libbb: introduce xmalloc_xopen_read_close and use where appropriate

instead of xmalloc_open_read_close.

function                                             old     new   delta
xmalloc_xopen_read_close                               -      34     +34
xmalloc_open_read_close                              163     171      +8
passwd_main                                         1070    1074      +4
rexecve                                              254     257      +3
handle_incoming_and_exit                            2657    2659      +2
parse_command                                       1509    1510      +1
buffer_fill_and_print                                 76      73      -3
evaltreenr                                           599     589     -10
evaltree                                             599     589     -10
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 5/3 up/down: 52/-23)             Total: 29 bytes

include/libbb.h

@@ -556,7 +556,10 @@ extern char *reads(int fd, char *buf, size_t count);
 extern char *xmalloc_reads(int fd, char *pfx, size_t *maxsz_p);
 extern ssize_t read_close(int fd, void *buf, size_t maxsz);
 extern ssize_t open_read_close(const char *filename, void *buf, size_t maxsz);
+/* Returns NULL if file can't be opened */
 extern void *xmalloc_open_read_close(const char *filename, size_t *maxsz_p);
+/* Never returns NULL */
+extern void *xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p);
 
 extern ssize_t safe_write(int fd, const void *buf, size_t count);
 // NB: will return short write on error, not -1,
@@ -568,9 +571,9 @@ extern void xwrite(int fd, const void *buf, size_t count);
 extern void xprint_and_close_file(FILE *file);
 /* Reads up to (and including) TERMINATING_STRING: */
 extern char *xmalloc_fgets_str(FILE *file, const char *terminating_string);
-/* Chops off TERMINATING_STRING: from the end: */
+/* Chops off TERMINATING_STRING from the end: */
 extern char *xmalloc_fgetline_str(FILE *file, const char *terminating_string);
-/* Reads up to (and including) "\n" or NUL byte */
+/* Reads up to (and including) "\n" or NUL byte: */
 extern char *xmalloc_fgets(FILE *file);
 /* Chops off '\n' from the end, unlike fgets: */
 extern char *xmalloc_fgetline(FILE *file);

libbb/read.c

@@ -212,7 +212,9 @@ void *xmalloc_open_read_close(const char *filename, size_t *sizep)
 	int fd;
 	off_t len;
 
-	fd = xopen(filename, O_RDONLY);
+	fd = open(filename, O_RDONLY);
+	if (fd < 0)
+		return NULL;
 	/* /proc/N/stat files report len 0 here */
 	/* In order to make such files readable, we add small const */
 	len = xlseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
@@ -229,3 +231,11 @@ void *xmalloc_open_read_close(const char *filename, size_t *sizep)
 		*sizep = size;
 	return buf;
 }
+
+void *xmalloc_xopen_read_close(const char *filename, size_t *sizep)
+{
+	void *buf = xmalloc_open_read_close(filename, sizep);
+	if (!buf)
+		bb_perror_msg_and_die("can't read '%s'", filename);
+	return buf;
+}

miscutils/chat.c

@@ -363,7 +363,7 @@ int chat_main(int argc ATTRIBUTE_UNUSED, char **argv)
 				if ('@' == *buf) {
 					// skip the @ and any following white-space
 					trim(++buf);
-					buf = loaded = xmalloc_open_read_close(buf, NULL);
+					buf = loaded = xmalloc_xopen_read_close(buf, NULL);
 				}
 
 				// expand escape sequences in command

printutils/lpd.c

@@ -160,7 +160,7 @@ int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[])
 			// (we exit 127 if helper cannot be executed)
 			var[1] = '\0';
 			// read and delete ctrlfile
-			q = xmalloc_open_read_close(filenames[0], NULL);
+			q = xmalloc_xopen_read_close(filenames[0], NULL);
 			unlink(filenames[0]);
 			// provide datafile name
 			// we can use leaky setenv since we are about to exec or exit

util-linux/readprofile.c

@@ -109,9 +109,9 @@ int readprofile_main(int argc ATTRIBUTE_UNUSED, char **argv)
 	 * Use an fd for the profiling buffer, to skip stdio overhead
 	 */
 	len = MAXINT(ssize_t);
-	buf = xmalloc_open_read_close(proFile, &len);
+	buf = xmalloc_xopen_read_close(proFile, &len);
 	if (!optNative) {
-		int entries = len/sizeof(*buf);
+		int entries = len / sizeof(*buf);
 		int big = 0, small = 0, i;
 		unsigned *p;