contrib, lib/, src/, tests/: Use stpcpy(3) instead of its pattern

Signed-off-by: Alejandro Colomar <alx@kernel.org>

contrib/adduser.c

@@ -491,12 +491,12 @@ safeget (char *buf, int maxlen)
       bad = (!isalnum (c) && (c != '_') && (c != ' '));
       *(buf++) = c;
     }
-  *buf = '\0';
+  stpcpy(buf, "");
 
   if (bad)
     {
       printf ("\nString contained banned character. Please stick to alphanumerics.\n");
-      *bstart = '\0';
+      stpcpy(bstart, "");
     }
 }
 

lib/commonio.c

@@ -197,7 +197,7 @@ static int do_lock_file (const char *file, const char *lock, bool log)
 		errno = EINVAL;
 		return 0;
 	}
-	buf[len] = '\0';
+	stpcpy(&buf[len], "");
 	if (get_pid(buf, &pid) == -1) {
 		if (log) {
 			(void) fprintf (shadow_logfd,
@@ -659,7 +659,7 @@ int commonio_open (struct commonio_db *db, int mode)
 				goto cleanup_buf;
 			}
 		}
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 
 		line = strdup (buf);
 		if (NULL == line) {

lib/console.c

@@ -76,7 +76,7 @@ static bool is_listed (const char *cfgin, const char *tty, bool def)
 	 */
 
 	while (fgets (buf, sizeof (buf), fp) != NULL) {
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 		if (strcmp (buf, tty) == 0) {
 			(void) fclose (fp);
 			return true;

lib/copydir.c

@@ -17,6 +17,7 @@
 #include <sys/time.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "alloc/malloc.h"
 #include "alloc/x/xmalloc.h"
@@ -563,7 +564,7 @@ static /*@null@*/char *readlink_malloc (const char *filename)
 
 		if ((size_t) nchars < size) { /* The buffer was large enough */
 			/* readlink does not nul-terminate */
-			buffer[nchars] = '\0';
+			stpcpy(&buffer[nchars], "");
 			return buffer;
 		}
 

lib/fields.c

@@ -84,7 +84,7 @@ void change_field (char *buf, size_t maxsize, const char *prompt)
 	if (NULL == cp) {
 		return;
 	}
-	*cp = '\0';
+	stpcpy(cp, "");
 
 	if ('\0' != newf[0]) {
 		/*
@@ -92,7 +92,7 @@ void change_field (char *buf, size_t maxsize, const char *prompt)
 		 * makes it possible to change the field to empty, by
 		 * entering a space.  --marekm
 		 */
-		*strrspn(newf, " \t\n") = '\0';
+		stpcpy(strrspn(newf, " \t\n"), "");
 
 		cp = newf;
 		while (isspace (*cp)) {

lib/fputsx.c

@@ -10,6 +10,8 @@
 #include <config.h>
 
 #include <stdio.h>
+#include <string.h>
+
 #include "defines.h"
 #include "prototypes.h"
 
@@ -33,10 +35,8 @@ fgetsx(/*@returned@*/char *restrict buf, int cnt, FILE *restrict f)
 		ep = strrchr (cp, '\\');
 		if ((NULL != ep) && (*(ep + 1) == '\n')) {
 			cnt -= ep - cp;
-			if (cnt > 0) {
-				cp = ep;
-				*cp = '\0';
-			}
+			if (cnt > 0)
+				cp = stpcpy(ep, "");
 		} else {
 			break;
 		}

lib/getdate.y

@@ -646,7 +646,7 @@ static int LookupWord (char *buff)
   else if (strlen (buff) == 4 && buff[3] == '.')
     {
       abbrev = true;
-      buff[3] = '\0';
+      stpcpy(&buff[3], "");
     }
   else
     abbrev = false;
@@ -689,7 +689,7 @@ static int LookupWord (char *buff)
   i = strlen (buff) - 1;
   if (buff[i] == 's')
     {
-      buff[i] = '\0';
+      stpcpy(&buff[i], "");
       for (tp = UnitsTable; tp->name; tp++)
 	if (strcmp (buff, tp->name) == 0)
 	  {
@@ -723,7 +723,7 @@ static int LookupWord (char *buff)
       *p++ = *q;
     else
       i++;
-  *p = '\0';
+  stpcpy(p, "");
   if (0 != i)
     for (tp = TimezoneTable; NULL != tp->name; tp++)
       if (strcmp (buff, tp->name) == 0)
@@ -772,7 +772,7 @@ yylex (void)
 	  for (p = buff; (c = *yyInput++, isalpha (c)) || c == '.';)
 	    if (p < &buff[sizeof buff - 1])
 	      *p++ = c;
-	  *p = '\0';
+          stpcpy(p, "");
 	  yyInput--;
 	  return LookupWord (buff);
 	}

lib/getdef.c

@@ -560,7 +560,7 @@ static void def_load (void)
 		/*
 		 * Trim trailing whitespace.
 		 */
-		*strrspn(buf, " \t\n") = '\0';
+		stpcpy(strrspn(buf, " \t\n"), "");
 
 		/*
 		 * Break the line into two fields.
@@ -573,9 +573,9 @@ static void def_load (void)
 		if (*s == '\0')
 			continue;	/* only 1 field?? */
 
-		*s++ = '\0';
+		stpcpy(s++, "");
 		value = stpspn(s, " \"\t");	/* next nonwhite */
-		*strchrnul(value, '"') = '\0';
+		stpcpy(strchrnul(value, '"'), "");
 
 		/*
 		 * Store the value in def_table.

lib/gshadow.c

@@ -91,7 +91,7 @@ void endsgent (void)
 	}
 
 	strcpy (sgrbuf, string);
-	*strchrnul(sgrbuf, '\n') = '\0';
+	stpcpy(strchrnul(sgrbuf, '\n'), "");
 
 	/*
 	 * There should be exactly 4 colon separated fields.  Find
@@ -172,7 +172,7 @@ void endsgent (void)
 				return NULL;
 			}
 		}
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 		return (sgetsgent (buf));
 	}
 	return NULL;
@@ -244,53 +244,36 @@ int putsgent (const struct sgrp *sgrp, FILE * fp)
 	/*
 	 * Copy the group name and passwd.
 	 */
-
-	strcpy (cp, sgrp->sg_name);
-	cp += strlen (cp);
-	*cp++ = ':';
-
-	strcpy (cp, sgrp->sg_passwd);
-	cp += strlen (cp);
-	*cp++ = ':';
+	cp = stpcpy(stpcpy(cp, sgrp->sg_name), ":");
+	cp = stpcpy(stpcpy(cp, sgrp->sg_passwd), ":");
 
 	/*
 	 * Copy the administrators, separating each from the other
 	 * with a ",".
 	 */
-
 	for (i = 0; NULL != sgrp->sg_adm[i]; i++) {
-		if (i > 0) {
-			*cp++ = ',';
-		}
+		if (i > 0)
+			cp = stpcpy(cp, ",");
 
-		strcpy (cp, sgrp->sg_adm[i]);
-		cp += strlen (cp);
+		cp = stpcpy(cp, sgrp->sg_adm[i]);
 	}
-	*cp = ':';
-	cp++;
+	cp = stpcpy(cp, ":");
 
 	/*
 	 * Now do likewise with the group members.
 	 */
-
 	for (i = 0; NULL != sgrp->sg_mem[i]; i++) {
-		if (i > 0) {
-			*cp = ',';
-			cp++;
-		}
+		if (i > 0)
+			cp = stpcpy(cp, ",");
 
-		strcpy (cp, sgrp->sg_mem[i]);
-		cp += strlen (cp);
+		cp = stpcpy(cp, sgrp->sg_mem[i]);
 	}
-	*cp = '\n';
-	cp++;
-	*cp = '\0';
+	stpcpy(cp, "\n");
 
 	/*
 	 * Output using the function which understands the line
 	 * continuation conventions.
 	 */
-
 	if (fputsx (buf, fp) == EOF) {
 		free (buf);
 		return -1;

lib/hushed.c

@@ -72,7 +72,7 @@ bool hushed (const char *username)
 		return false;
 	}
 	for (found = false; !found && (fgets (buf, sizeof buf, fp) == buf);) {
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 		found = (strcmp (buf, pw->pw_shell) == 0) ||
 		        (strcmp (buf, pw->pw_name) == 0);
 	}

lib/loginprompt.c

@@ -87,7 +87,7 @@ void login_prompt (char *name, int namesize)
 	if (NULL == cp) {
 		exit (EXIT_FAILURE);
 	}
-	*cp = '\0';		/* remove \n [ must be there ] */
+	stpcpy(cp, "");		/* remove \n [ must be there ] */
 
 	/*
 	 * Skip leading whitespace.  This makes "  username" work right.
@@ -98,7 +98,7 @@ void login_prompt (char *name, int namesize)
 
 	for (i = 0; i < namesize - 1 && *cp != '\0'; name[i++] = *cp++);
 
-	name[i] = '\0';
+	stpcpy(&name[i], "");
 
 	/*
 	 * Set the SIGQUIT handler back to its original value

lib/obscure.c

@@ -189,12 +189,10 @@ static /*@observer@*//*@null@*/const char *obscure_msg (
 
 	new1 = xstrdup (new);
 	old1 = xstrdup (old);
-	if (newlen > maxlen) {
-		new1[maxlen] = '\0';
-	}
-	if (oldlen > maxlen) {
-		old1[maxlen] = '\0';
-	}
+	if (newlen > maxlen)
+		stpcpy(&new1[maxlen], "");
+	if (oldlen > maxlen)
+		stpcpy(&old1[maxlen], "");
 
 	msg = password_check (old1, new1, pwdp);
 

lib/port.c

@@ -152,7 +152,7 @@ again:
 	 * TTY devices.
 	 */
 
-	*strchrnul(buf, '\n') = '\0';
+	stpcpy(strchrnul(buf, '\n'), "");
 
 	port.pt_names = ttys;
 	for (cp = buf, j = 0; j < PORT_TTY; j++) {
@@ -165,12 +165,10 @@ again:
 			break;
 		}
 
-		if (',' == *cp) {	/* end of current tty name */
-			*cp++ = '\0';
-		}
+		if (',' == *cp)		/* end of current tty name */
+			stpcpy(cp++, "");
 	}
-	*cp = '\0';
-	cp++;
+	stpcpy(cp++, "");
 	port.pt_names[j] = NULL;
 
 	/*
@@ -186,8 +184,7 @@ again:
 
 		for (j = 1; ':' != *cp; cp++) {
 			if ((',' == *cp) && (j < PORT_IDS)) {
-				*cp = '\0';
-				cp++;
+				stpcpy(cp++, "");
 				port.pt_users[j] = cp;
 				j++;
 			}
@@ -201,8 +198,7 @@ again:
 		goto again;
 	}
 
-	*cp = '\0';
-	cp++;
+	stpcpy(cp++, "");
 
 	/*
 	 * Get the list of valid times.  The times field is the third

lib/readpassphrase.c

@@ -141,7 +141,7 @@ restart:
 			*p++ = ch;
 		}
 	}
-	*p = '\0';
+	stpcpy(p, "");
 	save_errno = errno;
 	if (!(term.c_lflag & ECHO))
 		(void)write(output, "\n", 1);

lib/salt.c

@@ -291,6 +291,7 @@ static /*@observer@*/unsigned long YESCRYPT_get_salt_cost (/*@null@*/const int *
 static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost)
 {
 	const size_t buf_begin = strlen (buf);
+	char  *p;
 
 	/*
 	 * Check if the result buffer is long enough.
@@ -302,17 +303,17 @@ static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long co
 	 */
 	assert (GENSALT_SETTING_SIZE > buf_begin + 4);
 
-	buf[buf_begin + 0] = 'j';
+	p = &buf[buf_begin];
+	p = stpcpy(p, "j");
 	if (cost < 3) {
-		buf[buf_begin + 1] = 0x36 + cost;
+		*p++ = 0x36 + cost;
 	} else if (cost < 6) {
-		buf[buf_begin + 1] = 0x34 + cost;
+		*p++ = 0x34 + cost;
 	} else {
-		buf[buf_begin + 1] = 0x3b + cost;
+		*p++ = 0x3b + cost;
 	}
-	buf[buf_begin + 2] = cost >= 3 ? 'T' : '5';
-	buf[buf_begin + 3] = '$';
-	buf[buf_begin + 4] = '\0';
+	p = stpcpy(p, (cost >= 3) ? "T" : "5");
+	stpcpy(p, "$");
 }
 #endif /* USE_YESCRYPT */
 
@@ -330,7 +331,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
 		strcat (salt, l64a (csrand ()));
 	} while (strlen (salt) < salt_size);
 
-	salt[salt_size] = '\0';
+	stpcpy(&salt[salt_size], "");
 
 	return salt;
 }
@@ -421,7 +422,7 @@ static /*@observer@*/const char *gensalt (size_t salt_size)
 		salt_len = GENSALT_SETTING_SIZE - 1;
 		rounds = 0;
 		memset(result, '.', salt_len);
-		result[salt_len] = '\0';
+		stpcpy(&result[salt_len], "");
 	}
 
 	char *retval = crypt_gensalt (result, rounds, NULL, 0);

lib/setupenv.c

@@ -56,7 +56,7 @@ static void read_env_file (const char *filename)
 		if (NULL == cp) {
 			break;
 		}
-		*cp = '\0';
+		stpcpy(cp, "");
 
 		cp = buf;
 		/* ignore whitespace and comments */
@@ -78,8 +78,7 @@ static void read_env_file (const char *filename)
 			continue;
 		}
 		/* NUL-terminate the name */
-		*cp = '\0';
-		cp++;
+		stpcpy(cp++, "");
 		val = cp;
 #if 0				/* XXX untested, and needs rewrite with fewer goto's :-) */
 /*
@@ -112,7 +111,7 @@ static void read_env_file (const char *filename)
 			goto finished;
 		} else if (isspace (*cp)) {
 			/* unescaped whitespace - end of string */
-			*cp = '\0';
+			stpcpy(cp, "");
 			goto finished;
 		} else {
 			cp++;

lib/sgetgrent.c

@@ -83,7 +83,7 @@ struct group *sgetgrent (const char *buf)
 		}
 	}
 	strcpy (grpbuf, buf);
-	*strchrnul(grpbuf, '\n') = '\0';
+	stpcpy(strchrnul(grpbuf, '\n'), "");
 
 	for (cp = grpbuf, i = 0; (i < NFIELDS) && (NULL != cp); i++)
 		grpfields[i] = strsep(&cp, ":");

lib/sgetspent.c

@@ -54,7 +54,7 @@ sgetspent(const char *string)
 		return NULL;	/* fail if too long */
 	}
 	strcpy (spwbuf, string);
-	*strchrnul(spwbuf, '\n') = '\0';
+	stpcpy(strchrnul(spwbuf, '\n'), "");
 
 	/*
 	 * Tokenize the string into colon separated fields.  Allow up to

lib/shadow.c

@@ -77,7 +77,7 @@ static struct spwd *my_sgetspent (const char *string)
 	if (strlen (string) >= sizeof spwbuf)
 		return 0;
 	strcpy (spwbuf, string);
-	*strchrnul(spwbuf, '\n') = '\0';
+	stpcpy(strchrnul(spwbuf, '\n'), "");
 
 	/*
 	 * Tokenize the string into colon separated fields.  Allow up to
@@ -202,7 +202,7 @@ struct spwd *fgetspent (FILE * fp)
 
 	if (fgets (buf, sizeof buf, fp) != NULL)
 	{
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 		return my_sgetspent (buf);
 	}
 	return 0;

lib/sssd.c

@@ -24,7 +24,7 @@ int
 sssd_flush_cache(int dbflags)
 {
 	int          status, code, rv;
-	int          i = 0;
+	char         *p;
 	char         *sss_cache_args = NULL;
 	const char   *cmd = "/usr/sbin/sss_cache";
 	const char   *spawnedArgs[] = {"sss_cache", NULL, NULL};
@@ -40,15 +40,13 @@ sssd_flush_cache(int dbflags)
 	    return -1;
 	}
 
-	sss_cache_args[i++] = '-';
-	if (dbflags & SSSD_DB_PASSWD) {
-		sss_cache_args[i++] = 'U';
-	}
-	if (dbflags & SSSD_DB_GROUP) {
-		sss_cache_args[i++] = 'G';
-	}
-	sss_cache_args[i++] = '\0';
-	if (i == 2) {
+	p = stpcpy(sss_cache_args, "-");
+	if (dbflags & SSSD_DB_PASSWD)
+		stpcpy(p, "U");
+	if (dbflags & SSSD_DB_GROUP)
+		stpcpy(p, "G");
+
+	if (*p == '\0') {
 		/* Neither passwd nor group, nothing to do */
 		free(sss_cache_args);
 		return 0;

lib/tcbfuncs.c

@@ -135,13 +135,13 @@ static /*@null@*/ char *shadowtcb_path_rel_existing (const char *name)
 	}
 	free (path);
 	if ((size_t)ret >= sizeof(link) - 1) {
-		link[sizeof(link) - 1] = '\0';
+		stpcpy(&link[sizeof(link) - 1], "");
 		fprintf (shadow_logfd,
 		         _("%s: Suspiciously long symlink: %s\n"),
 		         shadow_progname, link);
 		return NULL;
 	}
-	link[ret] = '\0';
+	stpcpy(&link[ret], "");
 	rval = strdup (link);
 	if (NULL == rval) {
 		OUT_OF_MEMORY;
@@ -200,7 +200,7 @@ static shadowtcb_status mkdir_leading (const char *name, uid_t uid)
 		goto out_free_path;
 	}
 	while ((ind = strchr (ptr, '/'))) {
-		*ind = '\0';
+		stpcpy(ind, "");
 		if (asprintf (&dir, TCB_DIR "/%s", path) == -1) {
 			OUT_OF_MEMORY;
 			return SHADOWTCB_FAILURE;
@@ -266,7 +266,7 @@ static shadowtcb_status rmdir_leading (char *path)
 	char *ind, *dir;
 	shadowtcb_status ret = SHADOWTCB_SUCCESS;
 	while ((ind = strrchr (path, '/'))) {
-		*ind = '\0';
+		stpcpy(ind, "");
 		if (asprintf (&dir, TCB_DIR "/%s", path) == -1) {
 			OUT_OF_MEMORY;
 			return SHADOWTCB_FAILURE;

lib/ttytype.c

@@ -49,7 +49,7 @@ void ttytype (const char *line)
 			continue;
 		}
 
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 
 		if (   (sscanf (buf, "%1023s %1023s", type, port) == 2)
 		    && (strcmp (line, port) == 0)) {

lib/tz.c

@@ -42,7 +42,7 @@
 
 		strcpy (tzbuf, def_tz);
 	} else {
-		*strchrnul(tzbuf, '\n') = '\0';
+		stpcpy(strchrnul(tzbuf, '\n'), "");
 	}
 
 	if (NULL != fp) {

lib/utmp.c

@@ -20,6 +20,7 @@
 #include <sys/socket.h>
 #include <netdb.h>
 #include <stdio.h>
+#include <string.h>
 #include <fcntl.h>
 
 #include "alloc/x/xcalloc.h"
@@ -46,7 +47,7 @@ is_my_tty(const char tty[UTX_LINESIZE])
 	/* tmptty shall be bigger than full_tty */
 	static char  tmptty[sizeof(full_tty) + 1];
 
-	full_tty[0] = '\0';
+	stpcpy(full_tty, "");
 	if (tty[0] != '/')
 		strcpy (full_tty, "/dev/");
 	strncat(full_tty, tty, UTX_LINESIZE);

src/chgpasswd.c

@@ -462,7 +462,7 @@ int main (int argc, char **argv)
 		line++;
 		cp = strrchr (buf, '\n');
 		if (NULL != cp) {
-			*cp = '\0';
+			stpcpy(cp, "");
 		} else {
 			fprintf (stderr, _("%s: line %d: line too long\n"),
 			         Prog, line);
@@ -482,7 +482,7 @@ int main (int argc, char **argv)
 		name = buf;
 		cp = strchr (name, ':');
 		if (NULL != cp) {
-			*cp = '\0';
+			stpcpy(cp, "");
 			cp++;
 		} else {
 			fprintf (stderr,

src/chpasswd.c

@@ -503,7 +503,7 @@ int main (int argc, char **argv)
 		line++;
 		cp = strrchr (buf, '\n');
 		if (NULL != cp) {
-			*cp = '\0';
+			stpcpy(cp, "");
 		} else {
 			if (feof (stdin) == 0) {
 
@@ -535,8 +535,7 @@ int main (int argc, char **argv)
 		name = buf;
 		cp = strchr (name, ':');
 		if (NULL != cp) {
-			*cp = '\0';
-			cp++;
+			stpcpy(cp++, "");
 		} else {
 			fprintf (stderr,
 			         _("%s: line %d: missing new password\n"),

src/groupadd.c

@@ -431,7 +431,7 @@ static void process_flags (int argc, char **argv)
 				exit (E_BAD_ARG);
 			}
 			/* terminate name, point to value */
-			*cp++ = '\0';
+			stpcpy(cp++, "");
 			if (putdef_str (optarg, cp, NULL) < 0) {
 				exit (E_BAD_ARG);
 			}

src/login_nopam.c

@@ -111,7 +111,7 @@ int login_access (const char *user, const char *from)
 			if (line[0] == '#') {
 				continue;	/* comment line */
 			}
-			*strrspn(line, " \t\n") = '\0';
+			stpcpy(strrspn(line, " \t\n"), "");
 			if (line[0] == '\0') {	/* skip blank lines */
 				continue;
 			}
@@ -182,7 +182,7 @@ static char *myhostname (void)
 
 	if (name[0] == '\0') {
 		gethostname (name, sizeof (name));
-		name[MAXHOSTNAMELEN] = '\0';
+		stpcpy(&name[MAXHOSTNAMELEN], "");
 	}
 	return (name);
 }
@@ -222,7 +222,7 @@ static bool user_match (const char *tok, const char *string)
 	 */
 	at = strchr (tok + 1, '@');
 	if (NULL != at) {	/* split user@host pattern */
-		*at = '\0';
+		stpcpy(at, "");
 		return (   user_match (tok, string)
 		        && from_match (at + 1, myhostname ()));
 #if HAVE_INNETGR

src/logoutd.c

@@ -200,11 +200,10 @@ main(int argc, char **argv)
 			}
 			/* child */
 
-			if (strncmp (ut->ut_line, "/dev/", 5) != 0) {
-				strcpy (tty_name, "/dev/");
-			} else {
-				tty_name[0] = '\0';
-			}
+			if (strncmp(ut->ut_line, "/dev/", 5) != 0)
+				strcpy(tty_name, "/dev/");
+			else
+				strcpy(tty_name, "");
 
 			STRNCAT(tty_name, ut->ut_line);
 #ifndef O_NOCTTY

src/newusers.c

@@ -1107,9 +1107,8 @@ int main (int argc, char **argv)
 				 Prog, line);
 			fail_exit (EXIT_FAILURE);
 		}
-		if (cp != NULL) {
-			*cp = '\0';
-		}
+		if (cp != NULL)
+			stpcpy(cp, "");
 
 		/*
 		 * Break the string into fields and screw around with them.

src/passwd.c

@@ -226,7 +226,7 @@ static int new_password (const struct passwd *pw)
 		erase_pass (clear);
 		strzero (cipher);
 	} else {
-		orig[0] = '\0';
+		strcpy(orig, "");
 	}
 
 	/*
@@ -514,9 +514,8 @@ static char *update_crypt_pw (char *cp)
 		}
 	}
 
-	if (dflg) {
-		*cp = '\0';
-	}
+	if (dflg)
+		strcpy(cp, "");
 
 	if (uflg && *cp == '!') {
 		if (cp[1] == '\0') {

src/suauth.c

@@ -81,7 +81,7 @@ int check_su_auth (const char *actual_id,
 			continue;
 		}
 
-		*strrspn(temp, " \t\n") = '\0';
+		stpcpy(strrspn(temp, " \t\n"), "");
 
 		posn = 0;
 		while (temp[posn] == ' ' || temp[posn] == '\t')

src/useradd.c

@@ -361,7 +361,7 @@ static void get_defaults (void)
 	 * values are used, everything else can be ignored.
 	 */
 	while (fgets (buf, sizeof buf, fp) == buf) {
-		*strchrnul(buf, '\n') = '\0';
+		stpcpy(strchrnul(buf, '\n'), "");
 
 		cp = strchr (buf, '=');
 		if (NULL == cp) {
@@ -605,7 +605,7 @@ static int set_defaults (void)
 	while (fgets (buf, sizeof buf, ifp) == buf) {
 		cp = strrchr (buf, '\n');
 		if (NULL != cp) {
-			*cp = '\0';
+			stpcpy(cp, "");
 		} else {
 			/* A line which does not end with \n is only valid
 			 * at the end of the file.
@@ -1358,8 +1358,7 @@ static void process_flags (int argc, char **argv)
 					exit (E_BAD_ARG);
 				}
 				/* terminate name, point to value */
-				*cp = '\0';
-				cp++;
+				stpcpy(cp++, "");
 				if (putdef_str (optarg, cp, NULL) < 0) {
 					exit (E_BAD_ARG);
 				}
@@ -2223,7 +2222,7 @@ static void create_home (void)
 	if (access (prefix_user_home, F_OK) == 0)
 		return;
 
-	path[0] = '\0';
+	strcpy(path, "");
 	bhome = strdup(prefix_user_home);
 	if (!bhome) {
 		fprintf(stderr,
@@ -2269,7 +2268,7 @@ static void create_home (void)
 					Prog, path);
 				fail_exit(E_HOMEDIR);
 			}
-			btrfs_check[strlen(path) - strlen(cp) - 1] = '\0';
+			stpcpy(&btrfs_check[strlen(path) - strlen(cp) - 1], "");
 			if (is_btrfs(btrfs_check) <= 0) {
 				fprintf(stderr,
 					_("%s: home directory \"%s\" must be mounted on BTRFS\n"),

tests/unit/test_chkname.c

@@ -139,10 +139,10 @@ test_is_valid_user_name_long(void **state)
 
 	memset(name, '_', max);
 
-	name[max] = '\0';
+	stpcpy(&name[max], "");
 	assert_true(false == is_valid_user_name(name));
 
-	name[max - 1] = '\0';
+	stpcpy(&name[max - 1], "");
 	assert_true(is_valid_user_name(name));
 
 	free(name);