rev: new applet

text   data    bss    dec    hexfilename
    377      0      0    377    179rev.o

Signed-off-by: Marek Polacek <mmpolacek@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

util-linux/rev.c

@@ -0,0 +1,121 @@
+/*
+ * rev implementation for busybox
+ *
+ * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
+ *
+ * Licensed under GPLv2, see file License in this tarball for details.
+ */
+
+//applet:IF_REV(APPLET(rev, _BB_DIR_BIN, _BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_REV) += rev.o
+
+//config:config REV
+//config:	bool "rev"
+//config:	default y
+//config:	help
+//config:	  Reverse lines of a file or files.
+
+//usage:#define rev_trivial_usage
+//usage:	"[FILE]..."
+//usage:#define rev_full_usage "\n\n"
+//usage:	"Reverse lines of FILE"
+
+#include "libbb.h"
+#include "unicode.h"
+
+#undef CHAR_T
+#if ENABLE_UNICODE_SUPPORT
+# define CHAR_T wchar_t
+#else
+# define CHAR_T char
+#endif
+
+/* In-place invert */
+static void strrev(CHAR_T *s, int len)
+{
+	int i;
+
+	if (len != 0) {
+		len--;
+		if (len != 0 && s[len] == '\n')
+			len--;
+	}
+
+	for (i = 0; i < len; i++, len--) {
+		CHAR_T c = s[i];
+		s[i] = s[len];
+		s[len] = c;
+	}
+}
+
+int rev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int rev_main(int argc UNUSED_PARAM, char **argv)
+{
+	int retval;
+	size_t bufsize;
+	char *buf;
+
+	init_unicode();
+
+	getopt32(argv, "");
+	argv += optind;
+	if (!argv[0])
+		argv = (char **)&bb_argv_dash;
+
+	retval = EXIT_SUCCESS;
+	bufsize = 256;
+	buf = xmalloc(bufsize);
+	do {
+		size_t pos;
+		FILE *fp;
+
+		fp = fopen_or_warn_stdin(*argv++);
+		if (!fp) {
+			retval = EXIT_FAILURE;
+			continue;
+		}
+
+		pos = 0;
+		while (1) {
+			/* Read one line */
+			buf[bufsize - 1] = 1; /* not 0 */
+			if (!fgets(buf + pos, bufsize - pos, fp))
+				break; /* EOF/error */
+			if (buf[bufsize - 1] == '\0' /* fgets filled entire buffer */
+			 && buf[bufsize - 2] != '\n' /* and did not read '\n' */
+			 && !feof(fp)
+			) {
+				/* Line is too long, extend buffer */
+				pos = bufsize - 1;
+				bufsize += 64 + bufsize / 8;
+				buf = xrealloc(buf, bufsize);
+				continue;
+			}
+
+			/* Process and print it */
+#if ENABLE_UNICODE_SUPPORT
+			{
+				wchar_t *tmp = xmalloc(bufsize * sizeof(wchar_t));
+				/* Convert to wchar_t (might error out!) */
+				int len  = mbstowcs(tmp, buf, bufsize);
+				if (len >= 0) {
+					strrev(tmp, len);
+					/* Convert back to char */
+					wcstombs(buf, tmp, bufsize);
+				}
+				free(tmp);
+			}
+#else
+			strrev(buf, strlen(buf));
+#endif
+			fputs(buf, stdout);
+		}
+		fclose(fp);
+	} while (*argv);
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+		free(buf);
+
+	fflush_stdout_and_exit(retval);
+}