Remove superfluous casts

-  Every non-const pointer converts automatically to void *.
-  Every pointer converts automatically to void *.
-  void * converts to any other pointer.
-  const void * converts to any other const pointer.
-  Integer variables convert to each other.

I changed the declaration of a few variables in order to allow removing
a cast.

However, I didn't attempt to edit casts inside comparisons, since they
are very delicate.  I also kept casts in variadic functions, since they
are necessary, and in allocation functions, because I have other plans
for them.

I also changed a few casts to int that are better as ptrdiff_t.

This change has triggered some warnings about const correctness issues,
which have also been fixed in this patch (see for example src/login.c).

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

lib/commonio.c

@@ -216,8 +216,8 @@ int do_fcntl_lock (const char *file, bool log, short type)
 	fd = open (file, O_WRONLY, 0600);
 	if (-1 == fd) {
 		if (log) {
-				(void) fprintf (shadow_logfd, "%s: %s: %s\n",
-				                shadow_progname, file, strerror (errno));
+			(void) fprintf (shadow_logfd, "%s: %s: %s\n",
+			                shadow_progname, file, strerror (errno));
 		}
 		return 0;
 	}
@@ -518,7 +518,7 @@ int commonio_open (struct commonio_db *db, int mode)
 		goto cleanup_ENOMEM;
 	}
 
-	while (db->ops->fgets (buf, (int) buflen, db->fp) == buf) {
+	while (db->ops->fgets (buf, buflen, db->fp) == buf) {
 		while (   ((cp = strrchr (buf, '\n')) == NULL)
 		       && (feof (db->fp) == 0)) {
 			size_t len;

lib/fields.c

@@ -74,7 +74,7 @@ void change_field (char *buf, size_t maxsize, const char *prompt)
 
 	printf ("\t%s [%s]: ", prompt, buf);
 	(void) fflush (stdout);
-	if (fgets (newf, (int) maxsize, stdin) != newf) {
+	if (fgets (newf, maxsize, stdin) != newf) {
 		return;
 	}
 

lib/get_gid.c

@@ -25,7 +25,7 @@ int get_gid (const char *gidstr, gid_t *gid)
 		return 0;
 	}
 
-	*gid = (gid_t)val;
+	*gid = val;
 	return 1;
 }
 

lib/get_pid.c

@@ -25,7 +25,7 @@ int get_pid (const char *pidstr, pid_t *pid)
 		return 0;
 	}
 
-	*pid = (pid_t)val;
+	*pid = val;
 	return 1;
 }
 

lib/get_uid.c

@@ -25,7 +25,7 @@ int get_uid (const char *uidstr, uid_t *uid)
 		return 0;
 	}
 
-	*uid = (uid_t)val;
+	*uid = val;
 	return 1;
 }
 

lib/getdef.c

@@ -13,6 +13,7 @@
 
 #include "prototypes.h"
 #include "defines.h"
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
@@ -191,7 +192,7 @@ static void def_load (void);
 	}
 
 	d = def_find (item);
-	return ((NULL == d)? (const char *) NULL : d->value);
+	return (NULL == d) ? NULL : d->value;
 }
 
 
@@ -249,7 +250,7 @@ int getdef_num (const char *item, int dflt)
 		return dflt;
 	}
 
-	return (int) val;
+	return val;
 }
 
 
@@ -284,7 +285,7 @@ unsigned int getdef_unum (const char *item, unsigned int dflt)
 		return dflt;
 	}
 
-	return (unsigned int) val;
+	return val;
 }
 
 
@@ -428,7 +429,7 @@ static /*@observer@*/ /*@null@*/struct itemdef *def_find (const char *name)
 	SYSLOG ((LOG_CRIT, "unknown configuration item `%s'", name));
 
 out:
-	return (struct itemdef *) NULL;
+	return NULL;
 }
 
 /*
@@ -540,12 +541,12 @@ static void def_load (void)
 	/*
 	 * Go through all of the lines in the file.
 	 */
-	while (fgets (buf, (int) sizeof (buf), fp) != NULL) {
+	while (fgets (buf, sizeof (buf), fp) != NULL) {
 
 		/*
 		 * Trim trailing whitespace.
 		 */
-		for (i = (int) strlen (buf) - 1; i >= 0; --i) {
+		for (i = (ptrdiff_t) strlen (buf) - 1; i >= 0; --i) {
 			if (!isspace (buf[i])) {
 				break;
 			}

lib/groupio.c

@@ -159,7 +159,7 @@ int gr_open (int mode)
 
 int gr_update (const struct group *gr)
 {
-	return commonio_update (&group_db, (const void *) gr);
+	return commonio_update (&group_db, gr);
 }
 
 int gr_remove (const char *name)
@@ -247,8 +247,8 @@ static int group_open_hook (void)
 
 	for (gr1 = group_db.head; NULL != gr1; gr1 = gr1->next) {
 		for (gr2 = gr1->next; NULL != gr2; gr2 = gr2->next) {
-			struct group *g1 = (struct group *)gr1->eptr;
-			struct group *g2 = (struct group *)gr2->eptr;
+			struct group *g1 = gr1->eptr;
+			struct group *g2 = gr2->eptr;
 			if (NULL != g1 &&
 			    NULL != g2 &&
 			    0 == strcmp (g1->gr_name, g2->gr_name) &&
@@ -302,8 +302,8 @@ static /*@null@*/struct commonio_entry *merge_group_entries (
 		return NULL;
 	}
 
-	gptr1 = (struct group *)gr1->eptr;
-	gptr2 = (struct group *)gr2->eptr;
+	gptr1 = gr1->eptr;
+	gptr2 = gr2->eptr;
 	if (NULL == gptr2 || NULL == gptr1) {
 		errno = EINVAL;
 		return NULL;
@@ -377,7 +377,7 @@ static int split_groups (unsigned int max_members)
 	struct commonio_entry *gr;
 
 	for (gr = group_db.head; NULL != gr; gr = gr->next) {
-		struct group *gptr = (struct group *)gr->eptr;
+		struct group *gptr = gr->eptr;
 		struct commonio_entry *new;
 		struct group *new_gptr;
 		unsigned int members = 0;
@@ -406,7 +406,7 @@ static int split_groups (unsigned int max_members)
 			errno = ENOMEM;
 			return 0;
 		}
-		new_gptr = (struct group *)new->eptr;
+		new_gptr = new->eptr;
 		new->line = NULL;
 		new->changed = true;
 

lib/gshadow.c

@@ -207,9 +207,9 @@ void endsgent (void)
 	}
 
 #ifdef	USE_NIS
-	while (fgetsx (buf, (int) buflen, fp) == buf)
+	while (fgetsx (buf, buflen, fp) == buf)
 #else
-	if (fgetsx (buf, (int) buflen, fp) == buf)
+	if (fgetsx (buf, buflen, fp) == buf)
 #endif
 	{
 		while (   ((cp = strrchr (buf, '\n')) == NULL)

lib/port.c

@@ -134,7 +134,7 @@ static struct port *getportent (void)
 	 * Lines which begin with '#' are all ignored.
 	 */
 
-	if (fgets (buf, (int) sizeof buf, ports) == 0) {
+	if (fgets (buf, sizeof buf, ports) == 0) {
 		errno = saveerr;
 		return 0;
 	}

lib/pwio.c

@@ -137,7 +137,7 @@ int pw_open (int mode)
 
 int pw_update (const struct passwd *pw)
 {
-	return commonio_update (&passwd_db, (const void *) pw);
+	return commonio_update (&passwd_db, pw);
 }
 
 int pw_remove (const char *name)

lib/sgroupio.c

@@ -253,7 +253,7 @@ int sgr_open (int mode)
 
 int sgr_update (const struct sgrp *sg)
 {
-	return commonio_update (&gshadow_db, (const void *) sg);
+	return commonio_update (&gshadow_db, sg);
 }
 
 int sgr_remove (const char *name)

lib/shadow.c

@@ -336,9 +336,9 @@ struct spwd *fgetspent (FILE * fp)
 	}
 
 #ifdef	USE_NIS
-	while (fgets (buf, (int) sizeof buf, fp) != NULL)
+	while (fgets (buf, sizeof buf, fp) != NULL)
 #else
-	if (fgets (buf, (int) sizeof buf, fp) != NULL)
+	if (fgets (buf, sizeof buf, fp) != NULL)
 #endif
 	{
 		cp = strchr (buf, '\n');

lib/shadowio.c

@@ -164,7 +164,7 @@ int spw_open (int mode)
 
 int spw_update (const struct spwd *sp)
 {
-	return commonio_update (&shadow_db, (const void *) sp);
+	return commonio_update (&shadow_db, sp);
 }
 
 int spw_remove (const char *name)

lib/subordinateio.c

@@ -355,13 +355,14 @@ static int subordinate_range_cmp (const void *p1, const void *p2)
 {
 	struct subordinate_range *range1, *range2;
 
-	if ((*(struct commonio_entry **) p1)->eptr == NULL)
-		return 1;
-	if ((*(struct commonio_entry **) p2)->eptr == NULL)
-		return -1;
 
-	range1 = ((struct subordinate_range *) (*(struct commonio_entry **) p1)->eptr);
-	range2 = ((struct subordinate_range *) (*(struct commonio_entry **) p2)->eptr);
+	range1 = (*(struct commonio_entry **) p1)->eptr;
+	if (range1 == NULL)
+		return 1;
+
+	range2 = (*(struct commonio_entry **) p2)->eptr;
+	if (range2 == NULL)
+		return -1;
 
 	if (range1->start < range2->start)
 		return -1;

lib/tcbfuncs.c

@@ -141,7 +141,7 @@ static /*@null@*/ char *shadowtcb_path_rel_existing (const char *name)
 		         shadow_progname, link);
 		return NULL;
 	}
-	link[(size_t)ret] = '\0';
+	link[ret] = '\0';
 	rval = strdup (link);
 	if (NULL == rval) {
 		OUT_OF_MEMORY;