1 files changed, 115 insertions, 41 deletions

diff --git a/coreutils/cmp.c b/coreutils/cmp.c
index 07bf3be92..43dbc842f 100644
--- a/coreutils/cmp.c
+++ b/coreutils/cmp.c
@@ -20,59 +20,133 @@
  *
  */
 
+/* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GNU format for -l. */
+/* http://www.opengroup.org/onlinepubs/007904975/utilities/cmp.html */
+
+/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
+ *
+ * Original version majorly reworked for SUSv3 compliance, bug fixes, and
+ * size optimizations.  Changes include:
+ * 1) Now correctly distingusishes between errors and actual file differences.
+ * 2) Proper handling of '-' args.
+ * 3) Actual error checking of i/o.
+ * 4) Accept SUSv3 -l option.  Note that we use the slightly nicer gnu format
+ *    in the '-l' case.
+ */
+
 #include <stdio.h>
-#include <string.h>
-#include <errno.h>
 #include <stdlib.h>
-#include <getopt.h>
+#include <unistd.h>
 #include "busybox.h"
 
+static FILE *cmp_xfopen_input(const char *filename)
+{
+	FILE *fp;
+
+	if ((fp = bb_wfopen_input(filename)) != NULL) {
+		return fp;
+	}
+
+	exit(bb_default_error_retval);	/* We already output an error message. */
+}
+
+static const char fmt_eof[] = "cmp: EOF on %s\n";
+static const char fmt_differ[] = "%s %s differ: char %d, line %d\n";
+#if 0
+static const char fmt_l_opt[] = "%.0s%.0s%d %o %o\n";	/* SUSv3 format */
+#else
+static const char fmt_l_opt[] = "%.0s%.0s%d %3o %3o\n";	/* nicer gnu format */
+#endif
+
+static const char opt_chars[] = "sl";
+
+enum {
+	OPT_s = 1,
+	OPT_l = 2
+};
+
 int cmp_main(int argc, char **argv)
 {
-	FILE *fp1 = NULL, *fp2 = stdin;
-	char *filename1, *filename2 = "-";
-	int c, c1, c2, char_pos = 1, line_pos = 1, silent = FALSE;
-
-	while ((c = getopt(argc, argv, "s")) != EOF) {
-		switch (c) {
-			case 's':
-				silent = TRUE;
-				break;
-			default:
-				show_usage();
-		}
+	FILE *fp1, *fp2, *outfile = stdout;
+	const char *filename1, *filename2;
+	const char *fmt;
+	int c1, c2, char_pos, line_pos;
+	int opt_flags;
+	int exit_val = 0;
+
+	bb_default_error_retval = 2;	/* 1 is returned if files are different. */
+
+	opt_flags = bb_getopt_ulflags(argc, argv, opt_chars);
+
+	if ((opt_flags == 3) || (((unsigned int)(--argc - optind)) > 1)) {
+		bb_show_usage();
 	}
 
-	filename1 = argv[optind];
-	switch (argc - optind) {
-		case 2:
-			fp2 = xfopen(filename2 = argv[optind + 1], "r");
-		case 1:
-			fp1 = xfopen(filename1, "r");
-			break;
-		default:
-			show_usage();
+	fp1 = cmp_xfopen_input(filename1 = *(argv += optind));
+
+	filename2 = "-";
+	if (*++argv) {
+		filename2 = *argv;
 	}
+	fp2 = cmp_xfopen_input(filename2);
 
+	if (fp1 == fp2) {			/* Paranioa check... stdin == stdin? */
+		/* Note that we don't bother reading stdin.  Neither does gnu wc.
+		 * But perhaps we should, so that other apps down the chain don't
+		 * get the input.  Consider 'echo hello | (cmp - - && cat -)'.
+		 */
+		return 0;
+	}
+
+	fmt = fmt_differ;
+	if (opt_flags == OPT_l) {
+		fmt = fmt_l_opt;
+	}
+
+	char_pos = 0;
+	line_pos = 1;
 	do {
-		c1 = fgetc(fp1);
-		c2 = fgetc(fp2);
-		if (c1 != c2) {
-			if (silent)
-				return EXIT_FAILURE;
-			if (c1 == EOF)
-				printf("EOF on %s\n", filename1);
-			else if (c2 == EOF)
-				printf("EOF on %s\n", filename2);
-			else
-				printf("%s %s differ: char %d, line %d\n", filename1, filename2,
-						char_pos, line_pos);
-			return EXIT_FAILURE;
+		c1 = getc(fp1);
+		c2 = getc(fp2);
+		++char_pos;
+		if (c1 != c2) {			/* Remember -- a read error may have occurred. */
+			exit_val = 1;		/* But assume the files are different for now. */
+			if (c2 == EOF) {
+				/* We know that fp1 isn't at EOF or in an error state.  But to
+				 * save space below, things are setup to expect an EOF in fp1
+				 * if an EOF occurred.  So, swap things around.
+				 */
+				fp1 = fp2;
+				filename1 = filename2;
+				c1 = c2;
+			}
+			if (c1 == EOF) {
+				bb_xferror(fp1, filename1);
+				fmt = fmt_eof;	/* Well, no error, so it must really be EOF. */
+				outfile = stderr;
+				/* There may have been output to stdout (option -l), so
+				 * make sure we fflush before writing to stderr. */
+				bb_xfflush_stdout();
+			}
+			if (opt_flags != OPT_s) {
+				if (opt_flags == OPT_l) {
+					line_pos = c1;	/* line_pos is unused in the -l case. */
+				}
+				bb_fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
+				if (opt_flags) {	/* This must be -l since not -s. */
+					/* If we encountered and EOF, the while check will catch it. */
+					continue;
+				}
+			}
+			break;
+		}
+		if (c1 == '\n') {
+			++line_pos;
 		}
-		char_pos++;
-		if (c1 == '\n')
-			line_pos++;
 	} while (c1 != EOF);
 
-	return EXIT_SUCCESS;
+	bb_xferror(fp1, filename1);
+	bb_xferror(fp2, filename2);
+
+	bb_fflush_stdout_and_exit(exit_val);
 }