;
 	}
 	eob = line + BUFSZ;
 
 	rv = 0;
-	while ((i = getc(fp)) != EOF) {
+	flockfile(fp);
+	while ((i = getc_unlocked(fp)) != EOF) {
 		*cp++ = (char)i;
 		if (i == '\0') {
 			cp = line;
@@ -293,6 +350,7 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 			eob = cp + BUFSZ;
 		}
 	}
+	funlockfile(fp);
 
 	wptmp.we_wordp[wptmp.we_wordc] = NULL;
 
@@ -300,28 +358,37 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 	(void) fclose(fp);	/* kill shell if still writing */
 
 wait_cleanup:
-	if (waitpid(pid, &status, 0) == -1)
-		rv = WRDE_ERRNO;
-	else if (rv == 0)
+	while (waitpid(pid, &status, 0) == -1) {
+		if (errno != EINTR) {
+			if (rv == 0)
+				rv = WRDE_ERRNO;
+			break;
+		}
+	}
+	if (rv == 0)
 		rv = WEXITSTATUS(status); /* shell WRDE_* status */
 
 cleanup:
 	if (rv == 0)
 		*wp = wptmp;
-	else {
-		if (tmpalloc)
-			wordfree(&wptmp);
-	}
+	else if (tmpalloc)
+		wordfree(&wptmp);
 
+	if (env)
+		free(env);
+	if (wd)
+		free(wd);
 	/*
-	 * Map ksh errors to wordexp() errors
+	 * Map ksh93 errors to |wordexp()| errors
 	 */
-	if (rv == 4)
-		rv = WRDE_CMDSUB;
-	else if (rv == 5)
-		rv = WRDE_BADVAL;
-	else if (rv == 6)
-		rv = WRDE_SYNTAX;
+	switch (rv) {
+		case 1:
+			rv = WRDE_BADVAL;
+			break;
+		case 127:
+			rv = WRDE_BADCHAR;
+			break;
+	}
 
 	(void) pthread_setcancelstate(cancel_state, NULL);
 	return (rv);
@@ -332,12 +399,6 @@ cleanup:
 extern	int __xpg4;	/* defined in _xpg4.c; 0 if not xpg4-compiled program */
 
 /*
- * Needs no locking if fetched only once.
- * See getenv()/putenv()/setenv().
- */
-extern	const char **_environ;
-
-/*
  * Do word expansion.
  * We just pass our arguments to shell with -E option.  Note that the
  * underlying shell must recognize the -E option, and do the right thing
@@ -374,7 +435,7 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 	static const char *xpg4_path = "/usr/xpg4/bin/sh";
 
 	/*
-	 * Do absolute minimum neccessary for the REUSE flag. Eventually
+	 * Do absolute minimum necessary for the REUSE flag. Eventually
 	 * want to be able to actually avoid excessive malloc calls.
 	 */
 	if (flags & WRDE_REUSE)
@@ -535,7 +596,8 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 	eob = line + BUFSZ;
 
 	rv = 0;
-	while ((i = getc(fp)) != EOF) {
+	flockfile(fp);
+	while ((i = getc_unlocked(fp)) != EOF) {
 		*cp++ = (char)i;
 		if (i == '\0') {
 			cp = line;
@@ -556,6 +618,7 @@ wordexp(const char *word, wordexp_t *wp, int flags)
 			eob = cp + BUFSZ;
 		}
 	}
+	funlockfile(fp);
 
 	wptmp.we_wordp[wptmp.we_wordc] = NULL;